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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
<strong>STODAFOR</strong><br />
STORM DAMAGED FOREST:<br />
EFFICIENT AND SAFE HARVESTING AND LOG CONSERVATION<br />
METHODS<br />
STATE-OF-THE-ART-PAPER<br />
Version 2005.02.16<br />
Project Coordinator: CTBA, 10 avenue de Saint Mandé 75012 Paris, www.ctba.fr<br />
Project partners: FVA (D), KVL (DK), EMPA (CH), CBE (P), BFH (D), UPM (E), DLFRI (DK), TTI (I), AFOCEL (F), TUD (D), BRE (UK),<br />
FMRE (A), ICSTM (UK), UOP (UK), NISK (N)<br />
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Table of Contents<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
1 Basic principles ……………………………………………………………………………………………… 8<br />
1.1 Reasons for and goals of log conservation ……………………………………………………………….. 8<br />
1.2 Deterioration of stored logs ……………………………………………………………………………… 9<br />
1.2.1 General description of fungal stain, mould and decay and insect damage plus wood species<br />
susceptibility …………………………………………………………………………………… 9<br />
1.2.2 Importance of wood moisture content ……………………………………………………….… 9<br />
1.2.3 Goal of log conservation …………………………………………………………………….… 11<br />
1.2.4 Choice of conservation method ………………………………………………………………… 11<br />
1.2.5 References …………………………………………………………………………………….... 11<br />
1.3 General recommendations ……………………………………………………………………………… 11<br />
1.4 Choice of conservation method …………………………………………………………………………. 11<br />
1.4.1 Storm damage potential scale ………………………………………………………………… 11<br />
1.4.2 Short description of different types of storm damaged trees ………………………………..… 12<br />
1.4.3 Research needs ………………………………………………………………………………… 13<br />
1.4.4 References …………………………………………………………………………………..… 13<br />
2 General considerations ………………………………………………………………………………………. 16<br />
2.1 Economic aspects ………………………………………………………………………………………… 16<br />
2.1.1 General remarks ……………………………………………………………………………… 16<br />
2.1.2 Storage period ………………………………………………………………………………… 16<br />
2.1.3 Time management (organization and speed of work) ………………………………………… 16<br />
2.1.4 Storage site ……………………………………………………………………………………. 16<br />
2.1.5 Tree species …………………………………………………………………………………… 16<br />
2.1.6 Research needs ………………………………………………………………………………… 17<br />
2.1.7 References ………………………….………………………………………………………….. 17<br />
2.2 Regulations / Laws …………………………………………………………………………………….. 17<br />
- Austria ………………………………………………………………………………..……………….. 17<br />
- Germany ……………………………………………………………………………….……………… 17<br />
- Great Britain …………………………………………………………………………….…………….. 18<br />
- Denmark ………………………………………………………………………………….……………. 18<br />
- France …………………………………………………………………………………….……………. 18<br />
- Italy ……………………………………………………………………………………….……………. 18<br />
- Norway ………………………………………………………………………………………………… 19<br />
- Portugal ……………………………………………………………………………………………....… 19<br />
- Spain …………………………………………………………………………………………………… 20<br />
- Switzerland ………………………………………………………………………….…………………. 20<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
2.3 Environmental impacts …………………………………………………………………………………… 21<br />
2.3.1 General remarks …………………………………………………………...…………………… 21<br />
2.3.2 Water spraying with open water systems ……………………………………………………… 22<br />
2.3.3 Water spraying in recycling water systems …………………………………………………… 22<br />
2.3.4 Pond storage …………………………………………………………………………………… 22<br />
2.3.5 Ground water pollution ………………………………………………………………………… 23<br />
2.3.6 Insecticide application ………………………………………………………………………… 23<br />
2.3.7 References ……………………………………………………………………………………… 23<br />
2.4 Management/Operation/Health and Safety …………………………………………………………….. 24<br />
2.4.1 Management/Operation ………………….…………………………………………………… 24<br />
2.4.2 Health and Safety ……………………………………………………………………………… 24<br />
2.4.3 Research needs ………………………………………………………………………………… 24<br />
2.4.4 References ……………………………………………………………………………………… 25<br />
2.5 Process monitoring and wood quality ………………………………………………………………….. 25<br />
2.5.1 Process monitoring ……………………………………………………….……………………. 25<br />
2.5.2 Wood quality …………………………………………………………………………………… 25<br />
2.5.2.1 General remarks ………………………………………………………………..…….. 25<br />
2.5.2.2 Wood quality related to storm and log conservation …………………………..…….. 27<br />
2.5.3 Research needs ………………………………………………………………………………… 29<br />
2.5.4 References ……………………………………..……………………………………………… 29<br />
3 Conservation methods ………………………………………………………………………………………. 30<br />
3.1 In-situ storage ……………………………………………………………………………………………. 31<br />
3.1.1 Live-conservation of wind-thrown trees ……………………………………………………….. 31<br />
3.1.1.1 Principle/description …………………………………………………………………. 31<br />
3.1.1.2 Advantages, disadvantages, practical experience …………………………………… 31<br />
3.1.1.2.1 Advantages, disadvantages …………...……………………………… 31<br />
3.1.1.2.2 Practical experience …………………………………………………… 31<br />
- Beech …………………………………………………………… 31<br />
- Spruce ……….…………………………………………………… 33<br />
- Pine ……………………………………………………………… 34<br />
- Maritime Pine …………………………………………………… 34<br />
- Douglas fir ………………………………………………………… 34<br />
3.1.1.3 Recommendations …………………………………………………………………… 34<br />
3.1.1.4 Quality monitoring …………………………………………………………………… 35<br />
3.1.1.5 Environmental issues ………………………………………………………………… 35<br />
3.1.1.6 Costs ………………………………………………………………………………….. 35<br />
3.1.1.7 Research needs ……………………………………………………………………… 35<br />
3.1.1.8 References ……………………………………………………………………………. 35<br />
3.1.2 Drying by transpiration ……………………………………………………………………….. 36<br />
3.1.2.1 Principle/description …………………………………………………………………… 36<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
3.1.2.2 Advantages, disadvantages, practical experience ………………………………...…… 36<br />
3.1.2.3 Recommendations (application, time limits) ………………………………………….. 36<br />
3.1.2.4 Quality monitoring ……………………………………………………………………. 36<br />
3.1.2.5 Environmental issues ………………………………………………………………… 36<br />
3.1.2.6 Costs …………………………………………………………………………………… 36<br />
3.1.2.7 Research needs ………………………………………………………………………… 36<br />
3.1.2.8 References ………………………………………………………………………….… 37<br />
3.2 Wet storage …………………………………………………………………………………………….. 37<br />
3.2.1 Compact pile with water sprinkling (logs with bark) …………………………………………. 37<br />
3.2.1.1 Principle/description ………………………………………………………………...… 37<br />
3.2.1.2 Advantages, disadvantages, practical experience ……………………………………… 38<br />
3.2.1.2.1 Advantages, disadvantages ……………………………………………… 38<br />
3.2.1.2.2 Practical experience ……………………………………………………… 39<br />
- Maritime Pine ( Pinus pinaster) ……………………………………..… 40<br />
- Spruce and Fir (P i c e a a b i e s a n d A b i e s a l b a) ………………………… 40<br />
- Beech ( F a g u s s y l v a t i c a) ………………………………………………… 40<br />
- Oak (Q u e r c u s s p e c.) …………………………………………………… 41<br />
3.2.1.3 Recommendations (application, time limits) ………………………………………… 41<br />
- Water supply ……………………………………………………………………….. 42<br />
- Log storage/Basic requirements …………………………………………………..… 43<br />
- Equipment ……………………………………………………………………….…… 43<br />
3.2.1.4 Quality monitoring …………………………………………………………………..… 44<br />
- Log storage / some pieces of advice ………………………………………………… 44<br />
3.2.1.5 Environmental issues ……………………………………………………………….… 45<br />
- Interval water spraying ……………………………………………………………… 45<br />
- Water spraying in recycling water systems ………………………………………… 46<br />
- Groundwater pollution ……………………………………………………………… 46<br />
3.2.1.6 Costs …………………………………………………………………………………. 47<br />
- General remarks ……………………………………………………………………… 47<br />
- Preliminary investments …………………………………………………………… 47<br />
- Functioning costs …………………………………………………………………… 48<br />
- Costs following the period of conservation ………………………………………… 49<br />
3.2.1.7 Research needs ………………………………………………………………………… 49<br />
3.2.1.8 References …………………………………………………………………………… 49<br />
3.2.2 Ponding/Immersion in fresh water water (log with bark) ……………………………………… 51<br />
3.2.2.1 Principle/description ………………………………………………………………...… 51<br />
3.2.2.2 Advantages, disadvantages, practical experience ………………………………….… 51<br />
3.2.2.2.1 Advantages, disadvantages ……………………………………………… 51<br />
3.2.2.2.2 Practical experience ……………………………………………………… 51<br />
3.2.2.3 Recommendation ……………………………………………………………………… 52<br />
3.2.2.4 Quality monitoring ………….………………………………………………………… 52<br />
3.2.2.5 Environmental issues ………………………………………………………….……… 52<br />
3.2.2.6 Costs ……………………………………………………………………………..…… 53<br />
3.2.2.7 Research needs ………………………………………………………………………… 53<br />
3.2.2.8 References …………………………………………………………………………….. 53<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
3.3 Storage under drying conditions …………………………………………………………………………. 54<br />
3.3.1 Log pre-drying in covered cross-piles (logs without bark) …………………………………….. 54<br />
3.3.1.1 Principle/description ………………………………………………………………… 54<br />
3.3.1.2 Advantages, disadvantages, practical experience …………………………………… 54<br />
3.3.1.3 Recommendations …………………………………………………………………… 54<br />
3.3.1.4 Quality monitoring …………………………………………………………………… 54<br />
3.3.1.5 Environmental issues ………………………………………………………………… 54<br />
3.3.1.6 Costs …………………………………………………………………………………… 55<br />
3.3.1.7 Research needs ………………………………………………………………………… 55<br />
3.3.1.8 References …………………………………………………………………………..… 55<br />
3.3.2 Rapid pre-drying in open cross-piles (logs without bark) …………………………………….. 55<br />
3.3.2.1 Principle/description ………………………………………………………………… 55<br />
3.3.2.2 Advantages, disadvantages, practical experience …………………………………… 55<br />
3.3.2.2.1 Advantages ………………………………………………………… 56<br />
3.3.2.2.2 Disadvantages ……...………………………………………………… 56<br />
3.3.2.2.3 Practical experience ………………………………………………… 57<br />
3.3.2.3 Recommendations …………………………………………………………………… 57<br />
3.3.2.4 Quality monitoring …………………………………………………………………… 58<br />
3.3.2.5 Environmental issues ………………………………………………………………… 58<br />
3.3.2.6 Costs ………………………………………………………………………………… 58<br />
3.3.2.7 Research needs ……………………………………………………………..………… 58<br />
3.3.2.8 References …………………………………………………………………………… 58<br />
3.4 Storage under humid conditions ………………………………………………………………………… 59<br />
3.4.1 Compact pile (logs with/without bark) …………………………………………………………. 59<br />
3.4.1.1 Principle /description ………………………………………………………………… 59<br />
3.4.1.2 Advantages, disadvantages, practical experience …………………………………… 59<br />
3.4.1.2.1 Advantages, disadvantages ……………………………………..… 59<br />
3.4.1.2.2 Practical experience …...…………………………………………… 59<br />
- Maritime Pine ……………………………………………………… 59<br />
3.4.1.3 Recommendations ………….………………………………………………………… 60<br />
3.4.1.4 Quality monitoring …………………………………………………………………… 60<br />
3.4.1.5 Environmental issues ………………………………………………………………… 60<br />
3.4.1.6 Costs …………………………………………………………………………………… 60<br />
3.4.1.7 Research needs ………………………………………………………………………… 61<br />
3.4.1.8 References ………………………………………………………………………..…… 61<br />
3.4.2 Compact pile covered with plastic sheets (logs with bark/without bark) ……………………… 61<br />
3.4.2.1 Principle/description ………………………………………………………………… 61<br />
3.4.2.2 Advantages, disadvantages, practical experience ……………………………………. 61<br />
3.4.2.3 Recommendations …………………………………………………………………… 62<br />
3.4.2.4 Quality monitoring …………………………………………………………………… 62<br />
3.4.2.5 Environmental issues ………………………………………………………………… 62<br />
3.4.2.6 Costs ………………………………………………………………………………… 62<br />
3.4.2.7 Research needs ……………………………………………………………………… 62<br />
3.4.2.8 References ……………………………………………………………………….…… 62<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
3.5 “Special” methods ……………………………………………………………………………………….. 63<br />
3.5.1 Log conservation under oxygen exclusion, compact pile wrapped in plastic sheets (logs with bark)<br />
3.5.1.1 Principle/description ………………………………………………………………… 63<br />
3.5.1.2 Advantages, disadvantages, practical experience …………………………………… 64<br />
3.5.1.2.1 Advantages ………………………………………………………… 64<br />
3.5.1.2.2 Disadvantages ……………………………………………………… 64<br />
3.5.1.2.3 Practical experience ……………………………………………….. 65<br />
3.5.1.3 Recommendations …………………………………………………………………… 65<br />
3.5.1.4 Quality monitoring …………………………………………………………………… 65<br />
3.5.1.5 Environmental issues ………………………………………………………………… 65<br />
3.5.1.6 Costs ………………………………………………………………………………… 66<br />
3.5.1.7 Research needs ……………………………………………………………………… 66<br />
3.5.1.8 References …………………………………………………………………………… 66<br />
3.5.2 Compact pile covered with geo textile fabric (logs with bark) ………………………………. 67<br />
3.5.2.1 Principle/description ………………………………………………………………… 67<br />
3.5.2.2 Advantages, disadvantages, practical experience …………………………………… 67<br />
3.5.2.3 Recommendations …………………………………………………………………… 67<br />
3.5.2.4 Quality monitoring …………………………………………………………………… 67<br />
3.5.2.5 Environmental issues ………………………………………………………………… 67<br />
3.5.2.6 Costs ………………………………………………………………………………… 67<br />
3.5.2.7 Research needs ……………………………………………………………………… 67<br />
3.5.2.8 References …………………………………………………………………………… 67<br />
3.5.3 Compact pile covered with a mineralic suspension …………………………………………… 67<br />
3.5.3.1 Principle/description …………………………………………………………….… 67<br />
3.5.3.2 Advantages, disadvantages, practical experience ……………………………….…… 68<br />
3.5.3.3 Recommendations ……………………………………………………………….…… 68<br />
3.5.3.4 Quality monitoring …………………………………………………………………… 68<br />
3.5.3.5 Environmental issues ………………………………………………………………… 68<br />
3.5.3.6 Costs …………………………………………………………………………………… 68<br />
3.5.3.7 Research needs ……………………………………………………………………….. 68<br />
3.5.3.8 References …………………………………………………………………………… 68<br />
3.5.4 Storage in gravel pits ………………………………………………………………………….. 69<br />
3.5.4.1 Principle/description ………………………………………………………………… 69<br />
3.5.4.2 Advantages, disadvantages, practical experience …………………………………… 69<br />
3.5.4.3 Recommendations …………………………………………………………………… 69<br />
3.5.4.4 Quality monitoring …………………………………………………………………… 69<br />
3.5.4.5 Environmental issues ………………………………………………………………… 69<br />
3.5.4.6 Costs ………………………………………………………………………………… 69<br />
3.5.4.7 Research needs ………………………………………………………………………… 69<br />
3.5.4.8 References …………………………………………………………………………… 69<br />
3.5.5 Storage in mines ……………………………………………………………………………….. 70<br />
3.5.5.1 Principle/description ………………………………………………………………… 70<br />
3.5.5.2 Advantages, disadvantages, practical experience …………………………………… 70<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
3.5.5.3 Recommendations …………………………………………………………………… 70<br />
3.5.5.4 Quality monitoring …………………………………………………………………… 70<br />
3.5.5.5 Environmental issues ………………………………………………………………… 70<br />
3.5.5.6 Costs ………………………………………………………………………………… 70<br />
3.5.5.7 Research needs ………………………………………………………………………… 70<br />
3.5.5.8 References …………………………………………………………………………… 70<br />
3.5.6 Compact pile above tree line (logs with bark) ………………………………………………….. 70<br />
3.5.6.1 Principle/description ………………………………………………………………… 70<br />
3.5.6.2 Advantages, disadvantages, practical experience …………………………………… 70<br />
3.5.6.3 Recommendations …………………………………………………………………… 71<br />
3.5.6.4 Quality monitoring …………………………………………………………………… 71<br />
3.5.6.5 Environmental issues ………………………………………………………………… 71<br />
3.5.6.6 Costs …………………………………………………………………………………… 71<br />
3.5.6.7 Research needs ………………………………………………………………………… 71<br />
3.5.6.8 References …………………………………………………………………………..… 71<br />
3.5.7 Storage in snow ………………………………………………………………………………… 71<br />
3.5.7.1 Principle/description …………………………………….…………………………… 71<br />
3.5.7.2 Advantages, disadvantages, practical experience ………….………………………… 72<br />
3.5.7.2.1 Advantages ………………………………………………………… 72<br />
3.5.7.2.2 Disadvantages ……………………………………………………… 72<br />
3.5.7.3 Recommendations ………………………………………….………………………… 73<br />
3.5.7.3.1 Temperature ………………………………………………………. 73<br />
3.5.7.3.2 Moisture content ………………………………………………….. 73<br />
3.5.7.3.3 Level of brightness ………………………………………………… 73<br />
3.5.7.3.4 Important factors, independent of the method …………………….. 74<br />
3.5.7.4 Quality monitoring …………………………………………………………………… 74<br />
3.5.7.5 Environmental issues ………………………………………………………………… 74<br />
3.5.7.6 Costs …………………………………………………………………………………… 74<br />
3.5.7.7 Research needs ………………………………………………………………………… 74<br />
3.5.7.8 References …………………………………………………………………………… 74<br />
3.5.8 Compact pile covered with organic material ………………………………………………….. 74<br />
3.5.8.1 Principle/description ………………………………………………………………… 74<br />
3.5.8.2 Advantages, disadvantages, practical experience ……………………………………… 74<br />
3.5.8.3 Recommendations ………………………………………………………………….… 75<br />
3.5.8.4 Quality monitoring ………………………………………………………………….… 75<br />
3.5.8.5 Environmental issues ………………………………………………………………… 75<br />
3.5.8.6 Costs ……………………………………………………………………………….… 76<br />
3.5.8.7 Research needs ……………………..………………………………………………… 76<br />
3.5.8.8 References ………………………………………………………………………….… 76<br />
3.6 Supplementary conservation measures …………………………………………………………………. 77<br />
3.6.1 Chemical wood protection ……………………………………………………………………… 77<br />
3.6.1.1 Principles/description ………………………………………………………………… 77<br />
- Log preparation …………………………………………………………………….. 77<br />
- Material …………………………………………………………………………….. 77<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- Methodology ……………………………………………………………………….. 77<br />
3.6.1.2 Precautions …………………………………………………………………………… 77<br />
3.6.2 Biological protection …………………………………………………………………………… 77<br />
3.6.2.1 Principles/description ………………………………………………………………… 77<br />
3.6.2.2 References …………………………………………………………………………… 77<br />
3.6.3 Physical protection ……………………………………………………………………………… 80<br />
End-sealing of hardwood logs ………………………………………………………………… 80<br />
Annex ………………………………………………………………………………………………………….. 81<br />
Terminology/Glossary ………………………………………………………………………………… 81<br />
1 Basic principles<br />
1.1 Reasons for and goals of log conservation<br />
By taking advantage of the machine-power available in today`s forestry, the salvaging of logs after storm damage<br />
could probably be carried out rather quickly. However, the large and sudden supply of raw material that subsequently<br />
becomes available may by far exceed the conversion and sales capabilities of the sawmilling industry, and the result<br />
could very well be a collapse of the round timber market. Eventually, a large proportion of the wood could be lost<br />
due to rot and insect infestation. Solutions such as storage of logs on site or in special storage yards should therefore<br />
be seriously considered in order to spread the supply of wood over a longer period of time and to avoid loss in value.<br />
During transportation out of the forest to the wood-processing enterprise the high-grade round timber is exposed to<br />
various dangers that contribute to a considerable loss in use value. In the following sections the causes of biotic and<br />
abiotic damage of round timber are demonstrated using selected examples. Advice for the proper handling of round<br />
timber during transportation is also provided.<br />
Depending on the length of time involved, log storage may be subdivided into two groups:<br />
a) Storage of round timber in the forest after tree harvesting (generally for a few days to a few weeks);<br />
b) Longer-term storage of round timber (subsequent to calamities, i.e. for a few months to several years).<br />
The risks associated with round timber storage are: formation of checks after drying or seasoning of the external log<br />
parts too close to fibre saturation point; discoloration; infestation with insects; destruction of the wood by infestation<br />
with fungi. These phenomena occur as a result of inappropriate storage and care of the timber. In general, this causes<br />
a partial reduction in the value of the wood. In extreme cases the round timber can be completely devalued.<br />
Depending on the duration of storage, a number of factors can contribute to a reduction in wood quality,<br />
necessitating various kinds of strategies for storage.<br />
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1.2 Deterioration of stored logs<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
1.2.1 General description of fungal stain, mould and decay and insect damage, plus wood species susceptibility<br />
Every year, forest sector industries worldwide lose millions of dollars when sap-staining fungi attack and discolour<br />
the sapwood of freshly felled timber. However, this damage is largely cosmetic, the strength of the wood is hardly<br />
impaired and decay is absent. Of all the conifer species, pines are the most susceptible to sap stain whilst species of<br />
spruce show some measure of resistance to infection. Three distinct groups of fungi are recognised as the cause<br />
of the problem.<br />
The first group, sometimes known as deep stainers, include the genera Ophiostoma, Ceratocystis and S p h a e r o p s i s ,<br />
which penetrate into the wood. Their pigmented hyphae grow in the tracheids and rays of the wood tissue producing<br />
a blue-black discolouration visible when affected logs are sawn. These fungi are commonly described as sapstain or<br />
bluestain fungi and are generally considered to be the most important and prolific of the three groups in softwoods.<br />
The second group comprises fungi which grow mainly on wood surfaces causing superficial staining and include<br />
black yeasts such as species of H o r m o n e m a , A u r e o b a s i d i u m , R h i n o c l a d i e l l a and P h i a l o p h o r a . These fungi are most<br />
frequently found after the initial stages of timber processing on timber and on debarked logs.<br />
Figure 1: Brown discoloration on spruce wood as a result of incorrect round wood<br />
storage (Source TUD)<br />
The third group also grow superficially, often on freshly felled timber,<br />
and discolour the wood by producing abundant pigmented spores.<br />
These are mainly mould fungi including Alternaria, Cladosporium,<br />
P e n i c i l l i u m and Trichoderma.<br />
Bark beetles (members of the family S c o l y t i d a e) spread the deepstaining<br />
fungi when they seek out breeding material in the form of<br />
weakened or felled trees during the summer. The females bore tunnels<br />
in the cambium and deposit their eggs. When the eggs hatch, the larvae create galleries below the bark and when<br />
mature, they pupate. Following the final metamorphosis, the adults bore their way through the bark and emerge via<br />
exit holes.<br />
Many staining fungi also gain access to wounds or cut log surfaces all the year round through rain-splash, the wind<br />
dispersal of infected fragments of wood and by casual dispersal by arthropods as they graze on fungal mycelia.<br />
However, the degree of infection is also dependent on the timber species, with marked differences occurring in<br />
susceptibility to sap stain. This may reflect qualitative and quantitative variation in the pre-formed anti-fungal<br />
constituents of conifer resin, which is known to differ between species.<br />
The ability of sapstain fungi to invade host cells may also be influenced by their ability to overcome cellular<br />
defences induced in living bark and wood following wounding and attack by pathogens. It has been stated that<br />
sapstain fungi range from truly pathogenic species, which invade healthy living trees, to those colonising weakened<br />
and stressed trees, to the saprotrophs found on dead timber. It has been shown for instance, that species of<br />
C e r a t o c y s t i s and Ophiostoma can respond very differently when introduced into living wood, reflecting their<br />
different pathogenic characteristics.<br />
1.2.2 Importance of wood moisture content<br />
It has been widely recognised that the moisture content of timber may play the most important role in determining<br />
the extent and diversity of fungal colonisation. Above fibre saturation point (approx. 20% moisture content) wood is<br />
vulnerable to infection and two forms of fungal decay are able to destroy the structure of wood cell walls leading to<br />
complete strength loss of the timber. White rot fungi are commonplace in the forest and the decay they produce<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
gives a familiar bleached appearance to the wood, particularly in hardwood species. These fungi produce enzymes<br />
capable of degrading all three of the major wood cell wall components: cellulose, hemicelluloses and lignin. Brown<br />
rot fungal attack causes the wood to become darker in appearance and only cellulose and hemicelluloses are<br />
destroyed; the lignin component is undamaged or slightly modified. Both types of decay are caused by<br />
basidiomycete fungi and the large reproductive fruit bodies which emerge from decaying wood bear an abundance<br />
of spores which are typically wind dispersed and germinate on exposed woody surfaces. White rot decay in<br />
hardwoods, notably in woodland situations, is also attributed to members of the higher ascomycetes. Like sapstain<br />
fungi, decay fungi exhibit a spectrum of invasive activity ranging from the truly pathogenic fungi, which attack<br />
standing trees, to the saprotrophic forms, which attack dead timber. The moisture content of the wood must not be<br />
too high, i.e. saturated and therefore oxygen depleted, or too low and therefore too dry, for these fungi to invade<br />
successfully.<br />
Drying of the wood beginning immediately after felling of the trees, causes the ratio of water content to air content in<br />
the cells to change. As a result, secondary pests such as fungi can infest the stored wood. For fresh wood with<br />
moisture contents of about 150% (coniferous woods) or 90% (broad-leaved species), based on oven-dried weight, the<br />
risk of secondary pests due to insufficient oxygen supply is low. At a wood moisture content below 100% or at about<br />
20% air volume in the wood, secondary pests enjoy good to ideal living conditions. The danger of an infestation<br />
with corresponding devaluation of the wood, is increased. . Below fibre saturation point (approx. 30% to 20% wood<br />
moisture) the risk of infestation with fungi decreases markedly due to lack of moisture (see Figure 2).<br />
Figure 2: Wood moisture content and its effect on the risk of the development of secondary pests<br />
(Wiebe 1990, modified)<br />
High or low wood moisture is therefore the best protection from fungal attack!<br />
Seasoning of round timber starts immediately after felling the tree by water evaporating form the log ends, and, on<br />
debarked logs, from the total stem surface. The rate of evaportaion depends on the number of log ends, so few<br />
resawing cuts should be made, and on the following conditions:<br />
- size of the debarked log surfaces;<br />
- the season of the felling and storage;<br />
- place of storage;<br />
- presence of live crown on the stem.<br />
The quality may deteriorate sequentially during the continuous drying process:<br />
- discoloration, followed by<br />
- infestation with fungi, followed by<br />
- attack by insects and finally<br />
- cracks.<br />
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1.2.3 Goal of log conservation<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Round wood storage aims at maintaining the properties of high-grade wood for the future buyer. In addition, round<br />
timber storage may ease problems for the timber market and stabilise wood prices.<br />
1.2.4 Choice of conservation method<br />
The choice of conservation method depends on the following factors:<br />
- kind of storm (see chapter 1.4, table 1)<br />
- kind of storm damaged trees (see chapter 1.4, table 2);<br />
- anticipated duration of storage (1 vegetation period up to several years);<br />
- availability of storage yards and their handling capacities;<br />
- staff and financial considerations;<br />
- legal aspects (see chapter 2.2);<br />
- industrial safety.<br />
1.2.5 References<br />
Wiebe, S. 1992: Untersuchungen zur Wundentwicklung und Wundbehandlung an Bäumen unter besonderer<br />
Berücksichtigung der Holzfeuchte. Inaugural-Dissertation, Fakultät für Forstwissenschaften, Ludwig-Maximilians-<br />
Universität München<br />
1.3 General recommendations<br />
In order to prevent loss of wood moisture, below 120% to 100% for coniferous trees and 80% for broad-leaved trees,<br />
round timber should not be debarked. Bark is regarded as the best packaging material for the logs and should only be<br />
removed if there is the risk of bark beetle infestation. Bark not only protects against moisture loss but also protects<br />
the wood from damage due to manipulation of the stem. Moreover, when assessing round timber quality, bark is also<br />
an indicator of local defects, i.e. wood characteristics.<br />
When storing the wood over a longer time period, two strategies may be pursued regarding moisture content of the<br />
wood:<br />
• allowing the wood moisture content to remain (or reach) as high as possible (above 100% or 80% related to<br />
oven-dry weight);<br />
• lowering the natural wood moisture to below fibre saturation point as fast as possible (about 20% of the<br />
wood moisture related to oven-dry weight).<br />
In Central Europe, the risk of log deterioration is highest from May to October for hardwood and from March to<br />
October for softwood<br />
1.4 Choice of conservation method<br />
1.4.1 Storm damage potential scale<br />
The following table gives a brief classification and description of storms and their devastation effects on single trees.<br />
To guarantee the comparatibility of future research work on storm damage of trees and forests this classification it is<br />
recommended that this classification is used to characterize particular storm events.<br />
Depending on the kind of stem damage caused by the storm, a distinction can be made between wind-throw, windbreakage<br />
or tilted stems hanging in the crowns of other trees. This is particularly the case for broad-leaved trees with<br />
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different types of crown damage (see Table 2 including the different types of storm damaged trees, Bues 2000). The<br />
following survey gives a short description of the types of damage and Table 2 shows the most suitable storage<br />
methods for storm damaged timber, depending on the respective type of damage. As storm damage, in general, leads<br />
to different patterns of damage on single trees and in stands, the forest worker can select the most suitable methods<br />
from a number of possibilities and organise conversion of the wind damaged timber, depending on the susceptibility<br />
of the respective wood species, their working capacities and the duration of storage.<br />
Table 1: Storm Damage-Potential Scale for woody plants, based on the Scaling after TORRO as adjusted to Middle Europe [TorDACH],<br />
Hubrig (2001)<br />
T0<br />
76 ± 14<br />
km/h<br />
T1<br />
104 ± 14<br />
km/h<br />
T2<br />
135 ± 16<br />
km/h<br />
T3<br />
167 ± 16<br />
km/h<br />
T4<br />
202 ± 18<br />
km/h<br />
T5<br />
238 ± 18<br />
km/h<br />
T6<br />
275 ± 20<br />
km/h<br />
T7<br />
315 ± 20<br />
km/h<br />
T9<br />
400 ±22<br />
km/h<br />
Incipient breaking off of single branches. Diseased (e.g. decayed trees) or particularly unstable trees (long thin stems, crown base<br />
higher up the stem, sparse system of shallow roots) may break or get uprooted (in the case of root rot and/or on unstable, wetted<br />
sites).<br />
Branches, even thick and healthy ones break to an increased extent, particularly during the growing season over which broadleaved<br />
trees are foliated. Diseased (e.g. decayed trees), or particularly unstable trees (long, thin stems, crown base higher up the<br />
stem, sparse system of shallow roots) often break or get uprooted. Trees with root damage/rot or on unstable, wetted sites are<br />
subject to wind-throw.<br />
Numerous branches, also thick and healthy ones break, in particular during the growing season when broad-leaved trees are<br />
foliated. Diseased (e.g. decayed trees), or unstable trees (long, thin stems, crown base higher up the stem, sparse system of<br />
shallow roots) are almost always broken or get uprooted. Trees with root damage/rot or on unstable wetted sites are almost<br />
always subject to complete wind-throw. Even lesser firmly rooted, healthy trees get uprooted if soils are water-soaked and<br />
wetted due to the weather at certain, not necessarily unstable sites (e.g. thick strata of loess-loams).<br />
Trees of less stable condition due to the specific species and varieties, e.g. broad-crowned lowland spruces are wind-thrown or<br />
break, while slim upland spruces or healthy oaks remain standing.<br />
Trees in forest stands which, due to the stand structure, have poor single tree stability (too narrow planting, lack of tending<br />
operations, in particular coniferous trees in monocultures) are often subject to wind-throw or breakage.<br />
During the period of sap flow trees with a firm rooting, but unstable stems, are often affected due to damage by pressure.<br />
Numerous branches, including thick and healthy ones break; even when broad-leaved trees are bare of foliage i.e. not during the<br />
growing season. Stable and healthy trees are also subject to wind-throw or breakage to a higher degree. During the time of sap<br />
flow, pressure damage occurs relatively often.<br />
Even stable trees/forest stands are almost always/completely wind-thrown or broken.<br />
Trees with large crowns, provided they are safely anchored by roots, are mostly broken. If trees remain standing at all, a larger<br />
number of branches, including the non-foliated ones, are torn off. The proportion of damage due to pressure is greatly reduced in<br />
favour of broken trees.<br />
Even the most stable trees or shrubs such as border trees, storm-proof hedges, bushes and field woods show almost 100%<br />
damage, either by uprooting, stem or crown breakage, or the tearing off of a large number of branches, including all twigs.<br />
No indigenous woody plants - if the stem remains standing - will survive such a storm without heavy damage.<br />
or T8 (356 ± 22 km/h), according to Fujita only beginning from F4 (334 B 422 km/h):<br />
Incipient debarking of the tree stems which remain standing, or parts of the trees (caused by debris such as sand and the like,<br />
flying around at high wind velocity).<br />
Total debarking of tree stems that remain standing, or of parts of the trees.<br />
1.4.2 Short description of different types of storm damaged trees<br />
Wind-thrown trees (coniferous trees or broad-leaved trees):<br />
- uprooted with little root contact with the moisture in the soil (1);<br />
- uprooted with good root contact with the moisture in the soil (2).<br />
Storm broken trees (coniferous trees or broad-leaved trees):<br />
- breakage near the stump (stems can be utilized as long poles without problems) (3);<br />
- breakage in 1/3 of the stem height (stem can only processed as short wood) (4).<br />
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Remark: Storm broken trees can show reduced wood moisture content due to pre-drying when left in the forest with<br />
the living crown over several days or weeks.<br />
Bent or leaning stems (coniferous trees or broad-leaved trees):<br />
- Only bent tree, root system not affected by storm (5);<br />
- Tree bent and root system slightly lifted, but still sufficient contact with soil moisture content (6);<br />
- Tilted tree hanging in the crown of a neighbouring tree, root system heavily damaged and insufficient root<br />
contact with soil moisture (7).<br />
Crown damages (mostly on broad-leaved trees):<br />
- Slight crown damage (single large branch missing) (8)<br />
- Heavy crown damage (more than half of the former crown is missing) (9)<br />
- Almost total loss of crown (10).<br />
1.4.3 Research needs<br />
- Deciding the appropriate conservation method for particular tree species.<br />
- Differences in suitability for storage between Spruce ( Picea abies) and Fir ( Abies alba).<br />
1.4.4 References<br />
Bues, C.T. 2000: Faserstauchungen in sturmgeschädigtem Fichtenholz. Holz-Zentralblatt 126 (Nr. 47/48): 647<br />
Hubrig, M. 2001: Tornado- und Downburstschadensskala für Holzgewächse, basierend auf der Skalierung nach<br />
TORRO angepaßt für Mitteleuropa (TorDACH). 2 nd Forum Kathastrophenvorsorge, Leipzig, 24/25 Sept. 2002:<br />
www: op.dlr.de<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Table 2: Most suitable options for log storage to maintain highest wood quality. Numbers 1 to 7 can be used for both soft- and hardwood speciesy. Numbers 1,3,4, and 7 are trees with little or no<br />
root contact. Numbers 8, 9 and 10 show additional damage to hardwoods<br />
Type of damage<br />
1<br />
2<br />
3<br />
4<br />
5<br />
6<br />
7<br />
Liveconservation<br />
-<br />
XX<br />
_<br />
_<br />
XX<br />
XX<br />
-<br />
In-situ storage<br />
Drying by<br />
transpiration<br />
X<br />
-<br />
X<br />
X<br />
-<br />
-<br />
X<br />
Compact pile<br />
with water<br />
sprinkling<br />
X*<br />
X<br />
X*<br />
-*<br />
X<br />
X<br />
X*<br />
Wet storage<br />
Ponding/<br />
immersion in<br />
fresh water<br />
X*<br />
X<br />
X*<br />
-*<br />
X<br />
X<br />
X*<br />
Most suitable options for log storage<br />
- 14 -<br />
Storage under drying conditions<br />
Log pre-drying<br />
in covered crosspiles<br />
X<br />
X<br />
X*<br />
X*<br />
X<br />
X<br />
X<br />
Rapid log pre-drying in<br />
open cross piles<br />
X<br />
X<br />
X<br />
X<br />
X<br />
X<br />
X<br />
Storage under humid conditions<br />
Compact piles<br />
-*<br />
X<br />
X*<br />
X*<br />
X<br />
X<br />
X*<br />
Compact piles<br />
covered with<br />
plastic sheets<br />
-*<br />
X<br />
X*<br />
-*<br />
X<br />
X<br />
X*<br />
Special methods<br />
Log conservation<br />
under oxygen<br />
exclusion<br />
-*<br />
X<br />
X*<br />
-<br />
X<br />
X<br />
X*
Type of damage<br />
8<br />
9<br />
10<br />
Liveconservation<br />
XX<br />
X<br />
-<br />
In-situ storage<br />
Drying by<br />
transpiration<br />
-<br />
-<br />
-<br />
Compact pile<br />
with water<br />
sprinkling<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Wet storage<br />
Ponding/<br />
immersion in<br />
fresh water<br />
Relevant notes: X possible option<br />
XX most preferable option<br />
- not recommended<br />
* time factor (moisture content) is relevant<br />
X<br />
X<br />
X*<br />
X<br />
X<br />
X*<br />
Most suitable options for log storage<br />
- 15 -<br />
Storage under drying conditions<br />
Log pre-drying<br />
in covered crosspiles<br />
-<br />
-<br />
-<br />
Rapid log pre-drying in<br />
open cross piles<br />
-<br />
-<br />
-<br />
Storage under humid conditions<br />
Compact piles<br />
X<br />
X*<br />
X*<br />
Compact piles<br />
covered with<br />
plastic sheets<br />
X<br />
X*<br />
X*<br />
Special methods<br />
Log conservation<br />
under oxygen<br />
exclusion<br />
X<br />
X<br />
X*
2 General considerations<br />
2.1 Economic aspects<br />
2.1.1 General remarks<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Different economic aspects must be considered. The primary goal is to maintain the monetary value of round wood<br />
by protecting its quality. Furthermore after a storm a marketing strategy must be organized in order to control the<br />
sale of round wood and to prevent the depreciation of its value. This situation demands the temporary storage of the<br />
wood.<br />
The benefits of maintaining the value of the wood and avoiding price reductions must be considered in relation to the<br />
cost of storing the wood. Capital costs may be very important because the total costs of logging and storage<br />
(including transport, equipment, maintenance etc.), as well as the value of the wood, may be tied up for a prolonged<br />
period of time, leading to a heavy financial burden.<br />
An important issue is the choice of the conservation method. The following points must be considered:<br />
2.1.2 Storage period<br />
Capital and maintenance costs are strongly influenced by the length of the planned storage period, depending on the<br />
conservation method used (e.g. dry storage up to 5 months or wet storage up to several years).<br />
2.1.3 Time management (organization and speed of work)<br />
It is important to maintain the value of the wood by correct handling of the logs during and after the logging<br />
operation (e.g. no unnecessary delay between cutting in the forest and the onset of water sprinkling at the storage<br />
site). There will often be a shortage of logging equipment following a storm. To meet the time limits of wood<br />
deterioration it may be necessary to use less-than-optimal equipment, thus increasing costs compared to normal<br />
operations.<br />
2.1.4 Storage site<br />
On-site storage (i.e. in the forest) is relatively cheap, whereas establishing a special storage site may lead to costs<br />
such as land rent, equipment, communication with the authorities, solving of environmental issues etc.<br />
2.1.5 Tree species<br />
Vulnerability to deterioration and the quality expectated by the end-user varies widely between different tree species.<br />
True heartwood species (e.g. Oaks) often have good keeping ability without the need to take any precautions,<br />
whereas sapwood species (e.g. Maple) require immediate action. Slight discoloration may be tolerable in some<br />
species (e.g. Spruce for structural use) but not for others (Pine for furniture or flooring). Depending on the special<br />
features of the species the best conservation strategy must be chosen.<br />
If the total wind-throw does not exceed the amount of timber that can be sold within a year, the most advantageous<br />
solution is normally to leave the trees untouched in the forest, as long as not too many are broken or severely<br />
damaged. Delimbing and further processing will then wait until just prior to industrial utilization. However, in order<br />
for this to be successful it is important that the roots have enough soil-contact to provide the crown with water. Also,<br />
the re-planting of the area must be considered, as invading grass and weeds may become cumbersome if the ground<br />
is left untouched for a whole growing season before planting.<br />
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For maintaining wood quality over longer periods of time, storage under sprinklers is believed to be the best solution.<br />
2.1.6 Research needs<br />
Impact of log conservation on the wood market (e.g. which and how much wood has to be stored).<br />
2.1.7 References<br />
Baur, P. et al. 2003: LOTHAR Ökonomische Auswirkungen des Sturms Lothar im Schweizer Wald, Teil I.<br />
Einkommens- und Vermögenswirkungen für die Waldwirtschaft und gesamtwirtschaftliche Beurteilung des Sturms.<br />
Umwelt-Materialien Nr. 157, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 190 p.<br />
Baur, P. et al. 2003: LOTHAR Ökonomische Auswirkungen des Sturms Lothar im Schweizer Wald, Teil II.<br />
Verteilung der Auswirkungen auf bäuerliche und öffentliche WaldeigentümerInnen: Ergebnisse einer Befragung.<br />
Umwelt-Materialien Nr. 158, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 204 p.<br />
Bärtschli, H. et al. 2003: LOTHAR Holzpreise und Holzvermarktung. Umwelt-Materialien Nr. 160, Bundesamt für<br />
Umwelt, Wald und Landschaft, Bern, Switzerland. 82 p.<br />
2.2 Regulations/Laws<br />
The regulations and laws will be presented in Table 3 a- j separately for each country. Regulations and laws are<br />
available for the following countries: Austria (Österreich), Germany (Deutschland), Great Britain, Denmark, France,<br />
Italy (Italia), Norway (Norge), Portugal, Spain (España), Switzerland (Schweiz).<br />
- Austria<br />
Area<br />
Laws/regulations<br />
Table 3 a - j: National regulations and laws<br />
Work Safety Forstgesetz (1975)<br />
Land- und forstwirtschaftliche Unfallverhütungsverordnung<br />
Land- und forstwirtschaftliche Dienstnehmerschutzverordnung<br />
NÖ Landarbeitsordnung 1973<br />
Steiermärkische land- und forstwirtschaftliche<br />
Dienstnehmerschutzverordnung<br />
Land- und forstwirtschaftliche Sicherheits- und Gesundheitsschutz-<br />
Verordnung<br />
Water discharge Wasserrechtsgesetz (1959)<br />
AEV Pflanzenschutzmittel<br />
Allgemeine Abwasseremissionsverordnung<br />
Transport Ein- und Durchfuhr von Nadelholz mit Rinde<br />
Kraftfahrgesetz Abschnitt II<br />
Straßenverkehrsordnung §42,45,61,71<br />
Water storage<br />
Sprinkling<br />
Wasserrechtsgesetz (1959)<br />
- 17 -<br />
Required approvals: authorities<br />
Bundesgesetz<br />
Landesgesetz (OÖ)<br />
Landesgesetz (Salzburg, Burgenland)<br />
Landesgesetz (Niederösterreich, Wien)<br />
Landesgesetz (Steiermark)<br />
Landesgesetz (Tirol)Forstgesetz (1975)<br />
Bundesgesetz<br />
Bundesgesetz<br />
Bundesgesetz<br />
BGBl.Nr. 536/1988<br />
BGBl.Nr. 267/1967 zuletzt geändert durch BGBl. I<br />
Nr. 60/2003<br />
BGBl.Nr. 159/1960 idgF<br />
Bundesgesetz<br />
Treatment Forstschutzverordnung BGBl. II Nr. 19/2003<br />
- Germany<br />
Area<br />
Laws/regulations<br />
Required approvals: authorities<br />
Water storage Wasserhaushaltsgesetz (WHG) Rahmengesetz des Bundes<br />
Wassergesetze der Länder Wasserwirtschaftsämter
Sprinkling<br />
Storage under<br />
drying conditions<br />
- Great Britain<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Verordnung über Pläne und Beilagen in wasserrechtlichen<br />
Verfahren (WPBV)<br />
Wasserhaushaltsgesetz (WHG)<br />
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Rahmengesetz des Bundes<br />
Wassergesetze der Länder Wasserwirtschaftsämter<br />
Abwasserabgabegesetz<br />
Baugenehmigung Landesbauordnung<br />
Area Laws/regulations Required approvals: authorities<br />
- Denmark<br />
Area Laws/regulations Required approvals: authorities<br />
Road transport Færdselsloven, LBK 712 af 02/082001 Excessive loads: Rigspolitichefgen<br />
Working safety Lov om arbejdsmiljø LBK 784 af 11/10/1999 Arbejdstilsynet<br />
Storage in general Lov om planlægning LBK 763 af 11/09/2002<br />
Amtskommunen<br />
Lov om naturbeskyttelse LBK 577 af 04/02/2002<br />
Skov- og Naturstyreisen<br />
Wet storage Lov om miljøbeskyttelse LBK 753 af 25/08/2001<br />
Lov om vandløb LBK 632 af 23/06/2001<br />
- France<br />
Area<br />
Laws/regulations<br />
Water storage - Installation du site :<br />
Arrêté relatif aux prescriptions générales applicables aux<br />
installations classées pour la protection de l’environnement<br />
soumises à déclaration sous la rubrique n°1531<br />
Use of chemical<br />
wood protection<br />
- Italy<br />
- Prélèvement dans un cours d’eau :<br />
Décret n°94-354<br />
- Collecte et analyse des rejets d’eau :<br />
Arrêté n°1531<br />
- Traitement insecticides des grumes :<br />
Info – Santé – Forêts, note technique n°1<br />
Amtskommunen<br />
Amtskommunen<br />
Required approvals: authorities<br />
- Service du préfet<br />
- Direction départementale de l’agriculture et de la<br />
forêt<br />
- Police de l’eau<br />
-<br />
- Inspection des installations classées<br />
- Département de la santé des forêts<br />
Area Laws/regulations Required approvals: authorities<br />
Work safety<br />
Transport<br />
D. Lgs. n. 277 del 15.08.1991 “Protezione dei lavoratori contro il<br />
rischio di esposizione ad agenti chimici, fisici e biologici”<br />
D. Lgs. n. 626 del 19.09.1994 “Linee guida sulia sicurezza nei<br />
luoghi di lavoro”<br />
Dlg. 30.04.1992 n. 285, articoli 10,61,62 del Codice della strada<br />
ASL<br />
ASL
- Norway<br />
Agreement between forest related employers and workers<br />
associations 2002 - 2004<br />
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4.4 Safety routines<br />
Transport regulations Norwegian Pollution Control Authority<br />
Road transport regulations Public Road Administration<br />
- Portugal<br />
Area<br />
Segurança no<br />
Trabalho<br />
Descarga de<br />
águas<br />
Armazenamento<br />
de águas<br />
paradas<br />
Laws/regulations<br />
Decreto-Lei n° 141/95 de 14 de Junho e<br />
Portaria n° 1456-A/95, de 11 de Dezembro<br />
Estebelece os sistemas e os principios de<br />
sinalização de segurança<br />
Define a posição e o uso de sinalização<br />
Decretos-Leis n os 26/94 de 1 de Fevereiro, 7/95<br />
de 29 de Março e 109/2000, de 30 de Junho<br />
Define os serviços de saúde, higiene e<br />
segurança no trabalho<br />
Estabelece as medidas de segurança, higiene e<br />
saúde no local de trabalho<br />
Decreto-Lei n° 349/93, de 1 de Outobro e<br />
Portaria n° 988/93, de 6 de Outobro<br />
Estabelece os equipamentos de protecção<br />
individual que poderão ser utilizados pelos<br />
trabalhadores<br />
Decreto-Lei n° 347/93, de 1 de Outobro e<br />
Portaria n° 987/93, de 6 de Outobro<br />
Estabelece a organização do trabalho e<br />
regulamentação geral do trabalho<br />
Decreto-Lei n° 330/93, de 23 de Setembro<br />
Estabelecimento de regas na movimentação<br />
manual de cargas<br />
Decreto-Lei n° 72/92, de 28 de Abril e Portaria<br />
n° 9/92, de 28 de Abril<br />
Estabelecimento de protecções correctas ao<br />
nivel do ruido, no local de trabalho<br />
Decreto-Lei n° 441/91, de 14 de Novembro<br />
Estebelecer o enquadramento da saúde, higiene<br />
e segurança no trabalho<br />
Portaria n° 429/99<br />
Estabelecimento do limite da descarga das<br />
águas residuais, nos leitos de água ou no solo.<br />
Decreto-Lei n° 236/98<br />
Estabelecimento de normas, critérios e<br />
objectivos para a protecção dos recursos<br />
hidricos e para melhorar a qualidade da água.<br />
(Este decreto revougou o decreto-lei n° 74/90<br />
de 7 de Março)<br />
Em Portugal não existe legislação especifica<br />
sobre este assunto<br />
Transporte Portaria n° 960/2000 de 9 de Outobro<br />
Altera a portaria n° 1029/97, no qual regula os<br />
limites de pesos e dimensões dos veículos<br />
Despacho n° 14339/2000 de 14 Julho<br />
Averbamento do peso bruto<br />
Required approvals: authorities<br />
Todas as portarias e os decretos de leis são válidos somente para<br />
Portugal<br />
A legislação é estabelecida pelo Ministério do Trabalho<br />
A legislação é estabelecida pelo:<br />
- Ministério de Economia;<br />
- Ministério da Saúde;<br />
- Ministério do Ambiente.<br />
Direcção-Geral da Viação (DGV), no qual é a instituição<br />
responsável por efectuar os regulamentos relacionadas com os<br />
veiculos e as suas cargas (www.dgv.pt)<br />
Esta legislação é estebelecada pela Direcção-Geral de Viação<br />
- 19 -
- Spain<br />
Area<br />
Decreto-Lei n° 72/2000 de 6 de Maio<br />
Aprova o regulamento da CE de modelo de<br />
automóveis e reboques, seus sistemas,<br />
componentes e unidades téchnicas<br />
Portaria n° 1092/97 de 3 Novembro<br />
Regulamenta os limites de peso e dimensção<br />
dos veículos. Revoga a portaria n° 850/94, de<br />
22 de Setembro<br />
Despacho da Dirrecção-Geral da Viação n°<br />
45/98 de 24 de Março<br />
O valor máximo da largura das caixas dos<br />
veículos<br />
Portaria n° 855/94 de 21 de Novembro<br />
Define os limites dimensionais dos veículos<br />
Portaria n° 855/94 de 23 Setembro<br />
Define as categorias da modelos da veiculos<br />
Regulations<br />
Work Ley 45/1999 de desplazamientos de<br />
trabajadores en el marco de una prestación de<br />
servicios transnacional<br />
Ley del estatuto de los trabajadores. R.D<br />
legislativo 1/1995<br />
Transport Ley 16/87 30-7 de Ordenación de transportes<br />
terrestres<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Organisms<br />
- Ministerio de Trabajo y Asuntos Sociales.<br />
Agustin de Bethencourt 4. Tf: 91 363 00 00<br />
http://www.mtas.es/<br />
- Dirección General de Transportes por carretera. Ministerio de<br />
Fomento.<br />
Paseo de la Castellana 67. Tf: 91 597 70 03<br />
http://www.mfom.es/<br />
Railroad Ley 39/2003 del sector ferroviario - Subdirección general de planes y proyectos de infraestructuras<br />
ferroviarias<br />
- Subdirección general de construcción de infraestructuras<br />
ferroviarias<br />
Plaza de Sagrados Corazones 7. 28071 Madrid.<br />
Tf: 91 597 70 00<br />
- RENFE<br />
Avda. Pio XII 110. Edificio Caracorlas (Chamartín). Madrid<br />
Tf: 91 733 91 62<br />
- FEVE<br />
C/General Rodrigo 6. 28003 Madrid.<br />
Tf: 91 453 38 00<br />
Ports Ley 27/1992 de puertos y de la marina mercante Dirección General de la Marina Mercante. Ministerio de Fomento.<br />
Paseo de la Castellana 67. Tf: 91 597 70 03<br />
http://www.mfom.es/<br />
Puertos del estado<br />
Avda. del Partenón 10. Campo de las naciones. 28071 Madrid<br />
Tf: 91 524 55 00<br />
Health and<br />
safety<br />
Ley 31/1995 de prevención de riesgos laborales<br />
R.D. 39/1997 Reglamento de servicios de<br />
prevención<br />
- INSH<br />
Torrelaguna 73. 28027 Madrid<br />
Tf: 91 363 41 00<br />
http://www.mtas.es/insht/index.htm<br />
- Fundación F4<br />
Apto. Correos 2212. 3180 Pamplona<br />
http://www.fundacionf4.com<br />
- 20 -
- Switzerland<br />
Area<br />
Use of chemical<br />
wood protection<br />
Regulations / laws<br />
- Verordnung über<br />
umweltgefährdende Stoffe<br />
- Verordnung über den Wald<br />
Water storage - Bundesgesetz über den Schutz der<br />
Gewässer<br />
- Bundesgesetz über die Fischerei<br />
- Bundesgesetz über die<br />
Binnenschiffahrt<br />
Working safety - Verordnung über<br />
umweltgefährdende Stoffe<br />
- Verhaltensregeln Arbeitshygiene<br />
- Signalisationsverordnung<br />
2.3 Environmental impacts<br />
2.3.1 General remarks<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Required approvals: authorities<br />
Anwendungsbewilligung: kantonale Forstdienste<br />
Wasserentnahme ab Bach: Kantonale Fachstelle für Wasserwirtschaft oder<br />
Gewässerschutz, evtl. kantonale Fischereiverwaltung (bei Fischgewässern)<br />
Wasserentnahme ab Hydrant: Wasserwerk der Gemeinde<br />
Lagerung in stehenden Gewässern: Kantonales Verkehrs- und Schiffahrtsamt<br />
Wasserableitung in Gewässer: Kantonale Fachstelle für Wasserwirtschaft<br />
oder Gewässerschutz, evtl. kantonale Fischereiverwaltung (bei<br />
Fischgewässern)<br />
(je nach Kanton ist nicht immer die gleiche Fachstelle zuständig!)<br />
Information erhältlich bei SUVA Luzern<br />
Wet storage, in particular water spraying of round timber, is a common method of wood storage subsequent to forest<br />
calamities. While pond storage used to be common, nowadays water spraying tends to be applied, using open water<br />
systems or recycling water systems. In the course of ponding or water spraying, organic substances – primarily<br />
sugars and phenolic substances – are leached from the bark, and to a much smaller extent from the wood.<br />
Additionally, small amounts of ionic substances (salts and acids) are leached out, and solid particles are washed from<br />
the bark surface. The deposition of bark particles on the bottom may have a detrimental effect on ponds used for<br />
wood storage. This problem can be largely avoided by the use of water spraying instead of pond storage.<br />
The potential environmentally negative effects of the dissolved and suspended substances can be characterized by the<br />
following water properties:<br />
- COD- v a l u e ( c h e m i c a l o x y g e n d e m a n d )<br />
The COD-value or the chemical oxygen demand indicates the amount of oxygen necessary for chemical degradation<br />
of the slowly decomposing organic compounds contained in the water. In order to evaluate investigation results of<br />
wastewater analyses, the guide value given here is the one generally used for municipal wastewater subsequent to<br />
biological clarification, i.e. prior to the feeding into natural flowing water. It corresponds to 140 mg COD per litre of<br />
water.<br />
- BOD- v a l u e ( b i o l o g i c a l o x y g e n d e m a n d )<br />
The BOD-value or the biological (biochemical) oxygen demand indicates the amount of oxygen that is consumed in<br />
the course of seven days during degradation of the rapidly degrading, organic compounds contained in the water.<br />
- p H-V a l u e ( d e g r e e o f a c i d i t y ) a nd electrical conductivity<br />
The degree of acidity is a measure of the H + -ion concentration, whereas and electrical conductivity refers to the total<br />
load of dissolved ionic substances.<br />
- Plant nutrients and other salts<br />
In addition to ammonium (NH4) and total nitrogen investigations occasionally also focus on phosphate, nitrate and<br />
nitrite as well as single ions such as metal ions and chloride.<br />
From experience, it is known that the most important property is the oxygen demand (COD- and BOD-values). The<br />
runoff water rarely contains toxic levels of any compound, but the breakdown of organic matter may deprive natural<br />
- 21 -
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
recipients of all oxygen, with detrimental effects upon flora and fauna.<br />
2.3.2 Water spraying with open water systems<br />
Normally, discontinuous (interval) spraying is applied, e.g. running the sprinklers for 20 minutes every hour. The<br />
spraying intensity often corresponds to 40-45 millimetres precipitation per day. Spraying may be suspended during<br />
night and in rainy and/or cold weather.<br />
The loads of suspended and dissolved matter in the discharge water increase over the first few weeks, or in some<br />
cases up to three months. Thereafter, over a period of 1 to 2 years, they approach the measured values of the intakewater.<br />
The environmental effects of the wastewater may be reduced by sedimentation basins (removal of bark<br />
particles etc.) and by buffering through lime gravel.<br />
By the use of climate-adapted water spraying (e.g. the Swedish TYKOFLEX system) the need for water and energy<br />
for pumping can be greatly reduced, still maintaining a satisfactory protection of the wood (Liukko 1997). The<br />
amount of runoff water is similarly reduced, but on the other hand the concentration of dissolved and suspended<br />
matter in the effluent is increased (Myhra and Gjengedal 1998).<br />
2.3.3 Water spraying in recycling water systems<br />
Recycling of log spraying water has two purposes, both of which are relevant to the environment:<br />
1) The need for fresh water can be greatly reduced, and<br />
2) Polluted runoff water can (al least partly) be prevented from entering natural waterways.<br />
Concerning (1) a considerable part of the water is lost to evaporation and to infiltration into the ground. Practical<br />
experience from Denmark indicates that 50 - 60% of the water can often be recycled when the storage yard is<br />
established on forest or arable land. With wet stores established on a concrete or asphalt surface (sawmills yards) this<br />
figure can be increased.<br />
COD-values may reach very high levels in the recycled water, in single cases up to several hundred mg per litre.<br />
Also in the long run (1 to 2 years) the load of organic matter in the recycled water will remain at a relatively high<br />
level, even though an intensive aeration is achieved by the sprinkling operation. However, observing an appropriate<br />
rate of dilution, there should be little risk in feeding excess runoff water into natural streams.<br />
2.3.4 Pond storage<br />
Storing of stem wood in natural, small-scale stagnant water bodies is, as a rule, an interference that cannot be offset<br />
and thus is to be refused. Particularly the leaching out of soluble material from the bark and the settling of larger<br />
amounts of bark to the bottom may lead to intolerable stresses in small stagnant ponds or pools, which cannot be<br />
emptied or cleared. Moreover, the riparian zones are considerably damaged, having a negative impact on flora and<br />
fauna. Soil material is pushed into the water by the traffic, or washed into the water by subsequent precipitation.<br />
Smaller drainable water bodies can be used for water storage, provided:<br />
- they are not located in particularly sensitive zones of water management;<br />
- they are not located in protected areas;<br />
- the management is harmless to the water body.<br />
Log storage in larger lakes will hardly affect water quality, if the storage zone is confined to only a small proportion<br />
of the water surface. In this context, however, concerns of bank protection, nature conservation and species<br />
protection as well as possible danger of drifting need to be taken into consideration. It seems to be advantageous not<br />
to hinder inflow and discharge of water from the lake.<br />
- 22 -
2.3.5 Groundwater pollution<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
In general, little attention has been paid to the risk of groundwater pollution from dissolved wood and bark<br />
constituents infiltrating the ground. As far as the authors are aware, no evidence of groundwater pollution resulting<br />
from wood storage has been reported in the European literature. In one or two cases Danish authorities have been<br />
monitoring groundwater quality in the vicinity of wet storage yards after the 1999 storm, but no results have been<br />
published yet.<br />
The load of dissolved and suspended matter in the water infiltrating into the ground can partly be controlled by the<br />
choice of material for constructing the storage yard (Myhra and Gjengedal 1998).<br />
2.3.6 Insecticide application<br />
The use of insecticides is restricted in all European countries and should be performed in accordance with national<br />
laws. Insecticide treatments are only provided for protection of sawlogs (see Figure 3), not for controlling the bark<br />
beetle population in general. At sites where logs are conserved in wet<br />
storage, the use of insecticides is ruled out due to their toxic effect on<br />
aquatic organisms.<br />
Figure 3: Insecticide application (Photo HFM)<br />
The function of insecticide application is to prevent or repel the adult<br />
beetles from boring into the bark in order to lay their eggs. Once the<br />
beetles are under the bark or within the wood they are largely safe from<br />
chemical sprays and the application of insecticides is useless.<br />
Therefore, the treatment must be carried out in late winter or in the<br />
early spring before the adult beetles begin their search for breeding material. If the expected duration of storage<br />
extends beyond one summer, other ways of protecting the timber should be sought.<br />
A l t e r n a t i v e s t o i n s e c t i c i d e s<br />
a) To reduce the beetle attack effectively, storage periods must be reduced, particularly in the spring.<br />
Logistics could be improved in order to minimize the time between logging and conversion, or processing<br />
speed could be reduced in favor of live conservation, provided that the fallen trees have maintained<br />
sufficient root contact.<br />
b) Dry storage is another possibility to avoid a beetle attack. The logs must be debarked, transported out of the<br />
forest and stored in open sites. The durability of the storage should not exceed 5 - 6 months. A beetle<br />
infestation cannot be excluded totally, but very few species will attack debarked logs.<br />
c) In wet storage with proper intensity and coverage of the sprinklers, the beetles will die and the brood cannot<br />
develop further.<br />
2.3.7 References<br />
Borga, P. ; Elowson, T. ; Liukko, K. 1996: Umweltbelastung durch Abwässer bei der Nadelnutzholz-Beregnung.<br />
Holz-Zentralblatt 122: 2146<br />
Liukko, K., 1997: Climate-adapted wet storage of saw timber and pulpwood: An alternative method of sprinkling<br />
and its effect on freshness of round timber and environment. Silvestria No. 51. SLU, Uppsala. 44 pp. + 4 artikler.<br />
Myhra, ?.;Gjengedal, ?. 1998: Avrenning fra tømmervanning. Norwegian Institute of Wood Technology (NTI),<br />
Rapport no. 41, Oslo, March 1998, 33 p<br />
Stoll, M. 1990: Zur Bewertung der Abwasserbelastung durch Naßkonservierung von Kalamitätsholz. Holz-<br />
Zentralblatt 116: 1042<br />
Tingleff, T. 1991: Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets<br />
- 23 -
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
sprinklerdepoter i 1982-1985. Dansk Skovbrugs Tidsskrift, 1991, pp. 115-226.<br />
2.4 Management/Operation/Health and Safety<br />
2.4.1 Management/Operation<br />
On-site storage (leaving the trees where they have fallen) generally puts little strain on the management and<br />
operations of the forest owner. An inventory of the wind-thrown logs is appropriate and quality assessments (drying<br />
damage, insect attacks, discoloration and fungal attack) should be carried out at regular intervals.<br />
If the logs are to be stored in piles in the forest, more stringent organisation is required machinery with appropriate<br />
performance and capacity should be chosen. Serious consideration should be given to limiting machinery traffic on<br />
vulnerable forest soils, in order to avoid soil disturbance and compaction. The piles should be postioned in such a<br />
way as to assure favourable storage conditions (shade, shelter) and also to facilitate easy loading and transportation.<br />
All-season lorry access to the piles may not be possible without serious damage to the forest roads.<br />
Storage yards are even more demanding of facilities and management. If wet storage is to be employed, the<br />
minimum demands are:<br />
- the ground should be trafficable by heavy lorries even in a soaked condition,<br />
- access roads should be usable during all seasons,<br />
- water supply should be adequate,<br />
- electric power for pumps etc.,should be available<br />
- the yard should be sheltered from strong winds,<br />
- daily inspection should be possible.<br />
In addition, the possibility of re-circulating runoff water may be necessary. To fulfil those demands, a storage yard at<br />
a sawmill or another industry will often be the best choice. Here, trafficable ground, access roads, power and<br />
personnel is often available, minimizing the cost of establishing and operating new sites.<br />
2.4.2 Health and safety<br />
The maintenance of logs under humid conditions i.e. compact piles covered with plastic sheets, or using “special”<br />
methods involving wrapping in plastic sheets or covering with geo-textile fabric, may result in the growth of<br />
thermotolerant and thermophilic moulds and actinomycetes on the timber. The high humidity under the sheeting plus<br />
elevated temperatures resulting from incident sunlight may generate temperatures in excess of 40 o C which will<br />
support the growth of these freely sporulating micro-organisms. At the same time, the elevated temperatures will<br />
inhibit and possibly inactivate the vegetative hyphae of decay and sapstain fungi.<br />
The production of large quantities of mould and actinomycete spores is a potential health hazard, since inhalation of<br />
significant numbers of spores could generate allergenic responses in operators removing the sheeting. This risk can<br />
be avoided by the wearing of protective face masks during this operation.<br />
Logs in wet storage may become very slippery, presenting a risk for the personnel involved in inspection and<br />
maintenance of the sprinklers. Also, the risk of logs sliding or rolling down when climbing the stacks must be<br />
considered.<br />
2.4.3 Research needs<br />
Health risks due to mould fungi (particularly with logs stored under plastic sheets).<br />
Optimal storage size depending on conservation method.<br />
- 24 -
2.4.4 References<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Hammer, S. et al. 2003: LOTHAR Zwischenevaluation der kantonalen Strategien zur Bewältigung von Lothar am<br />
Beispiel der Kantone Bern, Waadt, Luzern und Aargau. Umwelt-Materialien Nr. 154, Bundesamt für Umwelt, Wald<br />
und Landschaft, Bern, Switzerland. 112 p.<br />
Hänsli, C. et al. 2003: LOTHAR Sturmschäden im Wald, 1999. Eine vergleichende Analyse der politischen Prozesse<br />
und der staatlichen Massnahmen nach «Lothar» und «Martin» in der Schweiz, Deutschland und Frankreich –<br />
Synthesebericht. Umwelt-Materialien Nr. 159, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 93<br />
p.<br />
Hofer, P. et al. 2003: LOTHAR Optimierung der Holztransporte nach Sturmereignissen. Umwelt-Materialien Nr.<br />
161, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 97 p.<br />
2.5 Process monitoring and wood quality<br />
2.5.1 Process monitoring<br />
Process monitoring is an important part of conservation work. By implementing proper monitoring procedures it is<br />
possible to document the development of wood quality in relation to operational parameters (e.g. watering intensity)<br />
and the initial condition of the wood. Monitoring of storage conditions as well as wood quality should be carried out<br />
over the entire duration of the storage. Records of wood quality in relation to species, character of storm damage,<br />
logistics and storage conditions may provide valuable help for decision-making in the event of future storm<br />
calamities.<br />
2.5.2 Wood quality<br />
2.5.2.1 General remarks<br />
Currently in the EU member states over 60 million m 3 sawn of softwood timber (mainly Spruce and Pine) and over<br />
20 million m 3 sawn of hardwood timber (mainly Oak and Beech) is produced per year. This represents a total value<br />
of some 12-14.000 million Euro for softwood and approximately 4-8 million Euro for hardwood. The majority of the<br />
softwood material is currently used in the building sector in the form of structural components, joinery, furniture,<br />
cladding (facade, wall cladding and flooring) and in temporary structures. A high proportion of the structural<br />
components (beams, roof-truss timber, purlins, studs, glulam timber) have to be kiln dried to approximately 18 - 20%<br />
moisture content, then graded for strength and preservative treated. Other products may have to be dried to lower<br />
moisture contents that correspond to their likely in-service moisture content (approximately 10% for interior joinery<br />
and 16% for exterior joinery) they are also appearance graded for surface defects and growth rate. The hardwoods<br />
are used for decorative purposes such as furniture and interior panels. These also need to be kiln dried and graded for<br />
appearance.<br />
In many areas of Europe the amount of material from forests is increasing annually and the majority of this is fastgrown<br />
softwoods. Overall timber production in the EU has increased by about 20% with the entry of the 10 new<br />
members in May 2004. The output from existing states is also increasing. For example, in the UK the output from<br />
their forests is estimated to increase from the current figure of 7 million m 3 to 17 m 3 in 2015. Maintaining the value<br />
and hence a viable wood industry across Europe relies on keeping a balance between the supply and demand of<br />
material from the forests. Increases in the availability of wood from the forest, which can be caused by storms, could<br />
generally influence supply and demand and lower the value of the wood. This could be prevented by not allowing the<br />
blown timber to come onto the market. This would be achieved by storing the storm timber and controlling its<br />
release onto the market. However, in general the quality of the timber after storage has a strong influence on the<br />
economics of the system used. Timber quality is so important in establishing fitness for purpose for its intended use<br />
and it needs to have reliable quality to consistently complete with other material, such as steel, and plastic.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Nowadays, timber end-users often claim that timber does not come-up to their expectations. One of the main reasons<br />
is that the industry is unable to identify performance requirements. The structure of the timber industry with its<br />
predominance of small companies has stood in the way of joint marketing concepts and market surveys. Neither<br />
consumers nor producers are aware of the wood properties which govern performance and, as a result, the current<br />
grading rules are more production-oriented than consumer-oriented. Consequently, timber products are not<br />
manufactured as well as they might be, nor are they specified as they could be. The current standardisation work still<br />
follows the traditional approach, in that it is production-oriented rather than consumer-oriented. The relevant<br />
standardisation committees are becoming increasingly aware of this deficiency, but are not equipped to take the<br />
necessary steps. If the new and existing material is not to the correct standard when delivered to the market place and<br />
if it does not perform to specification then timber will loose its market share. The aim should be to increase market<br />
share and make more use of Europe’s environmentally friendly and renewable resources. Therefore, if timber<br />
conservation, after storm damage, is to be worthwhile and economically viable the same criteria must be applied to<br />
the stored timber as to the conventionally harvested timber. Whether the stored timber is eventually going to be used<br />
for paper making or for construction, it must be fit for purpose.<br />
For example, for the CONSTRUCTION sector timber must have:<br />
• Sufficient STRENGTH<br />
• Sufficient STIFFNESS<br />
• The correct target moisture content<br />
• Appropriate form i.e. be dry and straight with low twist, spring, bow and stay STRAIGHT in service despite<br />
changes in local environmental conditions<br />
• Good sawing accuracy<br />
• Sufficient durability lamin<br />
• Look good<br />
For joinery use extra requirements would include:<br />
• Control of defects and growth rate<br />
Stored timber can achieve these requirements, but it is important that quality control systems are available and are<br />
actively applied. Regular monitoring of the stored timber is essential to detect the onset of any deterioration. It is also<br />
very important that stored timber can be dried efficiently so that it has the correct moisture attributes for its intended<br />
purpose of use. These are:<br />
• the correct target moisture content<br />
• low moisture gradient<br />
• low batch variability<br />
• appropriate form i.e be dried straight with only low twist, spring , bow and remain straight in service<br />
• service despite changes of climate<br />
If the timber is to be used in a moisture-hazardous environment, it must have the correct durability or treated with<br />
preservative for its designated end-use. The conserved timber will have different porosity depending on the time it<br />
has spent in the store, probably under water spray. Again the conserved timber should be monitored for deterioration<br />
in this respect.<br />
A proportion of the naturally harvested timber in Europe will be poor quality and will need re-engineering. It will<br />
need to be end-jointed, edge jointed and laminated to make it longer, wider and thicker wih reduced defects.<br />
Conserved storm damaged material will be the same, but the stored timber must have good gluing properties and be<br />
capable of using green gluing technology.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Therefore, in general the important properties concerning wood quality to establish fitness for purpose for particular<br />
end-uses are:<br />
• stiffness<br />
• strength<br />
• durability<br />
• gluability<br />
• treatability<br />
• dryability.<br />
2.5.2.2 Wood quality related to storm and log conservation<br />
Low-weight wood is characterized by high strength. In this context, tensile strength along the grain represents the<br />
highest strength, followed by bending strength and compression strength to the grain, accounting for only about 50%<br />
of tensile strength. In the case of a strong bending – e.g. due to storm – and if the compression strength is exceeded<br />
at the compressed side of the stem, slip planes (Figure 4) occur long before rupture of fibres at the tension-stressed<br />
side of the stem causing the stem to break.<br />
Figure 4: Slip planes in Spruce tracheids (Photo TUD)<br />
Slip planes are damaged spots in the wood (of a tree stem).<br />
Across them the fibre walls have been more or less<br />
compressed and buckled due to excessive pressure acting in<br />
longitudinal direction, so that the wood at this spot has<br />
partially or totally lost its coherence and hence its strength.<br />
Fibre cracks are ruptures of wood fibres in the wood having<br />
been damaged before due to slip planes (see Figure 5).<br />
Slip planes can be recognized by local cushion overgrowths (occlusion<br />
rolls, see Figure 6) above compressed stem cross sections. If storm is the<br />
cause of strong bending of the stem, the occlusion bumps (“Wulstholz”)<br />
are located on the leeward side of the stem.<br />
Figure 6: Seven tree rings forming an occlusion bump (“Wulstholz”) over a<br />
compression failure – radial section (Photo TUD)<br />
Contrary to occluded knots, wounds and stem-rots, the occlusion bumps<br />
Figure 5: Fibre cracks in Spruce tracheids (Photo TUD)<br />
Slip planes and fibre cracks can be summarized as<br />
compression failures. Preconditions for the occurrence of<br />
slip planes or secondarily of fibre ruptures are a sudden<br />
setting free of the tree (e.g. conditions of growth changed by<br />
man e.g. by felling of neighbouring shelter trees or by<br />
removal of neighbouring houses) and a crown set free<br />
unilaterally which facilitates a bending of the tree without<br />
touching neighbouring crowns (no leaning of the crown to<br />
one of the neighbouring trees possible).<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
run above the slip planes at an angle of 45° to 60° relative to the horizontal line with abrupt terraced transition to the<br />
unaffected stem surface (see Figure 7, right). Slip planes and fibre cracks are potential spots of breakage in the stem<br />
of trees that decrease the static properties of the tree stem and may lead to a sudden stem breakage. The danger of a<br />
sudden stem breakage exists as long as no sufficiently thick wood layer has formed in terms of a shock-absorbing<br />
occlusion bump above the compression failures by the tree.<br />
Figure 7: Left: Bumps over compression failures (slip planes) on Spruce in bark. Centre: clearly visible fresh compression<br />
failures on debarked Spruce wood surface. Right: cracks in Spruce bark are reliable signs of fibre cracks in the wood<br />
(Photos HFM, TUD)<br />
If fibre cracks can be diagnosed on wood surfaces not covered with bark, there is extreme danger of stem breakage.<br />
Sawn timber produced from such type of stems must not be used as construction timber due to its low strength<br />
properties and the hazard of breakage (see Figure 8).<br />
Figure 8: Compression failures in Spruce boards: left and certre: clearly visible slip planes. Right: fibre crack (Photos<br />
HFM, TUD)<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
To sum up, each slip plane represents a static damage of the tree stem. If “Wulstholz” is clearly visible the breaking<br />
strength of a tree is impaired and the extraction of high-grade sawn wood reduced.<br />
Regarding the mechanical damages in the stems of wind-thrown trees, the phenomenon of compression failures is of<br />
particular significance for the utilization of the timber. With large stem deflexions under strong winds the axial<br />
compression strength of the wood can locally be exceeded, causing a buckling of the wood fibres. These distorted<br />
fibres are week points in the wood structure, which can lead to characteristic brittle fractures already at a relatively<br />
low stress in bending or tension. The presence of compression failures in construction timber must therefore be<br />
excluded with reasonable certainty.<br />
“Wulstholz” is characterized by increased xylem production leading to bulges. The S2-layers of “Wulstholz”tracheids<br />
are thicker than the corresponding cell wall layers in normal wood, and the cell lumen diameter is<br />
significantly reduced. The tracheid length decreases gradually from an average of 4 mm to 2.5 mm compared to<br />
normal wood, and the tracheids are shifted against each other longitudinally. “Wulstholz” contains a higher<br />
concentration of lignin than normal wood, whereas the concentration of glucose in the hydrolysates is reduced. The<br />
hemicellulose-concentration, particularly the mannose-content, is significantly higher compared to normal wood.<br />
The compression strength and the modulus of elasticity, despite a higher density, are significantly reduced (Koch et<br />
a l . 2000).<br />
The primary goal of storage is to conserve the quality of the wood for future use in the wood processing industry,<br />
hence quality parameters are the most important figures to monitor, as a considerable loss of value can occur over<br />
time if the wrong storage method is used. However, quality monitoring usually implies laborious and destructive<br />
procedures, e.g. crosscutting and inspecting a number of logs, or processing a number of logs with subsequent<br />
quality assessment of the boards. As far as wood quality is concerned, three non-destructive (or “less destructive”)<br />
methods have been tested and correlated to the results obtained with the usual destructive methods: ultrasound<br />
analysis (Sylvatest/ CTBA); vibrator analysis; and mechanical resistance analysis. This latter is achieved thanks to a<br />
machine called “resistograph,, which measures the resistance to penetration of a drill into the wood in a diametrical<br />
direction. The non-destructive methods appear to be an efficient way of monitoring the mechanical properties of the<br />
wood, since their results are well correlated with the ones obtained using destructive methods to measure stiffness<br />
(MOE) and strength (MOR) (Anonymus 2001).<br />
2.5.3 Research needs<br />
Fast and easy detection/monitoring methods for wood degradation.<br />
2.5.4 References<br />
Anonymus 2001: Site atelier de conservation longue durée du Pin maritime (Experimental site for maritime pine's<br />
log conservation (Pinus Pinaster) using three different methods); DERF/ INRA / AFOCEL/ CTBA; Intermediary<br />
report.<br />
Koch, G.; Bauch, J.; Puls, J.; Schwab, E. 2000: Biological, Chemical and Mechanical Characteristics of „Wulstholz“<br />
as a Resopnse to Mechanical Stress in Living Trees of Picea abies [L.] Karst. Holzforschung 54: 137 - 143<br />
Additional literature not cited:<br />
Arnold, M. 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes.<br />
144 (11): 843-858<br />
Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrungen nach dem Orkan „Lothar“ (1999). Projekt<br />
WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion ((available as pdf: www.empa.ch/holz ?<br />
Holztechnologie)<br />
Arnold, M.; Sell, J., 1992: Qualitätserhaltung von Rundholz bei längerer Lagerung - I. Das Projekt 'Lagerung von<br />
Sturmholz'. Forschungs- u. Arbeitsber. EMPA-Abt. Holz, Nr. 115/25, EMPA, Dübendorf, Switzerland.<br />
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3 Conservation methods<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
In order to drawn unambiguous conclusions regarding the different conservation methods, it is important to review<br />
them and to define the terminology used.<br />
Table 4 lists known conservation methods. They are grouped according to the storage conditions of the logs (wet,<br />
dry, humid) to reflect the particular importance of wood moisture content in their preservation. For the 'hybrid' and<br />
more 'exotic' methods a 'Special' group is used. 'Supplementary conservation measures' are occasionally used in<br />
combination with one of the main conservation methods (e.g. chemical wood protection or end-grain sealing with<br />
compact piles). However, only selected combinations are effective and some are even prohibited (e.g. chemical wood<br />
protection with wet storage). The table contains all the reported conservation methods, irrespective of how much<br />
they are being used or how proven they are.<br />
Table 4: Systematics of conservation methods<br />
Group (Principle) Method Description<br />
In-situ storage<br />
Live-conservation of wind-thrown trees In-situ storage of living, uprooted trees with sufficient root<br />
Logs left untouched in place in<br />
contact<br />
th e s t a n d Drying by transpiration In-situ storage of entire trees (with crown) with a cross-cut at<br />
the stem base<br />
Wet storage<br />
S t o r a g e u n d e r ( c o n trolled) wet<br />
conditions keeping the wood<br />
s a t u r a t e d<br />
Storage under drying<br />
conditions<br />
Storage under (uncontrolled)<br />
conditions resulting in slow or<br />
fast drying of the logs<br />
Storage under humid<br />
conditions<br />
Storage under (uncontrolled)<br />
changing conditions<br />
'Special' methods<br />
Supplementary conservation<br />
measures<br />
Compact pile with water sprinkling Compact pile with water sprinkling (logs with bark)<br />
Ponding (immersion in water) Storage of logs in running or standing water (logs with bark)<br />
Log pre-drying in covered cross-pile Pre-drying of logs in covered cross-pile (logs debarked)<br />
Rapid log pre-drying in open cross-pile Rapid log pre-drying in open cross-pile (logs debarked)<br />
Compact pile Compact pile (logs with bark/debarked)<br />
Compact pile covered with plastic sheets Compact pile covered with plastic sheets (logs with<br />
bark/debarked)<br />
Log conservation under oxygen exclusion,<br />
compact pile wrapped in plastic sheets<br />
- 30 -<br />
Compact pile wrapped and sealed in plastic sheets resulting in<br />
oxygen free conservation atmosphere (logs with bark)<br />
Compact pile covered with geo textile fabric Compact pile covered with geo textile fabric (logs with bark)<br />
Compact pile covered with a mineralic<br />
suspension<br />
Compact pile covered with a thin layer of mineralic suspension<br />
(protection against insects)<br />
Storage in gravel pits Compact pile buried in a hole in the ground or on level ground<br />
covered with thick layer of clay/soil<br />
Storage in mines Storage in unused mine tunnels<br />
Compact pile above timberline Compact pile above timberline (logs with bark)<br />
Storage in snow Compact pile covered with snow<br />
Compact pile covered with organic material Compact pile covered with bark chips, wood chips, sawdust etc.<br />
Chemical protection Wood protection by chemical agents<br />
Biological protection Wood protection by biological agents<br />
Supplementary to main<br />
methods ('integrated methods') Physical protection Wood protection by physical measures (e.g. end-grain sealing)
3.1 In-situ storage<br />
3.1.1 Live-conservation of wind-thrown trees<br />
3.1.1.1 Principle/description<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- Principle:<br />
Natural water balance and the natural defence of the trees are to<br />
be maintained and desiccation is to be delayed.<br />
- Tree species:<br />
Experiences and research results are available for Beech,<br />
Douglas Fir, Spruce, Pine and Maritime Pine<br />
Figure 9: Live conservation of wind- thrown spruce trees (PhotoHFM)<br />
- Preconditions:<br />
Root plate merely lifted up, not shifted laterally; roots need to<br />
have sufficient contact with the soil (the existing contact<br />
between root-stock/soil should account at least 20 to 25% of the root volume); minor stem and crown damage; no<br />
direct solar irradiation on stem and root plate; no risk of infestation with beetles.<br />
3.1.1.2 Advantages, disadvantages, practical experience<br />
3.1.1.2.1 Advantages, disadvantages<br />
- Advantages<br />
• Immediate storage without prior tree processing (delimbing, bucking, debarking, log transportation) and storage<br />
site preparation<br />
• No technical equipment necessary<br />
• Low cost (only for wood quality control)<br />
• Live conservation can be regarded as a cheap alternative to other conservation methods, but only for a limited<br />
time period. For deep-rooted tree species this method conserves the value of the wood whilst more urgent storm<br />
damage can be dealth with.<br />
- Disadvantages<br />
• Dependence on climatic conditions<br />
• No control over the development of wood moisture content<br />
• Storage time is limited as unacceptable secondary wood defects can develop<br />
• Risk of bark-beetle attack. Even before storm damage. the existing bark beetle population can seriously affect<br />
conservation<br />
• The decision about whether the storm-damaged trees should be left in living conservation depends largely on the<br />
personal experience of the forest worker<br />
3.1.1.2.2 Practical experience<br />
• Beech (Fagus sylvatica)<br />
Sawing<br />
- Influence of e x p o s u r e t o sunlight o n t h e c o n s e r v a t i o n of w i n d b l o w n t r e e s<br />
Winkler (2002) reports that as far as live-conservation is concerned, the general results are rather encouraging : after<br />
one year, the percentage of logs attacked by fungi (involving an economics loss) ranges from 7% to 16% for<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
scattered blown trees and 29% for blown trees located in totally damaged area (i.e. exposed to 100% sunlight). After<br />
2 years, the percentage of wood deterioration increases considerably with regard to scattered blown trees, ranging<br />
from 27% to 35% (average made for each sample area). In highly exposed areas, wood deterioration reached more<br />
than 55% after 2 years of conservation.<br />
Eisenbarth (1995) has made similar observations and suggests proceeding as follows:<br />
a.) Windthrow across whole areas without any canopy left<br />
Selective log processing of high-grade timber assortments according to fixed orders and just in time. A storage of the<br />
processed logs in piles during the growing season should be avoided by all means. High-grade log assortments<br />
should be processed to sawn timber under the responsibility forest owner as soon as possible and stored as sawn<br />
timber. Successive log processing of medium log qualities according to the marketing situation and the actual<br />
demand. On-site live-storage of blown trees can be done up to the early autumn after a winter windthrow (loss of<br />
value up to 40%).<br />
b.) Single wind-blows beneath the canopy of the remaining stand<br />
After the clearing of the wind-blown area the log processing can be started in the early autumn after a winter windblow.<br />
It is also possible to leave the logs lying up to the end of the following winter at the latest, i.e. up to the<br />
beginning of the second growing season following the storm damage (the observed loss of value was up to 35%). For<br />
the in situ live-conserved beeches of the winter storm-throw of 1990 a loss of value occurred already after the first<br />
growing season. Those losses in value, derived from the devaluation of the sawn timber of grade 2 down to grade 3<br />
(DIN 68369) due to influences from storage, turned out to vary greatly, depending on the kind of in situ live-storage<br />
(single wind-throw beneath canopy or area-throw without shading).<br />
In the case of in situ live-conserved Beeches following winter storm-throw, only minor quality losses were<br />
discernible up to the following early autumn. On the other hand, in-situ live-conserved Beeches in open spaces had<br />
already been subject to apparent devaluations. After two growing seasons drastic loss of quality was apparent in<br />
Beech trees in open spaces, and scattered wind-thrown wood beneath canopy was already deteriorating. In<br />
conclusion, scattered wood from winter storm-throw Beech can still be live-stored for up to one year, (comprising<br />
one growing period and the subsequent winter season) with tolerable losses in value averaging 35%.<br />
German experiences were satisfying up to one vegetation period; relevant for the quality conservation is storage<br />
under shadow and a low leaf mass:<br />
- Low risk: single and planar throw at north and south slopes;<br />
- Higher risk: planar throw, south and west exposition;<br />
- Sunburn damages lead to hard loss of quality B they are possible especially with planar throw and at south slopes.<br />
- I n f l u e n c e of c r o w n c u t t i n g o n c o n s e r v a t i o n ( a c c o r d i n g t o B e r g s t e d )<br />
Following the 1967 storms in Denmark, a black-bluish discoloration of the wood was frequently encountered in<br />
Beech that had been live-stored on heavy, waterlogged clay soil. The discoloration is believed to have arisen from<br />
iron-II-ions being translocated into the live tissues through the broken roots.<br />
Research concerning this problem has been carried out in Denmark in order to determine the extent of blue-staining<br />
on these types of soil. The study included whole toppled trees (with crown left intact) as well as polled trees (crowns<br />
cut off). The trees were wind-thrown in February and the crown cut off in April the same year. The conclusions of<br />
the study were:<br />
1) Wind-thrown beeches left with roots on clay soils near ground water level will, during the growing season, be<br />
strongly exposed to blue-staining if root fractures reach down into the ground water.<br />
2) Polling does not prevent discolouration, but experiences show that it can reduce the number of affected trees from<br />
approximately 80% to app. 60% and the extent of the discolouration axially and radially in the stems to app. 50%.<br />
Furthermore, the polled trees show the lowest colour–intensity. Even though the frequency, extent and intensity of<br />
the discolouration vary strongly within the site, the conclusion is that on all sites where blue-staining in wind-thrown<br />
Beech is a problem, a reduction of the damages as described above can be expected if the live crown is cut off.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
In this context it should also be mentioned that leaning trees standing on heavy clay soil may be affected by bluestaining,<br />
if the leaning is caused by a storm and broken roots in this connection have been pushed down into the<br />
ground on lee side, reaching the ground water (Moltesen 1968).<br />
Kraft Pulp<br />
There is a strong correlation between pulp and paper properties and moisture content (AFOCEL 2002). Studies after<br />
the 1999 storm in France revealed that an important decrease in pulp yield occurred during the second year of<br />
storage. The pulp yield decreased by 5% within the second spring/summer period. Nevertheless, the pulp properties<br />
following the first live-conservation year remained good and steady.<br />
• Spruce (Picea abies)<br />
The duration of forest protection is very relevant for Spruce; there is good evidence that conservation can be<br />
guaranteed for a period of 6 to 12 month.<br />
- For Spruce large areas on north slopes are more suitable for live-conservation than plain and south slopes; Spruce<br />
with flat root in wet areas are not good for live-conservation.<br />
Figure 11: Cross section of a frozen Spruce stem at 3 m stem height<br />
showing irregular sapwood distribution according to water reduction after<br />
one vegetation period of live-conservation (Photo HFM) <br />
Figure 10: Cross section of a frozen Spruce stem at stump height<br />
showing irregular sapwood distribution according to water reduction<br />
after one vegetation period of live-conservation (Photo HFM)<br />
Figure 12: Cross section of a frozen Spruce stem at 9 m height<br />
showing irregular sapwood distribution according to water reduction<br />
after one vegetation period of live-conservation (Photo HFM)<br />
After the storm in February 1969 a Danish investigation<br />
was carried out with the aim of assessing various methods<br />
of storing wind-thrown Norway Spruce logs. Among these<br />
was storage with root plate at point of falling (Moltesen and<br />
Riisgaard Pedersen 1969). Spruce seems to do better when<br />
whole areas are wind-thrown compared to if only some of<br />
the trees lie down, possibly because the crown withers<br />
more quickly when the tree lies in the shade.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
The trees left at point of falling after the storm in February 1967 all came into leaf in 1967 and most of them were<br />
alive throughout the year. During spring and early summer nearly all the trees withered, especially the ones with<br />
reduced crown volume, but all the way up to May 1968 (15 months after the storm) they showed moisture content<br />
that was only slightly lower than that of standing trees and that was highest for trees with reduced crowns.<br />
Damages at time of sawing (16 months after the storm) were modest for trees left at point of falling with untouched<br />
crowns. Trees with reduced crowns were appreciably more damaged, and when the sawing was postponed for<br />
another four months, damage had sometimes more than doubled (Moltesen & Riisgaard Pedersen 1969).<br />
• Pine (Pinus sylvestris)<br />
The duration of forest protection is similar to that of Spruce.<br />
Storage until winter is possible, as long as there is good root contact.<br />
Where the stem touches the soil surface there is a danger of bark damage and blue stain.<br />
• Maritime Pine (Pinus pinaster)<br />
- Sawing<br />
The contamination of wind-thrown trees by fungi remains limited. In the southwest of France, one year after the<br />
storm, 40% of saw logs observed were not contaminated by blue stain. Before insect attack occurred no bluestain<br />
damage was noticed on logs on the dry site, but there were several logs contaminated on the wet site. On such land,<br />
tree contamination could have happened through broken roots. After insect attack, contamination of the logs rapidly<br />
reached 60% on both types of site.<br />
Three years after the storm some wind-thrown trees were still harvested, sawn and used for pallet making.<br />
If a storm occurs during winter, we can make this simple recommendation: to harvest wind-thrown trees on wet sites<br />
first and to harvest quickly before insects attacks.<br />
- Kraft Pulp<br />
Blown trees stored on site were well preserved until the end of the first summer. Fibre and paper properties were<br />
affected initiallly, then pulping yield, but much less than in harvested logs. The degradation between stands was<br />
heterogeneous, which means that practical methods of selection should be set up to define different qualities of wood<br />
assortments (exposure to the sun, tree volume and type of soil determine the evolution of wood quality). Two years<br />
after the hurricane, the majority of the trees left on site could still be used for Kraft pulp and paper. However, after<br />
more than two years the paper properties decreased rapidly and the wind-thrown wood could only be used for pulp<br />
when mixed with fresh wood.<br />
• Douglas fir (Pseudotsuga menziesii)<br />
- Kraft Pulp<br />
Very good conservation was maintained during the first two years of storage. After three years a steady decrease in<br />
paper properties ocurred.<br />
3.1.1.3 Recommendations (application, time limits)<br />
From the economic point of view, wood storage should only be applied, if the number of wind-thrown logs is so<br />
great, that a conversion cannot be completed prior to the growing season, as well as in the case of lack of marketing<br />
and storage possibilities. Generally speaking, the quality of i n -situ conservation depends on the three following<br />
factors:<br />
Table 5: Susceptibility of the species<br />
Species Very susceptible (1 vegetation period, risk of blue stain) Susceptible (1 vegetation period) Resistant (2 vegetation periods)<br />
Softwood Pine – Spruce Maritime Pine Douglas Fir - Larch - Cedar -Yew<br />
Hardwood Maple – Hornbeam – Ash - Poplar Beech – Elm – Alder – Cherry -<br />
Walnut<br />
Oak – Chestnut – False acacia<br />
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a) Susceptibility of the species<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
b) Type of damage to trees: the greater the contact between the root system and the ground, the better the<br />
conservation.<br />
c) Degree of dissemination of the wind-blown trees: either disseminated wind-blown trees (i.e. sun-protected trees)<br />
or widely exposed to sunlight. The more the blown trees are exposed to the sunlight, the higher the deterioration rate<br />
because of a more rapid decrease in wood moisture content.<br />
3.1.1.4 Quality monitoring<br />
Live conservation of trees allows the quality to be monitores throughout storage time in the stand. It is therefore<br />
possible for the forester to monitor the condition of the trees. The following indicators of vitality can be taken into<br />
account:<br />
• Sprouting behaviour; ability of the tree-top to straighten up; resin exudation; bluish-silvery needle discoloration;<br />
occurrence of shade indicators (bark covered with green algae or root plate covered with plants); changes in<br />
moisture content (drying from below to above and from inside to outside).<br />
• Some further technical damages must be taken into account, because of environmental disturbances (e.g. snow<br />
breakage) while living storage of the trees.<br />
Since there is a significant correlation between tree moisture content and degradation (R²=0.56), a simple way to<br />
monitor the quality of wood stored in situ is to measure wood moisture content (Winkler 2002)<br />
3.1.1.5 Environmental issues<br />
The storage method itself has no impact on the environment. The risk of bark beetle attack and spreading of bark<br />
beetles should be considered when no chemical pest control is used. The application of chemicals can harm the<br />
environment.<br />
3.1.1.6 Costs<br />
The expense of frequent quality monitoring (once per month) and for checking moisture content would be incurred.<br />
3.1.1.7 Research needs<br />
- Statistical data on the amount of live-conserved wood is rarely availabl, because in practice live-conservation of<br />
wind-thrown trees is usually still not considered and used as a conservation method and therefore not accounted for<br />
in wood storage statistics. Moreover, very little is known about the deliberate use of this method to set harvesting<br />
priorities.<br />
- More research is needed into the optimal time to remove tree crowns in order to minimize blue-staining of the<br />
wood.<br />
- Definition/assessment of ‘safe’ conditions for live-conservation is needed.<br />
The sustainment of wood quality is the first goal of log conservation and there are still some doubts concerning the<br />
size of the storm damaged forest and exposure to sunlight for example. However, it is very important to discover<br />
more about live-conservation because, if wood quality can be conserved sucessfully, it is a cheap and<br />
environmentally-friendly method.<br />
3.1.1.8 References<br />
Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrung nach dem Orkan „Lothar“ (1999). Projekt WN<br />
19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (available as pdf : www.empa.ch/holz ? Holztechnologie)<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Eisenbarth E. 1995: Schnittholzeigenschaffen bei Lebendlagerung von Rotbuche ( F a g u s s y l v a t i c a L.) aus<br />
Wintersturmwurf 1990 im Abhängigkeit von Lagerart und Lagerdauer. Mitteilungen aus der Forstlichen Versuchs<br />
und Forschungsanstalt Rheinland, Nr. 33/95<br />
Klaiber, V.; Seeling, U.; Mutz, R., 2002: Holzfeuchte in Fichtenstämmen (Picea abies (L.) Karst.) bei<br />
Ganzbaumlagerung im Bestand. Schweiz. Z. Forstwes.153 (6): 210-218<br />
Moltesen, P. 1968: Blåfarvning i stormfældet bøg. Forstlig Budstikke 1968, vol. 28, p. 1-2.<br />
Moltesen, P. & Riisgaard Pedersen, E. 1969: Forsøg med opbevaring af stormfældet rødgran: Afbarkning, kemisk<br />
beskyttelse og rodlagring. Dansk Skovforenings Tidsskrift 1969, vol. 54, p. 1-56.<br />
Thorlacius-Ussing, H. 2000: Tag det med ro – stormfaldserfaringer 1981 fra Rold skov. Skoven no. 1, 2000, p. 11-<br />
12.<br />
Winkler, I. 2002: Assessment and improvement of live conservation method of blown trees for beech ( Fagus<br />
sylvatica); CTBA, DERF, DERF; August 2002<br />
3.1.2 Drying by transpiration<br />
3.1.2.1 Principle/description<br />
Accelerated decrease of wood moisture content in wind-thrown trees after a cross-cut at the stem base by<br />
evapotranspiration from the crown that is still green.<br />
3.1.2.2 Advantages, disadvantages, practical experience<br />
This method is suitable only for a short time (weeks) of delayed processing and the climatic conditions during this<br />
period are crucial for its success. Apart from a few trials no practical experience is available so far. Only a few<br />
scientific publications describe this pre-drying process and give some information about the practicability of this<br />
technique (see references)., although it is not very successful.<br />
3.1.2.3 Recommendations (application, time limits)<br />
Based on the very limited experience it is not possible to give specific recommendations.<br />
3.1.2.4 Quality monitoring<br />
- Observation of the wilt of the crown.<br />
- Monitoring wood moisture content.<br />
3.1.2.5 Environmental issues<br />
No negative impact to be expected. The local situation regarding forest pathology (mainly bark beetles) has to be<br />
considered.<br />
3.1.2.6 Costs<br />
Special expenses are incurred for the cross-cut at the stem base and the frequent quality monitoring.<br />
3.1.2.7 Research needs<br />
Controlled experiments of this method are needed, particularly in comparison to live-conservation.<br />
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3.1.2.8 References<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Garrett, L. D. 1985: Delayed processing of felled trees to reduce wood moisture content. Forest Prod. J. (35)3: 55 –<br />
59.<br />
Klaiber, V.; Seeling, U.; Mutz, R.. 2002: Holzfeuchte in Fichtenstämmen (Picea abies (L.) Karst.) bei<br />
Ganzbaumlagerung im Bestand. Schweiz. Z. Forstwes.153 (6): 210-218<br />
Sachsse, H.; Oliver-Villanueva, J.-V. 1991: Physiologische Trocknung und Lebendkonservierung von<br />
sturmgeworfenen Bäumen. Forstarchiv 62: 51 – 56<br />
3.2 Wet storage<br />
3.2.1 Compact pile with water sprinkling (logs with bark)<br />
3.2.1.1 Principle/description<br />
Storage of compact piles of logs with bark under sprinklers is<br />
the most common way of storing wind-thrown trees. The<br />
experiences referred to in the following account are from the<br />
two storms in 1967 and the storm in November 1981 in<br />
Denmark, the storms in 1982, 1984 and 1997 in France, and<br />
the storms in 1990 and in December 1999 in many European<br />
countries.<br />
Figure 13: Typical log yard for wet storage of Spruce logs (Photo TUD)<br />
Using artificial water spraying the desiccation of round timber<br />
can be prevented by maintaining the green wood condition<br />
(i.e. maintaining wood moisture as high as possible).<br />
A general view of the storage in short lengths is given in Figure 14 below.<br />
Figure 14: Basic implementation for storage (Moreau 2000)<br />
It has been claimed that the main goal of wet storage is to keep the moisture content of the wood as high as possible,<br />
and attempts have been made to even increase the moisture content above the level present in the standing tree.<br />
However, observations indicate that an important part of the wood protection results from the bacterial flora present<br />
on the constantly humid log surfaces. Due to the metabolism of the bacteria and other simple organisms present in<br />
the slimy surface covering developing on the logs, this layer acts as an oxygen barrier, and it is also believed to have<br />
an antagonistic effect preventing wood-destroying fungi from establishing themselves in the wood (Moltesen and<br />
Riisgaard Pedersen 1969). From this point of view it is sufficient, but also of utmost importance to keep all log<br />
surfaces wet at all times. Apart from fulfilling this goal there is no reason to pour excessive amounts of water over<br />
the wood in an attempt to raise the moisture content above the level present in the standing tree.<br />
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Tree species<br />
Experiences and research results are available for Beech ( F a g u s s y l v a t i c a), Spruce ( Picea abies), Pine ( Pinus sp.),<br />
Fir ( Abies alba) and Oak (Quercus sp.).<br />
Preconditions<br />
Points to be considered when storing logs under sprinklers:<br />
- The location of the sprinkler storage (a wind-protected site is preferable)<br />
- The condition of the soil and the terrain at the site (vehicle traffic, drainage etc.)<br />
- Permission to set up the storage site must be obtained<br />
- Accessibility to water<br />
- Accessibility to electricity<br />
- Distance to a sawmill<br />
- Feasibility of surveillance/control<br />
The road-system in the are must be capable of withstanding the<br />
water, as well as the lorries transporting the timber.<br />
3.2.1.2 Advantages, disadvantages, practical experience<br />
3.2.1.2.1 Advantages, disadvantages<br />
Advantages<br />
•<br />
•<br />
Long-lasting storage method.<br />
In comparison to other storage methods, relatively safe<br />
round timber storage method.<br />
Figure 15: Different degrees of brown-reddish<br />
discoloration on outer parts of sapwood caused by<br />
bark extractives during wood drying (Photo TUD)<br />
• Large quantities of timber may be stored (up to tens of thousands cubic meters).<br />
• Much information on storage technique and wood quality is available.<br />
• An accepted conservation method by most of the wood processing<br />
industry.<br />
• Wood quality monitoring possible by water spraying management.<br />
• Water sprayed timber can be sawn more rapidly than fresh cut timber.<br />
• Even a short period of conservation may lead to significant savings of<br />
raw materials, especially during spring and summer time (e.g. Oak).<br />
• Compared to immersion in water, handling of logs is much easier.<br />
Disadvantages<br />
• Significant investments that may have to made prior to storage (cf.<br />
3.2.1.2.6. Costs).<br />
• Brownish-reddish discoloration occurs in the outer part of the sapwood<br />
during drying of Spruce as a consequence of bark leaching and oxidation<br />
processes between bark extractives and cellulose.<br />
• Over penetration of coats and paints (see Figure 16), especially in the<br />
case of Pine, due to heterogeneous bacteria attack of pit membranes can<br />
lead to a rejection of water-sprayed wood by certain wood processing<br />
industries (e.g. window frame manufacturers or furniture industry (see<br />
Willeitner 1971.)<br />
• After 2 or 3 years of storage, risk of fungal attack ( A r m i l l a r i a s p e c.),<br />
even under best sprinkling conditions, can lead to a very rapid<br />
deterioration of the timber within a few months (see Figure 17).<br />
• With regard to softwood, an increase in processing time for kiln drying<br />
has to be expected provided that no pre-drying has been performed.<br />
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Figure 16 Treatment with a blue test liquid<br />
shows over penetration due to pith<br />
membrane destruction (Photo TUD)
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
• During the hot season, one or even two daily inspections are necessary.<br />
• Compared to immersion, a greater amount of water is required.<br />
3.2.1.2.2 Practical experience<br />
In 2000, a number of interviews were carried out with sawmills storing logs from the storm in 1999 under sprinklers.<br />
The coordination between forests sawmills and truck-drivers was a problem at many places. Some had problems with<br />
insufficient lorry capacity, which meant that it was not possible to meet the time limit, which is the time limit set<br />
from when the tree is cut until it is placed under sprinklers and which ranges from few days to few weeks according<br />
to weather conditions. In one case, the processing in the forest was the limiting factor. In another case, the<br />
segregation of species into separate piles delayed the building of the sprinkler-system, and in a third case<br />
administrative matters concerning measurement of the wood delayed the operation because different haulage<br />
contractors using different measurement systems were employed.<br />
Figure 17: Armillaria rizomorphea and hyphae (Photo HFM)<br />
In France, administrative matters concerning security and environment issues and employment laws were highly<br />
responsible for delaying or even sometimes preventing storage under sprinklers (Braune et al. 2002). In Denmark, at<br />
least one sawmill had good experiences with storing wood under sprinklers for long periods (4 - 5 years) (Bergstedt<br />
2000a). However, according to Thorlacius-Ussing (2000) logs should not be stored for more than 4 years under<br />
sprinklers. Concerning the amount and interval of sprinkling, different opinions are put forward. In at least one case,<br />
the Beech logs are watered continuously, as this is found to be important. One sawmill warns against the use of too<br />
much water because of discoloration and destruction of the wood. This company furthermore states that the focus on<br />
the need of watering the butt-ends is exaggerated, referring to the company Tykoflex, which is not used to sprinkling<br />
the butt-ends separately.<br />
Figure 18: Decay caused by Armillaria spec. (Photo HFM)<br />
In Europe, the sprinkling period varies according to latitude. The hotter the climate, the longer the period is. For<br />
instance, the logs are normally sprinkled from April to October in Denmark (Tingleff 1991), from May to September<br />
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in Norway (Myhra 1998), and from March to the end of October in France (Anonymus 1994), but variations may<br />
occur according to weather conditions.<br />
• Maritime Pine (Pinus pinaster)<br />
S a w l o g<br />
Pine in good condition after three years. Significant improvement in mechanical properties with regard to vinyl<br />
gluing (comparison between fresh and water-sprayed timber). Using MUF glue, the mechanical characteristics of the<br />
bond remain the same (D. Reuling & al., 2003). Some discoloration may occur after two years (black line, between<br />
rings).<br />
K i l n d r y i n g : Compared to green wood, the drying rate of water-sprayed timber increases greatly. However, since the<br />
moisture content is generally higher, this gain is offset by the much larger amount of water to withdraw. For<br />
instance, some measurements carried out in a French sawmill lead to an increase in the processing time of 7%<br />
(Vautherin P. a n d a l .; ongoing research), but these figures should be considered with cautioun since the results<br />
depend on the initial and final moisture content of the timber.<br />
K r a f t p u l p w o o d<br />
Storage of Maritime Pine under water sprinkling, provided it is well carried out, preserves the wood quality for<br />
pulpwood very efficiently. After more than 40 months of wet storage, the quality of pulping logs of is maintained.<br />
Even notice a steady increase of the pulp yield is observed due to a decrease in the quantity of wood extracts.<br />
• Spruce and Fir (Picea abies and Abies alba)<br />
S a w l o g<br />
Both retained good mechanical and aesthetic properties over a period of three years. Thereafter, the logs with bark<br />
could suffer stronger fungal attack (Armillaria attack).<br />
S a w i n g p r o c e s s: At an equal energy consumption level and for the same log diameter, the speed of the sawing<br />
process seems to be 10% to 20% higher for the water sprayed logs than for the green logs. However, it should be<br />
noticed that the time spent by the blade in the wood (which is the time measured in the study) represents 25% of the<br />
total sawing process (sawing + movement of the bogie carriage for log saw + log turning). In other words, the gain in<br />
productivity can be estimated between 2.5% and 5% (Vautherin P. e t a l .; ongoing research).<br />
D e b a r k i n g: easier but the size of the bark pieces is also bigger and they can obstruct or clog up the debarker.<br />
C o l o u r: Immediately after the sawing process, the boards issued from the water sprayed logs seem to be slightly<br />
darker. However, this difference tends to disappear after the drying process (Vautherin P. et a l .; ongoing research).<br />
K i l n d r y i n g : Just like Maritime Pine, the drying rate of water sprayed timber increases greatly compared to green<br />
wood. However, since the moisture content is generally higher, this gain is offset by the much larger amount of water<br />
to withdraw. For instance, some measurements carried out in a French sawmill lead to an increase in the processing<br />
time of 35% (Vautherin P. and al.; ongoing research) but these figures should be considered with cautioun since the<br />
results depend on the initial and final moisture content of the wood.<br />
More specifically to Spruce:<br />
Brown coloration in peripheral parts of the log was observed.<br />
Soak preservation treatment: improvement in product impregnation is obvious, but product consumption increases<br />
(Anonymous 2001b)<br />
M e c h a n i c a l a n d K r a f t p u l p<br />
Wood discoloration occurred after less than 6 months of storage, resulting in a significant decrease in mechanical<br />
pulp whiteness. No problem with kraft pulp.<br />
• Beech (Fagus sylvatica)<br />
Aesthetic matters: After 6-12 months, discoloration occurred which seemd to increase when the bark was damaged.<br />
This can be reduced by using a steam processto homogenise the colour providing that a light-coloured prodyct is not<br />
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required. To achieve the smae colour, the steaming process is estimated to be between 15% and 20% shorter for<br />
water-sprayed wood compared with fresh timber. It is strongly advised to kiln dry the timber rapidly after processing<br />
to prevent any further discoloration. Some Danish studies concluded that after 18-24 months, the logs can still be<br />
used for veneer manufacture and after 24-36 months, they may be used for flooring provided that the wood is either<br />
stained or steamed.<br />
Mechanical properties remain unchanged after 4 years, according to some German studies<br />
• Oak (Quercus spec.) (Vautherin P. e t a l .; ongoing research)<br />
After three years positives results were obtained,.but discoloration of sapwood may occur in certain cases (35% of<br />
discoloured sapwood has been observed in one sawmill).<br />
K i l n- d r y i n g: characteristics, including discoloration, are similar to green wood, provided that the planks have been<br />
pre-dried. Homogeneity was slightly better.<br />
L o g i s t i cs: The benefits of this conservation method are significant. Actually, the latter prevents the wood from<br />
deteriorating during springtime (dote, mould, brown striped, etc.) and from being downgraded.<br />
With regards to productivity, debarking and colour, the same remarks as those for Fir are applicable.<br />
3.2.1.3 Recommendations (application, time limits)<br />
Experiences have shown that long lasting storage of Conifer and deciduous trees under sprinklers can be carried out<br />
with good results, and that only a few elementary precautions need to be taken (Tingleff 1991):<br />
1. Only freshly cut or wind-thrown trees should be stored.<br />
2. All stems should be generously cut clean of visible breaks and any infection by fungi since hyphae from the fungi<br />
can be present further up the stem.<br />
3. The time lapse between cutting the wood and when it is under water should be as short as possible period,<br />
especially during the warm season. The interval can range range from a few days to 2-3 weeks, depending on<br />
weather conditions.<br />
4. When building the timber stacks the butt end surfaces must be placed carefully so that they are all flush with each<br />
other<br />
5. A separate sprinkler-pipe to sprinkle directly on the end surfaces (especially the butt ends) should be established<br />
6. Daily inspections are necessary in order to find and solve problems before any damage results.<br />
7. Logs must not be debarked to prevent any drying.<br />
8. Logs should be processed as soon as possible after storage.<br />
9. Sawn boards from water sprayed logs must be correctly dried (air or kiln dried).<br />
Remark: During the sawing process 6% of the logs appear to be damaged physically by the storm (such as internal<br />
checks).<br />
Furthermore, when arranging the timber at the site is normally preferable to sort according to size; for instance, into<br />
two separate stores, one containing logs with a mid-diameter less than 25 cm and another with a mid-diameter<br />
exceeding 25 cm. Similarly, it is normally advantageous to separate different tree species, as the end surfaces of the<br />
logs normally become dark-coloured within a few months of storage and it may be very difficult to identify different<br />
tree species in a wet store. Finally, the logs should also be sorted according to the owner or/and by type of end<br />
product. However, interviews after the 1999 storm in Denmark revealed the view among some sawmillers that the<br />
important matter is to get the logs under water as quickly as possible. Separating the species may take too long,<br />
leading to quality losses.<br />
With regard to water-spraying, round timber discoloration and changes similar to that ocurring in ponded timber,<br />
have to be expected when the wood has dried. Water-sprayed round timber, like ponded timber, is also characterised<br />
by a gain in weight of up to 15% compared to green timber. This could lead to some breakage during handling of the<br />
logs. They may also become very slippery and they should be handled very carefully.<br />
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It is important not to carry out preliminary drying of the wet-stored logs prior to their dispatch because of the risk of<br />
secondary pests. On the other hand, when stored under sprinklers the moisture content of the logs is determined<br />
mainly by the moisture content in the logs at the time when they were put into store (Moltesen et al. 1974). Rewetting<br />
of logs that have partly dried prior to storage is a slow and uncertain process, particularly for Spruce.<br />
The goal is therefore to bring the wood into wet storage under sprinklers as quickly as possible after the trees have<br />
been cut, and then to be sure to keep all surfaces constantly wet.<br />
It is also recommended that storage yards that have already been established are maintained for future wind-throws.<br />
In the meantime they can be used as buffer-areas for wood storage (Tingleff 1991).<br />
Climate controlled sprinkling of timber, which involves sprinkling according to weather conditions, has been in use<br />
for some years with good results, maintaining wood quality while reducing water and energy consumption. A<br />
Norwegian project with the objective to document the effect of climate controlled sprinkling of timber with respect<br />
to wood quality and water consumption has recently been conducted (Myhra 1998). Not surprisingly, the climate<br />
controlled sprinkling reduced water consumption considerably compared to sprinkling with constant watering<br />
intensity. The interesting observation in this context is however, that the amount of water applied during periods of<br />
warm and dry weather was much higher than the traditional watering intensity. Water spraying, depending on the<br />
season of the year, ranges from 9 to 16 hours per day in areas with cold climates.<br />
It it important to consider, whether the log piles should be arranged along the road (longitudinally) or with the logs<br />
perpendicular to the road (transversely). Stacking along the road makes it easier to sell the timber in small quantities<br />
without having to move the water pipelines, but it also has a tendency to take up more space. If the stacking is done<br />
with a crane mounted on the transport lorry, the fastest and easiest solution is to stack the logs perpendicular to the<br />
road. Also, sprinkling of the log ends can be easily arranged in this way, as sprinklers can be placed along the roads.<br />
Using a lorry-mounted crane, a suitable stacking height is around 4 metres, although much higher piles can be made<br />
with special equipment (6m). To some extent the sprinkling intensity must be adjusted to the stacking height,<br />
ensuring that all logs in the pile are kept wet at all times.<br />
It is important that either sufficient access to water is achieved or the stacks are dimensioned to the available amount<br />
of water. Furthermore, it is important that the butt-ends are flush with each other in order to let the water run down<br />
the end surface of all the stems (Tingleff 1991; Anonymus 1994).<br />
The following information is obtained from French experiences.<br />
Water supply:<br />
- Minimum: 4 to 5 m 3 of water/hour/1000m 3 of logs, which corresponds approximately to 50 mm/day = 50 l/m 2 of<br />
surface sprayed/day and also 500m 3 /day/ha. Actually, the amount of water to apply is subject to some debate.<br />
Under Northern conditions (Denmark) the very minimum amount for Spruce is considered to be 25 mm per 24<br />
hours for spruce and 40 mm for Beech, but since it is impossible to achieve completely uniform spreading of the<br />
water, the sprinkler system should be dimensioned to deliver at least 50 mm per 24 hours (Tingleff 1991).<br />
- When air temperature is more than 10°C, water spraying must not be interrupted, especially during the day.<br />
- When it is freezing, below 0°C, water spraying may be stopped. It is then advisable to drain the remaining water<br />
from all the pipes.<br />
- A water recycling system can save between 50 and 80% of water depending on the type of soil and the soil<br />
drainage system (Anonymous; 2001a)<br />
- Wind influence: if the site undergoes many changes of wind direction, some parts may be badly water sprayed.<br />
Two solutions are suggested:<br />
• The site location chosen is protected naturally from wind, e.g. a valley bottom.<br />
• The number of sprinklers should be increased (which means pressure capacity must be increased).<br />
i.e. some overlap between the sprinklers is recommended.<br />
- Ground bearing capacity: must be sufficient to withstand a 50 tons truck. If a long period of water storage is<br />
envisaged, the appropriate infrastructure should be developed (water drainage, sufficient pathway width,<br />
gravelled pathways, etc).<br />
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- Environment/surroundings.<br />
• The site should be far from a forest infested by wood-destroying insects.<br />
• The site must be far from inhabited areas.<br />
Log storage /Basic requirements:<br />
Careful storage will save space, decrease the number of necessary sprinklers and increase the wood volume/wood<br />
surface ratio.<br />
- Logs must be stacked in parallel<br />
- Butts must be aligned vertically. This will allow efficient water streaming on all the logs ends.<br />
- Logs must be stacked near pathways and perpendicular to them in order to facilitate handling at the end of<br />
conservation.<br />
- Piles should not exceed 5m in height to remain within normal crane capacity.<br />
- For long length storage, head-to-foot storage save sspace and increase the used surface.<br />
Remark: The wood surface/wood volume ratio can range from 7,000 m 3 /ha to 18,000 m 3 /ha, depending on the height<br />
of the stored piles, the length of the logs and the quality of stacking.<br />
Equipment:<br />
The hydraulic pump: Pump capacity should be directly related to water requirement. Two phenomena should be<br />
taken into account:<br />
- Hydraulic loss related to the distance from the pump: if the level remains the same, the hydraulic loss is equal to 2.5<br />
daN /100m from the pump provided that the water flow is equal to 20 m 3 /h and that the pipe diameter is 3 inches.<br />
- Hydraulic loss related to the height: 1 daN loss per 10m increase in height.<br />
R e m a r k s:<br />
- The expected volumes of timber at the beginning of the project are always underestimated.<br />
- It is important to filter the water before it reaches the pump, especially if the water supply comes directly from a<br />
river.<br />
The construction of a shelter around the pump can protect it from vandalism, snow, heavy rain, etc.<br />
An alarm can also be provided in case of an abnormal decrease in pressure.<br />
The sprinklers:<br />
- The distance between sprinklers depends on the type of sprinklers and the capacity of the hydraulic pump, the<br />
idea being to keep a steady stream on all log ends. However, the following figures may be given as an example<br />
(cf. figure):<br />
• 8-12m apart for sprinklers located on top of the pile<br />
• 4-8m apart for sprinklers located at the side of the pile<br />
Figure 19: Short length storage, detail of the water system (Moreau 2000)<br />
Remark: the utilisation of sprinklers on both sides of the pile is not necessary provided that the logs are correctly<br />
stacked and their length is at least 10m. For shorter lengths (< 10m), spraying is recommended on both sides.<br />
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T h e p i p e s: both flexible pipes (hose) and rigid pipes may be used provided that:<br />
- They are protected<br />
- Their coupling is easy<br />
- Some intermediary gate valves are included at strategic points.<br />
3.2.1.4 Quality monitoring<br />
- Log appearance: Green/white/black streaks will appear at the ends of each log.<br />
- No pollution is observed. Only an increase of organic compounds is likely to occur at the beginning of the water<br />
spraying, but this phenomenon decreases rapidly after a 2-3 months period.<br />
- Maintenance/monitoring of the system: The pipes may be repeatedly filled up by suspended particles in the<br />
water and must be cleaned regulalry. This is expensive but essential. During warm periods, 1one or two daily<br />
maintenance checks are necessary since the logs may be exposed to fungal attack after only 3-4 days without<br />
water.<br />
- Water discharge must be channelled to prevent the ground from collapsing. The best solution is to use a water<br />
recycling pond.<br />
Long-term wet storage (up to 5 years) of round timber under sprinklers leads to a significant increase in the bacterial<br />
population in softwoods, notably in Pine, and a marked depletion of soluble carbohydrates. The permeability of the<br />
wood is increased because of bacterial degradation of the pit membranes, although the strength properties of the<br />
wood are more or less unimpaired. Sawn round timber is bright in appearance even after 4 years storage and sawn<br />
timber from long term stored logs suffers very little fungal defacement for up to 3 months when kept in humid<br />
conditions. This is attributed to depleted carbohydrate reserves in the wood and the presence of significant numbers<br />
of bacteria. In comparison, sawn timber from 6 months wet-stored logs is badly defaced after 3 months in damp<br />
conditions, exhibiting an early flush of moulds followed by progressive development of sapstain.<br />
A comparison of the physical properties between fresh felled wood and wood stored under sprinklers for four years<br />
showed no significant differences regarding specific gravity, modulus of elasticity, bending strength and<br />
compression strength.<br />
Fungi and discoloration cause some problems if not dealt with. Fungi and discoloration nearly always spread from<br />
the central part of the butt. In some cases fruit bodies of Fomes annosus have been found, sometimes destroying the<br />
heartwood from the butt and 3-4 m up the stem. In these cases, in spite of careful removal of all butt ends with<br />
visible fungal attack, hyphae of F . a n n o s u s must have still been present in the logs at the time of storing. Placing the<br />
logs within the site either along the road or perpendicular to the road has shown no significant influence on the extent<br />
of storage defects (Moltesen et al. 1974).<br />
Even though treatment with certain chemicals is banned in many European countries today, the results of an older<br />
Danish survey concerning sap displacement treatment and penetration/retention of chemicals in stored wood could<br />
be of some interest. The material tested had been stored under water sprinklers for 11-20 months or fully submerged<br />
in a lake for three years. Treatment with Boliden K33 (CCA) (open tank suction) showed that 22% of the poles<br />
stored for 11 months under sprinklers, 53% of those stored for 20 months under sprinklers and 67% of those stored<br />
in a lake for 3 years were rejected, based on the Danish quality requirements of delivery, compared to 11% in both<br />
control series (freshly felled wood). Pressure treatment (full-cell) of water stored poles with Boliden K33 after airdrying<br />
to app. 28% gave a similarly poor result while pressure treatment (Rueping) of water-stored poles with<br />
creosote gave very good penetration as well as retention.<br />
The results with Boliden K33 are surprising because of the well known bacterial destruction of the membranes in the<br />
tori and the parenchymatic cells which takes place during water sprinkling (Moltesen e t a l. 1972). A Norwegian<br />
study (Myhra 1998) showed that permeability of pine timber is considerably increased, although unevenly, when the<br />
timber is stored under sprinklers for more than 10 weeks. Furthermore, the results with Boliden K33 are contrary to<br />
all known foreign results. However, the hypothesis is put forward that the main reason for the unsatisfactory result of<br />
the treatment with Boliden K33 might be coagulation of the bacterial slime when mixed with the salt, blocking the<br />
pathways for the liquid (Moltesen e t a l . 1972).<br />
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However, it cannot be denied that the wood treatment process is generally improved, but leads to an overconsumption<br />
of preservative chemicals (Moreau 2000).<br />
From other experiences, it should be mentioned that timber kept in storage under sprinklers needed up to twice the<br />
time to reach the same moisture content in the drying process, compared to freshly cut wood (Tingleff 1991).<br />
With regard to quality, there are some rules that must be observed concerning the insects alreadt present in the wood<br />
and the possible infestation of adjacent forest areas. Permanent sprinkling must be carried out because these storage<br />
sites always attract fungi and insects. If interval sprinkling is to be used, it is essential that itfirst be proved to be<br />
effective.<br />
Depending on the intensity of the sprinkling it must be decided whether the piles should stay or should be removed,<br />
since the amount of water available must be adapted to the storage capacity.<br />
3.2.1.5 Environmental issues<br />
Wet storage, in particular water spraying of round timber, is a common method of wood storage subsequent to forest<br />
calamities. While pond storage used to be common, nowadays water spraying tends to be applied, using open water<br />
systems or recycling water systems. In this way, environmental stress due to bark accumulating in the sediment of<br />
water bodies, is decreased, although the properties of the wastewater from water sprays, has an environmentally<br />
negative effect, similarly to that of ponds when compared to flowing water (see chapter 2.3).<br />
The most important characteristic is the COD-value. In order to evaluate investigation results of wastewater analyses,<br />
the guide value given here is generally valid for communal wastewaters subsequent to biological clarification, i.e.<br />
prior to feeding into the flowing water. It corresponds to 140 mg COD per litre of water.<br />
- Interval water spraying<br />
For interval water spraying at 40-45 mm/h the characteristics increase over the first few weeks and in some cases up<br />
to three months. Thereafter, over a period of 1 to 2 years, they approach the measured values of the intake-water. In<br />
particular, the following findings were obtained by investigations conducted in 1967, 1972 and particularly 1984<br />
(according to Stoll 1990):<br />
COD: The values measured at the trickling water discharge, depending on the size of pile, during the initial phase<br />
were between 30 and 110 mg/l and then dropped to negligible values after the first month and sometimes only after<br />
three months. In the case of large-scale piles of more than 40,000 solid m 3 the short term stress in some individual<br />
cases may increase up to two to three times the limit value, declining, however, to harmless values after a period of 2<br />
to 3 months.<br />
BOD: In general, this value has been found to fall short of the COD values by the factor 3 to 5.<br />
pH-value, electrical conductivity:, the content of acids, salts, ions, metals and total nitrogen indicate a slightly<br />
increased value over the first few weeks. They remain, however, far below the required guide values for clarified<br />
waters. Over the first few weeks the pH-value slightly increases (>1 pH-unit), thereafter approaching the starting<br />
value. The investigations point to no alarming levels in the wastewater due to water spraying,, over the short or long<br />
term. These low levels can be reduced further by sedimentation basins (removal of bark particles etc.) and by<br />
buffering through lime gravel.<br />
Regarding nitrate, the concentration decreased after the log piles had been water-sprayed.<br />
In Norway a project was conducted in 1996/1997 with the following three objectives: 1) to investigate if there is a<br />
difference in the quality of waste water from climate controlled sprinkling compared to traditional sprinkling of<br />
timber; 2) to investigate the effect of a sand filter under a timber pile; and 3) to investigate the quality of the waste<br />
water from a timber yard.<br />
The results from the experiments showed high concentrations of organic substances (COD and DOC) and total<br />
phosphorus and potassium in the wastewater during the first two weeks after the sprinkling started. Comparison of<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
climate controlled and traditional sprinkling of timber generally showed no marked difference. Comparison of the<br />
timber pile with and without sand filter as an under layer showed that the sand filter retained nitrogen and<br />
phosphorus. The sand filter showed a leakage of calcium, iron, potassium, magnesium and manganese at the end of<br />
the experimental period. In the wastewater from the timber yard, the analysis showed high concentrations of carbon<br />
bound to particles in the water. This carbon is less biologically available, and will probably have insignificant<br />
influence on the environment (Myhra & Gjengedal, 1998).<br />
- Water spraying in recycling water systems<br />
Experiences from Denmark as well as Norway and Sweden show that the COD values of the wastewater coming<br />
from the timber piles is very high during the first couple of months (figures between 200 and 300 mg/l are common),<br />
after which it decreases to a much lower level (normally around or below 50 mg/l). The surveys show that during the<br />
first months of sprinkling, the water running off the stems contains such large amounts of dissolved organic<br />
substances that if discharged directly into streams it can cause damaging pollution. However, this only occurs in<br />
situations where the discharged amount is very high compared to the amount and renewal of water in the stream. If<br />
there is a risk of this, the water should be recycled.<br />
The advantages of using recycled water:<br />
1. The water is oxidised, leading to a biological degradation of the organic substances<br />
2. The use of water is reduced<br />
3. Less energy is required to pump up water (Moltesen 1982).<br />
Recycling the water admittedly also has some disadvantages:<br />
1. Suspended solid particles in the water bay cause malfunctioning of the sprinklers<br />
2. The large reproduction of micro-organisms in the sprinkling water may cause bacterial slime to form, in extreme<br />
cases clogging the sprinklers.<br />
3. Observations indicate that breakdown of pit membranes in Conifer timber may proceed faster if the sprinkling<br />
water is recycled, leading to permeability changes (Bergstedt 2000b).<br />
The values measured for pH, conductivity, concentration of various metal salts, ions, total nitrogen etc. are not<br />
significant in this context. However, the increase of the COD-values is critical. In single cases they may increase to<br />
three or four times the required wastewater guide value. Also, in the long run (1 to 2 years) the load of the used water<br />
will remain as expected at a relatively high level. Though being considerably higher than in sewage waters after<br />
biological clarification, the total amount of these concentrations, however, is very low compared to communal<br />
sewage waters and there is no problem feeding thewastewaters into flowing waters.<br />
- Groundwater pollution<br />
No systematic investigations of groundwater pollution in connection with wet storage of logs have been carried out<br />
so far. Sampling is not expected to show any serious changes in groundwater quality.<br />
A potential risk of polluting the ground water is only present if the soil is easily penetrated and where the surface of<br />
the groundwater is near ground level. However, the sprinkling results in leaching of organic and inorganic substances<br />
from the bark and the wood into the wastewater from the timber yard, which means that even on soils with good<br />
penetration the effect will decrease because of small particles of bark infiltrating the upper layer of the soil,<br />
preventing the water from passing through quickly. This means that solved as well as unsolved matter, as the water<br />
sinks, will be absorbed partly by soil particles and partly by micro-organisms (Moltesen 1982).<br />
The conclusion from storage sites after the storms in 1967 was that storage of barked Spruce logs under sprinklers<br />
creates no severe risk of pollution to the environment, if certain precautions are taken in vulnerable environments<br />
and if this method is only used once. There was no severe or long-lasting environmental damage in any of the large<br />
stocks in Denmark (Moltesen 1982). However, if the tendency is that the storage site will continue to be used for<br />
storage in the future, the environment will be affected to a higher extent and other precautions must be taken.<br />
- 46 -
3.2.1.6 Costs<br />
- General remarks<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
This is a relatively expensive method that is suitable for the conservation of large amounts of logs, especially after<br />
calamities. The total costs in the first year are generally rather high due to the costs of investment. Thereafter the<br />
incidental ongoing costs are relatively low. This method has been in use for a long time now and it is one of the most<br />
practical and economical methods available for log conservation.<br />
In Denmark, the costs for establishing wet stores with sprinklers following the 1999 storm was in approximately 10<br />
Euro per m 3 , including drilling of wells for water procurement . The annual running costs are estimated to be in the<br />
range of 1 to 2 Euro/m 3 .<br />
The cost of setting up a storage yard with logs along the road were in 1981/1982 believed to be 50% higher than a<br />
storage site with logs perpendicular to the road. The operating costs were the same for the two. The value loss during<br />
wet storage compared to freshly cut wood is difficult to work out, but several sawmills in Denmark have estimated<br />
that it is in the range of 2-4% of the prices of raw material. This is in addition to the loss in income from the sale of<br />
bark.<br />
In one forest district, the extent of damage to stored logs from the storms in 1967, together with the economic<br />
consequences, were examined in three test cuttings. They showed that when stored for just over two years the<br />
decrease in value of round-wood was just below 2%, compared to a decrease of 6% when stored for 4 years<br />
(Moltesen et al. 1974).<br />
In Germany figures can be taken from the storage of 100.000 to 120.000 m 3 of Spruce long pole under sprinklers<br />
(Haupthoff, 2000). The investments costs (installation of the log yard, construction of roads, sprinkling facilities etc.)<br />
were 0.35 Euro/m 3 . The monthly costs for 18 hours daily sprinkling were 0.28Euro/m 3 . The water consumption was<br />
180 m 3 /hour. After 3 to 4 years a price of 55 to 65 Euro/m 3 could be achieved on the national round timber market.<br />
The French (Anonymus 1994) state that comparing the cost of implementating different conservation methods is a<br />
very difficult task, as many parameters must be taken into account: e.g.:<br />
- Type of conservation methods<br />
- Initial site condition (such as transport accessibility; infrastructure, etc.)<br />
- Distance from the location of the water supply<br />
- Equipment (depending on the log storage method: tight or scattered piles)<br />
- Electrical wiring<br />
- Etc.<br />
There are three types of costs: preliminary investments; functioning costs; and costs following the period of<br />
conservation. In general, the costs depend greatly on the investors’ policy.<br />
Preliminary investments<br />
- Infrastructure<br />
- 0 to 5.500 €/ha for a site partially or totally prepared (in terms of transport accessibility).<br />
- 7.000 to 9.500 €/ha for a site where considerable road reinforcement has to be carried out.<br />
- 13.500 to 19.000 €/ha for a site where almost everything has to be done.<br />
- Equipment necessary for water spraying the logs<br />
- 1.8 €/m 3 for efficient/tight storage.<br />
- up to 2.6 €/m 3 for scattered storage (scattered piles).<br />
- 47 -
- Electrical wiring<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- 0.3 to 1 €/m 3 depending on the distance from the electrical source.<br />
- Labour force necessary to set up the site<br />
- 0.3 €/m 3 .<br />
To illustrate these figures, the mean, the minimum and the maximum prices with regard to 15 sites in Aquitaine after<br />
the 1999 storm in France, are summarised in the table below (D. Reuling; CTBA info n° 99; March-April 2003).<br />
Table 6: Preliminary investments<br />
Inverstments<br />
Infrastructure<br />
Electrical wiring<br />
Water spraying equipment<br />
Miscellaneous<br />
TOTAL<br />
Mean<br />
(EURO/m 3 )<br />
7.65<br />
0.61<br />
2.24<br />
2.62<br />
13.13<br />
- 48 -<br />
Min<br />
(EURO/m 3 )<br />
1.42<br />
0.25<br />
0.81<br />
Max<br />
(EURO/m 3 )<br />
Another practical way to visualise the costs of preliminary investment could be with the following pie chart Figure<br />
20:<br />
Water spraying device<br />
17%<br />
Remarks (S. Costa; L. Ibanez 2003):<br />
Miscellaneous<br />
20%<br />
Electricity wiring<br />
4%<br />
• There is usually a significant difference in investments based on whether the site is designed to be permanent or<br />
not. A permanent site costs in average 6 €/m 3 more than a non-permanent site.<br />
• Usually, more investments are dedicated to hardwood conservation than for softwood due to a higher initial<br />
value of the raw material.<br />
• A recycled water system costs around 30% more than an open water system. For this reason, it is advised to<br />
implement a recycling system just in case of a shortage of water at the vicinity of the storage yard.<br />
Functioning costs<br />
- Rent or purchase of the terrain: 0.07 €/m 3 /year<br />
- Electrical consumption: 0.37 to 0.55 €/m 3<br />
0.46<br />
5.93<br />
24.2<br />
1.07<br />
3.09<br />
6.86<br />
33.76<br />
Infrastructure<br />
(including the price of the terrain)<br />
59%
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- Water consumption: 0.1 €/m 3<br />
- Maintenance: 0.1 €/m 3<br />
- Insurance: 0.1 €/m 3<br />
- Daily monitoring: 0.91 and 1.31 €/m 3 depending on the distance of the site from the company in charge of<br />
the storage yard.<br />
- Installing/dismantling of the water spraying device: 0.1 €/m 3<br />
-<br />
More globally, the functioning costs range from approximately 1.43 to 2.2 €/m 3<br />
Costs following the period of conservation<br />
- Log handling: 0 to 2.3 €/m 3<br />
- Site restoration: 0.1 to 0.76 €/m 3<br />
- Log transport: 2 to 8.5 €/m 3 depending on the distance from the storage yard to the sawmill.<br />
3.2.1.7 Research needs<br />
- A r m i l l a r i a attacks in water storage.<br />
3.2.1.8 References<br />
Anonymous 2001a: Impact des aires de stockage de bois par aspersion sur le milieu naturel en Franche-Comté<br />
(Environmental impact of water spraying conservation method in Franche-Comté) ; ADIB ; October 2001<br />
Anonymous 2001b: Résultat de la 2ieme campagne de sciage-test de bois chablis résineux stockés sous arrosage<br />
(Results of the second campaign of sawing-test for wind-blown softwood stored under water spraying) ; ADIB ;<br />
November 2001<br />
Anonymous 1994: Manuel d’exploitation Forestière – Tome 2, AFOCEL CTBA<br />
Arnold, M., 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes.<br />
144(11):843-858<br />
Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrungen nach dem Orkan „Lothar“ (1999). Projekt<br />
WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (unpublished report)<br />
Arnold, M.; Sell, J., 1992: Qualitätserhaltung von Rundholz bei längerer Lagerung - I. Das Projekt 'Lagerung von<br />
Sturmholz'. Forschungs- u. Arbeitsber. EMPA-Abt. Holz, Nr. 115/25, EMPA, Dübendorf, Switzerland.<br />
Braune et al. July 2002: Le stockage du bois après la tempête de 1999. Retour sur l’expérience de la Lorraine.<br />
ENGREF, Rapport de l’exercice MIF<br />
Bergstedt, A. 2000a: Besøg på vandlagre af stormfældet nåletræ, september-oktober 2000. Internal report, KVL, 14<br />
p.<br />
Bergstedt, A. 2000b: Lagring af råtræ. Skoven, no. 1, pp. 38-40.<br />
Bonnet, J.L.; Mirjolet J. 2002: Evolution des propriétés du bois de hêtre et plus particulièrement sa coloration lors de<br />
conservation par immersion ou aspersion (Assessment of the beech (Fagus sylvatica) properties and more precisely<br />
its coloration following a period of immersion or water spraying) Paris: CTBA internal report ; 2002<br />
Borga, P. ; Elowson, T. ; Liukko, K. 1996: Umweltbelastung durch Abwässer bei der Nadelnutzholz-Beregnung.<br />
Holz-Zentralblatt 122: 2146<br />
Costa, S.; Ibanez, L. 2003: Evaluation du stockage des bois en France après les tempêtes de décembre 1999; LEF;<br />
décembre 2003<br />
- 49 -
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Engesser, R. 2003: Pilzbefall an nassgelagertem „Lothar“-Rundholz. Wald und Holz 11: 52 - 55<br />
Haupthoff, W. 2000: Sturmholz-Nasslager bei Gaggenau-Bad Rothenfels. Holz-Zentralblatt: 1199<br />
Helgerud, H. H.; Gjengedal, E. 1998: Avrenning fra tømmervanning. Norwegian Institute of Wood Technology<br />
(NTI), Rapport no. 41, Oslo, March 1998, 33 p.<br />
Liukko, K., 1997: Climate-adapted wet storage of saw timber and pulpwood: An alternative method of sprinkling<br />
and its effect on freshness of round timber and environment. Silvestria No. 51. SLU, Uppsala. 44 pp. + 4 artikler.<br />
Moltesen, P.; Riisgaard Pedersen, E. 1969: Forsøg med opbevaring af stormfældet rødgran: Afbarkning, kemisk<br />
beskyttelse og rodlagring. Dansk Skovforenings Tidsskrift 1969, vol. 54, pp. 1-56.<br />
Moltesen, P.; Borsholt, E.; Bang, L. 1972: Forsøg med imprægnering af sprinkler- og vandlagrede granmaster.<br />
Dansk Skovforenings Tidsskrift, 1972, pp. 279-303.<br />
Moltesen, P.; Dalgas K.F.; Herløw, M. 1974: Lagring af stormfældet gran under overrisling. Dansk Skovforenings<br />
Tidsskrift, 1974, pp. 253-295.<br />
Moltesen, P. 1982: Forureningsrisiko ved lagring af uafbarket gran under overrisling eller i søer og damme. I n :<br />
Tingleff (1991), pp. 204-211<br />
Moreau J. et al. 2000 : Stockage des bois par aspersion. Aspect réglementaire, techniques et économiques. Afocel<br />
Myhra, H.H. 1998: Klimastyrt tømmervanning. Norwegian Institute of Wood Technology (NTI), Rapport no. 40,<br />
Oslo, March 1998, 43 p.<br />
Reuling, D.; L. Podgorski and G. Legrand 2003: Pin maritime : apte à la finition et au collage (Maritime pine :<br />
gluing and finishing possibilities) ; CTBA info ; CTBA ; July-August 2003<br />
Thorlacius-Ussing, H. 2000: Tag det med ro B stormfaldserfaringer 1981 fra Rold skov. Skoven no. 1, 2000, p. 11-<br />
12.<br />
Tingleff, T. 199): Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets<br />
sprinklerdepoter i 1982-1985. Dansk Skovbrugs Tidsskrift, 1991, pp. 115-226.<br />
Vautherin, P. 2000: La conservation des grumes Forêt de France n° 431.<br />
Vautherin, P. et al: Comparison between logs conserved under water spraying conditions and green timbers in terms<br />
of sawing, drying, and planing processes, and in terms of environmental and trade issues ; CTBA : ongoing research<br />
Willeitner, H. 1971: Anstrichschäden infolge Überaufnahmefähigkeit des Holzes. Holz-Zemtralblatt Nr. 157: 2291-<br />
2292<br />
Winkler, M. 2002: Erfolgreiche Nasslagerung von Zuger „Lothar“-Holz. Zürcher Wald 4: 14 – 18<br />
- 50 -
3.2.2 Ponding/Immersion (logs with bark)<br />
3.2.2.1 Principle/description<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- Principle<br />
Desiccation of the round timber may be prevented by<br />
immersion in water (ponding), thus maintaining or<br />
increasing the moisture content present in the standing<br />
tree. A secondary infestation of the wood is to be averted<br />
as far as possible.<br />
Figure 21: A forest lake is an ideal place for immersion of a small<br />
amount of round wood (Photo HFM)<br />
Tree species:<br />
Experiences and research results are available for Beech,<br />
Oak, Spruce, Pine, and Fir.<br />
Preconditions:<br />
Suitable water bodies; suitable infrastructure near the water bodies; permission from authorities; undamaged and<br />
freshly cut timber; unhealthy parts generously removed from the wood; and at least two thirds of the stem diameter<br />
permanently immersed.<br />
3.2.2.2 Advantages, disadvantages, practical experience<br />
3.2.2.2.1 Advantages, disadvantages<br />
Ponding/immersion is a long-term and safe round timber storage method in comparison to other storage methods. A<br />
considerable amount of information on this storage technique and the resulting wood quality is available. The<br />
conservation method is accepted by most of the wood processing industry. Wood stored under water can in some<br />
cases be sawn and dried more rapidly than freshly cut timber. Provided that the wood has been properly stored its<br />
quality can be maintained for several years.<br />
Spruce: A brownish-reddish discoloration of the outer sapwood occurs during storage due to bark substances being<br />
leached into the wood and subsequent oxidation processes between bark extractives and cellulose.<br />
Bacteria attacking pit membranes can cause increased permeability, leading to excessive and uneven penetration of<br />
coats and paints. This in turn can mean rejection of the wood by certain wood processing industries (e.g. windowframe<br />
manufacturers or the furniture industry).<br />
Beech: round timber ponding may cause a reddish-brown discoloration of both the log surfaces and the end faces,<br />
penetrating towards the stem centre at various lengths.<br />
3.2.2.2.2 Practical experience<br />
F r a n c e ( B e e c h ) (J.L. Bonnet and J Mirjolet 2002):<br />
- Change in colour was evident after one month of storage in immersion, compared to 6 months with water<br />
sprinkling. In order to maintain their value, the logs should be steamed following storage, for homogenisation of<br />
colour/darkening of the boards (for plywood it can ressemble exotic wood in appearance). To obtain the same<br />
hue, the duration of the steaming process is estimated to be between 20 and 25% less for immersed wood<br />
compared to fresh timber.<br />
- Immersed logs are darkener in colour than water sprayed ones.<br />
- After 2 years no degradation of mechanical properties was found.<br />
- If it is not possible to empty the pond, it can often prove difficult to find and remove the logs from the dark<br />
coloured water.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
In Denmark, ponding has not been common, but after the two wind-throws in 1967, ponding of logs with bark was<br />
tested, and some experience was gained from these experiments. Spruce and Beech were stored using this method.<br />
Rather large quantities of wood were stored in the lake Esrum Sø in North Sjælland, and smaller stores were<br />
established in natural ponds and in derelict, water-filled gravel pits.<br />
Both single-log storage and ponding of log bundles was tried. In both cases, problems occurred with logs that floated<br />
(Spruce), since the part of the log protruding above water level was subject to biological degradation which<br />
proceeded rather quickly. Conversely, the sunken logs (Beech) were well preserved, but proved very difficult to<br />
salvage from the bottom of the lake at the end of the storage period.<br />
3.2.2.3 Recommendations (application, time limits)<br />
Patzak and Löffler (1988) recommend the following minimum conditions to be observed for immersion storage of<br />
timber (see Table 7). Coniferous wood should be subject to loose bundling into units of 10 to 20 m;, whereas bundles<br />
of 6 to 12 m; apply to broad-leaved species. Bundles should be identified by fixing buoys to them so as to avoid loss<br />
of timber due to sinkers.<br />
It is advised to allow for control of the water level (by emptying/filling the tank/pond) to facilitate the storage and<br />
handling of the logs. The logs must be stored correctly to facilitate handling. Clay ground prevents water from<br />
leaking from the tank and seeping out through the soil.<br />
Table 7: Water storage of round timber, forms of storage and requirements (after Patzak and Löffler 1988)<br />
Single-log storage<br />
66% of log under water<br />
5.0 m5 surface/m; wood<br />
0.8 – 1.0 m<br />
single layer<br />
Ponding/immersion<br />
ponds, lakes, (rivers)<br />
Storage as rafts<br />
multiple layers<br />
70-75% of logs under water<br />
water surface (m²) required / m³ wood<br />
(minimum water surface = 500 m5)<br />
5.0 m5 /m;<br />
0.8 – 1.0 m<br />
3.0 m5/m;<br />
Water depth required<br />
(maximum 3 m)<br />
1.5 m<br />
- 52 -<br />
Storage in bundles<br />
80% of logs under water<br />
1.5 – 3.0 m5 surface/m; wood<br />
Due to its limited possibilities and for reasons of water protection, storage of round timber in stagnant water bodies<br />
tends to be rare. Wood quality evaluation and recommended time limits for different tree species are as follows:<br />
- Beech: positive, > 2 years (tannin discolorations).<br />
- Oak: very positive, > 2 years.<br />
- Spruce: positive, > 2 years (tannin discolorations).<br />
- Pine: very positive, > 2 years.<br />
- Fir: very positive, > 2 years.<br />
3.2.2.4 Quality monitoring<br />
No information available.<br />
3.2.2.5 Environmental issues<br />
Few studies of water quality have been performed concerning log storage in ponds. The findings largely coincide<br />
with the pollution values for runoff water from artificial water spraying of logs. Values depend strongly on the<br />
wood/water ratio and on the absence or presence of water flow through the pond.<br />
If the flora and fauna is to be protected from damage, it is important not to store large quantities of wood in small<br />
>2.0 m
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
bodies of water. In the Danish ponding experiments, flora and fauna were only seriously affected in one case: a pond<br />
in a former gravel pit, covering an area of 0.3 ha and having a depth between 1 - 4 m, where 1 800 m 3 of Beech logs<br />
were stored. When half of the logs had been placed in the pit, all the fish and crustacians died. However, the original<br />
conditions were re-established surprisingly quickly, as soon as the logs were removed.<br />
In Denmark the authorities are reluctant to allow storage in natural lakes or ponds because of uncertainty regarding<br />
the effect on the environment. Although no scientific studies have been undertaken, it is known that in extreme cases<br />
(cfr. above) the oxygen consumption during decomposition of the dissolved and suspended organic matter has had a<br />
fatal effect on fish and other aquatic organisms (Tingleff 1991).<br />
It is highly important not to immerse wood that has previously been chemically treated in order to prevent insect<br />
infestation.<br />
3.2.2.6 Costs<br />
Two different scenarios are possible:<br />
a. The pond already exists, no excavation works to be undertaken except gravelling of the embankment and<br />
some miscellaneous work such as setting up a device to fill and empty the pond: 15 EURO/m 3 plus<br />
VAT.<br />
b. The pond must be built, excavation work, embankment to be gravelled and other miscellaneous work: 35<br />
EURO/m 3 plus VAT.<br />
Operational costs: no maintenance should be necessary, but recovering the timber may become rather costly.<br />
R e m a r k s :<br />
- In spite of these rather high costs, it should be emphasised that these ponds may be also used for fishing, tourism,<br />
water reserves for animals, etc.<br />
- Moreover, if further storm damage occurs, the ponds can be re-used immediately at no expense.<br />
- Finally, these ponds can also be used to regulate timber supplies for sawmills<br />
3.2.2.7 Research needs<br />
No information available.<br />
3.2.2.8 References<br />
Bonnet, J.L.; Mirjolet, J. 2002: Evolution des propriétés du bois de hêtre et plus particulièrement sa coloration lors de<br />
conservation par immersion ou aspersion (Assessment of the beech (Fagus sylvatica) properties and more precisely<br />
its coloration following a period of immersion or water spraying) Paris: CTBA internal report.<br />
Patzak, P.; Löffler, H. 1988: Ökonomie der Langzeitlagerung von Stammholz und Schnittholz. Forstliche<br />
Forschungsberichte München, Nr. 88<br />
Tingleff, T. 1991: Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets<br />
sprinklerdepoter i 1982-1985. Dansk Skovbrugs Tidsskrift, 1991, pp. 115-226.<br />
Vautherin, P. 2000: La conservation des grumes Forêt de France n° 431 ; 2000<br />
- 53 -
3.3 Storage under drying conditions<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
3.3.1 Log pre-drying in covered cross-piles (logs without bark)<br />
3.3.1.1 Principle/description<br />
Storage of debarked logs in loose cross piles allows moderate drying of<br />
wood with a relatively low risk of infestation. To protect the piles against<br />
precipitation and direct sun light a wooden roof or a cover with plastic<br />
sheets is used (see Figures 22 and 23).<br />
Figure 22: Cross-pile with hard cover roof (sketch FVA)<br />
3.3.1.2 Advantages, disadvantages, practical experience<br />
3.3.1.3 Recommendations (application, time limits)<br />
The drying of logs was developed as a process for pre-drying<br />
construction timber. There are problems with log pre-drying in<br />
covered cross piles related to thelength of time needed.<br />
Furthermore, is it not possible to control the drying process. It<br />
is very important that the moisture content is less than 30%.<br />
When logs are stored for longer than 5 months there may be<br />
problems with cracks. This can lead to a reduction in wood<br />
quality, especially in the case of non-covered piles where<br />
cracks can cause infections, such as red stripe fungi.<br />
Figure 23: Cross-pile sheltered with plastic sheet (Photo BFH)<br />
The sawmill should be warned about the risks. In addition, the following points are important:<br />
- It is important to choose the correct site for storage. Wind-exposed places are recommended. When logs are stored<br />
for less than 5 months, they can be stored in direct sunlight.<br />
- When storage time is longer than 5 months, the risks are greater. Wetting must be avoided to prevent wood<br />
discoloration and decay.<br />
- Every log must be debarked and placed on the pile to allow good air circulation<br />
- To guarantee adequate air circulation logs must be stored in cross piles ensuring good stability.<br />
3.3.1.4 Quality monitoring<br />
This type of storage can work well with Spruce, Larch and<br />
Douglas fir, but Pine may well become stained during the storage<br />
period. It is recommended that only fresh, healthy cut wood with<br />
no signs of beetle or fungi attack is used for this method of<br />
storage.<br />
Figure 24: Covered cross-piles need continuous control against storm damages<br />
of the plastic sheets (Photo HFM)<br />
3.3.1.5 Environmental issues<br />
Log pre-drying in cross piles is a cost effective and ecological<br />
alternative to chemical wood protection and to kiln dried wood. There is no need to use insecticide after debarking.<br />
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Furthermore, CO2 emissions, caused by kiln drying, can be avoided.<br />
3.3.1.6 Costs<br />
An example of the costs in Southern Germany costs is approximately 10.23 €/cubic metre. This includes 8.18 Euros<br />
for transport of the logs to the storage site and 1.80 €/cubic metre for manipulation and maintenance of the pile.<br />
Extension of the storage period has little effect on the costs.<br />
3.3.1.7 Research needs<br />
- Comparative assessment of species susceptibility to staining up to and after 5 months storage.<br />
- Measurement of drying rate by moisture content determinations at different times of the year.<br />
3.3.1.8 References<br />
Anonymus 2000: Lagerung und Konservierung von Stammholz B Trockenlagerung: Merkblatt der FVA Baden-<br />
Württemberg Abt. Waldnutzung und Waldschutz<br />
Anonymus 2000: Trocknung von Rundholz für trockenes Schnittholz im Bauwesen. Informationsdienst Holz, 8<br />
pages.<br />
Anonymus 1995: Trockenkonservierung von Nadelrundholz als Alternative zur Berieselung und zur Erzeugung von<br />
trockenem Bauholz. Holz-Zentralblatt 121 (1995) Nr. 35 und 36:<br />
Wauer, A. 2000: Verfahren der Rundholzlagerung LWF Nr. 29: Berichte aus der bayerischen Landesanstalt für Wald<br />
und Forstwirtschaft<br />
Welling, J.; Lang, A.; Scharai-Rad, M.; Speckels, L. 2000: Trocknung ganzer Stämme im Wald.<br />
Forstmaschinenprofi Januar 2000 S.66 ff<br />
3.3.2 Rapid pre-drying in open cross piles (logs without bark)<br />
3.3.2.1 Principle/description<br />
P r i n c i p l e :<br />
By debarking and careful piling to allow for good aeration, wood moisture can be rapidly reduced to a level where<br />
there is no risk of infestation. (30-25% wood moisture related to oven-dry weight that is below fibre saturation<br />
point).<br />
Tree species:<br />
Experience research results are available for Douglas Fir,<br />
Spruce, Larch and Pine.<br />
Figure 25: Open cross piles: left cross pile sprayed with liquid choke to<br />
prevent logs against over heating due to direct sun light (Photo HFM)<br />
3.3.2.2 Advantages, disadvantages, practical experience<br />
Fairly large quantities of short Spruce timber (mostly in<br />
lengths of around 2.5 metres) were bought by the Danish<br />
packaging industry, and stored with bark under drying<br />
conditions, both in the open, in windy places in the storm<br />
felled forest or in special storage yards. The timber was stored in this way for up to two years with good results.<br />
Limited discoloration (red stripe caused mainly by S t e r e u m s a n g u i n o l e n t u m) and drying checks were allowable in<br />
the products (mainly pallets, some crates/boxes) and the losses in value were negligible. Some timber intended for<br />
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sawing of structural products was also stored in this way, but in this case it was stored for a shorter period of time<br />
and the timber was sawn before serious drying checks appeared.<br />
Fir/Spruce: 1 year but some aesthetic defects occur.<br />
3.3.2.2.1 Advantages<br />
• In the case of dry storage, timber designated for construction can be pre-dried without using kiln drying. Such<br />
timber shows no increased problems of deformation after sawing when compared to other timber. This storage<br />
method could allow traditionally-oriented sawmills to respond quickly to customer demand for construction<br />
wood. Furthermore, the pre-drying of logs in this way is viewed as an environmentally friendly option for<br />
construction.<br />
• The target moisture content of 25 - 30% in the sapwood is achieved with winter felling followed by drying in the<br />
spring and summer.<br />
• Rapid seasoning of the sapwood prevents fungal infections.<br />
• Expensive sheeting, which has a short lifespan, can be avoided.<br />
• Advanced piling technology allows for unidirectional piles to be handled faster and more economically.<br />
• The short time periods allow for continuous delivery of the pre-dried round wood to the sawmills in the peak<br />
summer periods.<br />
• The piles can be maintained within normal forest operations in the forest districts.<br />
• Investment costs for sprinklers are not incurred.<br />
• Permission according to water legislation is not necessary.<br />
• There is no environmental pollution due to discharge of water from sprinkling<br />
• The ease with which piles can be accessed for quality assessment of the wood means that timber can be sold<br />
when marketing.<br />
• Large piles of up to 200 m³ can be used, depending on the range of the truck-crane, the size of the storage yard<br />
and the intended volume of the quantities to be sold.<br />
• The conserved wood may be well below fibre saturation point, generally between 15 and 22%, depending on the<br />
weather. This permits the delivery of lumber that is dry, largely size-consistent, of arbitrary cross sections,<br />
without the need for further kiln-drying.<br />
• Sawn wood produced from the pre-dried round timber is largely size-consistent.<br />
• The sawn wood can be subsequently kiln-dried, which can be carried out quickly, economically and at a high<br />
drying capacity.<br />
• Round timber conservation is more economical and carries fewer risks than kiln-drying of large diameter<br />
lumber.<br />
• Pre-dried round timber can be transported more easily.<br />
• In periods of frost pre-dried round timber contains very little ice, compared to green round timber. It can,<br />
therefore, be easily sawn.<br />
• Insecticide application to round timber is unnecessary if debarking is performed early.<br />
3.3.2.2.2 Disadvantages<br />
During the process is it possible for cracks to appear and infection<br />
can occur due to debarking, especially where there are side cuts.<br />
Storage should be limited to less than 5 months and it should be<br />
remembered that it is generally more suitable for sawn timber rather<br />
than round wood.<br />
• Seasoning must be disrupted prior to reaching fibre saturation<br />
point to avoid excessive checking.<br />
• Depending on the weather, large checks may form after the<br />
initial drying. If sawing is not possible prior to this, then the<br />
unidirectional piles should be disassembled and loose piles<br />
formed to reduce the drying.<br />
• Air drying, by definition, is dependent on the weather and is<br />
therefore difficult to control.<br />
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Figure 26: Intensive cracks as a result of a drying<br />
process that is too rapid and to low under fibre<br />
saturation point (Photo HFM)
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
• If drying is too slow, fungal damage can occur. If drying is too fast and long, there is a risk of excessive checks<br />
(see Figure 26).<br />
• The forestry and timber industry lack experience of the method.<br />
• In the case of large storms the area needed for dry conservation is also large.<br />
• Sawing of pre-dried round timber requires more energy than sawing of green wood.<br />
• When sawing pre-dried round timber dust formation is more intense.<br />
• The pulp industry prefers wet chips. However, using dry woodchips for chipboard production has advantages.<br />
• Extra costs are incurred for round timber transportation, piling and maintenance.<br />
3.3.2.2.3 Practical experience<br />
- Before preparation<br />
Only healthy wood should be used. After debarking the logs should be pre-dried for one or two weeks.<br />
- Pile construction<br />
Firstly, a layer of strong logs should be made as a base for the pile. It is important that there is enough distance<br />
between this layer and the ground. Spacers should be used when the pile construction seems instable. The top layer<br />
should extend beyond the pile to facilitate covering. Construction takes 2.5 hour per 150m 3 , excluding transportation<br />
time.<br />
- Sheeting<br />
Sheeting, to protect the pile from rain, does not have to be carried out immediately, unless rain is likely. Plastic foil<br />
with a textile structure is recommended. Sheeting takes 1.5 hours per pile. With correct construction the pile is<br />
maintenance free.<br />
Experience (Spruce, Fir)<br />
• It is not possible to control the process, as the piles are exposed to prevailing weather conditions.<br />
• Excessive sunlight can cause cracks.<br />
• Spruce is more likely to crack than Fir.<br />
• Cracks can cause infection with blue stain and red stripe.<br />
• The process is relatively expensive.<br />
- Suitable tree species<br />
Conifers (without bark): Spruce, Fir, Douglas Fir, and Larch<br />
3.3.2.3 Recommendations (application, time limits)<br />
This expensive process should only be applied in with the cooperation of the buyer. If properly applied, this process<br />
can eliminate storage damage for up to three to five months. The success of the process depends on various<br />
conditions and beetle infestation can affect the quality of the wood. The use of plastic sheets requires neat piles and<br />
good spacing to soil level. The storage site should be situated in an airy, warm place that is not too exposed to solar<br />
radiation. The possibilities for successful conservation, especially in the case of Spruce and Fir, are good, but storage<br />
should take place not more than three weeks after debarking. Fast drying reduces moisture content, preventing<br />
biological damage, but if it is too rapid, cracks may occur.<br />
The success of dry conservation of coniferous round timber whilst maintaining wood quality depends on the<br />
conversion piling technique and on the local weather during the storage period. Only extremely rapid drying<br />
guarantees effective prevention of fungal discolorations.<br />
Dry conservation under bark is particularly suitable for higher-grade wind-blown wood, as in this case both wet<br />
storage and dry storage without bark are less effective because of the desiccation already set in. Wet storage is<br />
preferable to dry storage.<br />
Due to the potential of large equipment and personnel bottlenecks, this method cannot be applied on a very large<br />
scale. Recommendations and wood quality projections for different tree species are as follows:<br />
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- Douglas Fir: relatively positive, up to 2 years.<br />
- Spruce: relatively positive, up to 2 years (blue stain and red-striping); positive in the case of fast drying<br />
and storage only up to three months.<br />
- Larch: relatively positive, up to 2 years.<br />
- Pine: relatively negative, (blue stain).<br />
3.3.2.4 Quality monitoring<br />
This method can work well with Spruce, Larch and Douglas Fir, but blue stain is a major problem with Pine. It is<br />
recommended that fresh, healthy cut wood with no signs of beetle or fungi attack is used.<br />
3.3.2.5 Environmental issues<br />
Log pre-drying in cross piles is a cost effective and ecological<br />
alternative to chemical wood protection and to kiln dried wood.<br />
There is no need to use insecticide on the logs after fast<br />
debarking. Furthermore, high CO2 emissions caused by kiln<br />
drying, can be avoided<br />
Figure 27: Spraying of debarked logs against wood boring beetles should be<br />
avoided when ever possible (Photo HFM)<br />
3.3.2.6 Costs<br />
An example of the costs in Southern Germany costs is<br />
approximately 10.23 Euro/ cubic metre. This includes 8.18 EURO for transport of the logs to the storage site and<br />
1.79 EURO/cubic metre for manipulation and maintenance of the pile. Extension of the storage period has little<br />
effect on the costs.<br />
3.3.2.7 Research needs<br />
Apart from Pine, which is susceptible to blue stain, the relative susceptibilities of other common commercially<br />
important species should be determined for this method.<br />
3.3.2.8 References<br />
Anonymus 1995: Trockenkonservierung von Nadelrundholz als Alternative zur Berieselung und zur Erzeugung von<br />
trockenem Bauholz. Holz-Zentralblatt 121 (1995) Nr. 35 und 36:<br />
Anonymus 2000: Lagerung und Konservierung von Stammholz B Trockenlagerung: Merkblatt der FVA Baden-<br />
Württemberg Abt. Waldnutzung und Waldschutz<br />
Anonymus 2000: Trocknung von Rundholz für trockenes Schnittholz im Bauwesen. Informationsdienst Holz, 8<br />
pages.<br />
Wauer, A. 2000: Verfahren der Rundholzlagerung LWF Nr. 29: Berichte aus der bayerischen Landesanstalt für Wald<br />
und Forstwirtschaft<br />
Welling, J.; Lang, A.; Scharai-Rad, M.; Speckels, L. 2000: Trocknung ganzer Stämme im Wald.<br />
Forstmaschinenprofi Januar 2000 S.66 ff<br />
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3.4 Storage under humid conditions<br />
3.4.1 Compact pile (logs with/without bark)<br />
3.4.1.1 Principle/description<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
P r i n c i p l e :<br />
In large compact piles, logs at the centre dry slowly.<br />
However, the “uncontrolled” humid conditions that prevail<br />
with this method may lead to extended periods of high<br />
moisture and risk of wood decay (see chapter 1.2).<br />
Figure 28: The top of a hill is the wrong place for the storage of compact<br />
piles with bark due to exposure to sunlight and wind (Photo HFM)<br />
Tree species:<br />
Experience and research results are available for Spruce and<br />
Pine.<br />
Preconditions:<br />
Healthy green logs with undamaged outer bark and no other defects; rapid storage; storage possible within the stand,<br />
in shady locations or sheltered moist hollows.<br />
S t o r a g e :<br />
Large compact piles without bearers, alternating butt-end first and top-end first, and root collars trimmed.<br />
3.4.1.2 Advantages, disadvantages, practical experience<br />
3.4.1.2.1 Advantages, disadvantages<br />
• Logs can be stored within the stand in shady locations; on slopes of northern aspect; in sheltered hollows in<br />
conditions of high air humidity, and gentle winds.<br />
• Lower-grade logs must be placed in the bottom and uppermost pile layers to protect the main pile against soil<br />
moisture and exposure to sunlight and rain.<br />
• Length of extra-long logs allows for generous removal of infested parts. If possible, store uniform log lengths<br />
and grades with end-sealing.<br />
• It is possible to spray with insecticides during construction of the piles. Ripcord 40 [Cypermethrin] will be<br />
effective for over six months against wharf borers ( N a c e r d a m e l a n u r a) and bark-beetles in coniferous and<br />
broad-leaved trees.<br />
• For protection against Spruce Longhorn ( T e t r o p i u m c a s t a n e u m) the logs need to be debarked prior to mid-<br />
August.<br />
• The logs must be inspected on a regular basis.<br />
3.4.1.2.2 Practical experience<br />
Maritime Pine ( Pinus pinaster)<br />
- Kraft Pulp<br />
The quality of debarked logs of Maritime Pine windthrows stored in compact piles in southwest France was very<br />
bad. The drying rate of these logs was not fast enough to ensure optimal protection against fungal attack.<br />
After a six-month period of conservation (compact pile/log without bark/no water spraying) of Spruce (Picea abies)<br />
and Fir ( Abies alba), the measured loss in yield was 2% on average compared with the yield that would have been<br />
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obtained with green sawn timbers (quantitative criteria). With regard to the economic loss due to downgrading of the<br />
sawn timber (according to European standardisation), the average loss was 18.5% in cost (qualitative criteria) (Parrot<br />
and Faure 2001)<br />
3.4.1.3 Recommendations (application, time limits)<br />
Storage under humid conditions of large amounts of round timber is only recommended for healthy, green coniferous<br />
wood during the winter season, assuming the wood will be sold within one year. Maintaining wood quality greatly<br />
depends on the climatic conditions and is, therefore, not easy to predict.<br />
Wood quality evaluation and recommended time limits for different tree species are as follows:<br />
- Spruce: relatively positive, 1 year (blue stain and red-striping)<br />
- Pine: relatively negative, (blue stain)<br />
3.4.1.4 Quality monitoring<br />
Frequent monitoring of wood quality is necessary for this storage method. The drying rate of logs in compact piles<br />
with bark intact is slow compared to debarked logs and in a moist condition the wood will support infestation by<br />
staining and decay fungi. Although the bark acts as a barrier over most of the log surface, wood exposed by saw cuts<br />
will provide avenues for infection at the log ends and along the length of the stem where bark damage has occurred<br />
and branches have been removed. The speed of infestation is temperature-dependent and is more rapid during late<br />
spring, summer and early autumn; the length of this optimal period for fungal growth will also be influenced by<br />
altitude.<br />
An equally important seasonal effect is infestation of logs by bark beetles which are vectors of staining fungi and<br />
introduce spores to the wood surface having already bored through the bark to lay eggs. Insect infestations of this<br />
type occur in early to mid-summer and provide a more direct introduction of deep staining fungi than rain splash or<br />
wind dispersal. Beetle infestations can be alleviated by the application of insecticides, but the appropriate timing of<br />
application and the choice of insecticide chemical also require careful monitoring.<br />
The most important consideration when monitoring wood quality is to identify the species of tree. Susceptibility to<br />
sap-stain infection differs greatly between species. In a four-month field study carried out in southern England during<br />
the summer of 2001 five softwood species were compared for their susceptibility to sap stain. Logs (with bark) of<br />
Scots Pine and Lodgepole Pine showed ca. 6 – 60 times more susceptibility to infection than logs of Norway Spruce,<br />
Japanese Larch and Sitka Spruce respectively. The anecdotal evidence that Pine is more susceptible than Spruce was<br />
confirmed, but such significant differences identify the importance of accurate identification for effective long-term<br />
storage of wind-thrown trees. As a result short term storage of Spruce logs may not prove a problem whereas the<br />
damage to Pine could be considerable.<br />
3.4.1.5 Environmental issues<br />
Storage of compact piles of logs (with bark) within the stand poses few environmental hazards. The stored timber is<br />
in effect located at a site where naturally fallen trees would be found and where the normal processes of degradation<br />
would occur. The main difference is the large volume of timber created by compact piles of logs in a restricted area.<br />
This raises the possibility of more concentrated organic leachates from the bark entering the soil during heavy<br />
rainfall, particularly phenolic compounds. In all other respects the local environment is unaffected, except in<br />
situations where insecticide application is carried out.<br />
3.4.1.6 Costs<br />
The costs for this method of conservation are minimal in comparison to other methods. Ease of access to windblown<br />
sites by vehicles, equipment and manpower inevitably affects the cost of preparing a suitable storage site, the<br />
collection of suitable logs and building a compact pile. Other methods which involve the removal of logs from an<br />
area of storm-damaged forest will incur these costs too, plus additional costs in establishing facilities for<br />
conservation.<br />
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3.4.1.7 Research needs<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
The most important area of future research is to understand the difference in susceptibility to sap-stain infection and<br />
decay fungi that exist between different species of softwoods and hardwoods.<br />
In the first instance, a rank order of susceptibility must be established based on results from experimental field trials<br />
using logs of all commercially important European tree species. This ranking should define a susceptibility value for<br />
each species. That value should reflect the time it takes (on average) for each log species to be deteriorated by sapstain<br />
fungi to a point where the wood is no longer marketable. The same approach could be adopted for measuring<br />
susceptibility to decay fungi.<br />
Efficient monitoring of wood quality on site would be improved if each compact pile was made up from logs of one<br />
tree species. Following on from that, tests could then be carried out to determine whether the position of logs within<br />
the pile had any effect on their rate of drying and susceptibility to sap stain.<br />
3.4.1.8 References<br />
Arnold, M., 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes.<br />
144(11): 843-858.<br />
Parrot J.; S. Faure 2001: Suivi du sciage de sapin epicéa chablis/grumes écorcées stockées sans arrosage (Assessment<br />
of storage under drying conditions (compact pile/log without bark) of Spruce (Picea abies) and Fir (Abies alba));<br />
CTBA: unpublished internal report; 2001<br />
Young, E. J.; Eaton, R. A.; Webber, J. F. 2002: Susceptibility of harvested softwoods to infection by sap-staining<br />
fungi. Int. Res. Group on Wood Pres. IRG/WP 02-10435. pp12.<br />
3.4.2 Compact pile covered with plastic sheets (logs with/without bark)<br />
3.4.2.1 Principle/description<br />
Here the objective is to keep the logs as moist as possible in contrast to open, aerated piles. The wood should be<br />
stored in places with high air-moisture content. The logs should be stored as close to each other as possible. This can<br />
be achieved by alternating butt and top-ends next to each other, which reduces drying<br />
The conservation of wood with plastic sheets demands a neat pile with good spacing between the pile and the ground<br />
and possibly with under layers. The storage site should be situated in an airy, warm place that is not too exposed to<br />
solar radiation. The possibilities for successful conservation, especially in the case of Spruce and Fir, are good, but<br />
storage should take place not more than three weeks after debarking.<br />
These small, compact piles of logs covered with plastic sheets prevent the wood from drying and serve as protection<br />
against an infestation by wood boring insects.<br />
Note: This conservation method is very similar to log conservation under oxygen exclusion (chapter 3.5.1), but it is,<br />
in fact, a completely different method!<br />
3.4.2.2 Advantages, disadvantages, practical experience<br />
After the Lothar storm in 1999, about 190.000 m³ of Spruce, Fir and Pine logs were stored in compact piles covered<br />
with plastic sheets for up to two years in Switzerland. The results were very variable, ranging from good preservation<br />
of wood quality to almost complete devaluation. Unfortunately, the very heterogeneous conditions of the observed<br />
case studies do not allow a thorough assessment of the factors influencing the conservation result.<br />
In the case of large amounts of storm-damaged logs, this method can be a good alternative to wet and dry storage.<br />
After the 1967 wind-throws, some Beech in Denmark was stored under plastic sheets, either in small piles or as<br />
single logs lying on the forest floor. In general, the results were negative, as the plastic covering in most cases lead to<br />
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more fungal attack and discoloration than in unprotected logs left on the forest floor. Moreover, the plastic covering<br />
was in several cases damaged or destroyed by wind, animals or children.<br />
There is no need for chemical protection of the piles. This method can be used in areas where it is not possible to<br />
create wet storage sites. It is recommended that large trees are debarked. However, the logs must be homogenous in<br />
order to achieve good pile quality.<br />
Beech: up to 6 months<br />
3.4.2.3 Recommendations (application, time limit)<br />
Based on the limited experience of this method, only preliminary recommendations are possible. This method is<br />
mainly suitable for small, scattered log piles, which should be placed in the shade (e.g. along forest roads). The<br />
losses due to discoloration and fungal attack are smaller with long logs than with logs cut to short lengths because<br />
considerable sections of the affected end grain have to be removed before further processing.<br />
Special attention must be paid to damage to the covering by vandalism and animals.<br />
If chemical treatment is used the logs must be transported away from water protection areas, if not out of the forest<br />
completely. The roots should be removed in order to increase storage capacity. The bark should be as undamaged as<br />
possible. The piles should be stored without an under layer. These recommendations are based on experience.<br />
To avoid re-wetting it is recommended that the top layer of the pile is covered with plastic sheets. Black sheeting is<br />
recommended. Additionally, as an alternative to the plastic sheeting, a top layer of logs can be built as a roof to<br />
protect the pile. Finally, the top layer of logs should be longer than the piled logs (about 2m on both sides). Crosspiled<br />
storage should be avoided.<br />
3.4.2.4 Quality monitoring<br />
Because of the inaccessibility of the logs under the plastic sheets, no direct monitoring of wood quality is possible.<br />
The covering should be checked frequently and any defects or damage must be mended immediately<br />
3.4.2.5 Environmental issues<br />
There may be a possible health hazard to operators from mould fungi growing excessively under the plastic sheets.<br />
The unfamiliar, striking white appearance of the wrapped wood piles may raise questions from forest visitors and<br />
explanations should be diplayed on posters.<br />
3.4.2.6 Costs<br />
Special expenses for particularly careful piling, sheeting material, covering/uncovering operations, frequent checks<br />
and disposal of the sheeting material are incurred. This storage method costs approximately < 15 EURO/m³<br />
3.4.2.7 Research needs<br />
- Controlled experiments during normal harvesting operations.<br />
- Assessment of possible advantages over conventional compact piling.<br />
- Investigation of potential health hazards from mould fungi.<br />
3.4.2.8 References<br />
Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrungen nach dem Orkan „Lothar“ (1999). Projekt<br />
WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (unpublished report)<br />
Kunz, B. 2002: Werterhaltende Lagerung von Sturmholz unter Folien. Züricher Wald 4: 11 - 13<br />
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Luchsinger, M. 2002: Folienholzrecherche Kanton Zürich. Züricher Wald 4: 4 - 10<br />
Manser, P., 2000. Beurteilung der Lagerung von Rundholz unter Kunststoff-Folie. EMPA-Forschungsbericht<br />
740007/1. EMPA, St. Gallen, Switzerland. 10 p.<br />
Zeltner, S. 1995. Holzkonservierung: Mit Plastikfolien schützen? Wald und Holz 6:18-19<br />
3.5 “Special” methods<br />
3.5.1 Log conservation under oxygen exclusion, compact pile wrapped in plastic sheets (logs with bark)<br />
3.5.1.1 Principle/description<br />
- Principle<br />
This method conserves logs by the exlusion of oygen,<br />
thus avoiding attack by fungi and insects.<br />
Figure 29: Long poles wrapped in plastic sheets and sealed. An<br />
additional net stretched over the wrapped pile prevents it from<br />
damages caused by parts of the sheets, which can stream in the wind<br />
and causing porosity (Photo: Wood Packer)<br />
- Description<br />
The air in the wood, like atmospheric air, consists of<br />
nitrogen, oxygen and carbon dioxide. The nitrogen<br />
content is practically the same as in atmospheric air; the<br />
oxygen content is generally lower, varying between 0 and 20%, whereas the carbon dioxide content is higher,<br />
varying between 0 and 26%. The oxygen content is lowest during the growing season, when the carbon dioxide<br />
content is highest.<br />
Felling causes a change of the conditions mentioned, and if the temperature is high enough, the wood may suffer<br />
damage, which may be either of a physiogenic or of a biogenic nature. Physiogenic damage includes tylosis and<br />
discoloration and their occurrence depends on the presence of a certain amount of oxygen and water in the wood.<br />
Biogenic damage is discoloration and destruction due to attacks by certain fungi and/or insects. I would appear that<br />
damage does not occur if one of the following conditions is present: (1) the air content of the wood is below 5%, (2)<br />
the oxygen content of the wood is below 1 %, (3) the carbon dioxide content of the wood is above 70%.<br />
- Tree species<br />
The method is applicable for several tree species. The following species were tested: conifer trees (Spruce, Fir and<br />
Pine) and broad-leaved trees (Beech and Sycamore Maple)<br />
- Preconditions<br />
Flat terrain<br />
Plastic sheets of high diffusion resistance (e.g. PE-silo sheets)<br />
Gas-proof thermo-welding<br />
Healthy, green wood<br />
- Storage (for illustration of the different steps, see Figure 30 to 36)<br />
Storage in piles longitudinally or transversely to the forest roads<br />
All-sided wrapping in plastic sheets<br />
Gas-proof thermo-welding of the protruding ends of the sheets<br />
Checking the condition of the plastic sheet, sealing of leakages,<br />
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3.5.1.2 Advantages, disadvantages, practical experience<br />
An early experiment concerning long-term storage of Beech logs in air containing carbon dioxide was carried out in<br />
Denmark 1968. A total of four trials were carried out, each covering six summer months. In two of the trials small<br />
log sections, about 50 cm long, were kept in PVC-bags; in two trials Beech logs were left on the ground in piles of<br />
about 70 m³, stored under plastic tarpaulin. In both cases an atmosphere containing carbon dioxide was established<br />
by adding supplies of pure carbon dioxide.<br />
The log piles were covered with a tarpaulin made from 0.2 mm PVC sheet, and the edges of the tarpaulin were dug<br />
half a metre into the soil and covered. During the covering dry ice (frozen carbon dioxide) was inserted in sufficient<br />
quantity to replace the atmospheric air trapped under the tarpaulin. The tarpaulin was provided with valves situated<br />
on top of the pile, which were kept open until the out-flowing air<br />
contained no more oxygen. The tarpaulin remained weatherproof<br />
throughout the summer and autumn and was so tight within this<br />
period that further addition of carbon dioxide unnecessary. The<br />
wood inside was well preserved. During the winter, however, the<br />
tarpaulin was damaged by wind and the experiment was stopped<br />
before the wood was damaged.<br />
Figure 30: First step - cleaning the ground from stones or sharp parts and<br />
spreading the ground sheets (Photo Wood Packer)<br />
From this experiment it was concluded that if Beech wood is placed immediately after felling in an air mixture<br />
consisting of at least 40% carbon dioxide, a maximum of 3% oxygen and the remainder, nitrogen, no damage from<br />
fungi or insects would occur during storage over the six summer months. In Beech wood in which the harmful<br />
processes have already started, these processes will be brought to a stop when the wood is stored in the specified air<br />
mixture.<br />
3.5.1.2.1 Advantages<br />
• The conservation of quality within this method is considered to<br />
be good.<br />
• This type of conservation is suitable for long-term storage<br />
only.<br />
• Plastic film storage is mainly successful in terms of quality,<br />
fungi and beetle attack during storage.<br />
• Subsequent maintenance is low, thus saving costs.<br />
•<br />
Figure 31: Second step - log piling using the truck´s crane (Photo Wood Packer)<br />
3.5.1.2.2 Disadvantages<br />
• Mice, fox and marten damage might occur if quality of the plastic film is<br />
not sufficiently robust.<br />
• The condition of the underlying layer should be strictly defined (planar,<br />
sandy soil).<br />
• The demands on the packing team are high because of the large size of<br />
the objects that must be packed and air- proofed.<br />
• This method is especially applicable for regions where sprinkling storage<br />
is not an option.<br />
• To be effective, this conservation method requires more effort compared<br />
with traditional methods.<br />
Figure 32: Third step - after finishing the piling the upper parts of the stem cross sections must<br />
be smoothed by chain saw (Photo Wood Packer)<br />
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3.5.1.2.3. Practical experience<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Spruce and Fir:<br />
The unpacked wood shows no essential qualitative change and its use is not limited.<br />
Beech and Maple:<br />
Beech and Maple are more susceptible with this storage method. The risk of uneven colour in Beech could be<br />
reduced by steam-processing. There are positive results for Beech.<br />
France: After three years the wood quality remains good if the initial quality was good. Experiments are still<br />
ongoing.<br />
3.5.1.3 Recommendations (application, time limit)<br />
Setting up of signs warning of the danger, of suffocation for anyone crawling into the sheets.<br />
- Valuation:<br />
Experiments show that the value can be maintained over longer periods of time. In some cases, a thin layer of white<br />
mushrooms has been observed on the pile at the opening of the plastic sheets, but apparently without any influence<br />
on the wood quality. The same type of discoloration appears to occur both the drying-off and wet-storage method.<br />
- Beech: positive, hitherto 2 years<br />
- Spruce: positive, hitherto 3 years<br />
- Pine: positive, hitherto 3 years<br />
This method offers alternative long-term protection against insect<br />
and fungal attack without depending on climate, storage site, tree<br />
species and size of pile. It is applicable in nature-conservation and<br />
water protection areas too. The complete costs for the first year are<br />
comparable with those from water storage. The input for<br />
monitoring and maintenance is low. Monitoring to detect damage<br />
to the plastic film only needs to be carried out periodically.<br />
Figure 33: Fourth step - covering the pile with the first top sheet (Photo Wood<br />
Packer)<br />
3.5.1.4 Quality monitoring<br />
Quality monitoring is only possible after unpacking the piles. During the conservation period it is possible to<br />
measure the interior atmosphere (oxygen/carbon dioxide content) of the wrapped pile with a measuring instrument<br />
that remains outside the pile. It is possible to record changes in the interior climate of the wrapped pile at defined<br />
time intervals<br />
3.5.1.5 Environmental issues<br />
Environmentally conservation under oxygen exclusion has no<br />
influence in soil, air or water processes. However, the plastic film<br />
should be recycled or used for other applications (e.g. in agriculture<br />
etc.). There is no need for an external energy supply because<br />
conservation is achieved by the oxygen-free closing of the piles.<br />
Figure 34: Fifth step - covering the pile with the second top sheet (Photo Wood<br />
Packer)<br />
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3.5.1.6 Costs<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
The costs for this method depend on the amount of equipment and maintenance required, as well as on damage<br />
caused by humans or animals.<br />
In 1968 this method was more expensive than wet storage and<br />
was not suitable to use in the forest without modifications.<br />
However, one reason for this conclusion might have been that<br />
high quality and reasonably priced plastic sheeting was not<br />
available in the market at that time.<br />
Figure 35: Sixth step - sealing the different plastic layers with special melting<br />
device (Photo Wood Packer)<br />
The costs vary a lot depending on the size of the wrapped piles,<br />
skills and training of the workforce, the company in charge of the<br />
work and the type of plastic sheeting used. However, the following general prices may be given:<br />
- Double polyethylene sheets (usually used for short conservation periods due to their fragility): 10 to 15 EUR/m3<br />
- PVC sheet (more resistant than the latter and should be used for at<br />
least a two-year conservation period and for high valued timber): 30 to<br />
35 EUR/m3.<br />
Following conservation, the plastic sheets may be re-used, but the costs<br />
involved prevents any saving.<br />
Figure 36: Seventh and final step - Covering the wrapped and sealed pile with a wind<br />
net (Photo Wood Packer)<br />
3.5.1.7 Research needs<br />
Further information about the possibilities of using the method to avoid beetle attack and the ability to conserve the<br />
quality of the fresh wood. In particular, more information is required about the interior atmosphere in the pile<br />
covered with plastic film. Furthermore it is interesting to know more about the time intervals required and the<br />
amount of logs that can be used with this method. More tree species must be tested to consolidate existing<br />
knowledge.<br />
3.5.1.8 References<br />
Yde-Andersen, A. 1973: Opbevaring af bøgeved i kuldioxid-atmosfære. Det forstlige Forsøgsvæsen i Danmark, vol.<br />
33, pp. 243-280.<br />
Landesforstverwaltung Baden –Württemberg 2000: Handbuch Sturmschadensbewältigung, Kap. 4 Konservierung,<br />
Lagerung<br />
Maier, T. 1995: Alternative Holzkonservierung durch Sauerstoffentzug - Methodik und erste Ergebnisse. Vers. Ber.<br />
AWF 95/14<br />
Maier, T. 1997: Alternative Holzkonservierung durch Sauerstoffentzug - Lagerungsverlauf und Holzqualität bei der<br />
Auslagerung. Vers. Ber. AWF 97/7<br />
Schüler, G. 1998: Alternative Holzkonservierung durch Sauerstoffentzug - Umsetzung in die Praxis. Vers. Ber. AWF<br />
98/8<br />
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3.5.2 Compact pile covered with geo textile fabric (logs with bark)<br />
3.5.2.1 Principle/description<br />
A small compact pile of logs is covered with a net-like fabric (e.g. geo textile fabric), which prevents the wood from<br />
an infestation by wood-boring insects. Basically this is a variant of the conventional compact piling under “humid”<br />
conditions, but with an additional mechanical protection against insects.<br />
3.5.2.2 Advantages, disadvantages, practical experience<br />
This method has been used occasionally in Switzerland, but only limited reports are available. The method can be<br />
used only with comparably small piles.<br />
3.5.2.3 Recommendations (application, time limits)<br />
Because of the very limited experiences it is not possible to make any recommendations .<br />
3.5.2.4 Quality monitoring<br />
Because of the inaccessibility of the logs under the fabric, no direct monitoring of the wood quality is possible. The<br />
fabric should be checked frequently and any defects or damage must be mended immediately.<br />
3.5.2.5 Environmental issues<br />
No negative impact to be expected.<br />
3.5.2.6 Costs<br />
Special expenses for careful piling, fabric and covering/uncovering operations.<br />
3.5.2.7 Research needs<br />
Documented applications of this method.<br />
3.5.2.8 References<br />
Kramer, P., 2000: Holzlager abdecken: Vorteile mit Geovlies. Wald und Holz 3: 50-51<br />
Jansen, E., 1990: Schützt Seidengase das lagernde Rundholz vor Insektenbefall? Wald und Holz (71)7: 602 – 608<br />
3.5.3 Compact pile covered with a mineralic suspension<br />
3.5.3.1 Principle/description<br />
- Principle<br />
A small compact pile of logs is covered with a thin layer of a mineralic suspension, which prevents the wood from<br />
infestation by wood-boring insects (and possibly to a limited extent also by wood-destroying insects). Basically this<br />
is a variant of the conventional compact piling under “humid” conditions, but with an additional mechanical<br />
protection against insects and possibly some slowing down of the loss of wood moisture content.<br />
- Description<br />
Limestone powder is mixed with water to get a suspension, which is sprayed on the exterior side of the pile, to cover<br />
the whole pile in order to act as a protection against bark beetle. Upon removal most of the crust will flake off the<br />
logs.<br />
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3.5.3.2 Advantages, disadvantages, practical experience<br />
Some limited experience with this method has been reported from Baden-Württemberg, Germany (see references).<br />
This method seems to be applicable for short-term conservation in the forest as a protection against bark beetle<br />
attack. Problems for longer-term conservation involve the durability of the suspension which is strongly influenced<br />
by rainy weather. Furthermore the consumption of the suspension is very high.<br />
3.5.3.3 Recommendations (application, time limits)<br />
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Figure 37:<br />
Spruce logs covered by<br />
mineralic suspendsion<br />
(Pelz and Bastian<br />
2000)<br />
As a result of the limited experience, this method is not yet applicable for practical use. There are still some<br />
problems concerning the application and the equipment required. The gaps between the logs in the pile are usually<br />
too big, which increases the consumption of the suspension. Furthermore the durability of the covered suspension is<br />
not very high.<br />
3.5.3.4 Quality monitoring<br />
Because of the inaccessibility of the logs under the mineralic layer, no direct monitoring of the wood quality is<br />
possible. Frequent checks are required to ensure that the mineralic layer remains intact<br />
3.5.3.5 Environmental issues<br />
This method has no adverse environmental effect because the chemical suspension used has no dangerous contents.<br />
The suspension simply dissolves after use. However, this also causes a problem when the suspension leaches out too<br />
early.<br />
3.5.3.6 Costs<br />
Special expenses for the application of the mineralic suspension.<br />
Costs are dependant on the surface/volume ratio of the pile because only the exterior surface of the pile has to be<br />
covered by the suspension. Nowadays the costs are not comparable with traditional conservation methods. The costs<br />
may be lowered in the future depending on the progress in improving this method.<br />
3.5.3.7 Research needs<br />
- Documented application of this method.<br />
- Research to make this method applicable for practical use in the forestry industry in the future. The most important<br />
requirement is to improve technical equipment, especially for practical handling out in the forest.<br />
3.5.3.8 References<br />
Pelz, S.; Bastian, P. 2000: Neues Verfahren der Rundholzkonservierung: Mineralische Schutzhülle. AFZ/Der Wald<br />
20: 1101-1103
3.5.4 Storage in gravel pits<br />
3.5.4.1 Principles/description<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
A compact pile of logs, buried in a hole in the ground (e.g. old gravel pit) or on level ground, is covered with a thick<br />
layer of clay or soil. To decrease the soiling of the logs they can first be covered with a fleece. The wood is<br />
conserved in its 'original' state and protected against infestation by wood-destroying organisms.<br />
3.5.4.2 Advantages, disadvantages, practical experience<br />
After the Lothar storm in 1999 about 6.500 m³ of Spruce and Fir logs were stored in gravel pits in Switzerland for up<br />
to 2.5 years. In general, the preservation of the wood was very good. The contamination of the logs with soil/clay<br />
and remains of the fleece may cause problems for the further processing in sawmills. The major disadvantage of this<br />
method is that it is not possibile to stagger the input and removal of the logs.<br />
3.5.4.3 Recommendations (application, time limits)<br />
So far only limited experience is available. This method appears to be suitable particularly for long-term storage of<br />
several years and may therefore be an alternative to conservation by water sprinkling. It is important that the<br />
covering layer is waterproof, which is why clay is particularly suitable. To reduce erosion of the covering layer<br />
planting with grass/clover may be advisable. Because of the lack of suitable storage sites the application of this<br />
method is limited.<br />
3.5.4.4 Quality monitoring<br />
Because of the inaccessibility of the completely covered logs, no direct monitoring of the wood quality is possible.<br />
Frequent checks are necessary to ensure that the cover remains intact and any collapses or holes must be filled.<br />
Quality conservation during the storage period depends on the following factors:<br />
- Manipulation of the logs during input and removal of the wood. When there is too much bark damage, wood<br />
quality may be reduced by blue stain.<br />
- Durability of the cover material.<br />
- Compact piling of the logs (with few hollows).<br />
3.5.4.5 Environmental issues<br />
There are no known environmental influences on soil, air or water, provided that the logs are not treated with any<br />
chemical substances. So far this method can be regarded as environmentally harmless.<br />
3.5.4.6 Costs<br />
Special expenses for the covering/uncovering operations are incurred, which are quite high. The total costs are<br />
comparable to a compact pile with a water-sprinkling system. The costs can vary widely depending on the<br />
accessibility of the pit, the local situation and the level of maintenance required (e.g. groundwater running into the pit<br />
needs to be pumped out).<br />
3.5.4.7 Research needs<br />
- Suitability and behaviour of different wood species.<br />
- Assessment of long-term storage.<br />
3.5.4.8 References<br />
Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrungen nach dem Orkan „Lothar“ (1999). Projekt<br />
WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (available as pdf: www.empa.ch/holz ?<br />
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Holztechnologie)<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Anonymus 2002: Lagerung von Sturmholz: Es geht auch im Erdlager. Wald und Holz 12:48-50<br />
Anonymus 2002 : Stockage de bois sous glaise. Commune de Lausanne, Service des forêts, domaines et vignobles,<br />
Lausanne, Switzerland, 31 p.<br />
3.5.5 Storage in mines<br />
3.5.5.1 Principle/description<br />
The goal of this method is to keep humidity as high as possible. The preconditions of this storage method are low<br />
temperature in the mines and conservation of the logs with bark in equal length.<br />
3.5.5.2 Advantages, disadvantages, practical experience<br />
Damage from fungi and bark beetle attack were low during the test run. This method has not been used in practice.<br />
3.5.5.3 Recommendations (application, time limits)<br />
With regard to the results of the test run, the quality of the logs was strongly influenced by decay. Therefore, this<br />
method can not be recommended for further application in the forestry industry.<br />
3.5.5.4 Quality monitoring<br />
No experience.<br />
3.5.5.5 Environmental issues<br />
No experience.<br />
3.5.5.6 Costs<br />
No experience.<br />
3.5.5.7 Research needs<br />
Concerning the negative results of this method no more research activity is recommended.<br />
3.5.5.8 References<br />
Mahler, G.; Klebes, J.; Schröter, J. 1990/5: Hinweis zur Konservierung der Sturmwurfhölzer.<br />
3.5.6 Compact pile above tree line (logs with bark)<br />
3.5.6.1 Principle/description<br />
Basically this is conventional compact piling under “humid” conditions, but at higher elevations in the mountains<br />
above the tree line. By storing the logs in a mountainous climate (low temperatures and long winter season) the risk<br />
of degradation of the wood can be reduced, in particular the danger of infestation by insects can be minimized.<br />
3.5.6.2 Advantages, disadvantages, practical experience<br />
After the Vivian storm in 1990 about 25.000 m 3 of Spruce logs were stored on the Lukmanier pass (1900 m a.s.l) in<br />
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Switzerland for about two years. Overall, wood degradation appeared to be somewhat less than observed in logs<br />
stored at lower elevations during the same period, but nevertheless progressing. The wood moisture content dropped<br />
to a dangerous level after one year. Despite unfavourable conditions new insect infestations were observed<br />
originating from populations that were present in the stored logs.<br />
3.5.6.3 Recommendations (application, time limits)<br />
This special method may be suitable if the logs have to be transported by truck over mountain passes for further<br />
processing (e.g. along traditional export routes from Switzerland to Italy). The harvested logs are transported from<br />
the forests directly to the storage yard on the mountain pass.<br />
As with conventional compact-piling the duration of storage should not exceed one growing season. Particular care<br />
should be taken to avoid storage of logs that are already insect-infested.<br />
3.5.6.4 Quality monitoring<br />
- Observation of discoloration/fungal attack on fresh cross-cuts at end-grain of protruding logs.<br />
- Monitoring of wood moisture content.<br />
3.5.6.5 Environmental issues<br />
Very little impact to be expected. Some soiling of the storage site from fallen bark.<br />
3.5.6.6 Costs<br />
Standard expenses for transportation and piling. No additional special expenses if used in the intended context (see<br />
chapter 3.5.6.3).<br />
3.5.6.7 Research needs<br />
- Suitability and behaviour of different wood species.<br />
3.5.6.8 References<br />
Arnold, M. 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes.<br />
144(11):843-858<br />
Kucera, L.J.; Katuscak, S. 1993: Zustand des sturmgeworfenen Fichte-Rundholzes nach einjähriger Trockenlagerung<br />
am Lukmanier/GR. Schweiz. Z. Forstwes. 144(11):873-892<br />
Wermelinger, B.; v. Hirscheydt, J. 1996: Die Entwicklung von Insekten in Fichten-Hochlagern oberhalb der<br />
Baumgrenze. Schweiz. Z. Forstwes. 147(8):597-613<br />
3.5.7 Storage in snow<br />
3.5.7.1 Principle/description<br />
- Principle<br />
The covering of logs with snow leads to favourable storage conditions (mainly low temperature) which minimise the<br />
risk of degradation of the wood and thus preserve the wood in its original condition.<br />
- Description<br />
Supply and demand for timber is not in balance at different times of the year. In particular, in northern regions of<br />
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Europe, namely Scandinavia, more Spruce pulpwood is felled than is used during the winter, while, after the<br />
summer, timber harvesting is concentrated on sawn timber-dominated logging sites and little Spruce pulpwood is<br />
obtained from these sites. This difference in supply may cause some problems for pulp mills for two main reasons:<br />
on the one hand, it is difficult to import the raw material since quality, which is stringent in the pulp industry, is<br />
difficult to control; on the other hand, winter-felled timber does not retain the quality required of wood intended for<br />
grinding through the summer unless special measures are undertaken. For these reasons, different methods of cold<br />
storage were studied in Finland in 2000 to preserve wood quality for pulping. They were financed by a group of large<br />
companies including UPM-Kymmene and Stora Enso.<br />
Five different types of cold storage were tested on nine storage sites ranging from 2.000 m³ to 30.000 m³:<br />
• "Traditional cold storage": an elongated stack formation is covered with natural snow or artificial snow<br />
produced with a snow cannon. This is then covered with sawdust. This method is well known and its use dates to<br />
the early 1990s.<br />
• As above, but with bark used as the final covering.<br />
• The stacks are cooled using water. Protective logs are used on the sides of the Spruce stacks (Pine pulpwood)<br />
and on the top (Birch pulpwood).<br />
• The stacks are cooled using snow blown from around the stack, the procedure otherwise being as above, (the use<br />
of protective logs around the Spruce piles.)<br />
• Experimental method: the storage formation is covered with snow produced using a snow cannon and then by a<br />
covering of foil mattresses.<br />
The influence of the thickness of the different type of layers was also assessed.<br />
The principles of these types of storage are to maintain the moisture content as high as possible and the temperature<br />
as low as possible in order to protect the timber from fungal and insect attacks, as well as to maintain its brightness<br />
(blue reflectance factor). Maintaining a high blue reflectance factor helps to save a lot of money in terms of pulp<br />
bleaching. It should be noted that the cost of bleaching increases by 0.34–1.18 €/m 3 /blue reflectance factor percentile<br />
unit. Additional savings can be achieved by a more efficient use of Spruce pulpwood. Moreover, if the cold storage<br />
of Spruce pulpwood enables the use of sawn timber as pulpwood at the end of summer to be avoided, further savings<br />
are also possible. The difference in price at the mill gate between sawn timber and pulpwood is on average 17 €/m 3 .<br />
3.5.7.2 Advantages, disadvantages, practical experiences<br />
This conservation method is used occasionally in Scandinavian countries (e.g. Finland), normally with the use of<br />
snow cannons. Very little is known about these experiences. The use of snow and sawdust is the most common<br />
method.<br />
3.5.7.2.1 Advantages<br />
• Sawdust is usually easy to spread.<br />
• Sawdust can be reused. Repeated use of sawdust increases the mineral content of the sawdust.<br />
3.5.7.2.2 Disadvantages<br />
• Sub-zero temperatures are required at the beginning of storage.<br />
• It may be difficult to spread the sawdust.<br />
• The process stirs up sawdust, which is hard to remove from the logs.<br />
• Sometimes the stacks have to be watered to keep the dust down.<br />
• The sawdust can create problems with water circulation in the pulp mill if it enters the system together with the<br />
pulpwood logs.<br />
If protective coverings are used between the snow and the sawdust:<br />
- it is easier to recover the sawdust<br />
- the sawdust will not stick to the logs and enter the process.<br />
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The use of bark instead of sawdust has the following advantages:<br />
- it is dust free.<br />
- no bark is carried from the storage site into the process together with the logs.<br />
- the pieces of bark form a partially supportive layer with the result that once the snow melts, the bark will not fall<br />
between the logs in the stacks as sawdust would.<br />
- wood quality is the same regardless of whether bark or sawdust are used.<br />
When using foil mattresses to cover the stacks:<br />
- the covering stage was very labour-intensive.<br />
- dismantling the storage formation was difficult and the foil mattresses tore easily on removal.<br />
- in practice, mattresses could not be reused.<br />
The advantages of the water-cooled method was not having to rely on covering the stacks with snow and thus<br />
avoiding the strict schedule involved.<br />
3.5.7.3 Recommendations (application, time limits)<br />
The current experience is based on four-seven months storage from the winter season up to July or August. The<br />
methods have not been assessed for a longer period yet.<br />
3.5.7.3.1 Temperature<br />
With regard to temperature, it remained fairly constant up to mid-May, whatever the storage method. It was not until<br />
after the end of May, that difference between storage methods became obvious. There was no significant variation in<br />
temperature between different parts of the same stack. However, it was observed that the temperatures inside the<br />
stacks remained around zero until they were to be dismantled only in the case of the methods using snow and<br />
sawdust or bark. With the water-cooled method, a sharp rise in temperature was observed from May to such a point<br />
that the inside temperature almost reached the outside temperature within 2 months.<br />
3.5.7.3.2 Moisture content<br />
Maintaining the moisture content as high as possible is of high importance since a decrease would involved a rise in<br />
pulp manufacturing costs and a decrease in fibre strength. In Scandinavia, changes in Spruce wood properties begin<br />
to occur when moisture levels fall below 45%. In winter-harvested Spruce pulpwood, moisture content ranges from<br />
55% to 60%, preventing blue staining and other fungal attacks.<br />
In the present study, the wood moisture content remained quite high and at least above 45% regardless of the storage<br />
method except in the outside part of the stacks on two out of the nine sites, where a protective layer of Beech or Pine<br />
was used.<br />
3.5.7.3.3 Level of brightness<br />
The blue reflectance factor of the wood was measured using the SCAN test method. The measurements were made<br />
using compacted samples made of ground wood. The results were not directly comparable with the blue reflectance<br />
factor of the equivalent mechanical pulps (GW, PGW and TMP) as they are clearly smaller in numerical value. The<br />
range in the average blue reflectance factor of the wood measured from the storage stacks was 5 units (49 – 54%)<br />
with the variance for the internal readings of the stacks being 3 units at the most.<br />
There were no significant differences in value of the blue reflectance factor between the various parts of the stacks.<br />
In the same way, the difference between methods was small, but the fact remains that the timber stored in water was<br />
darkest in colour.<br />
There was no significant decrease in values of the blue reflectance as the storage time increased.<br />
The blue reflectance value of wood was best preserved in storage stacks using an abundant cover of snow (> 40cm.)<br />
plus a covering layer of sawdust or bark.<br />
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3.5.7.3.4 Important factors, independent of the method<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
- Forestry machine contractors should be highly professional and the pulpwood cut to length (billets) should be<br />
closely stacked.<br />
- Storage should be based on a very firm site, preferably on an asphalt surface, at all times of year.<br />
- Cold storage should be located so as to enable the water from the melting snow to be diverted away from the<br />
storage.<br />
3.5.7.4 Quality monitoring<br />
No information available.<br />
3.5.7.5 Environmental issues<br />
No information available.<br />
3.5.7.6 Costs<br />
The total costs were most frequently within the range of 2.2-5.9 €/m 3 . In the case of the foil-mattress method: 11<br />
€/m 3 .<br />
The actual costs involved (excluding extra transportation and other expenses) were within the range of 1.6-4.3 €/m 3 .<br />
The methods have not yet become established practice. Costs will go down as the people involved become<br />
accustomed to using them.<br />
3.5.7.7 Research needs<br />
No information available.<br />
3.5.7.8 References<br />
The results were published in a Metsäteho guide entitled "Puutavaran kylmävarastointiohjeita tekijöille" (Practical<br />
instructions for the cold storage of timber).<br />
Makkonen-Spiecker, K. 1999: Schneelagerung von Holz in Finnland nimmt zu. AFZ/Der Wald 54: 1318<br />
3.5.8 Compact pile covered with organic material<br />
3.5.8.1 Principle/description<br />
Piled logs are covered with a layer of organic material (e.g. bark chips, wood chips, sawdust) to give some protection<br />
from the environment (mainly to prevent the wood from drying).<br />
3.5.8.2 Advantages, disadvantages, practical experience<br />
Some recent success with coverage of Spruce sawlogs with a layer of industrial wood and bark has been reported in<br />
Switzerland (see references).<br />
In 1968 Junckers Sawmill in Køge (Denmark) stored Beech logs in 3m high piles under a 75cm thick cover of fresh<br />
sawdust and chips, with good results. The storage period was from March 1968 to December/January 1968/1969 (a<br />
small amount was kept until June 1969). The temperature inside the pile increased to above 40°C during the first two<br />
months of storage and remained high during the whole storage period. This completely prevented attacks by wooddestroying<br />
fungi and probably also killed mycelia spores.<br />
No wood-destroying fungi can survive for a longer period of time at more than 40°C and only very few above 35°C.<br />
Also, the high CO2-content in the air inside the piles is believed to have contributed to the good results obtained from<br />
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this storage method. The moisture content of the logs decreased by only 10% from March 1968 to June 1969. This<br />
high moisture content may slow down, but not prevent growth of the wood-destroying fungi. It is however, assumed<br />
to be the main reason for the total absence of tylosis, to which also the high temperature may have contributed by<br />
killing the parenchymatic cells at an early stage.<br />
At the same time (1967) storage in piles covered with wet straw was put into practice in two forest districts, but with<br />
very poor results. In one district, piles of Beech logs were covered with two 50cm thick layers of straw separated by<br />
a plastic sheet. Under the plastic sheet and on the lower layer of straws, perforated tubes were placed two meters<br />
apart, through which water was added two hours a day. The result was an almost total destruction of the wood within<br />
a few months during the summer.<br />
In the piles with straw and with water being added two hours a day, the moisture content of the logs was kept at the<br />
same level as in freshly felled logs thoughout the entire storage period. The temperature inside the pile, however,<br />
increased to a level that was very favourable to fungal growth. As a result of this, and the high relative humidity, the<br />
logs were more badly damaged by wood-destroying fungi after one year of storage than logs which were only<br />
covered with one layer of straw, and these in turn were even more damaged than logs without any protection in the<br />
forest.<br />
The stored wood from Junckers sawmill became reddish in colour during storage, probably because of the relatively<br />
high temperature inside the pile, creating an effect similar to that of a low temperature steaming process. This<br />
discolouration has little practical importance if the wood is steamed before drying or, as at Junckers Sawmill, dried<br />
in hot presses. The value loss was estimated by the sawmill to be no more than 5%. From practical experiences the<br />
following can be mentioned:<br />
- the logs have to be freshly cut<br />
- the pile has to be covered with sawdust before the winter ends<br />
- a covering of at least 75cm fresh and wet sawdust has to be used, and this layer is to be held intact at all places<br />
during the entire storage period<br />
- inspections have to be made often to measure temperatures and take samples<br />
- the logs should be processed quickly after removal from the pile.<br />
The tests show that high water content in the logs does not protect them from deterioration, if other factors are<br />
optimal to fungal growth. It is uncertain whether or not a more densely packed covering of wet straw under the<br />
plastic sheet and straw packed densely between the rows of logs in the pile might raise the temperature above the<br />
critical level for wood-destroying fungi.<br />
3.5.8.3 Recommendations<br />
The Danish experiences show that, unless a high moisture content can be maintained together with a temperature that<br />
is too high for the wood-destroying fungi to survive, storage in piles covered with organic material is not safe.<br />
Storage of Beech in piles covered with sawdust, as carried out at Junckers Sawmill, is recommended if it is not<br />
considered too expensive. Based on the tests it is strongly recommended not to store Beech in piles covered with<br />
straw.<br />
3.5.8.4 Quality monitoring<br />
Because of the inaccessibility of the logs under the cover, no direct monitoring of wood quality is possible.<br />
3.5.8.5 Environmental issues<br />
No negative impact to be expected. The coverage material has to be disposed of (or left in the forest) after the<br />
removal of the logs.<br />
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3.5.8.6 Costs<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
The cost of storage at Junckers Sawmill was approximately double the price of sprinkler storage, transportation to<br />
the sawmill not included.<br />
3.5.8.7 Research needs<br />
If storage of logs in piles with layers of straw is still found interesting more research is needed in order to find out<br />
whether a thicker layer of straw may give the desired results. However, it seems that the material and economic<br />
resources required will exceed those required when sprinkling the logs and more research on this level can therefore<br />
only be recommended if other storage methods are found to be impossible. Instead, research should be directed<br />
towards the method used at Junckers Sawmill, to see if sawdust covering remains a possible alternative to other<br />
methods of storage.<br />
3.5.8.8 References<br />
Moltesen, P. 1971: Opbevaring af bøgekævler i kuler dækket med organisk materiale. Dansk Skovforenings<br />
Tidsskrift, 1971, Vol. 56, p. 109-131.<br />
Junker, E. 2002: Alternativen zur Nass- und Folienlagerung von Rundholz – Eindeckung mit Rinde. Zürcher Wald 4:<br />
19<br />
Ziegler, A. 2002: Alternativen zur Nass- und Folienlagerung von Rundholz – Eindeckung mit Industrieholz. Zürcher<br />
Wald 4: 18<br />
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3.6 Supplementary conservation measures<br />
3.6.1 Chemical wood protection<br />
3.6.1.1 Principles/description<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
In order to avoid attack from wood-boring insects and/or fungal discolouration, the wood may be treated with<br />
insecticides and/or fungicides.<br />
The function of insecticide application is to prevent or repel adult beetles from boring into the bark in order to lay<br />
their eggs. Once the beetles are under the bark or within the wood they are largely safe from chemical sprays and the<br />
application of insecticides is useless, hence the treatment must be carried out in late winter or in early spring, before<br />
the adult beetles begin their search for breeding material. If the expected duration of storage extends beyong one<br />
summer, other ways of protecting the timber should be sought.<br />
Log preparation:<br />
• Perfect delimbing.<br />
• Crosscutting to provide clean cut-ends.<br />
• Removal of lichens and mosses from the bark with a metallic brush.<br />
Material:<br />
• Small log storage: a garden home sprayer is sufficient.<br />
• Large log storage: a knapsack sprayer.<br />
Methodology:<br />
For efficient protection:<br />
• Treatment must be undertaken as soon as possible.<br />
• Temperature > 0°C.<br />
• Dry weather/no rain during application (pollution risk + inefficient treatment).<br />
• Each log must be completely treated, including the part in contact with the ground.<br />
• Wounded parts must be treated particularly carefully.<br />
• Application of an anti-check product where bark is missing.<br />
3.6.1.2 Precautions<br />
• Avoid contact with skin and mucous membranes.<br />
• Use protective clothing (trousers, gloves, glasses, etc.).<br />
• Avoid shaking the products during transportation.<br />
• Respect the chemical products’ specifications. Some products may be prohibited for use in forests.<br />
• Manufacturers’ recommendations, risk and COSHH assessments must be adhered to.<br />
3.6.2 Biological wood protection<br />
3.6.2.1 Principles/description<br />
At the present time it is felt that biocontrol cannot be recommended. However, it is felt that research that specifically<br />
address the shortcomings should be encouraged.<br />
Holdenrieder and Greig (1998) state that biological control of pathogenic fungi can either be through rapid<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
colonisation and defence of substratum, or by the takeover of the resource already in use by the pathogen, and as<br />
Gibbs and Smith (1978) pointed out, the former are likely to be more valuable as biological controls. It is known<br />
that the growth of decay fungi can be inhibited through the production of antibiotic substances, as well as by direct<br />
competition for the substrate. A number of studies have considered the use of non-decay fungi to control decay<br />
fungi, in particular Trichoderma, either as an integrated control with borate (Schoeman 1995), or alone (e.g. Richard<br />
e t a l . 1969; Bruce and King 1986; Schoeman e t a l . 1994; Anseylmi and Nicolotti 1997). More recently bluestain<br />
fungi have been considered as biocontrols for decay fungi (Brown, 2003).<br />
Although the use of biological controls can be a tempting option when compared to chemical control, a number of<br />
questions/issues need to be addressed if they are to be effective, including the following:<br />
• What time period does the biocontrol need to work for?<br />
• Biocontrol agents must have the ability to colonise wood without damaging it in a way which would make it<br />
unmarketable or which would decrease the service life. What is the planned end use of the timber? Is blue stain<br />
acceptable?<br />
• What are your target fungi for control? The number and diversity of potential target fungi occurring in<br />
seasoning timber can be large. Hence, one needs to consider how effectively this assortment of different fungi,<br />
all with different ecological strategies (Rayner and Boddy 1988), be controlled by a single species or isolate of a<br />
biocontrol fungus.<br />
• Rapid colonisation and assimilation of simple nutrients are attributes that can make fungi-effective biocontrol<br />
agents (Hulme and Shields 1970), hence one approach to choosing a potential biocontrol is to select species<br />
which are primary colonisers (Rayner and Webber 1984), such as bluestain fungi.<br />
• It is also possible that the combined activity of potential biocontrols such as bluestain and mould fungi<br />
accelerate the breakdown of the host defences, making it easier for the decay fungi to colonise the wood.<br />
• Environmental/climatic factors including temperature, rainfall and humidity have an effect on the drying rate,<br />
and hence both the seasoning period and growth potential of fungi, influencing colonisation, combativeness and<br />
competitive interactions between fungi.<br />
• Temperature influences which fungi are present, how well they survive and how well they compete<br />
with each other (Nicolotti and Varese 1996). For instance, if the temperature is high, bluestain fungi<br />
are more likely to become successfully established in the timber and well established fungi appear to be<br />
better at preventing ingress of their domain by decay fungi (Brown 2003).<br />
• Moisture content of the logs is also an important issue in the process of colonisation. Firstly, reduced<br />
fungal growth is found in saturated wood, such as that kept in wet stores (Webber and Gibbs 1996).<br />
Secondly, dry wood, with a moisture content of less than 20%, is equally unlikely to become colonised<br />
by fungi.<br />
• Product development in terms of production and formulation and registration would need to be addressed for<br />
any biocontrol agent.<br />
• The methods by which biocontrol agents are applied to the substrate that requires protection is also a key issue.<br />
• In terms of biocontrol selection, it is important to examine a range of isolates of the same species, not just one,<br />
as large variation in terms of growth rates and colonising ability can occur (Brown 2003).<br />
To conclude, biocontrols have advantages over traditional chemical methods: they are potentially less damaging to<br />
the environment, and they are more positively perceived by the public. However, if they are to be accepted by the<br />
forest industries it is essential that they are as effective as their chemical counterparts, be easy to handle in the field,<br />
and are as economically viable (Bruce 1998). However, although this is important, the pressure to adopt sustainable<br />
forestry methods, for example via the implementation of the UK Woodland Assurance Scheme (UKWAS 2000) is<br />
leading to a reduction of chemical applications in the forest environment. However, if biological control of storm<br />
damaged timber is to be considered, more research is needed in the areas outlined above. In the past, many<br />
biocontrol studies have been laboratory based, and although this is often the cheapest option in terms of time and<br />
money, it is unlikely to give a true picture of the situation in the field. In particularly greater thought needs to be<br />
given to climatic and environmental conditions which are likely to cause otherwise successful biocontrol agents to<br />
fail.<br />
3.6.2.2 References<br />
Anseylmi, N.; Nicolotti, G. 1998: Biological control of Heterobasidion annosum in the forest by non-pathogenic<br />
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wood destroying fungi. In,<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Delatour, C.; Guillaumin, J.J.; Lung-Escarmant, B.; Marcais, B. (Eds): Root and butt rots of forest trees: 9 th<br />
International Conference on root and butt rots. INRA, Paris, 421-428.<br />
Bruce, A. 1992: Biological control of wood decay. International Research Group on Wood Preservation,<br />
No.IRG/WP/1531- 92.<br />
Bruce, A.; King, B. 1986: Biological control of decay in creosote treated distribution poles. I. Establishment of<br />
immunising commensal fungi in poles. Material und Organismen 21: 1-13.<br />
Brown, A.V. 2003: Biological control of decay fungi in seasoning utility poles. PhD. Thesis, Imperial College,<br />
London.<br />
Freitag, M.; Morrell, J.J.; Bruce, A. 1991: Biological protection of wood: status and prospects. Biodeterioration<br />
Abstracts 5: 2-13.<br />
Holdenrieder, O.; Greig, B.J.W. 1998: Biological methods of control. In: Woodward, S.; Stenlid, J.; Karjalainen, R.;<br />
Hüttermann, A. (Eds): H e t e r o b a s i d i o n a n n o s u m. Biology, ecology, impact and control . CAB International,<br />
Wallingford: 235-258<br />
Gibbs, J. N.; Smith, M.E. 1978: Antagonism during the saprophytic phase of the life cycle of two pathogens of<br />
woody hosts – H e t e r o b a s i d i o n a n n o s u m and Ceratocystis ulmi. Annals of Applied Biology 89: 115-142.<br />
Hulme, M.A.; Shields, J.K. 1970: Biological control of decay fungi in wood by competition for non-structural<br />
carbohydrates. Nature 227: 300-301.<br />
Nicolotti, G.; Varese, G.C. 1996: Screening of antagonistic fungi against airborne infection by H e t e r o b a s i d i o n<br />
a n n o s u m on Norway spruce. Forest Ecology and Management 88: 249-257.<br />
Palfreyman, J. W.; Smith, G.M.; Bruce, A. 1996: Timber preservation: current status and future trends. Journal of the<br />
Institute of Wood Science 14: 3-8.<br />
Rayner, A.D.M,; Boddy, L. 1988: Fungal decomposition of wood: its biology and ecology. John Wiley & Sons,<br />
Chichester.<br />
Rayner, A.D.M.; Webber, J.F.W. 1984: Interspecific mycelium interactions - an overview. In: Jennings, D.H.;<br />
Rayner, A.D.M. (Eds): The ecology and physiology of the fungal mycelium. Symposium of British Mycological<br />
Society, Cambridge University Press, Cambridge: 384-417.<br />
Richard, J.; Wilson, M.M.; Bollen, W.B. 1969: Biological control of decay in Douglas Fir poles. Forest Products<br />
Journal 19: 41-45.<br />
Schoeman, M.W. 1995: Control of decay fungi in freshly felled pine. PhD. Thesis, Imperial College, London.<br />
Schoeman, M.W.; Webber, J.F.; Dickinson, D.J. 1994: A rapid method for screening potential biological control<br />
agents of wood decay. European Journal of Forest Pathology 24: 154-159.<br />
Schoeman, M.W.; Webber, J.F.; Dickinson, D.J. 1999: The development of ideas in biological control applied to<br />
forest products. International Biodeterioration and Biodegradation 43; 109-123.<br />
UKWAS. 2000: Certification for the UK Woodland Assurance Scheme. UKWAS Steering Group, Edinburgh.<br />
Webber , J.; Gibbs, J. 1996: Water storage of timber: Experience in Britain. Forestry Commission Bulletin 117,<br />
HSMO, London.<br />
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<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Young, E. J.; Eaton, R. A.; Webber, J. F. 2002: Susceptibility of harvested softwoods to infection by sap-staining<br />
fungi. Int. Res. Group on Wood Pres. IRG/WP 02-10435. pp12.<br />
3.6.3 Physical wood protection<br />
End-sealing of hardwood logs<br />
A well-known method for the protection of Beech-wood is the coating of exposed parts of the wood with a material<br />
preventing the passage of air and water. The effect of the method is prevention of drying and, probably, an increased<br />
carbon dioxide concentration within the log.<br />
Good results were achieved with the end-sealing of Danish Beech logs after the storms in 1967. The idea was to<br />
leave the logs on-site and at the same time to keep the moisture content high in the logs by closing all the bark-free<br />
parts on the log with a suitable compound. Among the best brands were Permaroof, originally a remedy for leaking<br />
roofs. This bitumen-based compound is still available on the market. The sealing compound, Allerød Pasta, also<br />
showed very good results, if it was not damaged by frost. By using Permaroof, the damage during storage were<br />
reduced by 50% and when used together with a biocide the effect was even greater. If used on the whole area of the<br />
log, the damages could be reduced by 85 - 90% (Moltesen and Grenaa Kristensen, 1969). Other sealants used<br />
commercially include wax dispersions, e.g. Anchorseal (Bates Co.) and Mobil-Cer (Mobil Oil).<br />
A finding of merely historical interest was that spraying of Norway Spruce logs with Santobrite<br />
(sodiumpentachlorophenate) + Borax + Lindane (HCH) + DDT and/or covered with plastic, showed almost 100%<br />
protection against insect damage, but the combination seemed to have no significant effect on red top rot (mainly<br />
S t e r e u m s a n g u i n o l e n t u m), probably because plastic covering alone appears to cause an increase in fungal attacks.<br />
Although chlorinated phenols can no longer be used, these results show that biocides can be very effective and it is<br />
hoped that safe, environmentally acceptable replacements may become available in the future.<br />
References:<br />
Moltesen, P.; Grenaa Kristensen, V. 1969: Afprøvning af kævlesmøringsmidler. Skoven, vol. 3, 1969, pp. 19-21.<br />
The End<br />
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Version 7,<br />
10.2.2004<br />
Annex 1: Terminology/Glossary<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
Terminology / Glossary regarding 'Log conservation' Note: The glossary is based mainly on existing English and German terms, which subsequently have been translated to the<br />
other languages<br />
Category English (synonym) Definition Remark Français (synonyme) Deutsch (Synonym) Italiano (sinonimo) Español (sinónimo) Portuguese (sinónimo)<br />
General term wind-blown timber<br />
(storm-damaged<br />
timber)<br />
General term log conservation (log<br />
storage)<br />
timber from trees<br />
damaged by a<br />
storm (broken,<br />
thrown or leaning<br />
trees)<br />
long-term (several<br />
months) storage of<br />
logs with the goal to<br />
preserve the wood<br />
quality<br />
chablis Sturmholz legno proveniente<br />
da schianti<br />
conservation des grumes<br />
(stockage des grumes)<br />
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Rundholzlagerung<br />
(Rundholzkonservieru<br />
ng)<br />
conservazione dei<br />
tronchi (stoccaggio<br />
dei tronchi)<br />
derribos madeira derrubada pelo<br />
vento<br />
conservación de<br />
trozas<br />
conservação de toros<br />
(armazenamento de<br />
toros)<br />
General term round timber harvested part of<br />
tree stem<br />
prEN844-12 bois rond Rundholz legno tondo madera en rollo rolaria<br />
General term long pole whole stem prEN844-12 grume Langholz fusto fuste árvore inteira<br />
General term cut to length stem cut into shorter<br />
billon Kurzholz (Trämel) toppo madera tronzada, madeira torada<br />
pieces<br />
trozas<br />
General term overcut<br />
addition in log<br />
surcote Übermass (Zumass) soprammisura holgura en longitud de medida acima do corte<br />
(overmeasure) length to account for<br />
staining in the endgrain<br />
tronzado<br />
estabelecido<br />
General term with bark logs with bark<br />
avec écorce in Rinde con corteccia con corteza, c/c com casca<br />
General term without bark logs with bark<br />
sans écorce entrindet scortecciato sin corteza, s/c sem casca (descascada)<br />
(debarked) removed<br />
General term conservation method particular technique<br />
méthode de conservation Lagerungsmethode metodo di método de<br />
método de conservação<br />
to achieve goal of<br />
log conservation<br />
conservazione conservación<br />
General term pile heap of logs pile Polter catasta pila pilha<br />
General term compact pile heap of closely piled<br />
logs<br />
pile compacte Haufenpolter catasta compatta pila compacta pilha compacta<br />
General term cross-pile heap of logs with<br />
pile à rangs croisés Lagenpolter catasta con strati pila encastillada pilha com troncos<br />
perpendicular<br />
perpendicolari<br />
cruzados<br />
intermediate layer of<br />
single logs allowing<br />
free ventilation<br />
transversalmente<br />
General term standing tree tree in upright<br />
arbre sur pied (arbre stehender Baum albero in piedi árbol en pie árvore em pé<br />
position (inclination<br />
90-60°)<br />
debout)<br />
General term leaning tree tree with inclination<br />
59-30°<br />
arbre penché angeschobener Baum albero inclinato árbol inclinado árvore inclinada<br />
General term uprooted tree thrown tree with<br />
inclination 29-0°<br />
arbre déraciné geworfener Baum albero sradicato árbol desarraigado árvore arrancada<br />
General term broken tree tree broken in 2 (or<br />
arbre cassé gebrochener Baum albero spezzato árbol tronchado árvore partida<br />
(snapped tree) more) separate
pieces<br />
Cons. method In-situ storage logs left untouched<br />
in place in the stand<br />
Cons. method live-conservation of<br />
wind-thrown trees<br />
Cons. method drying by<br />
transpiration<br />
in situ storage of<br />
living, uprooted<br />
trees with sufficient<br />
root contact<br />
in situ storage of<br />
entire trees (with<br />
crown) with a crosscut<br />
at the stem base<br />
Cons. method wet storage storage under<br />
(controlled) wet<br />
conditions keeping<br />
the wood saturated<br />
Cons. method compact pile with<br />
water sprinkling<br />
Cons. method ponding (immersion<br />
in water)<br />
Cons. method storage under drying<br />
conditions<br />
Cons. method log pre-drying in<br />
covered cross-pile<br />
Cons. method fast log pre-drying in<br />
open cross-pile<br />
Cons. method storage under humid<br />
conditions<br />
compact pile with<br />
water sprinkling<br />
(logs with bark)<br />
storage of (loating)<br />
logs in running or<br />
standing water (logs<br />
with bark)<br />
storage under<br />
(uncontrolled)<br />
conditions resulting<br />
in slow or fast<br />
drying of the logs<br />
pre-drying of logs in<br />
covered cross-pile<br />
(logs debarked)<br />
fast log pre-drying in<br />
open cross-pile<br />
(logs debarked)<br />
storage under<br />
(uncontrolled)<br />
changing conditions<br />
Cons. method compact pile compact pile (logs<br />
with bark /<br />
Cons. method compact pile<br />
covered with plastic<br />
sheets<br />
debarked)<br />
compact pile<br />
covered with plastic<br />
sheets (logs with<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
conservation in-situ Lagerung im Bestand stoccaggio in situ almacenamiento in<br />
situ<br />
chapter 3.1.1 conservation sur site des<br />
bois partiellement<br />
déracinés<br />
- 82 -<br />
Lebendkonservierung<br />
im Bestand<br />
chapter 3.1.2 séchage par transpiration Physiologische<br />
Trocknung<br />
(Ganzbaumlagerung)<br />
stoccaggio in piedi<br />
di alberi danneggiati<br />
dal vento (ma<br />
ancora radicati)<br />
Stagionatura per<br />
traspirazione<br />
conservación en vivo<br />
de árboles<br />
parcialmente<br />
desarraigados<br />
secado natural,<br />
secado al aire<br />
chapter 3.2 stockage sous eau Nasslagerung stoccaggio in acqua almacenamiento en<br />
húmedo<br />
chapter 3.2.1 pile compacte sous<br />
aspersion d'eau<br />
Nasslagerung durch<br />
Beregnung<br />
chapter 3.2.2 immersion Nasslagerung in<br />
Gewässern<br />
chapter 3.3 stockage sous conditions<br />
asséchantes<br />
chapter 3.3.1 stockage sous conditions<br />
sèches<br />
chapter 3.3.2 pré-séchage rapide des<br />
grumes stockées en pile<br />
croisée ouverte<br />
chapter 3.4 stockage sous conditions<br />
humides<br />
Rundholzvortrocknun<br />
g<br />
Rundholzvortrocknun<br />
g in gedecktem<br />
Lagenpolter<br />
Schnelle<br />
Rundholzvortrocknun<br />
g in offenem<br />
Lagenpolter<br />
Lagerung unter<br />
feuchten<br />
Bedingungen<br />
(Feuchtlagerung)<br />
catasta compatta<br />
con aspersione<br />
d'acqua<br />
pila compacta bajo<br />
aspersión<br />
armazenamento no local<br />
do povoamento<br />
conservação em vida de<br />
árvores derrubadas pelo<br />
vento<br />
secagem por evaporação<br />
conservação com água<br />
pilhas compactas com<br />
sistemas de expressão de<br />
água<br />
immersione inmersión conservação de toros por<br />
imersão<br />
stoccaggio al riparo<br />
dagli agenti<br />
atmosferici<br />
pre-essiccazione in<br />
cataste, con strati<br />
perpendicolari,<br />
coperte<br />
pre-essiccazione<br />
veloce in cataste,<br />
con strati<br />
perpendicolari, non<br />
coperte<br />
stoccaggio<br />
all'aperto<br />
almacenamiento en<br />
condiciones de<br />
secado al aire<br />
pre-secado de trozas<br />
en pilas encastilladas<br />
bajo cubierta<br />
pre-secado de trozas<br />
en pilas encastilladas<br />
descubiertas<br />
almacenamiento en<br />
condiciones húmedas<br />
no controladas<br />
armazenamento de toros<br />
ao ar livre<br />
pré-secagem dos troncos<br />
em pilhas cobertas<br />
pré-secagem de pilhas ao<br />
ar livre com troncos<br />
cruzados<br />
armazenamento em<br />
condições humidas<br />
chapter 3.4.1 pile compacte Haufenpolter catasta compatta pila compacta pilha compacta<br />
chapter 3.4.2 pile compacte recouverte<br />
d'une bâche plastique<br />
Haufenpolter mit<br />
Folien-Abdeckung<br />
catasta compatta<br />
coperta da teli di<br />
plastica<br />
pila compacta<br />
recubierta con<br />
plástico<br />
pilha compacta coberta<br />
com plásticos
ark / debarked)<br />
Cons. method 'special' methods conservation<br />
methods with<br />
protection<br />
mechanisms not<br />
fitting into main<br />
Cons. method log conservation<br />
under oxygen<br />
exclusion, compact<br />
pile wrapped in<br />
plastic sheets<br />
Cons. method compact pile<br />
covered with geo<br />
textile fabric<br />
Cons. method compact pile<br />
covered with a<br />
mineralic suspension<br />
categories<br />
compact pile<br />
wrapped and sealed<br />
in plastic sheets<br />
resulting in oxygen<br />
free conservation<br />
atmosphere (logs<br />
with bark)<br />
compact pile<br />
covered with geo<br />
textile fabric (logs<br />
with bark)<br />
compact pile<br />
covered with a thin<br />
layer of mineralic<br />
suspension<br />
(protection against<br />
insects)<br />
Cons. method storage in gravel pits compact pile buried<br />
in a hole in the<br />
ground or on level<br />
ground covered with<br />
thick layer of<br />
clay/soil<br />
Cons. method storage in mines storage in unused<br />
Cons. method compact pile above<br />
timberline<br />
mine tunnels<br />
compact pile above<br />
timberline (logs with<br />
bark)<br />
Cons. method storage in snow compact pile<br />
covered with snow<br />
Cons. method compact pile<br />
covered with organic<br />
material<br />
Cons. method supplementary<br />
conservation<br />
measures<br />
compact pile<br />
covered with bark<br />
chips, wood chips,<br />
sawdust etc.<br />
conservation<br />
measures<br />
supplementary to<br />
main methods<br />
('integrated<br />
methods')<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
chapter 3.5 méthodes spéciales Spezialverfahren metodi particolari métodos especiales métodos especiais<br />
chapter 3.5.1 conservation en<br />
atmosphère confiné, pile<br />
compacte enroulée dans<br />
une bâche en plastique<br />
scellée<br />
chapter 3.5.2 pile compact recouverte<br />
d'une feuille de géotextile<br />
chapter 3.5.3 pile compacte recouverte<br />
d'une suspension<br />
minérale<br />
- 83 -<br />
Rundholzkonservierun<br />
g durch<br />
Sauerstoffentzug<br />
Haufenpolter mit<br />
Geovlies-Abdeckung<br />
Haufenpolter mit<br />
mineralischer<br />
Schutzhülle<br />
stoccaggio del<br />
legno in assenza di<br />
ossigeno, cataste<br />
compatte avvolte da<br />
teli di plastica<br />
catasta compatta<br />
coperta con tessuto<br />
geotessile<br />
catasta compatta<br />
trattata con una<br />
sospensione<br />
minerale<br />
chapter 3.5.4 stockage sous terre Erdlagerung stoccaggio per<br />
interramento<br />
chapter 3.5.5 stockage dans des mines Lagerung in<br />
Bergwerken<br />
chapter 3.5.6 pile compacte stockée au- Haufenpolter oberhalb<br />
dessus de la limite Waldgrenze<br />
supérieure des forêts<br />
chapter 3.5.7 stockage sous la neige Lagerung unter<br />
Schnee<br />
chapter 3.5.8 pile compacte couverte de<br />
matière organique<br />
chapter 3.6 mesures supplémentaires<br />
de conservation<br />
Haufenpolter mit<br />
Abdeckung aus<br />
organischem Material<br />
zusätzliche<br />
Schutzmassnahme<br />
stoccaggio in<br />
miniera<br />
stoccaggio in<br />
altitudine<br />
stoccaggio sotto la<br />
neve<br />
stoccaggio con<br />
materiale organico<br />
misure<br />
supplementari di<br />
conservazione<br />
conservación en<br />
atmósfera pobre en<br />
oxígeno de pilas<br />
compactas bajo<br />
plástico hermético<br />
pila compacta<br />
cubierta por tejido<br />
geotextil<br />
pila compacta<br />
cubierta por una<br />
suspensión mineral<br />
almacenamiento de<br />
pilas enterradas<br />
almacenamiento en<br />
minas<br />
Pila compacta bajo el<br />
límitealtitudial del<br />
bosque<br />
almacenamiento bajo<br />
la nieve<br />
Pila compacta<br />
cubierta por materia<br />
orgánica<br />
medidas<br />
suplementarias de<br />
conservación<br />
conservação de troncos<br />
em pilhas seladas sem<br />
entrada de oxigénio<br />
cobertas com plásticos<br />
pilha compacta coberta<br />
com tela têxtil<br />
pilha compacta coberta<br />
com uma folha de mineral<br />
em suspenção<br />
armazenamento em<br />
subterrâneos ou ou pilhas<br />
cobertas com barro<br />
armazenamento em<br />
minas<br />
pilha compacta em zonas<br />
de montanha, acima da<br />
linha de crescimento da<br />
vegetação<br />
armazenamento na neve<br />
pilha compacta coberta<br />
com material orgânico<br />
medidas suplementares<br />
de conservação
Cons. method chemical protection wood protection by<br />
chemical<br />
agents<br />
Cons. method biological protection wood protection by<br />
biological agents<br />
Cons. method physical protection wood protection by<br />
physical measures<br />
(e.g. end-grain<br />
sealing)<br />
Processes input process of building<br />
up a log storage<br />
Processes removal process of<br />
extracting logs from<br />
a log storage<br />
Material sprinkler device to produce<br />
artificial rain<br />
<strong>STODAFOR</strong> State-of-the-Art paper LOG CONSERVATION<br />
chapter 3.6.1 protection chimique chemischer<br />
Holzschutz<br />
chapter 3.6.2 protection biologique biologischer<br />
Holzschutz<br />
chapter 3.6.3 protection physique physikalischer<br />
Holzschutz<br />
- 84 -<br />
protezione chimica protección química protecção química<br />
protezione biologica protección biológica protecção biológica<br />
protezione con<br />
mezzi fisici<br />
mise en place Einlagerung inizio (del processo<br />
di stoccaggio dei<br />
tronchi)<br />
reprise Auslagerung interruzione (del<br />
processo di<br />
stoccaggio dei<br />
tronchi)<br />
Protección fisica protecção física<br />
montaje entrada<br />
retirada remoção dos troncos do<br />
armazenamento<br />
arroseur Kreis-/Sektorregner aspersore aspersor aspersor