STODAFOR - Ctba

STODAFOR State-of-the-Art paper LOG CONSERVATION 

STODAFOR 

STORM DAMAGED FOREST: 

EFFICIENT AND SAFE HARVESTING AND LOG CONSERVATION 

METHODS 

STATE-OF-THE-ART-PAPER 

Version 2005.02.16 

Project Coordinator: CTBA, 10 avenue de Saint Mandé 75012 Paris, www.ctba.fr 

Project partners: FVA (D), KVL (DK), EMPA (CH), CBE (P), BFH (D), UPM (E), DLFRI (DK), TTI (I), AFOCEL (F), TUD (D), BRE (UK), 

FMRE (A), ICSTM (UK), UOP (UK), NISK (N) 

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Table of Contents 


1 Basic principles ……………………………………………………………………………………………… 8 

1.1 Reasons for and goals of log conservation ……………………………………………………………….. 8 

1.2 Deterioration of stored logs ……………………………………………………………………………… 9 

1.2.1 General description of fungal stain, mould and decay and insect damage plus wood species 

susceptibility …………………………………………………………………………………… 9 

1.2.2 Importance of wood moisture content ……………………………………………………….… 9 

1.2.3 Goal of log conservation …………………………………………………………………….… 11 

1.2.4 Choice of conservation method ………………………………………………………………… 11 

1.2.5 References …………………………………………………………………………………….... 11 

1.3 General recommendations ……………………………………………………………………………… 11 

1.4 Choice of conservation method …………………………………………………………………………. 11 

1.4.1 Storm damage potential scale ………………………………………………………………… 11 

1.4.2 Short description of different types of storm damaged trees ………………………………..… 12 

1.4.3 Research needs ………………………………………………………………………………… 13 

1.4.4 References …………………………………………………………………………………..… 13 

2 General considerations ………………………………………………………………………………………. 16 

2.1 Economic aspects ………………………………………………………………………………………… 16 

2.1.1 General remarks ……………………………………………………………………………… 16 

2.1.2 Storage period ………………………………………………………………………………… 16 

2.1.3 Time management (organization and speed of work) ………………………………………… 16 

2.1.4 Storage site ……………………………………………………………………………………. 16 

2.1.5 Tree species …………………………………………………………………………………… 16 


2.1.7 References ………………………….………………………………………………………….. 17 

2.2 Regulations / Laws …………………………………………………………………………………….. 17 

- Austria ………………………………………………………………………………..……………….. 17 

- Germany ……………………………………………………………………………….……………… 17 

- Great Britain …………………………………………………………………………….…………….. 18 

- Denmark ………………………………………………………………………………….……………. 18 

- France …………………………………………………………………………………….……………. 18 

- Italy ……………………………………………………………………………………….……………. 18 

- Norway ………………………………………………………………………………………………… 19 

- Portugal ……………………………………………………………………………………………....… 19 

- Spain …………………………………………………………………………………………………… 20 

- Switzerland ………………………………………………………………………….…………………. 20 

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2.3 Environmental impacts …………………………………………………………………………………… 21 

2.3.1 General remarks …………………………………………………………...…………………… 21 

2.3.2 Water spraying with open water systems ……………………………………………………… 22 

2.3.3 Water spraying in recycling water systems …………………………………………………… 22 

2.3.4 Pond storage …………………………………………………………………………………… 22 

2.3.5 Ground water pollution ………………………………………………………………………… 23 

2.3.6 Insecticide application ………………………………………………………………………… 23 

2.3.7 References ……………………………………………………………………………………… 23 

2.4 Management/Operation/Health and Safety …………………………………………………………….. 24 

2.4.1 Management/Operation ………………….…………………………………………………… 24 

2.4.2 Health and Safety ……………………………………………………………………………… 24 


2.4.4 References ……………………………………………………………………………………… 25 

2.5 Process monitoring and wood quality ………………………………………………………………….. 25 

2.5.1 Process monitoring ……………………………………………………….……………………. 25 

2.5.2 Wood quality …………………………………………………………………………………… 25 

2.5.2.1 General remarks ………………………………………………………………..…….. 25 

2.5.2.2 Wood quality related to storm and log conservation …………………………..…….. 27 


2.5.4 References ……………………………………..……………………………………………… 29 

3 Conservation methods ………………………………………………………………………………………. 30 

3.1 In-situ storage ……………………………………………………………………………………………. 31 

3.1.1 Live-conservation of wind-thrown trees ……………………………………………………….. 31 

3.1.1.1 Principle/description …………………………………………………………………. 31 

3.1.1.2 Advantages, disadvantages, practical experience …………………………………… 31 

3.1.1.2.1 Advantages, disadvantages …………...……………………………… 31 

3.1.1.2.2 Practical experience …………………………………………………… 31 

- Beech …………………………………………………………… 31 

- Spruce ……….…………………………………………………… 33 

- Pine ……………………………………………………………… 34 

- Maritime Pine …………………………………………………… 34 

- Douglas fir ………………………………………………………… 34 

3.1.1.3 Recommendations …………………………………………………………………… 34 

3.1.1.4 Quality monitoring …………………………………………………………………… 35 

3.1.1.5 Environmental issues ………………………………………………………………… 35 

3.1.1.6 Costs ………………………………………………………………………………….. 35 

3.1.1.7 Research needs ……………………………………………………………………… 35 

3.1.1.8 References ……………………………………………………………………………. 35 

3.1.2 Drying by transpiration ……………………………………………………………………….. 36 

3.1.2.1 Principle/description …………………………………………………………………… 36 

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3.1.2.2 Advantages, disadvantages, practical experience ………………………………...…… 36 

3.1.2.3 Recommendations (application, time limits) ………………………………………….. 36 

3.1.2.4 Quality monitoring ……………………………………………………………………. 36 


3.1.2.6 Costs …………………………………………………………………………………… 36 

3.1.2.7 Research needs ………………………………………………………………………… 36 

3.1.2.8 References ………………………………………………………………………….… 37 

3.2 Wet storage …………………………………………………………………………………………….. 37 

3.2.1 Compact pile with water sprinkling (logs with bark) …………………………………………. 37 

3.2.1.1 Principle/description ………………………………………………………………...… 37 

3.2.1.2 Advantages, disadvantages, practical experience ……………………………………… 38 

3.2.1.2.1 Advantages, disadvantages ……………………………………………… 38 

3.2.1.2.2 Practical experience ……………………………………………………… 39 

- Maritime Pine ( Pinus pinaster) ……………………………………..… 40 

- 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 

- Beech ( F a g u s s y l v a t i c a) ………………………………………………… 40 

- Oak (Q u e r c u s s p e c.) …………………………………………………… 41 

3.2.1.3 Recommendations (application, time limits) ………………………………………… 41 

- Water supply ……………………………………………………………………….. 42 

- Log storage/Basic requirements …………………………………………………..… 43 

- Equipment ……………………………………………………………………….…… 43 

3.2.1.4 Quality monitoring …………………………………………………………………..… 44 

- Log storage / some pieces of advice ………………………………………………… 44 

3.2.1.5 Environmental issues ……………………………………………………………….… 45 

- Interval water spraying ……………………………………………………………… 45 

- Water spraying in recycling water systems ………………………………………… 46 

- Groundwater pollution ……………………………………………………………… 46 

3.2.1.6 Costs …………………………………………………………………………………. 47 

- General remarks ……………………………………………………………………… 47 

- Preliminary investments …………………………………………………………… 47 

- Functioning costs …………………………………………………………………… 48 

- Costs following the period of conservation ………………………………………… 49 


3.2.1.8 References …………………………………………………………………………… 49 

3.2.2 Ponding/Immersion in fresh water water (log with bark) ……………………………………… 51 

3.2.2.1 Principle/description ………………………………………………………………...… 51 

3.2.2.2 Advantages, disadvantages, practical experience ………………………………….… 51 

3.2.2.2.1 Advantages, disadvantages ……………………………………………… 51 

3.2.2.2.2 Practical experience ……………………………………………………… 51 

3.2.2.3 Recommendation ……………………………………………………………………… 52 

3.2.2.4 Quality monitoring ………….………………………………………………………… 52 

3.2.2.5 Environmental issues ………………………………………………………….……… 52 

3.2.2.6 Costs ……………………………………………………………………………..…… 53 


3.2.2.8 References …………………………………………………………………………….. 53 

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3.3 Storage under drying conditions …………………………………………………………………………. 54 

3.3.1 Log pre-drying in covered cross-piles (logs without bark) …………………………………….. 54 

3.3.1.1 Principle/description ………………………………………………………………… 54 





3.3.1.6 Costs …………………………………………………………………………………… 55 


3.3.1.8 References …………………………………………………………………………..… 55 

3.3.2 Rapid pre-drying in open cross-piles (logs without bark) …………………………………….. 55 



3.3.2.2.1 Advantages ………………………………………………………… 56 

3.3.2.2.2 Disadvantages ……...………………………………………………… 56 

3.3.2.2.3 Practical experience ………………………………………………… 57 




3.3.2.6 Costs ………………………………………………………………………………… 58 

3.3.2.7 Research needs ……………………………………………………………..………… 58 

3.3.2.8 References …………………………………………………………………………… 58 

3.4 Storage under humid conditions ………………………………………………………………………… 59 

3.4.1 Compact pile (logs with/without bark) …………………………………………………………. 59 

3.4.1.1 Principle /description ………………………………………………………………… 59 


3.4.1.2.1 Advantages, disadvantages ……………………………………..… 59 

3.4.1.2.2 Practical experience …...…………………………………………… 59 

- Maritime Pine ……………………………………………………… 59 

3.4.1.3 Recommendations ………….………………………………………………………… 60 



3.4.1.6 Costs …………………………………………………………………………………… 60 


3.4.1.8 References ………………………………………………………………………..…… 61 

3.4.2 Compact pile covered with plastic sheets (logs with bark/without bark) ……………………… 61 


3.4.2.2 Advantages, disadvantages, practical experience ……………………………………. 61 




3.4.2.6 Costs ………………………………………………………………………………… 62 


3.4.2.8 References ……………………………………………………………………….…… 62 

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3.5 “Special” methods ……………………………………………………………………………………….. 63 

3.5.1 Log conservation under oxygen exclusion, compact pile wrapped in plastic sheets (logs with bark) 



3.5.1.2.1 Advantages ………………………………………………………… 64 

3.5.1.2.2 Disadvantages ……………………………………………………… 64 

3.5.1.2.3 Practical experience ……………………………………………….. 65 




3.5.1.6 Costs ………………………………………………………………………………… 66 


3.5.1.8 References …………………………………………………………………………… 66 

3.5.2 Compact pile covered with geo textile fabric (logs with bark) ………………………………. 67 






3.5.2.6 Costs ………………………………………………………………………………… 67 


3.5.2.8 References …………………………………………………………………………… 67 

3.5.3 Compact pile covered with a mineralic suspension …………………………………………… 67 

3.5.3.1 Principle/description …………………………………………………………….… 67 

3.5.3.2 Advantages, disadvantages, practical experience ……………………………….…… 68 

3.5.3.3 Recommendations ……………………………………………………………….…… 68 



3.5.3.6 Costs …………………………………………………………………………………… 68 

3.5.3.7 Research needs ……………………………………………………………………….. 68 

3.5.3.8 References …………………………………………………………………………… 68 

3.5.4 Storage in gravel pits ………………………………………………………………………….. 69 






3.5.4.6 Costs ………………………………………………………………………………… 69 


3.5.4.8 References …………………………………………………………………………… 69 

3.5.5 Storage in mines ……………………………………………………………………………….. 70 



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3.5.5.6 Costs ………………………………………………………………………………… 70 


3.5.5.8 References …………………………………………………………………………… 70 

3.5.6 Compact pile above tree line (logs with bark) ………………………………………………….. 70 






3.5.6.6 Costs …………………………………………………………………………………… 71 


3.5.6.8 References …………………………………………………………………………..… 71 

3.5.7 Storage in snow ………………………………………………………………………………… 71 

3.5.7.1 Principle/description …………………………………….…………………………… 71 

3.5.7.2 Advantages, disadvantages, practical experience ………….………………………… 72 

3.5.7.2.1 Advantages ………………………………………………………… 72 

3.5.7.2.2 Disadvantages ……………………………………………………… 72 

3.5.7.3 Recommendations ………………………………………….………………………… 73 

3.5.7.3.1 Temperature ………………………………………………………. 73 

3.5.7.3.2 Moisture content ………………………………………………….. 73 

3.5.7.3.3 Level of brightness ………………………………………………… 73 

3.5.7.3.4 Important factors, independent of the method …………………….. 74 



3.5.7.6 Costs …………………………………………………………………………………… 74 


3.5.7.8 References …………………………………………………………………………… 74 

3.5.8 Compact pile covered with organic material ………………………………………………….. 74 


3.5.8.2 Advantages, disadvantages, practical experience ……………………………………… 74 

3.5.8.3 Recommendations ………………………………………………………………….… 75 

3.5.8.4 Quality monitoring ………………………………………………………………….… 75 


3.5.8.6 Costs ……………………………………………………………………………….… 76 

3.5.8.7 Research needs ……………………..………………………………………………… 76 

3.5.8.8 References ………………………………………………………………………….… 76 

3.6 Supplementary conservation measures …………………………………………………………………. 77 

3.6.1 Chemical wood protection ……………………………………………………………………… 77 

3.6.1.1 Principles/description ………………………………………………………………… 77 

- Log preparation …………………………………………………………………….. 77 

- Material …………………………………………………………………………….. 77 

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- Methodology ……………………………………………………………………….. 77 

3.6.1.2 Precautions …………………………………………………………………………… 77 

3.6.2 Biological protection …………………………………………………………………………… 77 

3.6.2.1 Principles/description ………………………………………………………………… 77 

3.6.2.2 References …………………………………………………………………………… 77 

3.6.3 Physical protection ……………………………………………………………………………… 80 

End-sealing of hardwood logs ………………………………………………………………… 80 

Annex ………………………………………………………………………………………………………….. 81 

Terminology/Glossary ………………………………………………………………………………… 81 

1 Basic principles 

1.1 Reasons for and goals of log conservation 

By taking advantage of the machine-power available in today`s forestry, the salvaging of logs after storm damage 

could probably be carried out rather quickly. However, the large and sudden supply of raw material that subsequently 

becomes available may by far exceed the conversion and sales capabilities of the sawmilling industry, and the result 

could very well be a collapse of the round timber market. Eventually, a large proportion of the wood could be lost 

due to rot and insect infestation. Solutions such as storage of logs on site or in special storage yards should therefore 

be seriously considered in order to spread the supply of wood over a longer period of time and to avoid loss in value. 

During transportation out of the forest to the wood-processing enterprise the high-grade round timber is exposed to 

various dangers that contribute to a considerable loss in use value. In the following sections the causes of biotic and 

abiotic damage of round timber are demonstrated using selected examples. Advice for the proper handling of round 

timber during transportation is also provided. 

Depending on the length of time involved, log storage may be subdivided into two groups: 

a) Storage of round timber in the forest after tree harvesting (generally for a few days to a few weeks); 

b) Longer-term storage of round timber (subsequent to calamities, i.e. for a few months to several years). 

The risks associated with round timber storage are: formation of checks after drying or seasoning of the external log 

parts too close to fibre saturation point; discoloration; infestation with insects; destruction of the wood by infestation 

with fungi. These phenomena occur as a result of inappropriate storage and care of the timber. In general, this causes 

a partial reduction in the value of the wood. In extreme cases the round timber can be completely devalued. 

Depending on the duration of storage, a number of factors can contribute to a reduction in wood quality, 

necessitating various kinds of strategies for storage. 

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1.2 Deterioration of stored logs 


1.2.1 General description of fungal stain, mould and decay and insect damage, plus wood species susceptibility 

Every year, forest sector industries worldwide lose millions of dollars when sap-staining fungi attack and discolour 

the sapwood of freshly felled timber. However, this damage is largely cosmetic, the strength of the wood is hardly 

impaired and decay is absent. Of all the conifer species, pines are the most susceptible to sap stain whilst species of 

spruce show some measure of resistance to infection. Three distinct groups of fungi are recognised as the cause 

of the problem. 

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 , 

which penetrate into the wood. Their pigmented hyphae grow in the tracheids and rays of the wood tissue producing 

a blue-black discolouration visible when affected logs are sawn. These fungi are commonly described as sapstain or 

bluestain fungi and are generally considered to be the most important and prolific of the three groups in softwoods. 

The second group comprises fungi which grow mainly on wood surfaces causing superficial staining and include 

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 

frequently found after the initial stages of timber processing on timber and on debarked logs. 

Figure 1: Brown discoloration on spruce wood as a result of incorrect round wood 

storage (Source TUD) 

The third group also grow superficially, often on freshly felled timber, 

and discolour the wood by producing abundant pigmented spores. 

These are mainly mould fungi including Alternaria, Cladosporium, 

P e n i c i l l i u m and Trichoderma. 

Bark beetles (members of the family S c o l y t i d a e) spread the deepstaining 

fungi when they seek out breeding material in the form of 

weakened or felled trees during the summer. The females bore tunnels 

in the cambium and deposit their eggs. When the eggs hatch, the larvae create galleries below the bark and when 

mature, they pupate. Following the final metamorphosis, the adults bore their way through the bark and emerge via 

exit holes. 

Many staining fungi also gain access to wounds or cut log surfaces all the year round through rain-splash, the wind 

dispersal of infected fragments of wood and by casual dispersal by arthropods as they graze on fungal mycelia. 

However, the degree of infection is also dependent on the timber species, with marked differences occurring in 

susceptibility to sap stain. This may reflect qualitative and quantitative variation in the pre-formed anti-fungal 

constituents of conifer resin, which is known to differ between species. 

The ability of sapstain fungi to invade host cells may also be influenced by their ability to overcome cellular 

defences induced in living bark and wood following wounding and attack by pathogens. It has been stated that 

sapstain fungi range from truly pathogenic species, which invade healthy living trees, to those colonising weakened 

and stressed trees, to the saprotrophs found on dead timber. It has been shown for instance, that species of 

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 

different pathogenic characteristics. 

1.2.2 Importance of wood moisture content 

It has been widely recognised that the moisture content of timber may play the most important role in determining 

the extent and diversity of fungal colonisation. Above fibre saturation point (approx. 20% moisture content) wood is 

vulnerable to infection and two forms of fungal decay are able to destroy the structure of wood cell walls leading to 

complete strength loss of the timber. White rot fungi are commonplace in the forest and the decay they produce 

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gives a familiar bleached appearance to the wood, particularly in hardwood species. These fungi produce enzymes 

capable of degrading all three of the major wood cell wall components: cellulose, hemicelluloses and lignin. Brown 

rot fungal attack causes the wood to become darker in appearance and only cellulose and hemicelluloses are 

destroyed; the lignin component is undamaged or slightly modified. Both types of decay are caused by 

basidiomycete fungi and the large reproductive fruit bodies which emerge from decaying wood bear an abundance 

of spores which are typically wind dispersed and germinate on exposed woody surfaces. White rot decay in 

hardwoods, notably in woodland situations, is also attributed to members of the higher ascomycetes. Like sapstain 

fungi, decay fungi exhibit a spectrum of invasive activity ranging from the truly pathogenic fungi, which attack 

standing trees, to the saprotrophic forms, which attack dead timber. The moisture content of the wood must not be 

too high, i.e. saturated and therefore oxygen depleted, or too low and therefore too dry, for these fungi to invade 

successfully. 

Drying of the wood beginning immediately after felling of the trees, causes the ratio of water content to air content in 

the cells to change. As a result, secondary pests such as fungi can infest the stored wood. For fresh wood with 

moisture contents of about 150% (coniferous woods) or 90% (broad-leaved species), based on oven-dried weight, the 

risk of secondary pests due to insufficient oxygen supply is low. At a wood moisture content below 100% or at about 

20% air volume in the wood, secondary pests enjoy good to ideal living conditions. The danger of an infestation 

with corresponding devaluation of the wood, is increased. . Below fibre saturation point (approx. 30% to 20% wood 

moisture) the risk of infestation with fungi decreases markedly due to lack of moisture (see Figure 2). 

Figure 2: Wood moisture content and its effect on the risk of the development of secondary pests 

(Wiebe 1990, modified) 

High or low wood moisture is therefore the best protection from fungal attack! 

Seasoning of round timber starts immediately after felling the tree by water evaporating form the log ends, and, on 

debarked logs, from the total stem surface. The rate of evaportaion depends on the number of log ends, so few 

resawing cuts should be made, and on the following conditions: 

- size of the debarked log surfaces; 

- the season of the felling and storage; 

- place of storage; 

- presence of live crown on the stem. 

The quality may deteriorate sequentially during the continuous drying process: 

- discoloration, followed by 

- infestation with fungi, followed by 

- attack by insects and finally 

- cracks. 

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1.2.3 Goal of log conservation 


Round wood storage aims at maintaining the properties of high-grade wood for the future buyer. In addition, round 

timber storage may ease problems for the timber market and stabilise wood prices. 

1.2.4 Choice of conservation method 

The choice of conservation method depends on the following factors: 

- kind of storm (see chapter 1.4, table 1) 

- kind of storm damaged trees (see chapter 1.4, table 2); 

- anticipated duration of storage (1 vegetation period up to several years); 

- availability of storage yards and their handling capacities; 

- staff and financial considerations; 

- legal aspects (see chapter 2.2); 

- industrial safety. 

1.2.5 References 

Wiebe, S. 1992: Untersuchungen zur Wundentwicklung und Wundbehandlung an Bäumen unter besonderer 

Berücksichtigung der Holzfeuchte. Inaugural-Dissertation, Fakultät für Forstwissenschaften, Ludwig-Maximilians- 

Universität München 

1.3 General recommendations 

In order to prevent loss of wood moisture, below 120% to 100% for coniferous trees and 80% for broad-leaved trees, 

round timber should not be debarked. Bark is regarded as the best packaging material for the logs and should only be 

removed if there is the risk of bark beetle infestation. Bark not only protects against moisture loss but also protects 

the wood from damage due to manipulation of the stem. Moreover, when assessing round timber quality, bark is also 

an indicator of local defects, i.e. wood characteristics. 

When storing the wood over a longer time period, two strategies may be pursued regarding moisture content of the 

wood: 

• allowing the wood moisture content to remain (or reach) as high as possible (above 100% or 80% related to 

oven-dry weight); 

• lowering the natural wood moisture to below fibre saturation point as fast as possible (about 20% of the 

wood moisture related to oven-dry weight). 

In Central Europe, the risk of log deterioration is highest from May to October for hardwood and from March to 

October for softwood 

1.4 Choice of conservation method 

1.4.1 Storm damage potential scale 

The following table gives a brief classification and description of storms and their devastation effects on single trees. 

To guarantee the comparatibility of future research work on storm damage of trees and forests this classification it is 

recommended that this classification is used to characterize particular storm events. 

Depending on the kind of stem damage caused by the storm, a distinction can be made between wind-throw, windbreakage 

or tilted stems hanging in the crowns of other trees. This is particularly the case for broad-leaved trees with 

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different types of crown damage (see Table 2 including the different types of storm damaged trees, Bues 2000). The 

following survey gives a short description of the types of damage and Table 2 shows the most suitable storage 

methods for storm damaged timber, depending on the respective type of damage. As storm damage, in general, leads 

to different patterns of damage on single trees and in stands, the forest worker can select the most suitable methods 

from a number of possibilities and organise conversion of the wind damaged timber, depending on the susceptibility 

of the respective wood species, their working capacities and the duration of storage. 

Table 1: Storm Damage-Potential Scale for woody plants, based on the Scaling after TORRO as adjusted to Middle Europe [TorDACH], 

Hubrig (2001) 

T0 

76 ± 14 

km/h 

T1 

104 ± 14 

km/h 

T2 

135 ± 16 

km/h 

T3 

167 ± 16 

km/h 

T4 

202 ± 18 

km/h 

T5 

238 ± 18 

km/h 

T6 

275 ± 20 

km/h 

T7 

315 ± 20 

km/h 

T9 

400 ±22 

km/h 

Incipient breaking off of single branches. Diseased (e.g. decayed trees) or particularly unstable trees (long thin stems, crown base 

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 

sites). 

Branches, even thick and healthy ones break to an increased extent, particularly during the growing season over which broadleaved 

trees are foliated. Diseased (e.g. decayed trees), or particularly unstable trees (long, thin stems, crown base higher up the 

stem, sparse system of shallow roots) often break or get uprooted. Trees with root damage/rot or on unstable, wetted sites are 

subject to wind-throw. 

Numerous branches, also thick and healthy ones break, in particular during the growing season when broad-leaved trees are 

foliated. Diseased (e.g. decayed trees), or unstable trees (long, thin stems, crown base higher up the stem, sparse system of 

shallow roots) are almost always broken or get uprooted. Trees with root damage/rot or on unstable wetted sites are almost 

always subject to complete wind-throw. Even lesser firmly rooted, healthy trees get uprooted if soils are water-soaked and 

wetted due to the weather at certain, not necessarily unstable sites (e.g. thick strata of loess-loams). 

Trees of less stable condition due to the specific species and varieties, e.g. broad-crowned lowland spruces are wind-thrown or 

break, while slim upland spruces or healthy oaks remain standing. 

Trees in forest stands which, due to the stand structure, have poor single tree stability (too narrow planting, lack of tending 

operations, in particular coniferous trees in monocultures) are often subject to wind-throw or breakage. 

During the period of sap flow trees with a firm rooting, but unstable stems, are often affected due to damage by pressure. 

Numerous branches, including thick and healthy ones break; even when broad-leaved trees are bare of foliage i.e. not during the 

growing season. Stable and healthy trees are also subject to wind-throw or breakage to a higher degree. During the time of sap 

flow, pressure damage occurs relatively often. 

Even stable trees/forest stands are almost always/completely wind-thrown or broken. 

Trees with large crowns, provided they are safely anchored by roots, are mostly broken. If trees remain standing at all, a larger 

number of branches, including the non-foliated ones, are torn off. The proportion of damage due to pressure is greatly reduced in 

favour of broken trees. 

Even the most stable trees or shrubs such as border trees, storm-proof hedges, bushes and field woods show almost 100% 

damage, either by uprooting, stem or crown breakage, or the tearing off of a large number of branches, including all twigs. 

No indigenous woody plants - if the stem remains standing - will survive such a storm without heavy damage. 

or T8 (356 ± 22 km/h), according to Fujita only beginning from F4 (334 B 422 km/h): 

Incipient debarking of the tree stems which remain standing, or parts of the trees (caused by debris such as sand and the like, 

flying around at high wind velocity). 

Total debarking of tree stems that remain standing, or of parts of the trees. 

1.4.2 Short description of different types of storm damaged trees 

Wind-thrown trees (coniferous trees or broad-leaved trees): 

- uprooted with little root contact with the moisture in the soil (1); 

- uprooted with good root contact with the moisture in the soil (2). 

Storm broken trees (coniferous trees or broad-leaved trees): 

- breakage near the stump (stems can be utilized as long poles without problems) (3); 

- breakage in 1/3 of the stem height (stem can only processed as short wood) (4). 

- 12 -


Remark: Storm broken trees can show reduced wood moisture content due to pre-drying when left in the forest with 

the living crown over several days or weeks. 

Bent or leaning stems (coniferous trees or broad-leaved trees): 

- Only bent tree, root system not affected by storm (5); 

- Tree bent and root system slightly lifted, but still sufficient contact with soil moisture content (6); 

- Tilted tree hanging in the crown of a neighbouring tree, root system heavily damaged and insufficient root 

contact with soil moisture (7). 

Crown damages (mostly on broad-leaved trees): 

- Slight crown damage (single large branch missing) (8) 

- Heavy crown damage (more than half of the former crown is missing) (9) 

- Almost total loss of crown (10). 

1.4.3 Research needs 

- Deciding the appropriate conservation method for particular tree species. 

- Differences in suitability for storage between Spruce ( Picea abies) and Fir ( Abies alba). 


Bues, C.T. 2000: Faserstauchungen in sturmgeschädigtem Fichtenholz. Holz-Zentralblatt 126 (Nr. 47/48): 647 

Hubrig, M. 2001: Tornado- und Downburstschadensskala für Holzgewächse, basierend auf der Skalierung nach 

TORRO angepaßt für Mitteleuropa (TorDACH). 2 nd Forum Kathastrophenvorsorge, Leipzig, 24/25 Sept. 2002: 

www: op.dlr.de 

- 13 -


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 

root contact. Numbers 8, 9 and 10 show additional damage to hardwoods 

Type of damage 

1 

2 

3 

4 

5 

6 

7 

Liveconservation 

- 

XX 

_ 

_ 

XX 

XX 

- 

In-situ storage 

Drying by 

transpiration 

X 

- 

X 

X 

- 

- 

X 

Compact pile 

with water 

sprinkling 

X* 

X 

X* 

-* 

X 

X 

X* 

Wet storage 

Ponding/ 

immersion in 

fresh water 

X* 

X 

X* 

-* 

X 

X 

X* 

Most suitable options for log storage 

- 14 - 

Storage under drying conditions 

Log pre-drying 

in covered crosspiles 

X 

X 

X* 

X* 

X 

X 

X 

Rapid log pre-drying in 

open cross piles 

X 

X 

X 

X 

X 

X 

X 

Storage under humid conditions 

Compact piles 

-* 

X 

X* 

X* 

X 

X 

X* 

Compact piles 

covered with 

plastic sheets 

-* 

X 

X* 

-* 

X 

X 

X* 

Special methods 

Log conservation 

under oxygen 

exclusion 

-* 

X 

X* 

- 

X 

X 

X*

Type of damage 

8 

9 

10 

Liveconservation 

XX 

X 

- 


Drying by 

transpiration 

- 

- 

- 

Compact pile 

with water 

sprinkling 


Wet storage 

Ponding/ 

immersion in 

fresh water 

Relevant notes: X possible option 

XX most preferable option 

- not recommended 

* time factor (moisture content) is relevant 

X 

X 

X* 

X 

X 

X* 

Most suitable options for log storage 

- 15 - 

Storage under drying conditions 

Log pre-drying 

in covered crosspiles 

- 

- 

- 

Rapid log pre-drying in 

open cross piles 

- 

- 

- 

Storage under humid conditions 

Compact piles 

X 

X* 

X* 

Compact piles 

covered with 


X 

X* 

X* 

Special methods 

Log conservation 

under oxygen 

exclusion 

X 

X 

X*

2 General considerations 

2.1 Economic aspects 

2.1.1 General remarks 


Different economic aspects must be considered. The primary goal is to maintain the monetary value of round wood 

by protecting its quality. Furthermore after a storm a marketing strategy must be organized in order to control the 

sale of round wood and to prevent the depreciation of its value. This situation demands the temporary storage of the 

wood. 

The benefits of maintaining the value of the wood and avoiding price reductions must be considered in relation to the 

cost of storing the wood. Capital costs may be very important because the total costs of logging and storage 

(including transport, equipment, maintenance etc.), as well as the value of the wood, may be tied up for a prolonged 

period of time, leading to a heavy financial burden. 

An important issue is the choice of the conservation method. The following points must be considered: 

2.1.2 Storage period 

Capital and maintenance costs are strongly influenced by the length of the planned storage period, depending on the 

conservation method used (e.g. dry storage up to 5 months or wet storage up to several years). 

2.1.3 Time management (organization and speed of work) 

It is important to maintain the value of the wood by correct handling of the logs during and after the logging 

operation (e.g. no unnecessary delay between cutting in the forest and the onset of water sprinkling at the storage 

site). There will often be a shortage of logging equipment following a storm. To meet the time limits of wood 

deterioration it may be necessary to use less-than-optimal equipment, thus increasing costs compared to normal 

operations. 

2.1.4 Storage site 

On-site storage (i.e. in the forest) is relatively cheap, whereas establishing a special storage site may lead to costs 

such as land rent, equipment, communication with the authorities, solving of environmental issues etc. 

2.1.5 Tree species 

Vulnerability to deterioration and the quality expectated by the end-user varies widely between different tree species. 

True heartwood species (e.g. Oaks) often have good keeping ability without the need to take any precautions, 

whereas sapwood species (e.g. Maple) require immediate action. Slight discoloration may be tolerable in some 

species (e.g. Spruce for structural use) but not for others (Pine for furniture or flooring). Depending on the special 

features of the species the best conservation strategy must be chosen. 

If the total wind-throw does not exceed the amount of timber that can be sold within a year, the most advantageous 

solution is normally to leave the trees untouched in the forest, as long as not too many are broken or severely 

damaged. Delimbing and further processing will then wait until just prior to industrial utilization. However, in order 

for this to be successful it is important that the roots have enough soil-contact to provide the crown with water. Also, 

the re-planting of the area must be considered, as invading grass and weeds may become cumbersome if the ground 

is left untouched for a whole growing season before planting. 

- 16 -


For maintaining wood quality over longer periods of time, storage under sprinklers is believed to be the best solution. 


Impact of log conservation on the wood market (e.g. which and how much wood has to be stored). 


Baur, P. et al. 2003: LOTHAR Ökonomische Auswirkungen des Sturms Lothar im Schweizer Wald, Teil I. 

Einkommens- und Vermögenswirkungen für die Waldwirtschaft und gesamtwirtschaftliche Beurteilung des Sturms. 

Umwelt-Materialien Nr. 157, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 190 p. 

Baur, P. et al. 2003: LOTHAR Ökonomische Auswirkungen des Sturms Lothar im Schweizer Wald, Teil II. 

Verteilung der Auswirkungen auf bäuerliche und öffentliche WaldeigentümerInnen: Ergebnisse einer Befragung. 

Umwelt-Materialien Nr. 158, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 204 p. 

Bärtschli, H. et al. 2003: LOTHAR Holzpreise und Holzvermarktung. Umwelt-Materialien Nr. 160, Bundesamt für 

Umwelt, Wald und Landschaft, Bern, Switzerland. 82 p. 

2.2 Regulations/Laws 

The regulations and laws will be presented in Table 3 a- j separately for each country. Regulations and laws are 

available for the following countries: Austria (Österreich), Germany (Deutschland), Great Britain, Denmark, France, 

Italy (Italia), Norway (Norge), Portugal, Spain (España), Switzerland (Schweiz). 

- Austria 

Area 

Laws/regulations 

Table 3 a - j: National regulations and laws 

Work Safety Forstgesetz (1975) 

Land- und forstwirtschaftliche Unfallverhütungsverordnung 

Land- und forstwirtschaftliche Dienstnehmerschutzverordnung 

NÖ Landarbeitsordnung 1973 

Steiermärkische land- und forstwirtschaftliche 

Dienstnehmerschutzverordnung 

Land- und forstwirtschaftliche Sicherheits- und Gesundheitsschutz- 

Verordnung 

Water discharge Wasserrechtsgesetz (1959) 

AEV Pflanzenschutzmittel 

Allgemeine Abwasseremissionsverordnung 

Transport Ein- und Durchfuhr von Nadelholz mit Rinde 

Kraftfahrgesetz Abschnitt II 

Straßenverkehrsordnung §42,45,61,71 

Water storage 

Sprinkling 

Wasserrechtsgesetz (1959) 

- 17 - 

Required approvals: authorities 

Bundesgesetz 

Landesgesetz (OÖ) 

Landesgesetz (Salzburg, Burgenland) 

Landesgesetz (Niederösterreich, Wien) 

Landesgesetz (Steiermark) 

Landesgesetz (Tirol)Forstgesetz (1975) 

Bundesgesetz 

Bundesgesetz 

Bundesgesetz 

BGBl.Nr. 536/1988 

BGBl.Nr. 267/1967 zuletzt geändert durch BGBl. I 

Nr. 60/2003 

BGBl.Nr. 159/1960 idgF 

Bundesgesetz 

Treatment Forstschutzverordnung BGBl. II Nr. 19/2003 

- Germany 

Area 



Water storage Wasserhaushaltsgesetz (WHG) Rahmengesetz des Bundes 

Wassergesetze der Länder Wasserwirtschaftsämter

Sprinkling 

Storage under 

drying conditions 

- Great Britain 


Verordnung über Pläne und Beilagen in wasserrechtlichen 

Verfahren (WPBV) 

Wasserhaushaltsgesetz (WHG) 

- 18 - 

Rahmengesetz des Bundes 

Wassergesetze der Länder Wasserwirtschaftsämter 

Abwasserabgabegesetz 

Baugenehmigung Landesbauordnung 

Area Laws/regulations Required approvals: authorities 

- Denmark 


Road transport Færdselsloven, LBK 712 af 02/082001 Excessive loads: Rigspolitichefgen 

Working safety Lov om arbejdsmiljø LBK 784 af 11/10/1999 Arbejdstilsynet 

Storage in general Lov om planlægning LBK 763 af 11/09/2002 

Amtskommunen 

Lov om naturbeskyttelse LBK 577 af 04/02/2002 

Skov- og Naturstyreisen 

Wet storage Lov om miljøbeskyttelse LBK 753 af 25/08/2001 

Lov om vandløb LBK 632 af 23/06/2001 

- France 

Area 


Water storage - Installation du site : 

Arrêté relatif aux prescriptions générales applicables aux 

installations classées pour la protection de l’environnement 

soumises à déclaration sous la rubrique n°1531 

Use of chemical 

wood protection 

- Italy 

- Prélèvement dans un cours d’eau : 

Décret n°94-354 

- Collecte et analyse des rejets d’eau : 

Arrêté n°1531 

- Traitement insecticides des grumes : 

Info – Santé – Forêts, note technique n°1 

Amtskommunen 

Amtskommunen 


- Service du préfet 

- Direction départementale de l’agriculture et de la 

forêt 

- Police de l’eau 

- 

- Inspection des installations classées 

- Département de la santé des forêts 


Work safety 

Transport 

D. Lgs. n. 277 del 15.08.1991 “Protezione dei lavoratori contro il 

rischio di esposizione ad agenti chimici, fisici e biologici” 

D. Lgs. n. 626 del 19.09.1994 “Linee guida sulia sicurezza nei 

luoghi di lavoro” 

Dlg. 30.04.1992 n. 285, articoli 10,61,62 del Codice della strada 

ASL 

ASL

- Norway 

Agreement between forest related employers and workers 

associations 2002 - 2004 


4.4 Safety routines 

Transport regulations Norwegian Pollution Control Authority 

Road transport regulations Public Road Administration 

- Portugal 

Area 

Segurança no 

Trabalho 

Descarga de 

águas 

Armazenamento 

de águas 

paradas 


Decreto-Lei n° 141/95 de 14 de Junho e 

Portaria n° 1456-A/95, de 11 de Dezembro 

Estebelece os sistemas e os principios de 

sinalização de segurança 

Define a posição e o uso de sinalização 

Decretos-Leis n os 26/94 de 1 de Fevereiro, 7/95 

de 29 de Março e 109/2000, de 30 de Junho 

Define os serviços de saúde, higiene e 

segurança no trabalho 

Estabelece as medidas de segurança, higiene e 

saúde no local de trabalho 

Decreto-Lei n° 349/93, de 1 de Outobro e 

Portaria n° 988/93, de 6 de Outobro 

Estabelece os equipamentos de protecção 

individual que poderão ser utilizados pelos 

trabalhadores 

Decreto-Lei n° 347/93, de 1 de Outobro e 

Portaria n° 987/93, de 6 de Outobro 

Estabelece a organização do trabalho e 

regulamentação geral do trabalho 

Decreto-Lei n° 330/93, de 23 de Setembro 

Estabelecimento de regas na movimentação 

manual de cargas 

Decreto-Lei n° 72/92, de 28 de Abril e Portaria 

n° 9/92, de 28 de Abril 

Estabelecimento de protecções correctas ao 

nivel do ruido, no local de trabalho 

Decreto-Lei n° 441/91, de 14 de Novembro 

Estebelecer o enquadramento da saúde, higiene 

e segurança no trabalho 

Portaria n° 429/99 

Estabelecimento do limite da descarga das 

águas residuais, nos leitos de água ou no solo. 

Decreto-Lei n° 236/98 

Estabelecimento de normas, critérios e 

objectivos para a protecção dos recursos 

hidricos e para melhorar a qualidade da água. 

(Este decreto revougou o decreto-lei n° 74/90 

de 7 de Março) 

Em Portugal não existe legislação especifica 

sobre este assunto 

Transporte Portaria n° 960/2000 de 9 de Outobro 

Altera a portaria n° 1029/97, no qual regula os 

limites de pesos e dimensões dos veículos 

Despacho n° 14339/2000 de 14 Julho 

Averbamento do peso bruto 


Todas as portarias e os decretos de leis são válidos somente para 

Portugal 

A legislação é estabelecida pelo Ministério do Trabalho 

A legislação é estabelecida pelo: 

- Ministério de Economia; 

- Ministério da Saúde; 

- Ministério do Ambiente. 

Direcção-Geral da Viação (DGV), no qual é a instituição 

responsável por efectuar os regulamentos relacionadas com os 

veiculos e as suas cargas (www.dgv.pt) 

Esta legislação é estebelecada pela Direcção-Geral de Viação 

- 19 -

- Spain 

Area 

Decreto-Lei n° 72/2000 de 6 de Maio 

Aprova o regulamento da CE de modelo de 

automóveis e reboques, seus sistemas, 

componentes e unidades téchnicas 

Portaria n° 1092/97 de 3 Novembro 

Regulamenta os limites de peso e dimensção 

dos veículos. Revoga a portaria n° 850/94, de 

22 de Setembro 

Despacho da Dirrecção-Geral da Viação n° 

45/98 de 24 de Março 

O valor máximo da largura das caixas dos 

veículos 

Portaria n° 855/94 de 21 de Novembro 

Define os limites dimensionais dos veículos 

Portaria n° 855/94 de 23 Setembro 

Define as categorias da modelos da veiculos 

Regulations 

Work Ley 45/1999 de desplazamientos de 

trabajadores en el marco de una prestación de 

servicios transnacional 

Ley del estatuto de los trabajadores. R.D 

legislativo 1/1995 

Transport Ley 16/87 30-7 de Ordenación de transportes 

terrestres 


Organisms 

- Ministerio de Trabajo y Asuntos Sociales. 

Agustin de Bethencourt 4. Tf: 91 363 00 00 

http://www.mtas.es/ 

- Dirección General de Transportes por carretera. Ministerio de 

Fomento. 

Paseo de la Castellana 67. Tf: 91 597 70 03 

http://www.mfom.es/ 

Railroad Ley 39/2003 del sector ferroviario - Subdirección general de planes y proyectos de infraestructuras 

ferroviarias 

- Subdirección general de construcción de infraestructuras 

ferroviarias 

Plaza de Sagrados Corazones 7. 28071 Madrid. 

Tf: 91 597 70 00 

- RENFE 

Avda. Pio XII 110. Edificio Caracorlas (Chamartín). Madrid 

Tf: 91 733 91 62 

- FEVE 

C/General Rodrigo 6. 28003 Madrid. 

Tf: 91 453 38 00 

Ports Ley 27/1992 de puertos y de la marina mercante Dirección General de la Marina Mercante. Ministerio de Fomento. 

Paseo de la Castellana 67. Tf: 91 597 70 03 

http://www.mfom.es/ 

Puertos del estado 

Avda. del Partenón 10. Campo de las naciones. 28071 Madrid 

Tf: 91 524 55 00 

Health and 

safety 

Ley 31/1995 de prevención de riesgos laborales 

R.D. 39/1997 Reglamento de servicios de 

prevención 

- INSH 

Torrelaguna 73. 28027 Madrid 

Tf: 91 363 41 00 

http://www.mtas.es/insht/index.htm 

- Fundación F4 

Apto. Correos 2212. 3180 Pamplona 

http://www.fundacionf4.com 

- 20 -

- Switzerland 

Area 

Use of chemical 

wood protection 

Regulations / laws 

- Verordnung über 

umweltgefährdende Stoffe 

- Verordnung über den Wald 

Water storage - Bundesgesetz über den Schutz der 

Gewässer 

- Bundesgesetz über die Fischerei 

- Bundesgesetz über die 

Binnenschiffahrt 

Working safety - Verordnung über 

umweltgefährdende Stoffe 

- Verhaltensregeln Arbeitshygiene 

- Signalisationsverordnung 

2.3 Environmental impacts 

2.3.1 General remarks 



Anwendungsbewilligung: kantonale Forstdienste 

Wasserentnahme ab Bach: Kantonale Fachstelle für Wasserwirtschaft oder 

Gewässerschutz, evtl. kantonale Fischereiverwaltung (bei Fischgewässern) 

Wasserentnahme ab Hydrant: Wasserwerk der Gemeinde 

Lagerung in stehenden Gewässern: Kantonales Verkehrs- und Schiffahrtsamt 

Wasserableitung in Gewässer: Kantonale Fachstelle für Wasserwirtschaft 

oder Gewässerschutz, evtl. kantonale Fischereiverwaltung (bei 

Fischgewässern) 

(je nach Kanton ist nicht immer die gleiche Fachstelle zuständig!) 

Information erhältlich bei SUVA Luzern 

Wet storage, in particular water spraying of round timber, is a common method of wood storage subsequent to forest 

calamities. While pond storage used to be common, nowadays water spraying tends to be applied, using open water 

systems or recycling water systems. In the course of ponding or water spraying, organic substances – primarily 

sugars and phenolic substances – are leached from the bark, and to a much smaller extent from the wood. 

Additionally, small amounts of ionic substances (salts and acids) are leached out, and solid particles are washed from 

the bark surface. The deposition of bark particles on the bottom may have a detrimental effect on ponds used for 

wood storage. This problem can be largely avoided by the use of water spraying instead of pond storage. 

The potential environmentally negative effects of the dissolved and suspended substances can be characterized by the 

following water properties: 

- 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 ) 

The COD-value or the chemical oxygen demand indicates the amount of oxygen necessary for chemical degradation 

of the slowly decomposing organic compounds contained in the water. In order to evaluate investigation results of 

wastewater analyses, the guide value given here is the one generally used for municipal wastewater subsequent to 

biological clarification, i.e. prior to the feeding into natural flowing water. It corresponds to 140 mg COD per litre of 

water. 

- 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 ) 

The BOD-value or the biological (biochemical) oxygen demand indicates the amount of oxygen that is consumed in 

the course of seven days during degradation of the rapidly degrading, organic compounds contained in the water. 

- 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 

The degree of acidity is a measure of the H + -ion concentration, whereas and electrical conductivity refers to the total 

load of dissolved ionic substances. 

- Plant nutrients and other salts 

In addition to ammonium (NH4) and total nitrogen investigations occasionally also focus on phosphate, nitrate and 

nitrite as well as single ions such as metal ions and chloride. 

From experience, it is known that the most important property is the oxygen demand (COD- and BOD-values). The 

runoff water rarely contains toxic levels of any compound, but the breakdown of organic matter may deprive natural 

- 21 -


recipients of all oxygen, with detrimental effects upon flora and fauna. 

2.3.2 Water spraying with open water systems 

Normally, discontinuous (interval) spraying is applied, e.g. running the sprinklers for 20 minutes every hour. The 

spraying intensity often corresponds to 40-45 millimetres precipitation per day. Spraying may be suspended during 

night and in rainy and/or cold weather. 

The loads of suspended and dissolved matter in the discharge water increase over the first few weeks, or in some 

cases up to three months. Thereafter, over a period of 1 to 2 years, they approach the measured values of the intakewater. 

The environmental effects of the wastewater may be reduced by sedimentation basins (removal of bark 

particles etc.) and by buffering through lime gravel. 

By the use of climate-adapted water spraying (e.g. the Swedish TYKOFLEX system) the need for water and energy 

for pumping can be greatly reduced, still maintaining a satisfactory protection of the wood (Liukko 1997). The 

amount of runoff water is similarly reduced, but on the other hand the concentration of dissolved and suspended 

matter in the effluent is increased (Myhra and Gjengedal 1998). 

2.3.3 Water spraying in recycling water systems 

Recycling of log spraying water has two purposes, both of which are relevant to the environment: 

1) The need for fresh water can be greatly reduced, and 

2) Polluted runoff water can (al least partly) be prevented from entering natural waterways. 

Concerning (1) a considerable part of the water is lost to evaporation and to infiltration into the ground. Practical 

experience from Denmark indicates that 50 - 60% of the water can often be recycled when the storage yard is 

established on forest or arable land. With wet stores established on a concrete or asphalt surface (sawmills yards) this 

figure can be increased. 

COD-values may reach very high levels in the recycled water, in single cases up to several hundred mg per litre. 

Also in the long run (1 to 2 years) the load of organic matter in the recycled water will remain at a relatively high 

level, even though an intensive aeration is achieved by the sprinkling operation. However, observing an appropriate 

rate of dilution, there should be little risk in feeding excess runoff water into natural streams. 

2.3.4 Pond storage 

Storing of stem wood in natural, small-scale stagnant water bodies is, as a rule, an interference that cannot be offset 

and thus is to be refused. Particularly the leaching out of soluble material from the bark and the settling of larger 

amounts of bark to the bottom may lead to intolerable stresses in small stagnant ponds or pools, which cannot be 

emptied or cleared. Moreover, the riparian zones are considerably damaged, having a negative impact on flora and 

fauna. Soil material is pushed into the water by the traffic, or washed into the water by subsequent precipitation. 

Smaller drainable water bodies can be used for water storage, provided: 

- they are not located in particularly sensitive zones of water management; 

- they are not located in protected areas; 

- the management is harmless to the water body. 

Log storage in larger lakes will hardly affect water quality, if the storage zone is confined to only a small proportion 

of the water surface. In this context, however, concerns of bank protection, nature conservation and species 

protection as well as possible danger of drifting need to be taken into consideration. It seems to be advantageous not 

to hinder inflow and discharge of water from the lake. 

- 22 -

2.3.5 Groundwater pollution 


In general, little attention has been paid to the risk of groundwater pollution from dissolved wood and bark 

constituents infiltrating the ground. As far as the authors are aware, no evidence of groundwater pollution resulting 

from wood storage has been reported in the European literature. In one or two cases Danish authorities have been 

monitoring groundwater quality in the vicinity of wet storage yards after the 1999 storm, but no results have been 

published yet. 

The load of dissolved and suspended matter in the water infiltrating into the ground can partly be controlled by the 

choice of material for constructing the storage yard (Myhra and Gjengedal 1998). 

2.3.6 Insecticide application 

The use of insecticides is restricted in all European countries and should be performed in accordance with national 

laws. Insecticide treatments are only provided for protection of sawlogs (see Figure 3), not for controlling the bark 

beetle population in general. At sites where logs are conserved in wet 

storage, the use of insecticides is ruled out due to their toxic effect on 

aquatic organisms. 

Figure 3: Insecticide application (Photo HFM) 

The function of insecticide application is to prevent or repel the adult 

beetles from boring into the bark in order to lay their eggs. Once the 

beetles are under the bark or within the wood they are largely safe from 

chemical sprays and the application of insecticides is useless. 

Therefore, the treatment must be carried out in late winter or in the 

early spring before the adult beetles begin their search for breeding material. If the expected duration of storage 

extends beyond one summer, other ways of protecting the timber should be sought. 

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 

a) To reduce the beetle attack effectively, storage periods must be reduced, particularly in the spring. 

Logistics could be improved in order to minimize the time between logging and conversion, or processing 

speed could be reduced in favor of live conservation, provided that the fallen trees have maintained 

sufficient root contact. 

b) Dry storage is another possibility to avoid a beetle attack. The logs must be debarked, transported out of the 

forest and stored in open sites. The durability of the storage should not exceed 5 - 6 months. A beetle 

infestation cannot be excluded totally, but very few species will attack debarked logs. 

c) In wet storage with proper intensity and coverage of the sprinklers, the beetles will die and the brood cannot 

develop further. 


Borga, P. ; Elowson, T. ; Liukko, K. 1996: Umweltbelastung durch Abwässer bei der Nadelnutzholz-Beregnung. 

Holz-Zentralblatt 122: 2146 

Liukko, K., 1997: Climate-adapted wet storage of saw timber and pulpwood: An alternative method of sprinkling 

and its effect on freshness of round timber and environment. Silvestria No. 51. SLU, Uppsala. 44 pp. + 4 artikler. 

Myhra, ?.;Gjengedal, ?. 1998: Avrenning fra tømmervanning. Norwegian Institute of Wood Technology (NTI), 

Rapport no. 41, Oslo, March 1998, 33 p 

Stoll, M. 1990: Zur Bewertung der Abwasserbelastung durch Naßkonservierung von Kalamitätsholz. Holz- 

Zentralblatt 116: 1042 

Tingleff, T. 1991: Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets 

- 23 -


sprinklerdepoter i 1982-1985. Dansk Skovbrugs Tidsskrift, 1991, pp. 115-226. 

2.4 Management/Operation/Health and Safety 

2.4.1 Management/Operation 

On-site storage (leaving the trees where they have fallen) generally puts little strain on the management and 

operations of the forest owner. An inventory of the wind-thrown logs is appropriate and quality assessments (drying 

damage, insect attacks, discoloration and fungal attack) should be carried out at regular intervals. 

If the logs are to be stored in piles in the forest, more stringent organisation is required machinery with appropriate 

performance and capacity should be chosen. Serious consideration should be given to limiting machinery traffic on 

vulnerable forest soils, in order to avoid soil disturbance and compaction. The piles should be postioned in such a 

way as to assure favourable storage conditions (shade, shelter) and also to facilitate easy loading and transportation. 

All-season lorry access to the piles may not be possible without serious damage to the forest roads. 

Storage yards are even more demanding of facilities and management. If wet storage is to be employed, the 

minimum demands are: 

- the ground should be trafficable by heavy lorries even in a soaked condition, 

- access roads should be usable during all seasons, 

- water supply should be adequate, 

- electric power for pumps etc.,should be available 

- the yard should be sheltered from strong winds, 

- daily inspection should be possible. 

In addition, the possibility of re-circulating runoff water may be necessary. To fulfil those demands, a storage yard at 

a sawmill or another industry will often be the best choice. Here, trafficable ground, access roads, power and 

personnel is often available, minimizing the cost of establishing and operating new sites. 

2.4.2 Health and safety 

The maintenance of logs under humid conditions i.e. compact piles covered with plastic sheets, or using “special” 

methods involving wrapping in plastic sheets or covering with geo-textile fabric, may result in the growth of 

thermotolerant and thermophilic moulds and actinomycetes on the timber. The high humidity under the sheeting plus 

elevated temperatures resulting from incident sunlight may generate temperatures in excess of 40 o C which will 

support the growth of these freely sporulating micro-organisms. At the same time, the elevated temperatures will 

inhibit and possibly inactivate the vegetative hyphae of decay and sapstain fungi. 

The production of large quantities of mould and actinomycete spores is a potential health hazard, since inhalation of 

significant numbers of spores could generate allergenic responses in operators removing the sheeting. This risk can 

be avoided by the wearing of protective face masks during this operation. 

Logs in wet storage may become very slippery, presenting a risk for the personnel involved in inspection and 

maintenance of the sprinklers. Also, the risk of logs sliding or rolling down when climbing the stacks must be 

considered. 


Health risks due to mould fungi (particularly with logs stored under plastic sheets). 

Optimal storage size depending on conservation method. 

- 24 -



Hammer, S. et al. 2003: LOTHAR Zwischenevaluation der kantonalen Strategien zur Bewältigung von Lothar am 

Beispiel der Kantone Bern, Waadt, Luzern und Aargau. Umwelt-Materialien Nr. 154, Bundesamt für Umwelt, Wald 

und Landschaft, Bern, Switzerland. 112 p. 

Hänsli, C. et al. 2003: LOTHAR Sturmschäden im Wald, 1999. Eine vergleichende Analyse der politischen Prozesse 

und der staatlichen Massnahmen nach «Lothar» und «Martin» in der Schweiz, Deutschland und Frankreich – 

Synthesebericht. Umwelt-Materialien Nr. 159, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 93 

p. 

Hofer, P. et al. 2003: LOTHAR Optimierung der Holztransporte nach Sturmereignissen. Umwelt-Materialien Nr. 

161, Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland. 97 p. 

2.5 Process monitoring and wood quality 

2.5.1 Process monitoring 

Process monitoring is an important part of conservation work. By implementing proper monitoring procedures it is 

possible to document the development of wood quality in relation to operational parameters (e.g. watering intensity) 

and the initial condition of the wood. Monitoring of storage conditions as well as wood quality should be carried out 

over the entire duration of the storage. Records of wood quality in relation to species, character of storm damage, 

logistics and storage conditions may provide valuable help for decision-making in the event of future storm 

calamities. 

2.5.2 Wood quality 

2.5.2.1 General remarks 

Currently in the EU member states over 60 million m 3 sawn of softwood timber (mainly Spruce and Pine) and over 

20 million m 3 sawn of hardwood timber (mainly Oak and Beech) is produced per year. This represents a total value 

of some 12-14.000 million Euro for softwood and approximately 4-8 million Euro for hardwood. The majority of the 

softwood material is currently used in the building sector in the form of structural components, joinery, furniture, 

cladding (facade, wall cladding and flooring) and in temporary structures. A high proportion of the structural 

components (beams, roof-truss timber, purlins, studs, glulam timber) have to be kiln dried to approximately 18 - 20% 

moisture content, then graded for strength and preservative treated. Other products may have to be dried to lower 

moisture contents that correspond to their likely in-service moisture content (approximately 10% for interior joinery 

and 16% for exterior joinery) they are also appearance graded for surface defects and growth rate. The hardwoods 

are used for decorative purposes such as furniture and interior panels. These also need to be kiln dried and graded for 

appearance. 

In many areas of Europe the amount of material from forests is increasing annually and the majority of this is fastgrown 

softwoods. Overall timber production in the EU has increased by about 20% with the entry of the 10 new 

members in May 2004. The output from existing states is also increasing. For example, in the UK the output from 

their forests is estimated to increase from the current figure of 7 million m 3 to 17 m 3 in 2015. Maintaining the value 

and hence a viable wood industry across Europe relies on keeping a balance between the supply and demand of 

material from the forests. Increases in the availability of wood from the forest, which can be caused by storms, could 

generally influence supply and demand and lower the value of the wood. This could be prevented by not allowing the 

blown timber to come onto the market. This would be achieved by storing the storm timber and controlling its 

release onto the market. However, in general the quality of the timber after storage has a strong influence on the 

economics of the system used. Timber quality is so important in establishing fitness for purpose for its intended use 

and it needs to have reliable quality to consistently complete with other material, such as steel, and plastic. 

- 25 -


Nowadays, timber end-users often claim that timber does not come-up to their expectations. One of the main reasons 

is that the industry is unable to identify performance requirements. The structure of the timber industry with its 

predominance of small companies has stood in the way of joint marketing concepts and market surveys. Neither 

consumers nor producers are aware of the wood properties which govern performance and, as a result, the current 

grading rules are more production-oriented than consumer-oriented. Consequently, timber products are not 

manufactured as well as they might be, nor are they specified as they could be. The current standardisation work still 

follows the traditional approach, in that it is production-oriented rather than consumer-oriented. The relevant 

standardisation committees are becoming increasingly aware of this deficiency, but are not equipped to take the 

necessary steps. If the new and existing material is not to the correct standard when delivered to the market place and 

if it does not perform to specification then timber will loose its market share. The aim should be to increase market 

share and make more use of Europe’s environmentally friendly and renewable resources. Therefore, if timber 

conservation, after storm damage, is to be worthwhile and economically viable the same criteria must be applied to 

the stored timber as to the conventionally harvested timber. Whether the stored timber is eventually going to be used 

for paper making or for construction, it must be fit for purpose. 

For example, for the CONSTRUCTION sector timber must have: 

• Sufficient STRENGTH 

• Sufficient STIFFNESS 

• The correct target moisture content 

• Appropriate form i.e. be dry and straight with low twist, spring, bow and stay STRAIGHT in service despite 

changes in local environmental conditions 

• Good sawing accuracy 

• Sufficient durability lamin 

• Look good 

For joinery use extra requirements would include: 

• Control of defects and growth rate 

Stored timber can achieve these requirements, but it is important that quality control systems are available and are 

actively applied. Regular monitoring of the stored timber is essential to detect the onset of any deterioration. It is also 

very important that stored timber can be dried efficiently so that it has the correct moisture attributes for its intended 

purpose of use. These are: 

• the correct target moisture content 

• low moisture gradient 

• low batch variability 

• appropriate form i.e be dried straight with only low twist, spring , bow and remain straight in service 

• service despite changes of climate 

If the timber is to be used in a moisture-hazardous environment, it must have the correct durability or treated with 

preservative for its designated end-use. The conserved timber will have different porosity depending on the time it 

has spent in the store, probably under water spray. Again the conserved timber should be monitored for deterioration 

in this respect. 

A proportion of the naturally harvested timber in Europe will be poor quality and will need re-engineering. It will 

need to be end-jointed, edge jointed and laminated to make it longer, wider and thicker wih reduced defects. 

Conserved storm damaged material will be the same, but the stored timber must have good gluing properties and be 

capable of using green gluing technology. 

- 26 -


Therefore, in general the important properties concerning wood quality to establish fitness for purpose for particular 

end-uses are: 

• stiffness 

• strength 

• durability 

• gluability 

• treatability 

• dryability. 

2.5.2.2 Wood quality related to storm and log conservation 

Low-weight wood is characterized by high strength. In this context, tensile strength along the grain represents the 

highest strength, followed by bending strength and compression strength to the grain, accounting for only about 50% 

of tensile strength. In the case of a strong bending – e.g. due to storm – and if the compression strength is exceeded 

at the compressed side of the stem, slip planes (Figure 4) occur long before rupture of fibres at the tension-stressed 

side of the stem causing the stem to break. 

Figure 4: Slip planes in Spruce tracheids (Photo TUD) 

Slip planes are damaged spots in the wood (of a tree stem). 

Across them the fibre walls have been more or less 

compressed and buckled due to excessive pressure acting in 

longitudinal direction, so that the wood at this spot has 

partially or totally lost its coherence and hence its strength. 

Fibre cracks are ruptures of wood fibres in the wood having 

been damaged before due to slip planes (see Figure 5). 

Slip planes can be recognized by local cushion overgrowths (occlusion 

rolls, see Figure 6) above compressed stem cross sections. If storm is the 

cause of strong bending of the stem, the occlusion bumps (“Wulstholz”) 

are located on the leeward side of the stem. 

Figure 6: Seven tree rings forming an occlusion bump (“Wulstholz”) over a 

compression failure – radial section (Photo TUD) 

Contrary to occluded knots, wounds and stem-rots, the occlusion bumps 

Figure 5: Fibre cracks in Spruce tracheids (Photo TUD) 

Slip planes and fibre cracks can be summarized as 

compression failures. Preconditions for the occurrence of 

slip planes or secondarily of fibre ruptures are a sudden 

setting free of the tree (e.g. conditions of growth changed by 

man e.g. by felling of neighbouring shelter trees or by 

removal of neighbouring houses) and a crown set free 

unilaterally which facilitates a bending of the tree without 

touching neighbouring crowns (no leaning of the crown to 

one of the neighbouring trees possible). 

- 27 -


run above the slip planes at an angle of 45° to 60° relative to the horizontal line with abrupt terraced transition to the 

unaffected stem surface (see Figure 7, right). Slip planes and fibre cracks are potential spots of breakage in the stem 

of trees that decrease the static properties of the tree stem and may lead to a sudden stem breakage. The danger of a 

sudden stem breakage exists as long as no sufficiently thick wood layer has formed in terms of a shock-absorbing 

occlusion bump above the compression failures by the tree. 

Figure 7: Left: Bumps over compression failures (slip planes) on Spruce in bark. Centre: clearly visible fresh compression 

failures on debarked Spruce wood surface. Right: cracks in Spruce bark are reliable signs of fibre cracks in the wood 

(Photos HFM, TUD) 

If fibre cracks can be diagnosed on wood surfaces not covered with bark, there is extreme danger of stem breakage. 

Sawn timber produced from such type of stems must not be used as construction timber due to its low strength 

properties and the hazard of breakage (see Figure 8). 

Figure 8: Compression failures in Spruce boards: left and certre: clearly visible slip planes. Right: fibre crack (Photos 

HFM, TUD) 

- 28 -


To sum up, each slip plane represents a static damage of the tree stem. If “Wulstholz” is clearly visible the breaking 

strength of a tree is impaired and the extraction of high-grade sawn wood reduced. 

Regarding the mechanical damages in the stems of wind-thrown trees, the phenomenon of compression failures is of 

particular significance for the utilization of the timber. With large stem deflexions under strong winds the axial 

compression strength of the wood can locally be exceeded, causing a buckling of the wood fibres. These distorted 

fibres are week points in the wood structure, which can lead to characteristic brittle fractures already at a relatively 

low stress in bending or tension. The presence of compression failures in construction timber must therefore be 

excluded with reasonable certainty. 

“Wulstholz” is characterized by increased xylem production leading to bulges. The S2-layers of “Wulstholz”tracheids 

are thicker than the corresponding cell wall layers in normal wood, and the cell lumen diameter is 

significantly reduced. The tracheid length decreases gradually from an average of 4 mm to 2.5 mm compared to 

normal wood, and the tracheids are shifted against each other longitudinally. “Wulstholz” contains a higher 

concentration of lignin than normal wood, whereas the concentration of glucose in the hydrolysates is reduced. The 

hemicellulose-concentration, particularly the mannose-content, is significantly higher compared to normal wood. 

The compression strength and the modulus of elasticity, despite a higher density, are significantly reduced (Koch et 

a l . 2000). 

The primary goal of storage is to conserve the quality of the wood for future use in the wood processing industry, 

hence quality parameters are the most important figures to monitor, as a considerable loss of value can occur over 

time if the wrong storage method is used. However, quality monitoring usually implies laborious and destructive 

procedures, e.g. crosscutting and inspecting a number of logs, or processing a number of logs with subsequent 

quality assessment of the boards. As far as wood quality is concerned, three non-destructive (or “less destructive”) 

methods have been tested and correlated to the results obtained with the usual destructive methods: ultrasound 

analysis (Sylvatest/ CTBA); vibrator analysis; and mechanical resistance analysis. This latter is achieved thanks to a 

machine called “resistograph,, which measures the resistance to penetration of a drill into the wood in a diametrical 

direction. The non-destructive methods appear to be an efficient way of monitoring the mechanical properties of the 

wood, since their results are well correlated with the ones obtained using destructive methods to measure stiffness 

(MOE) and strength (MOR) (Anonymus 2001). 


Fast and easy detection/monitoring methods for wood degradation. 


Anonymus 2001: Site atelier de conservation longue durée du Pin maritime (Experimental site for maritime pine's 

log conservation (Pinus Pinaster) using three different methods); DERF/ INRA / AFOCEL/ CTBA; Intermediary 

report. 

Koch, G.; Bauch, J.; Puls, J.; Schwab, E. 2000: Biological, Chemical and Mechanical Characteristics of „Wulstholz“ 

as a Resopnse to Mechanical Stress in Living Trees of Picea abies [L.] Karst. Holzforschung 54: 137 - 143 

Additional literature not cited: 

Arnold, M. 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes. 

144 (11): 843-858 

Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrungen nach dem Orkan „Lothar“ (1999). Projekt 

WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion ((available as pdf: www.empa.ch/holz ? 

Holztechnologie) 

Arnold, M.; Sell, J., 1992: Qualitätserhaltung von Rundholz bei längerer Lagerung - I. Das Projekt 'Lagerung von 

Sturmholz'. Forschungs- u. Arbeitsber. EMPA-Abt. Holz, Nr. 115/25, EMPA, Dübendorf, Switzerland. 

- 29 -

3 Conservation methods 


In order to drawn unambiguous conclusions regarding the different conservation methods, it is important to review 

them and to define the terminology used. 

Table 4 lists known conservation methods. They are grouped according to the storage conditions of the logs (wet, 

dry, humid) to reflect the particular importance of wood moisture content in their preservation. For the 'hybrid' and 

more 'exotic' methods a 'Special' group is used. 'Supplementary conservation measures' are occasionally used in 

combination with one of the main conservation methods (e.g. chemical wood protection or end-grain sealing with 

compact piles). However, only selected combinations are effective and some are even prohibited (e.g. chemical wood 

protection with wet storage). The table contains all the reported conservation methods, irrespective of how much 

they are being used or how proven they are. 

Table 4: Systematics of conservation methods 

Group (Principle) Method Description 


Live-conservation of wind-thrown trees In-situ storage of living, uprooted trees with sufficient root 

Logs left untouched in place in 

contact 

th e s t a n d Drying by transpiration In-situ storage of entire trees (with crown) with a cross-cut at 

the stem base 

Wet storage 

S t o r a g e u n d e r ( c o n trolled) wet 

conditions keeping the wood 

s a t u r a t e d 

Storage under drying 

conditions 

Storage under (uncontrolled) 

conditions resulting in slow or 

fast drying of the logs 

Storage under humid 

conditions 

Storage under (uncontrolled) 

changing conditions 

'Special' methods 

Supplementary conservation 

measures 

Compact pile with water sprinkling Compact pile with water sprinkling (logs with bark) 

Ponding (immersion in water) Storage of logs in running or standing water (logs with bark) 

Log pre-drying in covered cross-pile Pre-drying of logs in covered cross-pile (logs debarked) 

Rapid log pre-drying in open cross-pile Rapid log pre-drying in open cross-pile (logs debarked) 

Compact pile Compact pile (logs with bark/debarked) 

Compact pile covered with plastic sheets Compact pile covered with plastic sheets (logs with 

bark/debarked) 

Log conservation under oxygen exclusion, 

compact pile wrapped in plastic sheets 

- 30 - 

Compact pile wrapped and sealed in plastic sheets resulting in 

oxygen free conservation atmosphere (logs with bark) 

Compact pile covered with geo textile fabric Compact pile covered with geo textile fabric (logs with bark) 

Compact pile covered with a mineralic 

suspension 

Compact pile covered with a thin layer of mineralic suspension 

(protection against insects) 

Storage in gravel pits Compact pile buried in a hole in the ground or on level ground 

covered with thick layer of clay/soil 

Storage in mines Storage in unused mine tunnels 

Compact pile above timberline Compact pile above timberline (logs with bark) 

Storage in snow Compact pile covered with snow 

Compact pile covered with organic material Compact pile covered with bark chips, wood chips, sawdust etc. 

Chemical protection Wood protection by chemical agents 

Biological protection Wood protection by biological agents 

Supplementary to main 

methods ('integrated methods') Physical protection Wood protection by physical measures (e.g. end-grain sealing)

3.1 In-situ storage 

3.1.1 Live-conservation of wind-thrown trees 

3.1.1.1 Principle/description 


- Principle: 

Natural water balance and the natural defence of the trees are to 

be maintained and desiccation is to be delayed. 

- Tree species: 

Experiences and research results are available for Beech, 

Douglas Fir, Spruce, Pine and Maritime Pine 

Figure 9: Live conservation of wind- thrown spruce trees (PhotoHFM) 

- Preconditions: 

Root plate merely lifted up, not shifted laterally; roots need to 

have sufficient contact with the soil (the existing contact 

between root-stock/soil should account at least 20 to 25% of the root volume); minor stem and crown damage; no 

direct solar irradiation on stem and root plate; no risk of infestation with beetles. 

3.1.1.2 Advantages, disadvantages, practical experience 

3.1.1.2.1 Advantages, disadvantages 

- Advantages 

• Immediate storage without prior tree processing (delimbing, bucking, debarking, log transportation) and storage 

site preparation 

• No technical equipment necessary 

• Low cost (only for wood quality control) 

• Live conservation can be regarded as a cheap alternative to other conservation methods, but only for a limited 

time period. For deep-rooted tree species this method conserves the value of the wood whilst more urgent storm 

damage can be dealth with. 

- Disadvantages 

• Dependence on climatic conditions 

• No control over the development of wood moisture content 

• Storage time is limited as unacceptable secondary wood defects can develop 

• Risk of bark-beetle attack. Even before storm damage. the existing bark beetle population can seriously affect 

conservation 

• The decision about whether the storm-damaged trees should be left in living conservation depends largely on the 

personal experience of the forest worker 

3.1.1.2.2 Practical experience 

• Beech (Fagus sylvatica) 

Sawing 

- 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 

Winkler (2002) reports that as far as live-conservation is concerned, the general results are rather encouraging : after 

one year, the percentage of logs attacked by fungi (involving an economics loss) ranges from 7% to 16% for 

- 31 -


scattered blown trees and 29% for blown trees located in totally damaged area (i.e. exposed to 100% sunlight). After 

2 years, the percentage of wood deterioration increases considerably with regard to scattered blown trees, ranging 

from 27% to 35% (average made for each sample area). In highly exposed areas, wood deterioration reached more 

than 55% after 2 years of conservation. 

Eisenbarth (1995) has made similar observations and suggests proceeding as follows: 

a.) Windthrow across whole areas without any canopy left 

Selective log processing of high-grade timber assortments according to fixed orders and just in time. A storage of the 

processed logs in piles during the growing season should be avoided by all means. High-grade log assortments 

should be processed to sawn timber under the responsibility forest owner as soon as possible and stored as sawn 

timber. Successive log processing of medium log qualities according to the marketing situation and the actual 

demand. On-site live-storage of blown trees can be done up to the early autumn after a winter windthrow (loss of 

value up to 40%). 

b.) Single wind-blows beneath the canopy of the remaining stand 

After the clearing of the wind-blown area the log processing can be started in the early autumn after a winter windblow. 

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 

beginning of the second growing season following the storm damage (the observed loss of value was up to 35%). For 

the in situ live-conserved beeches of the winter storm-throw of 1990 a loss of value occurred already after the first 

growing season. Those losses in value, derived from the devaluation of the sawn timber of grade 2 down to grade 3 

(DIN 68369) due to influences from storage, turned out to vary greatly, depending on the kind of in situ live-storage 

(single wind-throw beneath canopy or area-throw without shading). 

In the case of in situ live-conserved Beeches following winter storm-throw, only minor quality losses were 

discernible up to the following early autumn. On the other hand, in-situ live-conserved Beeches in open spaces had 

already been subject to apparent devaluations. After two growing seasons drastic loss of quality was apparent in 

Beech trees in open spaces, and scattered wind-thrown wood beneath canopy was already deteriorating. In 

conclusion, scattered wood from winter storm-throw Beech can still be live-stored for up to one year, (comprising 

one growing period and the subsequent winter season) with tolerable losses in value averaging 35%. 

German experiences were satisfying up to one vegetation period; relevant for the quality conservation is storage 

under shadow and a low leaf mass: 

- Low risk: single and planar throw at north and south slopes; 

- Higher risk: planar throw, south and west exposition; 

- Sunburn damages lead to hard loss of quality B they are possible especially with planar throw and at south slopes. 

- 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 ) 

Following the 1967 storms in Denmark, a black-bluish discoloration of the wood was frequently encountered in 

Beech that had been live-stored on heavy, waterlogged clay soil. The discoloration is believed to have arisen from 

iron-II-ions being translocated into the live tissues through the broken roots. 

Research concerning this problem has been carried out in Denmark in order to determine the extent of blue-staining 

on these types of soil. The study included whole toppled trees (with crown left intact) as well as polled trees (crowns 

cut off). The trees were wind-thrown in February and the crown cut off in April the same year. The conclusions of 

the study were: 

1) Wind-thrown beeches left with roots on clay soils near ground water level will, during the growing season, be 

strongly exposed to blue-staining if root fractures reach down into the ground water. 

2) Polling does not prevent discolouration, but experiences show that it can reduce the number of affected trees from 

approximately 80% to app. 60% and the extent of the discolouration axially and radially in the stems to app. 50%. 

Furthermore, the polled trees show the lowest colour–intensity. Even though the frequency, extent and intensity of 

the discolouration vary strongly within the site, the conclusion is that on all sites where blue-staining in wind-thrown 

Beech is a problem, a reduction of the damages as described above can be expected if the live crown is cut off. 

- 32 -


In this context it should also be mentioned that leaning trees standing on heavy clay soil may be affected by bluestaining, 

if the leaning is caused by a storm and broken roots in this connection have been pushed down into the 

ground on lee side, reaching the ground water (Moltesen 1968). 

Kraft Pulp 

There is a strong correlation between pulp and paper properties and moisture content (AFOCEL 2002). Studies after 

the 1999 storm in France revealed that an important decrease in pulp yield occurred during the second year of 

storage. The pulp yield decreased by 5% within the second spring/summer period. Nevertheless, the pulp properties 

following the first live-conservation year remained good and steady. 

• Spruce (Picea abies) 

The duration of forest protection is very relevant for Spruce; there is good evidence that conservation can be 

guaranteed for a period of 6 to 12 month. 

- For Spruce large areas on north slopes are more suitable for live-conservation than plain and south slopes; Spruce 

with flat root in wet areas are not good for live-conservation. 

Figure 11: Cross section of a frozen Spruce stem at 3 m stem height 

showing irregular sapwood distribution according to water reduction after 

one vegetation period of live-conservation (Photo HFM) 

Figure 10: Cross section of a frozen Spruce stem at stump height 

showing irregular sapwood distribution according to water reduction 

after one vegetation period of live-conservation (Photo HFM) 

Figure 12: Cross section of a frozen Spruce stem at 9 m height 

showing irregular sapwood distribution according to water reduction 

after one vegetation period of live-conservation (Photo HFM) 

After the storm in February 1969 a Danish investigation 

was carried out with the aim of assessing various methods 

of storing wind-thrown Norway Spruce logs. Among these 

was storage with root plate at point of falling (Moltesen and 

Riisgaard Pedersen 1969). Spruce seems to do better when 

whole areas are wind-thrown compared to if only some of 

the trees lie down, possibly because the crown withers 

more quickly when the tree lies in the shade. 

- 33 -


The trees left at point of falling after the storm in February 1967 all came into leaf in 1967 and most of them were 

alive throughout the year. During spring and early summer nearly all the trees withered, especially the ones with 

reduced crown volume, but all the way up to May 1968 (15 months after the storm) they showed moisture content 

that was only slightly lower than that of standing trees and that was highest for trees with reduced crowns. 

Damages at time of sawing (16 months after the storm) were modest for trees left at point of falling with untouched 

crowns. Trees with reduced crowns were appreciably more damaged, and when the sawing was postponed for 

another four months, damage had sometimes more than doubled (Moltesen & Riisgaard Pedersen 1969). 

• Pine (Pinus sylvestris) 

The duration of forest protection is similar to that of Spruce. 

Storage until winter is possible, as long as there is good root contact. 

Where the stem touches the soil surface there is a danger of bark damage and blue stain. 

• Maritime Pine (Pinus pinaster) 

- Sawing 

The contamination of wind-thrown trees by fungi remains limited. In the southwest of France, one year after the 

storm, 40% of saw logs observed were not contaminated by blue stain. Before insect attack occurred no bluestain 

damage was noticed on logs on the dry site, but there were several logs contaminated on the wet site. On such land, 

tree contamination could have happened through broken roots. After insect attack, contamination of the logs rapidly 

reached 60% on both types of site. 

Three years after the storm some wind-thrown trees were still harvested, sawn and used for pallet making. 

If a storm occurs during winter, we can make this simple recommendation: to harvest wind-thrown trees on wet sites 

first and to harvest quickly before insects attacks. 

- Kraft Pulp 

Blown trees stored on site were well preserved until the end of the first summer. Fibre and paper properties were 

affected initiallly, then pulping yield, but much less than in harvested logs. The degradation between stands was 

heterogeneous, which means that practical methods of selection should be set up to define different qualities of wood 

assortments (exposure to the sun, tree volume and type of soil determine the evolution of wood quality). Two years 

after the hurricane, the majority of the trees left on site could still be used for Kraft pulp and paper. However, after 

more than two years the paper properties decreased rapidly and the wind-thrown wood could only be used for pulp 

when mixed with fresh wood. 

• Douglas fir (Pseudotsuga menziesii) 

- Kraft Pulp 

Very good conservation was maintained during the first two years of storage. After three years a steady decrease in 

paper properties ocurred. 

3.1.1.3 Recommendations (application, time limits) 

From the economic point of view, wood storage should only be applied, if the number of wind-thrown logs is so 

great, that a conversion cannot be completed prior to the growing season, as well as in the case of lack of marketing 

and storage possibilities. Generally speaking, the quality of i n -situ conservation depends on the three following 

factors: 

Table 5: Susceptibility of the species 

Species Very susceptible (1 vegetation period, risk of blue stain) Susceptible (1 vegetation period) Resistant (2 vegetation periods) 

Softwood Pine – Spruce Maritime Pine Douglas Fir - Larch - Cedar -Yew 

Hardwood Maple – Hornbeam – Ash - Poplar Beech – Elm – Alder – Cherry - 

Walnut 

Oak – Chestnut – False acacia 

- 34 -

a) Susceptibility of the species 


b) Type of damage to trees: the greater the contact between the root system and the ground, the better the 

conservation. 

c) Degree of dissemination of the wind-blown trees: either disseminated wind-blown trees (i.e. sun-protected trees) 

or widely exposed to sunlight. The more the blown trees are exposed to the sunlight, the higher the deterioration rate 

because of a more rapid decrease in wood moisture content. 

3.1.1.4 Quality monitoring 

Live conservation of trees allows the quality to be monitores throughout storage time in the stand. It is therefore 

possible for the forester to monitor the condition of the trees. The following indicators of vitality can be taken into 

account: 

• Sprouting behaviour; ability of the tree-top to straighten up; resin exudation; bluish-silvery needle discoloration; 

occurrence of shade indicators (bark covered with green algae or root plate covered with plants); changes in 

moisture content (drying from below to above and from inside to outside). 

• Some further technical damages must be taken into account, because of environmental disturbances (e.g. snow 

breakage) while living storage of the trees. 

Since there is a significant correlation between tree moisture content and degradation (R²=0.56), a simple way to 

monitor the quality of wood stored in situ is to measure wood moisture content (Winkler 2002) 

3.1.1.5 Environmental issues 

The storage method itself has no impact on the environment. The risk of bark beetle attack and spreading of bark 

beetles should be considered when no chemical pest control is used. The application of chemicals can harm the 

environment. 

3.1.1.6 Costs 

The expense of frequent quality monitoring (once per month) and for checking moisture content would be incurred. 

3.1.1.7 Research needs 

- Statistical data on the amount of live-conserved wood is rarely availabl, because in practice live-conservation of 

wind-thrown trees is usually still not considered and used as a conservation method and therefore not accounted for 

in wood storage statistics. Moreover, very little is known about the deliberate use of this method to set harvesting 

priorities. 

- More research is needed into the optimal time to remove tree crowns in order to minimize blue-staining of the 

wood. 

- Definition/assessment of ‘safe’ conditions for live-conservation is needed. 

The sustainment of wood quality is the first goal of log conservation and there are still some doubts concerning the 

size of the storm damaged forest and exposure to sunlight for example. However, it is very important to discover 

more about live-conservation because, if wood quality can be conserved sucessfully, it is a cheap and 

environmentally-friendly method. 

3.1.1.8 References 

Arnold, M. 2003: Synthesebericht „Rundholzlagerung“ – Erfahrung nach dem Orkan „Lothar“ (1999). Projekt WN 

19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (available as pdf : www.empa.ch/holz ? Holztechnologie) 

- 35 -


Eisenbarth E. 1995: Schnittholzeigenschaffen bei Lebendlagerung von Rotbuche ( F a g u s s y l v a t i c a L.) aus 

Wintersturmwurf 1990 im Abhängigkeit von Lagerart und Lagerdauer. Mitteilungen aus der Forstlichen Versuchs 

und Forschungsanstalt Rheinland, Nr. 33/95 

Klaiber, V.; Seeling, U.; Mutz, R., 2002: Holzfeuchte in Fichtenstämmen (Picea abies (L.) Karst.) bei 

Ganzbaumlagerung im Bestand. Schweiz. Z. Forstwes.153 (6): 210-218 

Moltesen, P. 1968: Blåfarvning i stormfældet bøg. Forstlig Budstikke 1968, vol. 28, p. 1-2. 

Moltesen, P. & Riisgaard Pedersen, E. 1969: Forsøg med opbevaring af stormfældet rødgran: Afbarkning, kemisk 

beskyttelse og rodlagring. Dansk Skovforenings Tidsskrift 1969, vol. 54, p. 1-56. 

Thorlacius-Ussing, H. 2000: Tag det med ro – stormfaldserfaringer 1981 fra Rold skov. Skoven no. 1, 2000, p. 11- 

12. 

Winkler, I. 2002: Assessment and improvement of live conservation method of blown trees for beech ( Fagus 

sylvatica); CTBA, DERF, DERF; August 2002 

3.1.2 Drying by transpiration 


Accelerated decrease of wood moisture content in wind-thrown trees after a cross-cut at the stem base by 

evapotranspiration from the crown that is still green. 


This method is suitable only for a short time (weeks) of delayed processing and the climatic conditions during this 

period are crucial for its success. Apart from a few trials no practical experience is available so far. Only a few 

scientific publications describe this pre-drying process and give some information about the practicability of this 

technique (see references)., although it is not very successful. 


Based on the very limited experience it is not possible to give specific recommendations. 


- Observation of the wilt of the crown. 

- Monitoring wood moisture content. 


No negative impact to be expected. The local situation regarding forest pathology (mainly bark beetles) has to be 

considered. 

3.1.2.6 Costs 

Special expenses are incurred for the cross-cut at the stem base and the frequent quality monitoring. 


Controlled experiments of this method are needed, particularly in comparison to live-conservation. 

- 36 -



Garrett, L. D. 1985: Delayed processing of felled trees to reduce wood moisture content. Forest Prod. J. (35)3: 55 – 

59. 

Klaiber, V.; Seeling, U.; Mutz, R.. 2002: Holzfeuchte in Fichtenstämmen (Picea abies (L.) Karst.) bei 

Ganzbaumlagerung im Bestand. Schweiz. Z. Forstwes.153 (6): 210-218 

Sachsse, H.; Oliver-Villanueva, J.-V. 1991: Physiologische Trocknung und Lebendkonservierung von 

sturmgeworfenen Bäumen. Forstarchiv 62: 51 – 56 

3.2 Wet storage 

3.2.1 Compact pile with water sprinkling (logs with bark) 


Storage of compact piles of logs with bark under sprinklers is 

the most common way of storing wind-thrown trees. The 

experiences referred to in the following account are from the 

two storms in 1967 and the storm in November 1981 in 

Denmark, the storms in 1982, 1984 and 1997 in France, and 

the storms in 1990 and in December 1999 in many European 

countries. 

Figure 13: Typical log yard for wet storage of Spruce logs (Photo TUD) 

Using artificial water spraying the desiccation of round timber 

can be prevented by maintaining the green wood condition 

(i.e. maintaining wood moisture as high as possible). 

A general view of the storage in short lengths is given in Figure 14 below. 

Figure 14: Basic implementation for storage (Moreau 2000) 

It has been claimed that the main goal of wet storage is to keep the moisture content of the wood as high as possible, 

and attempts have been made to even increase the moisture content above the level present in the standing tree. 

However, observations indicate that an important part of the wood protection results from the bacterial flora present 

on the constantly humid log surfaces. Due to the metabolism of the bacteria and other simple organisms present in 

the slimy surface covering developing on the logs, this layer acts as an oxygen barrier, and it is also believed to have 

an antagonistic effect preventing wood-destroying fungi from establishing themselves in the wood (Moltesen and 

Riisgaard Pedersen 1969). From this point of view it is sufficient, but also of utmost importance to keep all log 

surfaces wet at all times. Apart from fulfilling this goal there is no reason to pour excessive amounts of water over 

the wood in an attempt to raise the moisture content above the level present in the standing tree. 

- 37 -


Tree species 

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.), 

Fir ( Abies alba) and Oak (Quercus sp.). 

Preconditions 

Points to be considered when storing logs under sprinklers: 

- The location of the sprinkler storage (a wind-protected site is preferable) 

- The condition of the soil and the terrain at the site (vehicle traffic, drainage etc.) 

- Permission to set up the storage site must be obtained 

- Accessibility to water 

- Accessibility to electricity 

- Distance to a sawmill 

- Feasibility of surveillance/control 

The road-system in the are must be capable of withstanding the 

water, as well as the lorries transporting the timber. 



Advantages 

• 

• 

Long-lasting storage method. 

In comparison to other storage methods, relatively safe 

round timber storage method. 

Figure 15: Different degrees of brown-reddish 

discoloration on outer parts of sapwood caused by 

bark extractives during wood drying (Photo TUD) 

• Large quantities of timber may be stored (up to tens of thousands cubic meters). 

• Much information on storage technique and wood quality is available. 

• An accepted conservation method by most of the wood processing 

industry. 

• Wood quality monitoring possible by water spraying management. 

• Water sprayed timber can be sawn more rapidly than fresh cut timber. 

• Even a short period of conservation may lead to significant savings of 

raw materials, especially during spring and summer time (e.g. Oak). 

• Compared to immersion in water, handling of logs is much easier. 

Disadvantages 

• Significant investments that may have to made prior to storage (cf. 

3.2.1.2.6. Costs). 

• Brownish-reddish discoloration occurs in the outer part of the sapwood 

during drying of Spruce as a consequence of bark leaching and oxidation 

processes between bark extractives and cellulose. 

• Over penetration of coats and paints (see Figure 16), especially in the 

case of Pine, due to heterogeneous bacteria attack of pit membranes can 

lead to a rejection of water-sprayed wood by certain wood processing 

industries (e.g. window frame manufacturers or furniture industry (see 

Willeitner 1971.) 

• 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.), 

even under best sprinkling conditions, can lead to a very rapid 

deterioration of the timber within a few months (see Figure 17). 

• With regard to softwood, an increase in processing time for kiln drying 

has to be expected provided that no pre-drying has been performed. 

- 38 - 

Figure 16 Treatment with a blue test liquid 

shows over penetration due to pith 

membrane destruction (Photo TUD)


• During the hot season, one or even two daily inspections are necessary. 

• Compared to immersion, a greater amount of water is required. 


In 2000, a number of interviews were carried out with sawmills storing logs from the storm in 1999 under sprinklers. 

The coordination between forests sawmills and truck-drivers was a problem at many places. Some had problems with 

insufficient lorry capacity, which meant that it was not possible to meet the time limit, which is the time limit set 

from when the tree is cut until it is placed under sprinklers and which ranges from few days to few weeks according 

to weather conditions. In one case, the processing in the forest was the limiting factor. In another case, the 

segregation of species into separate piles delayed the building of the sprinkler-system, and in a third case 

administrative matters concerning measurement of the wood delayed the operation because different haulage 

contractors using different measurement systems were employed. 

Figure 17: Armillaria rizomorphea and hyphae (Photo HFM) 

In France, administrative matters concerning security and environment issues and employment laws were highly 

responsible for delaying or even sometimes preventing storage under sprinklers (Braune et al. 2002). In Denmark, at 

least one sawmill had good experiences with storing wood under sprinklers for long periods (4 - 5 years) (Bergstedt 

2000a). However, according to Thorlacius-Ussing (2000) logs should not be stored for more than 4 years under 

sprinklers. Concerning the amount and interval of sprinkling, different opinions are put forward. In at least one case, 

the Beech logs are watered continuously, as this is found to be important. One sawmill warns against the use of too 

much water because of discoloration and destruction of the wood. This company furthermore states that the focus on 

the need of watering the butt-ends is exaggerated, referring to the company Tykoflex, which is not used to sprinkling 

the butt-ends separately. 

Figure 18: Decay caused by Armillaria spec. (Photo HFM) 

In Europe, the sprinkling period varies according to latitude. The hotter the climate, the longer the period is. For 

instance, the logs are normally sprinkled from April to October in Denmark (Tingleff 1991), from May to September 

- 39 -


in Norway (Myhra 1998), and from March to the end of October in France (Anonymus 1994), but variations may 

occur according to weather conditions. 

• Maritime Pine (Pinus pinaster) 

S a w l o g 

Pine in good condition after three years. Significant improvement in mechanical properties with regard to vinyl 

gluing (comparison between fresh and water-sprayed timber). Using MUF glue, the mechanical characteristics of the 

bond remain the same (D. Reuling & al., 2003). Some discoloration may occur after two years (black line, between 

rings). 

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 

moisture content is generally higher, this gain is offset by the much larger amount of water to withdraw. For 

instance, some measurements carried out in a French sawmill lead to an increase in the processing time of 7% 

(Vautherin P. a n d a l .; ongoing research), but these figures should be considered with cautioun since the results 

depend on the initial and final moisture content of the timber. 

K r a f t p u l p w o o d 

Storage of Maritime Pine under water sprinkling, provided it is well carried out, preserves the wood quality for 

pulpwood very efficiently. After more than 40 months of wet storage, the quality of pulping logs of is maintained. 

Even notice a steady increase of the pulp yield is observed due to a decrease in the quantity of wood extracts. 

• Spruce and Fir (Picea abies and Abies alba) 

S a w l o g 

Both retained good mechanical and aesthetic properties over a period of three years. Thereafter, the logs with bark 

could suffer stronger fungal attack (Armillaria attack). 

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 

process seems to be 10% to 20% higher for the water sprayed logs than for the green logs. However, it should be 

noticed that the time spent by the blade in the wood (which is the time measured in the study) represents 25% of the 

total sawing process (sawing + movement of the bogie carriage for log saw + log turning). In other words, the gain in 

productivity can be estimated between 2.5% and 5% (Vautherin P. e t a l .; ongoing research). 

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. 

C o l o u r: Immediately after the sawing process, the boards issued from the water sprayed logs seem to be slightly 

darker. However, this difference tends to disappear after the drying process (Vautherin P. et a l .; ongoing research). 

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 

wood. However, since the moisture content is generally higher, this gain is offset by the much larger amount of water 

to withdraw. For instance, some measurements carried out in a French sawmill lead to an increase in the processing 

time of 35% (Vautherin P. and al.; ongoing research) but these figures should be considered with cautioun since the 

results depend on the initial and final moisture content of the wood. 

More specifically to Spruce: 

Brown coloration in peripheral parts of the log was observed. 

Soak preservation treatment: improvement in product impregnation is obvious, but product consumption increases 

(Anonymous 2001b) 

M e c h a n i c a l a n d K r a f t p u l p 

Wood discoloration occurred after less than 6 months of storage, resulting in a significant decrease in mechanical 

pulp whiteness. No problem with kraft pulp. 

• Beech (Fagus sylvatica) 

Aesthetic matters: After 6-12 months, discoloration occurred which seemd to increase when the bark was damaged. 

This can be reduced by using a steam processto homogenise the colour providing that a light-coloured prodyct is not 

- 40 -


required. To achieve the smae colour, the steaming process is estimated to be between 15% and 20% shorter for 

water-sprayed wood compared with fresh timber. It is strongly advised to kiln dry the timber rapidly after processing 

to prevent any further discoloration. Some Danish studies concluded that after 18-24 months, the logs can still be 

used for veneer manufacture and after 24-36 months, they may be used for flooring provided that the wood is either 

stained or steamed. 

Mechanical properties remain unchanged after 4 years, according to some German studies 

• Oak (Quercus spec.) (Vautherin P. e t a l .; ongoing research) 

After three years positives results were obtained,.but discoloration of sapwood may occur in certain cases (35% of 

discoloured sapwood has been observed in one sawmill). 

K i l n- d r y i n g: characteristics, including discoloration, are similar to green wood, provided that the planks have been 

pre-dried. Homogeneity was slightly better. 

L o g i s t i cs: The benefits of this conservation method are significant. Actually, the latter prevents the wood from 

deteriorating during springtime (dote, mould, brown striped, etc.) and from being downgraded. 

With regards to productivity, debarking and colour, the same remarks as those for Fir are applicable. 


Experiences have shown that long lasting storage of Conifer and deciduous trees under sprinklers can be carried out 

with good results, and that only a few elementary precautions need to be taken (Tingleff 1991): 

1. Only freshly cut or wind-thrown trees should be stored. 

2. All stems should be generously cut clean of visible breaks and any infection by fungi since hyphae from the fungi 

can be present further up the stem. 

3. The time lapse between cutting the wood and when it is under water should be as short as possible period, 

especially during the warm season. The interval can range range from a few days to 2-3 weeks, depending on 

weather conditions. 

4. When building the timber stacks the butt end surfaces must be placed carefully so that they are all flush with each 

other 

5. A separate sprinkler-pipe to sprinkle directly on the end surfaces (especially the butt ends) should be established 

6. Daily inspections are necessary in order to find and solve problems before any damage results. 

7. Logs must not be debarked to prevent any drying. 

8. Logs should be processed as soon as possible after storage. 

9. Sawn boards from water sprayed logs must be correctly dried (air or kiln dried). 

Remark: During the sawing process 6% of the logs appear to be damaged physically by the storm (such as internal 

checks). 

Furthermore, when arranging the timber at the site is normally preferable to sort according to size; for instance, into 

two separate stores, one containing logs with a mid-diameter less than 25 cm and another with a mid-diameter 

exceeding 25 cm. Similarly, it is normally advantageous to separate different tree species, as the end surfaces of the 

logs normally become dark-coloured within a few months of storage and it may be very difficult to identify different 

tree species in a wet store. Finally, the logs should also be sorted according to the owner or/and by type of end 

product. However, interviews after the 1999 storm in Denmark revealed the view among some sawmillers that the 

important matter is to get the logs under water as quickly as possible. Separating the species may take too long, 

leading to quality losses. 

With regard to water-spraying, round timber discoloration and changes similar to that ocurring in ponded timber, 

have to be expected when the wood has dried. Water-sprayed round timber, like ponded timber, is also characterised 

by a gain in weight of up to 15% compared to green timber. This could lead to some breakage during handling of the 

logs. They may also become very slippery and they should be handled very carefully. 

- 41 -


It is important not to carry out preliminary drying of the wet-stored logs prior to their dispatch because of the risk of 

secondary pests. On the other hand, when stored under sprinklers the moisture content of the logs is determined 

mainly by the moisture content in the logs at the time when they were put into store (Moltesen et al. 1974). Rewetting 

of logs that have partly dried prior to storage is a slow and uncertain process, particularly for Spruce. 

The goal is therefore to bring the wood into wet storage under sprinklers as quickly as possible after the trees have 

been cut, and then to be sure to keep all surfaces constantly wet. 

It is also recommended that storage yards that have already been established are maintained for future wind-throws. 

In the meantime they can be used as buffer-areas for wood storage (Tingleff 1991). 

Climate controlled sprinkling of timber, which involves sprinkling according to weather conditions, has been in use 

for some years with good results, maintaining wood quality while reducing water and energy consumption. A 

Norwegian project with the objective to document the effect of climate controlled sprinkling of timber with respect 

to wood quality and water consumption has recently been conducted (Myhra 1998). Not surprisingly, the climate 

controlled sprinkling reduced water consumption considerably compared to sprinkling with constant watering 

intensity. The interesting observation in this context is however, that the amount of water applied during periods of 

warm and dry weather was much higher than the traditional watering intensity. Water spraying, depending on the 

season of the year, ranges from 9 to 16 hours per day in areas with cold climates. 

It it important to consider, whether the log piles should be arranged along the road (longitudinally) or with the logs 

perpendicular to the road (transversely). Stacking along the road makes it easier to sell the timber in small quantities 

without having to move the water pipelines, but it also has a tendency to take up more space. If the stacking is done 

with a crane mounted on the transport lorry, the fastest and easiest solution is to stack the logs perpendicular to the 

road. Also, sprinkling of the log ends can be easily arranged in this way, as sprinklers can be placed along the roads. 

Using a lorry-mounted crane, a suitable stacking height is around 4 metres, although much higher piles can be made 

with special equipment (6m). To some extent the sprinkling intensity must be adjusted to the stacking height, 

ensuring that all logs in the pile are kept wet at all times. 

It is important that either sufficient access to water is achieved or the stacks are dimensioned to the available amount 

of water. Furthermore, it is important that the butt-ends are flush with each other in order to let the water run down 

the end surface of all the stems (Tingleff 1991; Anonymus 1994). 

The following information is obtained from French experiences. 

Water supply: 

- 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 

surface sprayed/day and also 500m 3 /day/ha. Actually, the amount of water to apply is subject to some debate. 

Under Northern conditions (Denmark) the very minimum amount for Spruce is considered to be 25 mm per 24 

hours for spruce and 40 mm for Beech, but since it is impossible to achieve completely uniform spreading of the 

water, the sprinkler system should be dimensioned to deliver at least 50 mm per 24 hours (Tingleff 1991). 

- When air temperature is more than 10°C, water spraying must not be interrupted, especially during the day. 

- When it is freezing, below 0°C, water spraying may be stopped. It is then advisable to drain the remaining water 

from all the pipes. 

- A water recycling system can save between 50 and 80% of water depending on the type of soil and the soil 

drainage system (Anonymous; 2001a) 

- Wind influence: if the site undergoes many changes of wind direction, some parts may be badly water sprayed. 

Two solutions are suggested: 

• The site location chosen is protected naturally from wind, e.g. a valley bottom. 

• The number of sprinklers should be increased (which means pressure capacity must be increased). 

i.e. some overlap between the sprinklers is recommended. 

- Ground bearing capacity: must be sufficient to withstand a 50 tons truck. If a long period of water storage is 

envisaged, the appropriate infrastructure should be developed (water drainage, sufficient pathway width, 

gravelled pathways, etc). 

- 42 -


- Environment/surroundings. 

• The site should be far from a forest infested by wood-destroying insects. 

• The site must be far from inhabited areas. 

Log storage /Basic requirements: 

Careful storage will save space, decrease the number of necessary sprinklers and increase the wood volume/wood 

surface ratio. 

- Logs must be stacked in parallel 

- Butts must be aligned vertically. This will allow efficient water streaming on all the logs ends. 

- Logs must be stacked near pathways and perpendicular to them in order to facilitate handling at the end of 

conservation. 

- Piles should not exceed 5m in height to remain within normal crane capacity. 

- For long length storage, head-to-foot storage save sspace and increase the used surface. 

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 

of the stored piles, the length of the logs and the quality of stacking. 

Equipment: 

The hydraulic pump: Pump capacity should be directly related to water requirement. Two phenomena should be 

taken into account: 

- Hydraulic loss related to the distance from the pump: if the level remains the same, the hydraulic loss is equal to 2.5 

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. 

- Hydraulic loss related to the height: 1 daN loss per 10m increase in height. 

R e m a r k s: 

- The expected volumes of timber at the beginning of the project are always underestimated. 

- It is important to filter the water before it reaches the pump, especially if the water supply comes directly from a 

river. 

The construction of a shelter around the pump can protect it from vandalism, snow, heavy rain, etc. 

An alarm can also be provided in case of an abnormal decrease in pressure. 

The sprinklers: 

- The distance between sprinklers depends on the type of sprinklers and the capacity of the hydraulic pump, the 

idea being to keep a steady stream on all log ends. However, the following figures may be given as an example 

(cf. figure): 

• 8-12m apart for sprinklers located on top of the pile 

• 4-8m apart for sprinklers located at the side of the pile 

Figure 19: Short length storage, detail of the water system (Moreau 2000) 

Remark: the utilisation of sprinklers on both sides of the pile is not necessary provided that the logs are correctly 

stacked and their length is at least 10m. For shorter lengths (< 10m), spraying is recommended on both sides. 

- 43 -


T h e p i p e s: both flexible pipes (hose) and rigid pipes may be used provided that: 

- They are protected 

- Their coupling is easy 

- Some intermediary gate valves are included at strategic points. 


- Log appearance: Green/white/black streaks will appear at the ends of each log. 

- No pollution is observed. Only an increase of organic compounds is likely to occur at the beginning of the water 

spraying, but this phenomenon decreases rapidly after a 2-3 months period. 

- Maintenance/monitoring of the system: The pipes may be repeatedly filled up by suspended particles in the 

water and must be cleaned regulalry. This is expensive but essential. During warm periods, 1one or two daily 

maintenance checks are necessary since the logs may be exposed to fungal attack after only 3-4 days without 

water. 

- Water discharge must be channelled to prevent the ground from collapsing. The best solution is to use a water 

recycling pond. 

Long-term wet storage (up to 5 years) of round timber under sprinklers leads to a significant increase in the bacterial 

population in softwoods, notably in Pine, and a marked depletion of soluble carbohydrates. The permeability of the 

wood is increased because of bacterial degradation of the pit membranes, although the strength properties of the 

wood are more or less unimpaired. Sawn round timber is bright in appearance even after 4 years storage and sawn 

timber from long term stored logs suffers very little fungal defacement for up to 3 months when kept in humid 

conditions. This is attributed to depleted carbohydrate reserves in the wood and the presence of significant numbers 

of bacteria. In comparison, sawn timber from 6 months wet-stored logs is badly defaced after 3 months in damp 

conditions, exhibiting an early flush of moulds followed by progressive development of sapstain. 

A comparison of the physical properties between fresh felled wood and wood stored under sprinklers for four years 

showed no significant differences regarding specific gravity, modulus of elasticity, bending strength and 

compression strength. 

Fungi and discoloration cause some problems if not dealt with. Fungi and discoloration nearly always spread from 

the central part of the butt. In some cases fruit bodies of Fomes annosus have been found, sometimes destroying the 

heartwood from the butt and 3-4 m up the stem. In these cases, in spite of careful removal of all butt ends with 

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 

logs within the site either along the road or perpendicular to the road has shown no significant influence on the extent 

of storage defects (Moltesen et al. 1974). 

Even though treatment with certain chemicals is banned in many European countries today, the results of an older 

Danish survey concerning sap displacement treatment and penetration/retention of chemicals in stored wood could 

be of some interest. The material tested had been stored under water sprinklers for 11-20 months or fully submerged 

in a lake for three years. Treatment with Boliden K33 (CCA) (open tank suction) showed that 22% of the poles 

stored for 11 months under sprinklers, 53% of those stored for 20 months under sprinklers and 67% of those stored 

in a lake for 3 years were rejected, based on the Danish quality requirements of delivery, compared to 11% in both 

control series (freshly felled wood). Pressure treatment (full-cell) of water stored poles with Boliden K33 after airdrying 

to app. 28% gave a similarly poor result while pressure treatment (Rueping) of water-stored poles with 

creosote gave very good penetration as well as retention. 

The results with Boliden K33 are surprising because of the well known bacterial destruction of the membranes in the 

tori and the parenchymatic cells which takes place during water sprinkling (Moltesen e t a l. 1972). A Norwegian 

study (Myhra 1998) showed that permeability of pine timber is considerably increased, although unevenly, when the 

timber is stored under sprinklers for more than 10 weeks. Furthermore, the results with Boliden K33 are contrary to 

all known foreign results. However, the hypothesis is put forward that the main reason for the unsatisfactory result of 

the treatment with Boliden K33 might be coagulation of the bacterial slime when mixed with the salt, blocking the 

pathways for the liquid (Moltesen e t a l . 1972). 

- 44 -


However, it cannot be denied that the wood treatment process is generally improved, but leads to an overconsumption 

of preservative chemicals (Moreau 2000). 

From other experiences, it should be mentioned that timber kept in storage under sprinklers needed up to twice the 

time to reach the same moisture content in the drying process, compared to freshly cut wood (Tingleff 1991). 

With regard to quality, there are some rules that must be observed concerning the insects alreadt present in the wood 

and the possible infestation of adjacent forest areas. Permanent sprinkling must be carried out because these storage 

sites always attract fungi and insects. If interval sprinkling is to be used, it is essential that itfirst be proved to be 

effective. 

Depending on the intensity of the sprinkling it must be decided whether the piles should stay or should be removed, 

since the amount of water available must be adapted to the storage capacity. 


Wet storage, in particular water spraying of round timber, is a common method of wood storage subsequent to forest 

calamities. While pond storage used to be common, nowadays water spraying tends to be applied, using open water 

systems or recycling water systems. In this way, environmental stress due to bark accumulating in the sediment of 

water bodies, is decreased, although the properties of the wastewater from water sprays, has an environmentally 

negative effect, similarly to that of ponds when compared to flowing water (see chapter 2.3). 

The most important characteristic is the COD-value. In order to evaluate investigation results of wastewater analyses, 

the guide value given here is generally valid for communal wastewaters subsequent to biological clarification, i.e. 

prior to feeding into the flowing water. It corresponds to 140 mg COD per litre of water. 

- Interval water spraying 

For interval water spraying at 40-45 mm/h the characteristics increase over the first few weeks and in some cases up 

to three months. Thereafter, over a period of 1 to 2 years, they approach the measured values of the intake-water. In 

particular, the following findings were obtained by investigations conducted in 1967, 1972 and particularly 1984 

(according to Stoll 1990): 

COD: The values measured at the trickling water discharge, depending on the size of pile, during the initial phase 

were between 30 and 110 mg/l and then dropped to negligible values after the first month and sometimes only after 

three months. In the case of large-scale piles of more than 40,000 solid m 3 the short term stress in some individual 

cases may increase up to two to three times the limit value, declining, however, to harmless values after a period of 2 

to 3 months. 

BOD: In general, this value has been found to fall short of the COD values by the factor 3 to 5. 

pH-value, electrical conductivity:, the content of acids, salts, ions, metals and total nitrogen indicate a slightly 

increased value over the first few weeks. They remain, however, far below the required guide values for clarified 

waters. Over the first few weeks the pH-value slightly increases (>1 pH-unit), thereafter approaching the starting 

value. The investigations point to no alarming levels in the wastewater due to water spraying,, over the short or long 

term. These low levels can be reduced further by sedimentation basins (removal of bark particles etc.) and by 

buffering through lime gravel. 

Regarding nitrate, the concentration decreased after the log piles had been water-sprayed. 

In Norway a project was conducted in 1996/1997 with the following three objectives: 1) to investigate if there is a 

difference in the quality of waste water from climate controlled sprinkling compared to traditional sprinkling of 

timber; 2) to investigate the effect of a sand filter under a timber pile; and 3) to investigate the quality of the waste 

water from a timber yard. 

The results from the experiments showed high concentrations of organic substances (COD and DOC) and total 

phosphorus and potassium in the wastewater during the first two weeks after the sprinkling started. Comparison of 

- 45 -


climate controlled and traditional sprinkling of timber generally showed no marked difference. Comparison of the 

timber pile with and without sand filter as an under layer showed that the sand filter retained nitrogen and 

phosphorus. The sand filter showed a leakage of calcium, iron, potassium, magnesium and manganese at the end of 

the experimental period. In the wastewater from the timber yard, the analysis showed high concentrations of carbon 

bound to particles in the water. This carbon is less biologically available, and will probably have insignificant 

influence on the environment (Myhra & Gjengedal, 1998). 

- Water spraying in recycling water systems 

Experiences from Denmark as well as Norway and Sweden show that the COD values of the wastewater coming 

from the timber piles is very high during the first couple of months (figures between 200 and 300 mg/l are common), 

after which it decreases to a much lower level (normally around or below 50 mg/l). The surveys show that during the 

first months of sprinkling, the water running off the stems contains such large amounts of dissolved organic 

substances that if discharged directly into streams it can cause damaging pollution. However, this only occurs in 

situations where the discharged amount is very high compared to the amount and renewal of water in the stream. If 

there is a risk of this, the water should be recycled. 

The advantages of using recycled water: 

1. The water is oxidised, leading to a biological degradation of the organic substances 

2. The use of water is reduced 

3. Less energy is required to pump up water (Moltesen 1982). 

Recycling the water admittedly also has some disadvantages: 

1. Suspended solid particles in the water bay cause malfunctioning of the sprinklers 

2. The large reproduction of micro-organisms in the sprinkling water may cause bacterial slime to form, in extreme 

cases clogging the sprinklers. 

3. Observations indicate that breakdown of pit membranes in Conifer timber may proceed faster if the sprinkling 

water is recycled, leading to permeability changes (Bergstedt 2000b). 

The values measured for pH, conductivity, concentration of various metal salts, ions, total nitrogen etc. are not 

significant in this context. However, the increase of the COD-values is critical. In single cases they may increase to 

three or four times the required wastewater guide value. Also, in the long run (1 to 2 years) the load of the used water 

will remain as expected at a relatively high level. Though being considerably higher than in sewage waters after 

biological clarification, the total amount of these concentrations, however, is very low compared to communal 

sewage waters and there is no problem feeding thewastewaters into flowing waters. 

- Groundwater pollution 

No systematic investigations of groundwater pollution in connection with wet storage of logs have been carried out 

so far. Sampling is not expected to show any serious changes in groundwater quality. 

A potential risk of polluting the ground water is only present if the soil is easily penetrated and where the surface of 

the groundwater is near ground level. However, the sprinkling results in leaching of organic and inorganic substances 

from the bark and the wood into the wastewater from the timber yard, which means that even on soils with good 

penetration the effect will decrease because of small particles of bark infiltrating the upper layer of the soil, 

preventing the water from passing through quickly. This means that solved as well as unsolved matter, as the water 

sinks, will be absorbed partly by soil particles and partly by micro-organisms (Moltesen 1982). 

The conclusion from storage sites after the storms in 1967 was that storage of barked Spruce logs under sprinklers 

creates no severe risk of pollution to the environment, if certain precautions are taken in vulnerable environments 

and if this method is only used once. There was no severe or long-lasting environmental damage in any of the large 

stocks in Denmark (Moltesen 1982). However, if the tendency is that the storage site will continue to be used for 

storage in the future, the environment will be affected to a higher extent and other precautions must be taken. 

- 46 -

3.2.1.6 Costs 

- General remarks 


This is a relatively expensive method that is suitable for the conservation of large amounts of logs, especially after 

calamities. The total costs in the first year are generally rather high due to the costs of investment. Thereafter the 

incidental ongoing costs are relatively low. This method has been in use for a long time now and it is one of the most 

practical and economical methods available for log conservation. 

In Denmark, the costs for establishing wet stores with sprinklers following the 1999 storm was in approximately 10 

Euro per m 3 , including drilling of wells for water procurement . The annual running costs are estimated to be in the 

range of 1 to 2 Euro/m 3 . 

The cost of setting up a storage yard with logs along the road were in 1981/1982 believed to be 50% higher than a 

storage site with logs perpendicular to the road. The operating costs were the same for the two. The value loss during 

wet storage compared to freshly cut wood is difficult to work out, but several sawmills in Denmark have estimated 

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 

bark. 

In one forest district, the extent of damage to stored logs from the storms in 1967, together with the economic 

consequences, were examined in three test cuttings. They showed that when stored for just over two years the 

decrease in value of round-wood was just below 2%, compared to a decrease of 6% when stored for 4 years 

(Moltesen et al. 1974). 

In Germany figures can be taken from the storage of 100.000 to 120.000 m 3 of Spruce long pole under sprinklers 

(Haupthoff, 2000). The investments costs (installation of the log yard, construction of roads, sprinkling facilities etc.) 

were 0.35 Euro/m 3 . The monthly costs for 18 hours daily sprinkling were 0.28Euro/m 3 . The water consumption was 

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. 

The French (Anonymus 1994) state that comparing the cost of implementating different conservation methods is a 

very difficult task, as many parameters must be taken into account: e.g.: 

- Type of conservation methods 

- Initial site condition (such as transport accessibility; infrastructure, etc.) 

- Distance from the location of the water supply 

- Equipment (depending on the log storage method: tight or scattered piles) 

- Electrical wiring 

- Etc. 

There are three types of costs: preliminary investments; functioning costs; and costs following the period of 

conservation. In general, the costs depend greatly on the investors’ policy. 

Preliminary investments 

- Infrastructure 

- 0 to 5.500 €/ha for a site partially or totally prepared (in terms of transport accessibility). 

- 7.000 to 9.500 €/ha for a site where considerable road reinforcement has to be carried out. 

- 13.500 to 19.000 €/ha for a site where almost everything has to be done. 

- Equipment necessary for water spraying the logs 

- 1.8 €/m 3 for efficient/tight storage. 

- up to 2.6 €/m 3 for scattered storage (scattered piles). 

- 47 -

- Electrical wiring 


- 0.3 to 1 €/m 3 depending on the distance from the electrical source. 

- Labour force necessary to set up the site 

- 0.3 €/m 3 . 

To illustrate these figures, the mean, the minimum and the maximum prices with regard to 15 sites in Aquitaine after 

the 1999 storm in France, are summarised in the table below (D. Reuling; CTBA info n° 99; March-April 2003). 

Table 6: Preliminary investments 

Inverstments 

Infrastructure 

Electrical wiring 

Water spraying equipment 

Miscellaneous 

TOTAL 

Mean 

(EURO/m 3 ) 

7.65 

0.61 

2.24 

2.62 

13.13 

- 48 - 

Min 

(EURO/m 3 ) 

1.42 

0.25 

0.81 

Max 

(EURO/m 3 ) 

Another practical way to visualise the costs of preliminary investment could be with the following pie chart Figure 

20: 

Water spraying device 

17% 

Remarks (S. Costa; L. Ibanez 2003): 

Miscellaneous 

20% 

Electricity wiring 

4% 

• There is usually a significant difference in investments based on whether the site is designed to be permanent or 

not. A permanent site costs in average 6 €/m 3 more than a non-permanent site. 

• Usually, more investments are dedicated to hardwood conservation than for softwood due to a higher initial 

value of the raw material. 

• A recycled water system costs around 30% more than an open water system. For this reason, it is advised to 

implement a recycling system just in case of a shortage of water at the vicinity of the storage yard. 

Functioning costs 

- Rent or purchase of the terrain: 0.07 €/m 3 /year 

- Electrical consumption: 0.37 to 0.55 €/m 3 

0.46 

5.93 

24.2 

1.07 

3.09 

6.86 

33.76 

Infrastructure 

(including the price of the terrain) 

59%


- Water consumption: 0.1 €/m 3 

- Maintenance: 0.1 €/m 3 

- Insurance: 0.1 €/m 3 

- Daily monitoring: 0.91 and 1.31 €/m 3 depending on the distance of the site from the company in charge of 

the storage yard. 

- Installing/dismantling of the water spraying device: 0.1 €/m 3 

- 

More globally, the functioning costs range from approximately 1.43 to 2.2 €/m 3 

Costs following the period of conservation 

- Log handling: 0 to 2.3 €/m 3 

- Site restoration: 0.1 to 0.76 €/m 3 

- Log transport: 2 to 8.5 €/m 3 depending on the distance from the storage yard to the sawmill. 


- A r m i l l a r i a attacks in water storage. 


Anonymous 2001a: Impact des aires de stockage de bois par aspersion sur le milieu naturel en Franche-Comté 

(Environmental impact of water spraying conservation method in Franche-Comté) ; ADIB ; October 2001 

Anonymous 2001b: Résultat de la 2ieme campagne de sciage-test de bois chablis résineux stockés sous arrosage 

(Results of the second campaign of sawing-test for wind-blown softwood stored under water spraying) ; ADIB ; 

November 2001 

Anonymous 1994: Manuel d’exploitation Forestière – Tome 2, AFOCEL CTBA 

Arnold, M., 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes. 

144(11):843-858 


WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (unpublished report) 

Arnold, M.; Sell, J., 1992: Qualitätserhaltung von Rundholz bei längerer Lagerung - I. Das Projekt 'Lagerung von 

Sturmholz'. Forschungs- u. Arbeitsber. EMPA-Abt. Holz, Nr. 115/25, EMPA, Dübendorf, Switzerland. 

Braune et al. July 2002: Le stockage du bois après la tempête de 1999. Retour sur l’expérience de la Lorraine. 

ENGREF, Rapport de l’exercice MIF 

Bergstedt, A. 2000a: Besøg på vandlagre af stormfældet nåletræ, september-oktober 2000. Internal report, KVL, 14 

p. 

Bergstedt, A. 2000b: Lagring af råtræ. Skoven, no. 1, pp. 38-40. 

Bonnet, J.L.; Mirjolet J. 2002: Evolution des propriétés du bois de hêtre et plus particulièrement sa coloration lors de 

conservation par immersion ou aspersion (Assessment of the beech (Fagus sylvatica) properties and more precisely 

its coloration following a period of immersion or water spraying) Paris: CTBA internal report ; 2002 

Borga, P. ; Elowson, T. ; Liukko, K. 1996: Umweltbelastung durch Abwässer bei der Nadelnutzholz-Beregnung. 

Holz-Zentralblatt 122: 2146 

Costa, S.; Ibanez, L. 2003: Evaluation du stockage des bois en France après les tempêtes de décembre 1999; LEF; 

décembre 2003 

- 49 -


Engesser, R. 2003: Pilzbefall an nassgelagertem „Lothar“-Rundholz. Wald und Holz 11: 52 - 55 

Haupthoff, W. 2000: Sturmholz-Nasslager bei Gaggenau-Bad Rothenfels. Holz-Zentralblatt: 1199 

Helgerud, H. H.; Gjengedal, E. 1998: Avrenning fra tømmervanning. Norwegian Institute of Wood Technology 

(NTI), Rapport no. 41, Oslo, March 1998, 33 p. 

Liukko, K., 1997: Climate-adapted wet storage of saw timber and pulpwood: An alternative method of sprinkling 

and its effect on freshness of round timber and environment. Silvestria No. 51. SLU, Uppsala. 44 pp. + 4 artikler. 

Moltesen, P.; Riisgaard Pedersen, E. 1969: Forsøg med opbevaring af stormfældet rødgran: Afbarkning, kemisk 

beskyttelse og rodlagring. Dansk Skovforenings Tidsskrift 1969, vol. 54, pp. 1-56. 

Moltesen, P.; Borsholt, E.; Bang, L. 1972: Forsøg med imprægnering af sprinkler- og vandlagrede granmaster. 

Dansk Skovforenings Tidsskrift, 1972, pp. 279-303. 

Moltesen, P.; Dalgas K.F.; Herløw, M. 1974: Lagring af stormfældet gran under overrisling. Dansk Skovforenings 

Tidsskrift, 1974, pp. 253-295. 

Moltesen, P. 1982: Forureningsrisiko ved lagring af uafbarket gran under overrisling eller i søer og damme. I n : 

Tingleff (1991), pp. 204-211 

Moreau J. et al. 2000 : Stockage des bois par aspersion. Aspect réglementaire, techniques et économiques. Afocel 

Myhra, H.H. 1998: Klimastyrt tømmervanning. Norwegian Institute of Wood Technology (NTI), Rapport no. 40, 

Oslo, March 1998, 43 p. 

Reuling, D.; L. Podgorski and G. Legrand 2003: Pin maritime : apte à la finition et au collage (Maritime pine : 

gluing and finishing possibilities) ; CTBA info ; CTBA ; July-August 2003 

Thorlacius-Ussing, H. 2000: Tag det med ro B stormfaldserfaringer 1981 fra Rold skov. Skoven no. 1, 2000, p. 11- 

12. 

Tingleff, T. 199): Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets 


Vautherin, P. 2000: La conservation des grumes Forêt de France n° 431. 

Vautherin, P. et al: Comparison between logs conserved under water spraying conditions and green timbers in terms 

of sawing, drying, and planing processes, and in terms of environmental and trade issues ; CTBA : ongoing research 

Willeitner, H. 1971: Anstrichschäden infolge Überaufnahmefähigkeit des Holzes. Holz-Zemtralblatt Nr. 157: 2291- 

2292 

Winkler, M. 2002: Erfolgreiche Nasslagerung von Zuger „Lothar“-Holz. Zürcher Wald 4: 14 – 18 

- 50 -

3.2.2 Ponding/Immersion (logs with bark) 



- Principle 

Desiccation of the round timber may be prevented by 

immersion in water (ponding), thus maintaining or 

increasing the moisture content present in the standing 

tree. A secondary infestation of the wood is to be averted 

as far as possible. 

Figure 21: A forest lake is an ideal place for immersion of a small 

amount of round wood (Photo HFM) 

Tree species: 

Experiences and research results are available for Beech, 

Oak, Spruce, Pine, and Fir. 

Preconditions: 

Suitable water bodies; suitable infrastructure near the water bodies; permission from authorities; undamaged and 

freshly cut timber; unhealthy parts generously removed from the wood; and at least two thirds of the stem diameter 

permanently immersed. 



Ponding/immersion is a long-term and safe round timber storage method in comparison to other storage methods. A 

considerable amount of information on this storage technique and the resulting wood quality is available. The 

conservation method is accepted by most of the wood processing industry. Wood stored under water can in some 

cases be sawn and dried more rapidly than freshly cut timber. Provided that the wood has been properly stored its 

quality can be maintained for several years. 

Spruce: A brownish-reddish discoloration of the outer sapwood occurs during storage due to bark substances being 

leached into the wood and subsequent oxidation processes between bark extractives and cellulose. 

Bacteria attacking pit membranes can cause increased permeability, leading to excessive and uneven penetration of 

coats and paints. This in turn can mean rejection of the wood by certain wood processing industries (e.g. windowframe 

manufacturers or the furniture industry). 

Beech: round timber ponding may cause a reddish-brown discoloration of both the log surfaces and the end faces, 

penetrating towards the stem centre at various lengths. 


F r a n c e ( B e e c h ) (J.L. Bonnet and J Mirjolet 2002): 

- Change in colour was evident after one month of storage in immersion, compared to 6 months with water 

sprinkling. In order to maintain their value, the logs should be steamed following storage, for homogenisation of 

colour/darkening of the boards (for plywood it can ressemble exotic wood in appearance). To obtain the same 

hue, the duration of the steaming process is estimated to be between 20 and 25% less for immersed wood 

compared to fresh timber. 

- Immersed logs are darkener in colour than water sprayed ones. 

- After 2 years no degradation of mechanical properties was found. 

- If it is not possible to empty the pond, it can often prove difficult to find and remove the logs from the dark 

coloured water. 

- 51 -


In Denmark, ponding has not been common, but after the two wind-throws in 1967, ponding of logs with bark was 

tested, and some experience was gained from these experiments. Spruce and Beech were stored using this method. 

Rather large quantities of wood were stored in the lake Esrum Sø in North Sjælland, and smaller stores were 

established in natural ponds and in derelict, water-filled gravel pits. 

Both single-log storage and ponding of log bundles was tried. In both cases, problems occurred with logs that floated 

(Spruce), since the part of the log protruding above water level was subject to biological degradation which 

proceeded rather quickly. Conversely, the sunken logs (Beech) were well preserved, but proved very difficult to 

salvage from the bottom of the lake at the end of the storage period. 


Patzak and Löffler (1988) recommend the following minimum conditions to be observed for immersion storage of 

timber (see Table 7). Coniferous wood should be subject to loose bundling into units of 10 to 20 m;, whereas bundles 

of 6 to 12 m; apply to broad-leaved species. Bundles should be identified by fixing buoys to them so as to avoid loss 

of timber due to sinkers. 

It is advised to allow for control of the water level (by emptying/filling the tank/pond) to facilitate the storage and 

handling of the logs. The logs must be stored correctly to facilitate handling. Clay ground prevents water from 

leaking from the tank and seeping out through the soil. 

Table 7: Water storage of round timber, forms of storage and requirements (after Patzak and Löffler 1988) 

Single-log storage 

66% of log under water 

5.0 m5 surface/m; wood 

0.8 – 1.0 m 

single layer 

Ponding/immersion 

ponds, lakes, (rivers) 

Storage as rafts 

multiple layers 

70-75% of logs under water 

water surface (m²) required / m³ wood 

(minimum water surface = 500 m5) 

5.0 m5 /m; 

0.8 – 1.0 m 

3.0 m5/m; 

Water depth required 

(maximum 3 m) 

1.5 m 

- 52 - 

Storage in bundles 

80% of logs under water 

1.5 – 3.0 m5 surface/m; wood 

Due to its limited possibilities and for reasons of water protection, storage of round timber in stagnant water bodies 

tends to be rare. Wood quality evaluation and recommended time limits for different tree species are as follows: 

- Beech: positive, > 2 years (tannin discolorations). 

- Oak: very positive, > 2 years. 

- Spruce: positive, > 2 years (tannin discolorations). 

- Pine: very positive, > 2 years. 

- Fir: very positive, > 2 years. 


No information available. 


Few studies of water quality have been performed concerning log storage in ponds. The findings largely coincide 

with the pollution values for runoff water from artificial water spraying of logs. Values depend strongly on the 

wood/water ratio and on the absence or presence of water flow through the pond. 

If the flora and fauna is to be protected from damage, it is important not to store large quantities of wood in small 

>2.0 m


bodies of water. In the Danish ponding experiments, flora and fauna were only seriously affected in one case: a pond 

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 

were stored. When half of the logs had been placed in the pit, all the fish and crustacians died. However, the original 

conditions were re-established surprisingly quickly, as soon as the logs were removed. 

In Denmark the authorities are reluctant to allow storage in natural lakes or ponds because of uncertainty regarding 

the effect on the environment. Although no scientific studies have been undertaken, it is known that in extreme cases 

(cfr. above) the oxygen consumption during decomposition of the dissolved and suspended organic matter has had a 

fatal effect on fish and other aquatic organisms (Tingleff 1991). 

It is highly important not to immerse wood that has previously been chemically treated in order to prevent insect 

infestation. 

3.2.2.6 Costs 

Two different scenarios are possible: 

a. The pond already exists, no excavation works to be undertaken except gravelling of the embankment and 

some miscellaneous work such as setting up a device to fill and empty the pond: 15 EURO/m 3 plus 

VAT. 

b. The pond must be built, excavation work, embankment to be gravelled and other miscellaneous work: 35 

EURO/m 3 plus VAT. 

Operational costs: no maintenance should be necessary, but recovering the timber may become rather costly. 

R e m a r k s : 

- In spite of these rather high costs, it should be emphasised that these ponds may be also used for fishing, tourism, 

water reserves for animals, etc. 

- Moreover, if further storm damage occurs, the ponds can be re-used immediately at no expense. 

- Finally, these ponds can also be used to regulate timber supplies for sawmills 




Bonnet, J.L.; Mirjolet, J. 2002: Evolution des propriétés du bois de hêtre et plus particulièrement sa coloration lors de 

conservation par immersion ou aspersion (Assessment of the beech (Fagus sylvatica) properties and more precisely 

its coloration following a period of immersion or water spraying) Paris: CTBA internal report. 

Patzak, P.; Löffler, H. 1988: Ökonomie der Langzeitlagerung von Stammholz und Schnittholz. Forstliche 

Forschungsberichte München, Nr. 88 

Tingleff, T. 1991: Sprinklerdeponering af stormfældet nåletræ B og nogle iagttagelser fra Statsskovvæsenets 


Vautherin, P. 2000: La conservation des grumes Forêt de France n° 431 ; 2000 

- 53 -

3.3 Storage under drying conditions 


3.3.1 Log pre-drying in covered cross-piles (logs without bark) 


Storage of debarked logs in loose cross piles allows moderate drying of 

wood with a relatively low risk of infestation. To protect the piles against 

precipitation and direct sun light a wooden roof or a cover with plastic 

sheets is used (see Figures 22 and 23). 

Figure 22: Cross-pile with hard cover roof (sketch FVA) 



The drying of logs was developed as a process for pre-drying 

construction timber. There are problems with log pre-drying in 

covered cross piles related to thelength of time needed. 

Furthermore, is it not possible to control the drying process. It 

is very important that the moisture content is less than 30%. 

When logs are stored for longer than 5 months there may be 

problems with cracks. This can lead to a reduction in wood 

quality, especially in the case of non-covered piles where 

cracks can cause infections, such as red stripe fungi. 

Figure 23: Cross-pile sheltered with plastic sheet (Photo BFH) 

The sawmill should be warned about the risks. In addition, the following points are important: 

- It is important to choose the correct site for storage. Wind-exposed places are recommended. When logs are stored 

for less than 5 months, they can be stored in direct sunlight. 

- When storage time is longer than 5 months, the risks are greater. Wetting must be avoided to prevent wood 

discoloration and decay. 

- Every log must be debarked and placed on the pile to allow good air circulation 

- To guarantee adequate air circulation logs must be stored in cross piles ensuring good stability. 


This type of storage can work well with Spruce, Larch and 

Douglas fir, but Pine may well become stained during the storage 

period. It is recommended that only fresh, healthy cut wood with 

no signs of beetle or fungi attack is used for this method of 

storage. 

Figure 24: Covered cross-piles need continuous control against storm damages 

of the plastic sheets (Photo HFM) 


Log pre-drying in cross piles is a cost effective and ecological 

alternative to chemical wood protection and to kiln dried wood. There is no need to use insecticide after debarking. 

- 54 -


Furthermore, CO2 emissions, caused by kiln drying, can be avoided. 

3.3.1.6 Costs 

An example of the costs in Southern Germany costs is approximately 10.23 €/cubic metre. This includes 8.18 Euros 

for transport of the logs to the storage site and 1.80 €/cubic metre for manipulation and maintenance of the pile. 

Extension of the storage period has little effect on the costs. 


- Comparative assessment of species susceptibility to staining up to and after 5 months storage. 

- Measurement of drying rate by moisture content determinations at different times of the year. 


Anonymus 2000: Lagerung und Konservierung von Stammholz B Trockenlagerung: Merkblatt der FVA Baden- 

Württemberg Abt. Waldnutzung und Waldschutz 

Anonymus 2000: Trocknung von Rundholz für trockenes Schnittholz im Bauwesen. Informationsdienst Holz, 8 

pages. 

Anonymus 1995: Trockenkonservierung von Nadelrundholz als Alternative zur Berieselung und zur Erzeugung von 

trockenem Bauholz. Holz-Zentralblatt 121 (1995) Nr. 35 und 36: 

Wauer, A. 2000: Verfahren der Rundholzlagerung LWF Nr. 29: Berichte aus der bayerischen Landesanstalt für Wald 

und Forstwirtschaft 

Welling, J.; Lang, A.; Scharai-Rad, M.; Speckels, L. 2000: Trocknung ganzer Stämme im Wald. 

Forstmaschinenprofi Januar 2000 S.66 ff 

3.3.2 Rapid pre-drying in open cross piles (logs without bark) 


P r i n c i p l e : 

By debarking and careful piling to allow for good aeration, wood moisture can be rapidly reduced to a level where 

there is no risk of infestation. (30-25% wood moisture related to oven-dry weight that is below fibre saturation 

point). 

Tree species: 

Experience research results are available for Douglas Fir, 

Spruce, Larch and Pine. 

Figure 25: Open cross piles: left cross pile sprayed with liquid choke to 

prevent logs against over heating due to direct sun light (Photo HFM) 


Fairly large quantities of short Spruce timber (mostly in 

lengths of around 2.5 metres) were bought by the Danish 

packaging industry, and stored with bark under drying 

conditions, both in the open, in windy places in the storm 

felled forest or in special storage yards. The timber was stored in this way for up to two years with good results. 

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 

the products (mainly pallets, some crates/boxes) and the losses in value were negligible. Some timber intended for 

- 55 -


sawing of structural products was also stored in this way, but in this case it was stored for a shorter period of time 

and the timber was sawn before serious drying checks appeared. 

Fir/Spruce: 1 year but some aesthetic defects occur. 

3.3.2.2.1 Advantages 

• In the case of dry storage, timber designated for construction can be pre-dried without using kiln drying. Such 

timber shows no increased problems of deformation after sawing when compared to other timber. This storage 

method could allow traditionally-oriented sawmills to respond quickly to customer demand for construction 

wood. Furthermore, the pre-drying of logs in this way is viewed as an environmentally friendly option for 

construction. 

• The target moisture content of 25 - 30% in the sapwood is achieved with winter felling followed by drying in the 

spring and summer. 

• Rapid seasoning of the sapwood prevents fungal infections. 

• Expensive sheeting, which has a short lifespan, can be avoided. 

• Advanced piling technology allows for unidirectional piles to be handled faster and more economically. 

• The short time periods allow for continuous delivery of the pre-dried round wood to the sawmills in the peak 

summer periods. 

• The piles can be maintained within normal forest operations in the forest districts. 

• Investment costs for sprinklers are not incurred. 

• Permission according to water legislation is not necessary. 

• There is no environmental pollution due to discharge of water from sprinkling 

• The ease with which piles can be accessed for quality assessment of the wood means that timber can be sold 

when marketing. 

• Large piles of up to 200 m³ can be used, depending on the range of the truck-crane, the size of the storage yard 

and the intended volume of the quantities to be sold. 

• The conserved wood may be well below fibre saturation point, generally between 15 and 22%, depending on the 

weather. This permits the delivery of lumber that is dry, largely size-consistent, of arbitrary cross sections, 

without the need for further kiln-drying. 

• Sawn wood produced from the pre-dried round timber is largely size-consistent. 

• The sawn wood can be subsequently kiln-dried, which can be carried out quickly, economically and at a high 

drying capacity. 

• Round timber conservation is more economical and carries fewer risks than kiln-drying of large diameter 

lumber. 

• Pre-dried round timber can be transported more easily. 

• In periods of frost pre-dried round timber contains very little ice, compared to green round timber. It can, 

therefore, be easily sawn. 

• Insecticide application to round timber is unnecessary if debarking is performed early. 

3.3.2.2.2 Disadvantages 

During the process is it possible for cracks to appear and infection 

can occur due to debarking, especially where there are side cuts. 

Storage should be limited to less than 5 months and it should be 

remembered that it is generally more suitable for sawn timber rather 

than round wood. 

• Seasoning must be disrupted prior to reaching fibre saturation 

point to avoid excessive checking. 

• Depending on the weather, large checks may form after the 

initial drying. If sawing is not possible prior to this, then the 

unidirectional piles should be disassembled and loose piles 

formed to reduce the drying. 

• Air drying, by definition, is dependent on the weather and is 

therefore difficult to control. 

- 56 - 

Figure 26: Intensive cracks as a result of a drying 

process that is too rapid and to low under fibre 

saturation point (Photo HFM)


• If drying is too slow, fungal damage can occur. If drying is too fast and long, there is a risk of excessive checks 

(see Figure 26). 

• The forestry and timber industry lack experience of the method. 

• In the case of large storms the area needed for dry conservation is also large. 

• Sawing of pre-dried round timber requires more energy than sawing of green wood. 

• When sawing pre-dried round timber dust formation is more intense. 

• The pulp industry prefers wet chips. However, using dry woodchips for chipboard production has advantages. 

• Extra costs are incurred for round timber transportation, piling and maintenance. 


- Before preparation 

Only healthy wood should be used. After debarking the logs should be pre-dried for one or two weeks. 

- Pile construction 

Firstly, a layer of strong logs should be made as a base for the pile. It is important that there is enough distance 

between this layer and the ground. Spacers should be used when the pile construction seems instable. The top layer 

should extend beyond the pile to facilitate covering. Construction takes 2.5 hour per 150m 3 , excluding transportation 

time. 

- Sheeting 

Sheeting, to protect the pile from rain, does not have to be carried out immediately, unless rain is likely. Plastic foil 

with a textile structure is recommended. Sheeting takes 1.5 hours per pile. With correct construction the pile is 

maintenance free. 

Experience (Spruce, Fir) 

• It is not possible to control the process, as the piles are exposed to prevailing weather conditions. 

• Excessive sunlight can cause cracks. 

• Spruce is more likely to crack than Fir. 

• Cracks can cause infection with blue stain and red stripe. 

• The process is relatively expensive. 

- Suitable tree species 

Conifers (without bark): Spruce, Fir, Douglas Fir, and Larch 


This expensive process should only be applied in with the cooperation of the buyer. If properly applied, this process 

can eliminate storage damage for up to three to five months. The success of the process depends on various 

conditions and beetle infestation can affect the quality of the wood. The use of plastic sheets requires neat piles and 

good spacing to soil level. The storage site should be situated in an airy, warm place that is not too exposed to solar 

radiation. The possibilities for successful conservation, especially in the case of Spruce and Fir, are good, but storage 

should take place not more than three weeks after debarking. Fast drying reduces moisture content, preventing 

biological damage, but if it is too rapid, cracks may occur. 

The success of dry conservation of coniferous round timber whilst maintaining wood quality depends on the 

conversion piling technique and on the local weather during the storage period. Only extremely rapid drying 

guarantees effective prevention of fungal discolorations. 

Dry conservation under bark is particularly suitable for higher-grade wind-blown wood, as in this case both wet 

storage and dry storage without bark are less effective because of the desiccation already set in. Wet storage is 

preferable to dry storage. 

Due to the potential of large equipment and personnel bottlenecks, this method cannot be applied on a very large 

scale. Recommendations and wood quality projections for different tree species are as follows: 

- 57 -


- Douglas Fir: relatively positive, up to 2 years. 

- Spruce: relatively positive, up to 2 years (blue stain and red-striping); positive in the case of fast drying 

and storage only up to three months. 

- Larch: relatively positive, up to 2 years. 

- Pine: relatively negative, (blue stain). 


This method can work well with Spruce, Larch and Douglas Fir, but blue stain is a major problem with Pine. It is 

recommended that fresh, healthy cut wood with no signs of beetle or fungi attack is used. 


Log pre-drying in cross piles is a cost effective and ecological 

alternative to chemical wood protection and to kiln dried wood. 

There is no need to use insecticide on the logs after fast 

debarking. Furthermore, high CO2 emissions caused by kiln 

drying, can be avoided 

Figure 27: Spraying of debarked logs against wood boring beetles should be 

avoided when ever possible (Photo HFM) 

3.3.2.6 Costs 

An example of the costs in Southern Germany costs is 

approximately 10.23 Euro/ cubic metre. This includes 8.18 EURO for transport of the logs to the storage site and 

1.79 EURO/cubic metre for manipulation and maintenance of the pile. Extension of the storage period has little 

effect on the costs. 


Apart from Pine, which is susceptible to blue stain, the relative susceptibilities of other common commercially 

important species should be determined for this method. 


Anonymus 1995: Trockenkonservierung von Nadelrundholz als Alternative zur Berieselung und zur Erzeugung von 

trockenem Bauholz. Holz-Zentralblatt 121 (1995) Nr. 35 und 36: 

Anonymus 2000: Lagerung und Konservierung von Stammholz B Trockenlagerung: Merkblatt der FVA Baden- 

Württemberg Abt. Waldnutzung und Waldschutz 

Anonymus 2000: Trocknung von Rundholz für trockenes Schnittholz im Bauwesen. Informationsdienst Holz, 8 

pages. 

Wauer, A. 2000: Verfahren der Rundholzlagerung LWF Nr. 29: Berichte aus der bayerischen Landesanstalt für Wald 

und Forstwirtschaft 

Welling, J.; Lang, A.; Scharai-Rad, M.; Speckels, L. 2000: Trocknung ganzer Stämme im Wald. 

Forstmaschinenprofi Januar 2000 S.66 ff 

- 58 -

3.4 Storage under humid conditions 

3.4.1 Compact pile (logs with/without bark) 



P r i n c i p l e : 

In large compact piles, logs at the centre dry slowly. 

However, the “uncontrolled” humid conditions that prevail 

with this method may lead to extended periods of high 

moisture and risk of wood decay (see chapter 1.2). 

Figure 28: The top of a hill is the wrong place for the storage of compact 

piles with bark due to exposure to sunlight and wind (Photo HFM) 

Tree species: 

Experience and research results are available for Spruce and 

Pine. 

Preconditions: 

Healthy green logs with undamaged outer bark and no other defects; rapid storage; storage possible within the stand, 

in shady locations or sheltered moist hollows. 

S t o r a g e : 

Large compact piles without bearers, alternating butt-end first and top-end first, and root collars trimmed. 



• Logs can be stored within the stand in shady locations; on slopes of northern aspect; in sheltered hollows in 

conditions of high air humidity, and gentle winds. 

• Lower-grade logs must be placed in the bottom and uppermost pile layers to protect the main pile against soil 

moisture and exposure to sunlight and rain. 

• Length of extra-long logs allows for generous removal of infested parts. If possible, store uniform log lengths 

and grades with end-sealing. 

• It is possible to spray with insecticides during construction of the piles. Ripcord 40 [Cypermethrin] will be 

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 

broad-leaved trees. 

• 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- 

August. 

• The logs must be inspected on a regular basis. 


Maritime Pine ( Pinus pinaster) 

- Kraft Pulp 

The quality of debarked logs of Maritime Pine windthrows stored in compact piles in southwest France was very 

bad. The drying rate of these logs was not fast enough to ensure optimal protection against fungal attack. 

After a six-month period of conservation (compact pile/log without bark/no water spraying) of Spruce (Picea abies) 

and Fir ( Abies alba), the measured loss in yield was 2% on average compared with the yield that would have been 

- 59 -


obtained with green sawn timbers (quantitative criteria). With regard to the economic loss due to downgrading of the 

sawn timber (according to European standardisation), the average loss was 18.5% in cost (qualitative criteria) (Parrot 

and Faure 2001) 


Storage under humid conditions of large amounts of round timber is only recommended for healthy, green coniferous 

wood during the winter season, assuming the wood will be sold within one year. Maintaining wood quality greatly 

depends on the climatic conditions and is, therefore, not easy to predict. 

Wood quality evaluation and recommended time limits for different tree species are as follows: 

- Spruce: relatively positive, 1 year (blue stain and red-striping) 

- Pine: relatively negative, (blue stain) 


Frequent monitoring of wood quality is necessary for this storage method. The drying rate of logs in compact piles 

with bark intact is slow compared to debarked logs and in a moist condition the wood will support infestation by 

staining and decay fungi. Although the bark acts as a barrier over most of the log surface, wood exposed by saw cuts 

will provide avenues for infection at the log ends and along the length of the stem where bark damage has occurred 

and branches have been removed. The speed of infestation is temperature-dependent and is more rapid during late 

spring, summer and early autumn; the length of this optimal period for fungal growth will also be influenced by 

altitude. 

An equally important seasonal effect is infestation of logs by bark beetles which are vectors of staining fungi and 

introduce spores to the wood surface having already bored through the bark to lay eggs. Insect infestations of this 

type occur in early to mid-summer and provide a more direct introduction of deep staining fungi than rain splash or 

wind dispersal. Beetle infestations can be alleviated by the application of insecticides, but the appropriate timing of 

application and the choice of insecticide chemical also require careful monitoring. 

The most important consideration when monitoring wood quality is to identify the species of tree. Susceptibility to 

sap-stain infection differs greatly between species. In a four-month field study carried out in southern England during 

the summer of 2001 five softwood species were compared for their susceptibility to sap stain. Logs (with bark) of 

Scots Pine and Lodgepole Pine showed ca. 6 – 60 times more susceptibility to infection than logs of Norway Spruce, 

Japanese Larch and Sitka Spruce respectively. The anecdotal evidence that Pine is more susceptible than Spruce was 

confirmed, but such significant differences identify the importance of accurate identification for effective long-term 

storage of wind-thrown trees. As a result short term storage of Spruce logs may not prove a problem whereas the 

damage to Pine could be considerable. 


Storage of compact piles of logs (with bark) within the stand poses few environmental hazards. The stored timber is 

in effect located at a site where naturally fallen trees would be found and where the normal processes of degradation 

would occur. The main difference is the large volume of timber created by compact piles of logs in a restricted area. 

This raises the possibility of more concentrated organic leachates from the bark entering the soil during heavy 

rainfall, particularly phenolic compounds. In all other respects the local environment is unaffected, except in 

situations where insecticide application is carried out. 

3.4.1.6 Costs 

The costs for this method of conservation are minimal in comparison to other methods. Ease of access to windblown 

sites by vehicles, equipment and manpower inevitably affects the cost of preparing a suitable storage site, the 

collection of suitable logs and building a compact pile. Other methods which involve the removal of logs from an 

area of storm-damaged forest will incur these costs too, plus additional costs in establishing facilities for 

conservation. 

- 60 -



The most important area of future research is to understand the difference in susceptibility to sap-stain infection and 

decay fungi that exist between different species of softwoods and hardwoods. 

In the first instance, a rank order of susceptibility must be established based on results from experimental field trials 

using logs of all commercially important European tree species. This ranking should define a susceptibility value for 

each species. That value should reflect the time it takes (on average) for each log species to be deteriorated by sapstain 

fungi to a point where the wood is no longer marketable. The same approach could be adopted for measuring 

susceptibility to decay fungi. 

Efficient monitoring of wood quality on site would be improved if each compact pile was made up from logs of one 

tree species. Following on from that, tests could then be carried out to determine whether the position of logs within 

the pile had any effect on their rate of drying and susceptibility to sap stain. 


Arnold, M., 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes. 

144(11): 843-858. 

Parrot J.; S. Faure 2001: Suivi du sciage de sapin epicéa chablis/grumes écorcées stockées sans arrosage (Assessment 

of storage under drying conditions (compact pile/log without bark) of Spruce (Picea abies) and Fir (Abies alba)); 

CTBA: unpublished internal report; 2001 

Young, E. J.; Eaton, R. A.; Webber, J. F. 2002: Susceptibility of harvested softwoods to infection by sap-staining 

fungi. Int. Res. Group on Wood Pres. IRG/WP 02-10435. pp12. 

3.4.2 Compact pile covered with plastic sheets (logs with/without bark) 


Here the objective is to keep the logs as moist as possible in contrast to open, aerated piles. The wood should be 

stored in places with high air-moisture content. The logs should be stored as close to each other as possible. This can 

be achieved by alternating butt and top-ends next to each other, which reduces drying 

The conservation of wood with plastic sheets demands a neat pile with good spacing between the pile and the ground 

and possibly with under layers. The storage site should be situated in an airy, warm place that is not too exposed to 

solar radiation. The possibilities for successful conservation, especially in the case of Spruce and Fir, are good, but 

storage should take place not more than three weeks after debarking. 

These small, compact piles of logs covered with plastic sheets prevent the wood from drying and serve as protection 

against an infestation by wood boring insects. 

Note: This conservation method is very similar to log conservation under oxygen exclusion (chapter 3.5.1), but it is, 

in fact, a completely different method! 


After the Lothar storm in 1999, about 190.000 m³ of Spruce, Fir and Pine logs were stored in compact piles covered 

with plastic sheets for up to two years in Switzerland. The results were very variable, ranging from good preservation 

of wood quality to almost complete devaluation. Unfortunately, the very heterogeneous conditions of the observed 

case studies do not allow a thorough assessment of the factors influencing the conservation result. 

In the case of large amounts of storm-damaged logs, this method can be a good alternative to wet and dry storage. 

After the 1967 wind-throws, some Beech in Denmark was stored under plastic sheets, either in small piles or as 

single logs lying on the forest floor. In general, the results were negative, as the plastic covering in most cases lead to 

- 61 -


more fungal attack and discoloration than in unprotected logs left on the forest floor. Moreover, the plastic covering 

was in several cases damaged or destroyed by wind, animals or children. 

There is no need for chemical protection of the piles. This method can be used in areas where it is not possible to 

create wet storage sites. It is recommended that large trees are debarked. However, the logs must be homogenous in 

order to achieve good pile quality. 

Beech: up to 6 months 

3.4.2.3 Recommendations (application, time limit) 

Based on the limited experience of this method, only preliminary recommendations are possible. This method is 

mainly suitable for small, scattered log piles, which should be placed in the shade (e.g. along forest roads). The 

losses due to discoloration and fungal attack are smaller with long logs than with logs cut to short lengths because 

considerable sections of the affected end grain have to be removed before further processing. 

Special attention must be paid to damage to the covering by vandalism and animals. 

If chemical treatment is used the logs must be transported away from water protection areas, if not out of the forest 

completely. The roots should be removed in order to increase storage capacity. The bark should be as undamaged as 

possible. The piles should be stored without an under layer. These recommendations are based on experience. 

To avoid re-wetting it is recommended that the top layer of the pile is covered with plastic sheets. Black sheeting is 

recommended. Additionally, as an alternative to the plastic sheeting, a top layer of logs can be built as a roof to 

protect the pile. Finally, the top layer of logs should be longer than the piled logs (about 2m on both sides). Crosspiled 

storage should be avoided. 


Because of the inaccessibility of the logs under the plastic sheets, no direct monitoring of wood quality is possible. 

The covering should be checked frequently and any defects or damage must be mended immediately 


There may be a possible health hazard to operators from mould fungi growing excessively under the plastic sheets. 

The unfamiliar, striking white appearance of the wrapped wood piles may raise questions from forest visitors and 

explanations should be diplayed on posters. 

3.4.2.6 Costs 

Special expenses for particularly careful piling, sheeting material, covering/uncovering operations, frequent checks 

and disposal of the sheeting material are incurred. This storage method costs approximately < 15 EURO/m³ 


- Controlled experiments during normal harvesting operations. 

- Assessment of possible advantages over conventional compact piling. 

- Investigation of potential health hazards from mould fungi. 



WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (unpublished report) 

Kunz, B. 2002: Werterhaltende Lagerung von Sturmholz unter Folien. Züricher Wald 4: 11 - 13 

- 62 -


Luchsinger, M. 2002: Folienholzrecherche Kanton Zürich. Züricher Wald 4: 4 - 10 

Manser, P., 2000. Beurteilung der Lagerung von Rundholz unter Kunststoff-Folie. EMPA-Forschungsbericht 

740007/1. EMPA, St. Gallen, Switzerland. 10 p. 

Zeltner, S. 1995. Holzkonservierung: Mit Plastikfolien schützen? Wald und Holz 6:18-19 

3.5 “Special” methods 

3.5.1 Log conservation under oxygen exclusion, compact pile wrapped in plastic sheets (logs with bark) 


- Principle 

This method conserves logs by the exlusion of oygen, 

thus avoiding attack by fungi and insects. 

Figure 29: Long poles wrapped in plastic sheets and sealed. An 

additional net stretched over the wrapped pile prevents it from 

damages caused by parts of the sheets, which can stream in the wind 

and causing porosity (Photo: Wood Packer) 

- Description 

The air in the wood, like atmospheric air, consists of 

nitrogen, oxygen and carbon dioxide. The nitrogen 

content is practically the same as in atmospheric air; the 

oxygen content is generally lower, varying between 0 and 20%, whereas the carbon dioxide content is higher, 

varying between 0 and 26%. The oxygen content is lowest during the growing season, when the carbon dioxide 

content is highest. 

Felling causes a change of the conditions mentioned, and if the temperature is high enough, the wood may suffer 

damage, which may be either of a physiogenic or of a biogenic nature. Physiogenic damage includes tylosis and 

discoloration and their occurrence depends on the presence of a certain amount of oxygen and water in the wood. 

Biogenic damage is discoloration and destruction due to attacks by certain fungi and/or insects. I would appear that 

damage does not occur if one of the following conditions is present: (1) the air content of the wood is below 5%, (2) 

the oxygen content of the wood is below 1 %, (3) the carbon dioxide content of the wood is above 70%. 

- Tree species 

The method is applicable for several tree species. The following species were tested: conifer trees (Spruce, Fir and 

Pine) and broad-leaved trees (Beech and Sycamore Maple) 

- Preconditions 

Flat terrain 

Plastic sheets of high diffusion resistance (e.g. PE-silo sheets) 

Gas-proof thermo-welding 

Healthy, green wood 

- Storage (for illustration of the different steps, see Figure 30 to 36) 

Storage in piles longitudinally or transversely to the forest roads 

All-sided wrapping in plastic sheets 

Gas-proof thermo-welding of the protruding ends of the sheets 

Checking the condition of the plastic sheet, sealing of leakages, 

- 63 -



An early experiment concerning long-term storage of Beech logs in air containing carbon dioxide was carried out in 

Denmark 1968. A total of four trials were carried out, each covering six summer months. In two of the trials small 

log sections, about 50 cm long, were kept in PVC-bags; in two trials Beech logs were left on the ground in piles of 

about 70 m³, stored under plastic tarpaulin. In both cases an atmosphere containing carbon dioxide was established 

by adding supplies of pure carbon dioxide. 

The log piles were covered with a tarpaulin made from 0.2 mm PVC sheet, and the edges of the tarpaulin were dug 

half a metre into the soil and covered. During the covering dry ice (frozen carbon dioxide) was inserted in sufficient 

quantity to replace the atmospheric air trapped under the tarpaulin. The tarpaulin was provided with valves situated 

on top of the pile, which were kept open until the out-flowing air 

contained no more oxygen. The tarpaulin remained weatherproof 

throughout the summer and autumn and was so tight within this 

period that further addition of carbon dioxide unnecessary. The 

wood inside was well preserved. During the winter, however, the 

tarpaulin was damaged by wind and the experiment was stopped 

before the wood was damaged. 

Figure 30: First step - cleaning the ground from stones or sharp parts and 

spreading the ground sheets (Photo Wood Packer) 

From this experiment it was concluded that if Beech wood is placed immediately after felling in an air mixture 

consisting of at least 40% carbon dioxide, a maximum of 3% oxygen and the remainder, nitrogen, no damage from 

fungi or insects would occur during storage over the six summer months. In Beech wood in which the harmful 

processes have already started, these processes will be brought to a stop when the wood is stored in the specified air 

mixture. 


• The conservation of quality within this method is considered to 

be good. 

• This type of conservation is suitable for long-term storage 

only. 

• Plastic film storage is mainly successful in terms of quality, 

fungi and beetle attack during storage. 

• Subsequent maintenance is low, thus saving costs. 

• 

Figure 31: Second step - log piling using the truck´s crane (Photo Wood Packer) 


• Mice, fox and marten damage might occur if quality of the plastic film is 

not sufficiently robust. 

• The condition of the underlying layer should be strictly defined (planar, 

sandy soil). 

• The demands on the packing team are high because of the large size of 

the objects that must be packed and air- proofed. 

• This method is especially applicable for regions where sprinkling storage 

is not an option. 

• To be effective, this conservation method requires more effort compared 

with traditional methods. 

Figure 32: Third step - after finishing the piling the upper parts of the stem cross sections must 

be smoothed by chain saw (Photo Wood Packer) 

- 64 -

3.5.1.2.3. Practical experience 


Spruce and Fir: 

The unpacked wood shows no essential qualitative change and its use is not limited. 

Beech and Maple: 

Beech and Maple are more susceptible with this storage method. The risk of uneven colour in Beech could be 

reduced by steam-processing. There are positive results for Beech. 

France: After three years the wood quality remains good if the initial quality was good. Experiments are still 

ongoing. 

3.5.1.3 Recommendations (application, time limit) 

Setting up of signs warning of the danger, of suffocation for anyone crawling into the sheets. 

- Valuation: 

Experiments show that the value can be maintained over longer periods of time. In some cases, a thin layer of white 

mushrooms has been observed on the pile at the opening of the plastic sheets, but apparently without any influence 

on the wood quality. The same type of discoloration appears to occur both the drying-off and wet-storage method. 

- Beech: positive, hitherto 2 years 

- Spruce: positive, hitherto 3 years 

- Pine: positive, hitherto 3 years 

This method offers alternative long-term protection against insect 

and fungal attack without depending on climate, storage site, tree 

species and size of pile. It is applicable in nature-conservation and 

water protection areas too. The complete costs for the first year are 

comparable with those from water storage. The input for 

monitoring and maintenance is low. Monitoring to detect damage 

to the plastic film only needs to be carried out periodically. 

Figure 33: Fourth step - covering the pile with the first top sheet (Photo Wood 

Packer) 


Quality monitoring is only possible after unpacking the piles. During the conservation period it is possible to 

measure the interior atmosphere (oxygen/carbon dioxide content) of the wrapped pile with a measuring instrument 

that remains outside the pile. It is possible to record changes in the interior climate of the wrapped pile at defined 

time intervals 


Environmentally conservation under oxygen exclusion has no 

influence in soil, air or water processes. However, the plastic film 

should be recycled or used for other applications (e.g. in agriculture 

etc.). There is no need for an external energy supply because 

conservation is achieved by the oxygen-free closing of the piles. 

Figure 34: Fifth step - covering the pile with the second top sheet (Photo Wood 

Packer) 

- 65 -

3.5.1.6 Costs 


The costs for this method depend on the amount of equipment and maintenance required, as well as on damage 

caused by humans or animals. 

In 1968 this method was more expensive than wet storage and 

was not suitable to use in the forest without modifications. 

However, one reason for this conclusion might have been that 

high quality and reasonably priced plastic sheeting was not 

available in the market at that time. 

Figure 35: Sixth step - sealing the different plastic layers with special melting 

device (Photo Wood Packer) 

The costs vary a lot depending on the size of the wrapped piles, 

skills and training of the workforce, the company in charge of the 

work and the type of plastic sheeting used. However, the following general prices may be given: 

- Double polyethylene sheets (usually used for short conservation periods due to their fragility): 10 to 15 EUR/m3 

- PVC sheet (more resistant than the latter and should be used for at 

least a two-year conservation period and for high valued timber): 30 to 

35 EUR/m3. 

Following conservation, the plastic sheets may be re-used, but the costs 

involved prevents any saving. 

Figure 36: Seventh and final step - Covering the wrapped and sealed pile with a wind 

net (Photo Wood Packer) 


Further information about the possibilities of using the method to avoid beetle attack and the ability to conserve the 

quality of the fresh wood. In particular, more information is required about the interior atmosphere in the pile 

covered with plastic film. Furthermore it is interesting to know more about the time intervals required and the 

amount of logs that can be used with this method. More tree species must be tested to consolidate existing 

knowledge. 


Yde-Andersen, A. 1973: Opbevaring af bøgeved i kuldioxid-atmosfære. Det forstlige Forsøgsvæsen i Danmark, vol. 

33, pp. 243-280. 

Landesforstverwaltung Baden –Württemberg 2000: Handbuch Sturmschadensbewältigung, Kap. 4 Konservierung, 

Lagerung 

Maier, T. 1995: Alternative Holzkonservierung durch Sauerstoffentzug - Methodik und erste Ergebnisse. Vers. Ber. 

AWF 95/14 

Maier, T. 1997: Alternative Holzkonservierung durch Sauerstoffentzug - Lagerungsverlauf und Holzqualität bei der 

Auslagerung. Vers. Ber. AWF 97/7 

Schüler, G. 1998: Alternative Holzkonservierung durch Sauerstoffentzug - Umsetzung in die Praxis. Vers. Ber. AWF 

98/8 

- 66 -


3.5.2 Compact pile covered with geo textile fabric (logs with bark) 


A small compact pile of logs is covered with a net-like fabric (e.g. geo textile fabric), which prevents the wood from 

an infestation by wood-boring insects. Basically this is a variant of the conventional compact piling under “humid” 

conditions, but with an additional mechanical protection against insects. 


This method has been used occasionally in Switzerland, but only limited reports are available. The method can be 

used only with comparably small piles. 


Because of the very limited experiences it is not possible to make any recommendations . 


Because of the inaccessibility of the logs under the fabric, no direct monitoring of the wood quality is possible. The 

fabric should be checked frequently and any defects or damage must be mended immediately. 


No negative impact to be expected. 

3.5.2.6 Costs 

Special expenses for careful piling, fabric and covering/uncovering operations. 


Documented applications of this method. 


Kramer, P., 2000: Holzlager abdecken: Vorteile mit Geovlies. Wald und Holz 3: 50-51 

Jansen, E., 1990: Schützt Seidengase das lagernde Rundholz vor Insektenbefall? Wald und Holz (71)7: 602 – 608 

3.5.3 Compact pile covered with a mineralic suspension 


- Principle 

A small compact pile of logs is covered with a thin layer of a mineralic suspension, which prevents the wood from 

infestation by wood-boring insects (and possibly to a limited extent also by wood-destroying insects). Basically this 

is a variant of the conventional compact piling under “humid” conditions, but with an additional mechanical 

protection against insects and possibly some slowing down of the loss of wood moisture content. 

- Description 

Limestone powder is mixed with water to get a suspension, which is sprayed on the exterior side of the pile, to cover 

the whole pile in order to act as a protection against bark beetle. Upon removal most of the crust will flake off the 

logs. 

- 67 -



Some limited experience with this method has been reported from Baden-Württemberg, Germany (see references). 

This method seems to be applicable for short-term conservation in the forest as a protection against bark beetle 

attack. Problems for longer-term conservation involve the durability of the suspension which is strongly influenced 

by rainy weather. Furthermore the consumption of the suspension is very high. 


- 68 - 

Figure 37: 

Spruce logs covered by 

mineralic suspendsion 

(Pelz and Bastian 

2000) 

As a result of the limited experience, this method is not yet applicable for practical use. There are still some 

problems concerning the application and the equipment required. The gaps between the logs in the pile are usually 

too big, which increases the consumption of the suspension. Furthermore the durability of the covered suspension is 

not very high. 


Because of the inaccessibility of the logs under the mineralic layer, no direct monitoring of the wood quality is 

possible. Frequent checks are required to ensure that the mineralic layer remains intact 


This method has no adverse environmental effect because the chemical suspension used has no dangerous contents. 

The suspension simply dissolves after use. However, this also causes a problem when the suspension leaches out too 

early. 

3.5.3.6 Costs 

Special expenses for the application of the mineralic suspension. 

Costs are dependant on the surface/volume ratio of the pile because only the exterior surface of the pile has to be 

covered by the suspension. Nowadays the costs are not comparable with traditional conservation methods. The costs 

may be lowered in the future depending on the progress in improving this method. 


- Documented application of this method. 

- Research to make this method applicable for practical use in the forestry industry in the future. The most important 

requirement is to improve technical equipment, especially for practical handling out in the forest. 


Pelz, S.; Bastian, P. 2000: Neues Verfahren der Rundholzkonservierung: Mineralische Schutzhülle. AFZ/Der Wald 

20: 1101-1103

3.5.4 Storage in gravel pits 

3.5.4.1 Principles/description 


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 

layer of clay or soil. To decrease the soiling of the logs they can first be covered with a fleece. The wood is 

conserved in its 'original' state and protected against infestation by wood-destroying organisms. 


After the Lothar storm in 1999 about 6.500 m³ of Spruce and Fir logs were stored in gravel pits in Switzerland for up 

to 2.5 years. In general, the preservation of the wood was very good. The contamination of the logs with soil/clay 

and remains of the fleece may cause problems for the further processing in sawmills. The major disadvantage of this 

method is that it is not possibile to stagger the input and removal of the logs. 


So far only limited experience is available. This method appears to be suitable particularly for long-term storage of 

several years and may therefore be an alternative to conservation by water sprinkling. It is important that the 

covering layer is waterproof, which is why clay is particularly suitable. To reduce erosion of the covering layer 

planting with grass/clover may be advisable. Because of the lack of suitable storage sites the application of this 

method is limited. 


Because of the inaccessibility of the completely covered logs, no direct monitoring of the wood quality is possible. 

Frequent checks are necessary to ensure that the cover remains intact and any collapses or holes must be filled. 

Quality conservation during the storage period depends on the following factors: 

- Manipulation of the logs during input and removal of the wood. When there is too much bark damage, wood 

quality may be reduced by blue stain. 

- Durability of the cover material. 

- Compact piling of the logs (with few hollows). 


There are no known environmental influences on soil, air or water, provided that the logs are not treated with any 

chemical substances. So far this method can be regarded as environmentally harmless. 

3.5.4.6 Costs 

Special expenses for the covering/uncovering operations are incurred, which are quite high. The total costs are 

comparable to a compact pile with a water-sprinkling system. The costs can vary widely depending on the 

accessibility of the pit, the local situation and the level of maintenance required (e.g. groundwater running into the pit 

needs to be pumped out). 


- Suitability and behaviour of different wood species. 

- Assessment of long-term storage. 



WN 19/01, EMPA, Abt. Holz / BUWAL, Eidg. Forstdirektion (available as pdf: www.empa.ch/holz ? 

- 69 -

Holztechnologie) 


Anonymus 2002: Lagerung von Sturmholz: Es geht auch im Erdlager. Wald und Holz 12:48-50 

Anonymus 2002 : Stockage de bois sous glaise. Commune de Lausanne, Service des forêts, domaines et vignobles, 

Lausanne, Switzerland, 31 p. 

3.5.5 Storage in mines 


The goal of this method is to keep humidity as high as possible. The preconditions of this storage method are low 

temperature in the mines and conservation of the logs with bark in equal length. 


Damage from fungi and bark beetle attack were low during the test run. This method has not been used in practice. 


With regard to the results of the test run, the quality of the logs was strongly influenced by decay. Therefore, this 

method can not be recommended for further application in the forestry industry. 


No experience. 



3.5.5.6 Costs 



Concerning the negative results of this method no more research activity is recommended. 


Mahler, G.; Klebes, J.; Schröter, J. 1990/5: Hinweis zur Konservierung der Sturmwurfhölzer. 

3.5.6 Compact pile above tree line (logs with bark) 


Basically this is conventional compact piling under “humid” conditions, but at higher elevations in the mountains 

above the tree line. By storing the logs in a mountainous climate (low temperatures and long winter season) the risk 

of degradation of the wood can be reduced, in particular the danger of infestation by insects can be minimized. 


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 

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Switzerland for about two years. Overall, wood degradation appeared to be somewhat less than observed in logs 

stored at lower elevations during the same period, but nevertheless progressing. The wood moisture content dropped 

to a dangerous level after one year. Despite unfavourable conditions new insect infestations were observed 

originating from populations that were present in the stored logs. 


This special method may be suitable if the logs have to be transported by truck over mountain passes for further 

processing (e.g. along traditional export routes from Switzerland to Italy). The harvested logs are transported from 

the forests directly to the storage yard on the mountain pass. 

As with conventional compact-piling the duration of storage should not exceed one growing season. Particular care 

should be taken to avoid storage of logs that are already insect-infested. 


- Observation of discoloration/fungal attack on fresh cross-cuts at end-grain of protruding logs. 

- Monitoring of wood moisture content. 


Very little impact to be expected. Some soiling of the storage site from fallen bark. 

3.5.6.6 Costs 

Standard expenses for transportation and piling. No additional special expenses if used in the intended context (see 

chapter 3.5.6.3). 


- Suitability and behaviour of different wood species. 


Arnold, M. 1993: Grundlagen und technisch-organisatorische Aspekte der Rundholzlagerung. Schweiz. Z. Forstwes. 

144(11):843-858 

Kucera, L.J.; Katuscak, S. 1993: Zustand des sturmgeworfenen Fichte-Rundholzes nach einjähriger Trockenlagerung 

am Lukmanier/GR. Schweiz. Z. Forstwes. 144(11):873-892 

Wermelinger, B.; v. Hirscheydt, J. 1996: Die Entwicklung von Insekten in Fichten-Hochlagern oberhalb der 

Baumgrenze. Schweiz. Z. Forstwes. 147(8):597-613 

3.5.7 Storage in snow 


- Principle 

The covering of logs with snow leads to favourable storage conditions (mainly low temperature) which minimise the 

risk of degradation of the wood and thus preserve the wood in its original condition. 

- Description 

Supply and demand for timber is not in balance at different times of the year. In particular, in northern regions of 

- 71 -


Europe, namely Scandinavia, more Spruce pulpwood is felled than is used during the winter, while, after the 

summer, timber harvesting is concentrated on sawn timber-dominated logging sites and little Spruce pulpwood is 

obtained from these sites. This difference in supply may cause some problems for pulp mills for two main reasons: 

on the one hand, it is difficult to import the raw material since quality, which is stringent in the pulp industry, is 

difficult to control; on the other hand, winter-felled timber does not retain the quality required of wood intended for 

grinding through the summer unless special measures are undertaken. For these reasons, different methods of cold 

storage were studied in Finland in 2000 to preserve wood quality for pulping. They were financed by a group of large 

companies including UPM-Kymmene and Stora Enso. 

Five different types of cold storage were tested on nine storage sites ranging from 2.000 m³ to 30.000 m³: 

• "Traditional cold storage": an elongated stack formation is covered with natural snow or artificial snow 

produced with a snow cannon. This is then covered with sawdust. This method is well known and its use dates to 

the early 1990s. 

• As above, but with bark used as the final covering. 

• The stacks are cooled using water. Protective logs are used on the sides of the Spruce stacks (Pine pulpwood) 

and on the top (Birch pulpwood). 

• The stacks are cooled using snow blown from around the stack, the procedure otherwise being as above, (the use 

of protective logs around the Spruce piles.) 

• Experimental method: the storage formation is covered with snow produced using a snow cannon and then by a 

covering of foil mattresses. 

The influence of the thickness of the different type of layers was also assessed. 

The principles of these types of storage are to maintain the moisture content as high as possible and the temperature 

as low as possible in order to protect the timber from fungal and insect attacks, as well as to maintain its brightness 

(blue reflectance factor). Maintaining a high blue reflectance factor helps to save a lot of money in terms of pulp 

bleaching. It should be noted that the cost of bleaching increases by 0.34–1.18 €/m 3 /blue reflectance factor percentile 

unit. Additional savings can be achieved by a more efficient use of Spruce pulpwood. Moreover, if the cold storage 

of Spruce pulpwood enables the use of sawn timber as pulpwood at the end of summer to be avoided, further savings 

are also possible. The difference in price at the mill gate between sawn timber and pulpwood is on average 17 €/m 3 . 

3.5.7.2 Advantages, disadvantages, practical experiences 

This conservation method is used occasionally in Scandinavian countries (e.g. Finland), normally with the use of 

snow cannons. Very little is known about these experiences. The use of snow and sawdust is the most common 

method. 


• Sawdust is usually easy to spread. 

• Sawdust can be reused. Repeated use of sawdust increases the mineral content of the sawdust. 


• Sub-zero temperatures are required at the beginning of storage. 

• It may be difficult to spread the sawdust. 

• The process stirs up sawdust, which is hard to remove from the logs. 

• Sometimes the stacks have to be watered to keep the dust down. 

• The sawdust can create problems with water circulation in the pulp mill if it enters the system together with the 

pulpwood logs. 

If protective coverings are used between the snow and the sawdust: 

- it is easier to recover the sawdust 

- the sawdust will not stick to the logs and enter the process. 

- 72 -


The use of bark instead of sawdust has the following advantages: 

- it is dust free. 

- no bark is carried from the storage site into the process together with the logs. 

- the pieces of bark form a partially supportive layer with the result that once the snow melts, the bark will not fall 

between the logs in the stacks as sawdust would. 

- wood quality is the same regardless of whether bark or sawdust are used. 

When using foil mattresses to cover the stacks: 

- the covering stage was very labour-intensive. 

- dismantling the storage formation was difficult and the foil mattresses tore easily on removal. 

- in practice, mattresses could not be reused. 

The advantages of the water-cooled method was not having to rely on covering the stacks with snow and thus 

avoiding the strict schedule involved. 


The current experience is based on four-seven months storage from the winter season up to July or August. The 

methods have not been assessed for a longer period yet. 

3.5.7.3.1 Temperature 

With regard to temperature, it remained fairly constant up to mid-May, whatever the storage method. It was not until 

after the end of May, that difference between storage methods became obvious. There was no significant variation in 

temperature between different parts of the same stack. However, it was observed that the temperatures inside the 

stacks remained around zero until they were to be dismantled only in the case of the methods using snow and 

sawdust or bark. With the water-cooled method, a sharp rise in temperature was observed from May to such a point 

that the inside temperature almost reached the outside temperature within 2 months. 

3.5.7.3.2 Moisture content 

Maintaining the moisture content as high as possible is of high importance since a decrease would involved a rise in 

pulp manufacturing costs and a decrease in fibre strength. In Scandinavia, changes in Spruce wood properties begin 

to occur when moisture levels fall below 45%. In winter-harvested Spruce pulpwood, moisture content ranges from 

55% to 60%, preventing blue staining and other fungal attacks. 

In the present study, the wood moisture content remained quite high and at least above 45% regardless of the storage 

method except in the outside part of the stacks on two out of the nine sites, where a protective layer of Beech or Pine 

was used. 

3.5.7.3.3 Level of brightness 

The blue reflectance factor of the wood was measured using the SCAN test method. The measurements were made 

using compacted samples made of ground wood. The results were not directly comparable with the blue reflectance 

factor of the equivalent mechanical pulps (GW, PGW and TMP) as they are clearly smaller in numerical value. The 

range in the average blue reflectance factor of the wood measured from the storage stacks was 5 units (49 – 54%) 

with the variance for the internal readings of the stacks being 3 units at the most. 

There were no significant differences in value of the blue reflectance factor between the various parts of the stacks. 

In the same way, the difference between methods was small, but the fact remains that the timber stored in water was 

darkest in colour. 

There was no significant decrease in values of the blue reflectance as the storage time increased. 

The blue reflectance value of wood was best preserved in storage stacks using an abundant cover of snow (> 40cm.) 

plus a covering layer of sawdust or bark. 

- 73 -

3.5.7.3.4 Important factors, independent of the method 


- Forestry machine contractors should be highly professional and the pulpwood cut to length (billets) should be 

closely stacked. 

- Storage should be based on a very firm site, preferably on an asphalt surface, at all times of year. 

- Cold storage should be located so as to enable the water from the melting snow to be diverted away from the 

storage. 





3.5.7.6 Costs 

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 

€/m 3 . 

The actual costs involved (excluding extra transportation and other expenses) were within the range of 1.6-4.3 €/m 3 . 

The methods have not yet become established practice. Costs will go down as the people involved become 

accustomed to using them. 




The results were published in a Metsäteho guide entitled "Puutavaran kylmävarastointiohjeita tekijöille" (Practical 

instructions for the cold storage of timber). 

Makkonen-Spiecker, K. 1999: Schneelagerung von Holz in Finnland nimmt zu. AFZ/Der Wald 54: 1318 

3.5.8 Compact pile covered with organic material 


Piled logs are covered with a layer of organic material (e.g. bark chips, wood chips, sawdust) to give some protection 

from the environment (mainly to prevent the wood from drying). 


Some recent success with coverage of Spruce sawlogs with a layer of industrial wood and bark has been reported in 

Switzerland (see references). 

In 1968 Junckers Sawmill in Køge (Denmark) stored Beech logs in 3m high piles under a 75cm thick cover of fresh 

sawdust and chips, with good results. The storage period was from March 1968 to December/January 1968/1969 (a 

small amount was kept until June 1969). The temperature inside the pile increased to above 40°C during the first two 

months of storage and remained high during the whole storage period. This completely prevented attacks by wooddestroying 

fungi and probably also killed mycelia spores. 

No wood-destroying fungi can survive for a longer period of time at more than 40°C and only very few above 35°C. 

Also, the high CO2-content in the air inside the piles is believed to have contributed to the good results obtained from 

- 74 -


this storage method. The moisture content of the logs decreased by only 10% from March 1968 to June 1969. This 

high moisture content may slow down, but not prevent growth of the wood-destroying fungi. It is however, assumed 

to be the main reason for the total absence of tylosis, to which also the high temperature may have contributed by 

killing the parenchymatic cells at an early stage. 

At the same time (1967) storage in piles covered with wet straw was put into practice in two forest districts, but with 

very poor results. In one district, piles of Beech logs were covered with two 50cm thick layers of straw separated by 

a plastic sheet. Under the plastic sheet and on the lower layer of straws, perforated tubes were placed two meters 

apart, through which water was added two hours a day. The result was an almost total destruction of the wood within 

a few months during the summer. 

In the piles with straw and with water being added two hours a day, the moisture content of the logs was kept at the 

same level as in freshly felled logs thoughout the entire storage period. The temperature inside the pile, however, 

increased to a level that was very favourable to fungal growth. As a result of this, and the high relative humidity, the 

logs were more badly damaged by wood-destroying fungi after one year of storage than logs which were only 

covered with one layer of straw, and these in turn were even more damaged than logs without any protection in the 

forest. 

The stored wood from Junckers sawmill became reddish in colour during storage, probably because of the relatively 

high temperature inside the pile, creating an effect similar to that of a low temperature steaming process. This 

discolouration has little practical importance if the wood is steamed before drying or, as at Junckers Sawmill, dried 

in hot presses. The value loss was estimated by the sawmill to be no more than 5%. From practical experiences the 

following can be mentioned: 

- the logs have to be freshly cut 

- the pile has to be covered with sawdust before the winter ends 

- 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 

during the entire storage period 

- inspections have to be made often to measure temperatures and take samples 

- the logs should be processed quickly after removal from the pile. 

The tests show that high water content in the logs does not protect them from deterioration, if other factors are 

optimal to fungal growth. It is uncertain whether or not a more densely packed covering of wet straw under the 

plastic sheet and straw packed densely between the rows of logs in the pile might raise the temperature above the 

critical level for wood-destroying fungi. 

3.5.8.3 Recommendations 

The Danish experiences show that, unless a high moisture content can be maintained together with a temperature that 

is too high for the wood-destroying fungi to survive, storage in piles covered with organic material is not safe. 

Storage of Beech in piles covered with sawdust, as carried out at Junckers Sawmill, is recommended if it is not 

considered too expensive. Based on the tests it is strongly recommended not to store Beech in piles covered with 

straw. 


Because of the inaccessibility of the logs under the cover, no direct monitoring of wood quality is possible. 


No negative impact to be expected. The coverage material has to be disposed of (or left in the forest) after the 

removal of the logs. 

- 75 -

3.5.8.6 Costs 


The cost of storage at Junckers Sawmill was approximately double the price of sprinkler storage, transportation to 

the sawmill not included. 


If storage of logs in piles with layers of straw is still found interesting more research is needed in order to find out 

whether a thicker layer of straw may give the desired results. However, it seems that the material and economic 

resources required will exceed those required when sprinkling the logs and more research on this level can therefore 

only be recommended if other storage methods are found to be impossible. Instead, research should be directed 

towards the method used at Junckers Sawmill, to see if sawdust covering remains a possible alternative to other 

methods of storage. 


Moltesen, P. 1971: Opbevaring af bøgekævler i kuler dækket med organisk materiale. Dansk Skovforenings 

Tidsskrift, 1971, Vol. 56, p. 109-131. 

Junker, E. 2002: Alternativen zur Nass- und Folienlagerung von Rundholz – Eindeckung mit Rinde. Zürcher Wald 4: 

19 

Ziegler, A. 2002: Alternativen zur Nass- und Folienlagerung von Rundholz – Eindeckung mit Industrieholz. Zürcher 

Wald 4: 18 

- 76 -

3.6 Supplementary conservation measures 

3.6.1 Chemical wood protection 



In order to avoid attack from wood-boring insects and/or fungal discolouration, the wood may be treated with 

insecticides and/or fungicides. 

The function of insecticide application is to prevent or repel adult beetles from boring into the bark in order to lay 

their eggs. Once the beetles are under the bark or within the wood they are largely safe from chemical sprays and the 

application of insecticides is useless, hence the treatment must be carried out in late winter or in early spring, before 

the adult beetles begin their search for breeding material. If the expected duration of storage extends beyong one 

summer, other ways of protecting the timber should be sought. 

Log preparation: 

• Perfect delimbing. 

• Crosscutting to provide clean cut-ends. 

• Removal of lichens and mosses from the bark with a metallic brush. 

Material: 

• Small log storage: a garden home sprayer is sufficient. 

• Large log storage: a knapsack sprayer. 

Methodology: 

For efficient protection: 

• Treatment must be undertaken as soon as possible. 

• Temperature > 0°C. 

• Dry weather/no rain during application (pollution risk + inefficient treatment). 

• Each log must be completely treated, including the part in contact with the ground. 

• Wounded parts must be treated particularly carefully. 

• Application of an anti-check product where bark is missing. 

3.6.1.2 Precautions 

• Avoid contact with skin and mucous membranes. 

• Use protective clothing (trousers, gloves, glasses, etc.). 

• Avoid shaking the products during transportation. 

• Respect the chemical products’ specifications. Some products may be prohibited for use in forests. 

• Manufacturers’ recommendations, risk and COSHH assessments must be adhered to. 

3.6.2 Biological wood protection 


At the present time it is felt that biocontrol cannot be recommended. However, it is felt that research that specifically 

address the shortcomings should be encouraged. 

Holdenrieder and Greig (1998) state that biological control of pathogenic fungi can either be through rapid 

- 77 -


colonisation and defence of substratum, or by the takeover of the resource already in use by the pathogen, and as 

Gibbs and Smith (1978) pointed out, the former are likely to be more valuable as biological controls. It is known 

that the growth of decay fungi can be inhibited through the production of antibiotic substances, as well as by direct 

competition for the substrate. A number of studies have considered the use of non-decay fungi to control decay 

fungi, in particular Trichoderma, either as an integrated control with borate (Schoeman 1995), or alone (e.g. Richard 

e t a l . 1969; Bruce and King 1986; Schoeman e t a l . 1994; Anseylmi and Nicolotti 1997). More recently bluestain 

fungi have been considered as biocontrols for decay fungi (Brown, 2003). 

Although the use of biological controls can be a tempting option when compared to chemical control, a number of 

questions/issues need to be addressed if they are to be effective, including the following: 

• What time period does the biocontrol need to work for? 

• Biocontrol agents must have the ability to colonise wood without damaging it in a way which would make it 

unmarketable or which would decrease the service life. What is the planned end use of the timber? Is blue stain 

acceptable? 

• What are your target fungi for control? The number and diversity of potential target fungi occurring in 

seasoning timber can be large. Hence, one needs to consider how effectively this assortment of different fungi, 

all with different ecological strategies (Rayner and Boddy 1988), be controlled by a single species or isolate of a 

biocontrol fungus. 

• Rapid colonisation and assimilation of simple nutrients are attributes that can make fungi-effective biocontrol 

agents (Hulme and Shields 1970), hence one approach to choosing a potential biocontrol is to select species 

which are primary colonisers (Rayner and Webber 1984), such as bluestain fungi. 

• It is also possible that the combined activity of potential biocontrols such as bluestain and mould fungi 

accelerate the breakdown of the host defences, making it easier for the decay fungi to colonise the wood. 

• Environmental/climatic factors including temperature, rainfall and humidity have an effect on the drying rate, 

and hence both the seasoning period and growth potential of fungi, influencing colonisation, combativeness and 

competitive interactions between fungi. 

• Temperature influences which fungi are present, how well they survive and how well they compete 

with each other (Nicolotti and Varese 1996). For instance, if the temperature is high, bluestain fungi 

are more likely to become successfully established in the timber and well established fungi appear to be 

better at preventing ingress of their domain by decay fungi (Brown 2003). 

• Moisture content of the logs is also an important issue in the process of colonisation. Firstly, reduced 

fungal growth is found in saturated wood, such as that kept in wet stores (Webber and Gibbs 1996). 

Secondly, dry wood, with a moisture content of less than 20%, is equally unlikely to become colonised 

by fungi. 

• Product development in terms of production and formulation and registration would need to be addressed for 

any biocontrol agent. 

• The methods by which biocontrol agents are applied to the substrate that requires protection is also a key issue. 

• In terms of biocontrol selection, it is important to examine a range of isolates of the same species, not just one, 

as large variation in terms of growth rates and colonising ability can occur (Brown 2003). 

To conclude, biocontrols have advantages over traditional chemical methods: they are potentially less damaging to 

the environment, and they are more positively perceived by the public. However, if they are to be accepted by the 

forest industries it is essential that they are as effective as their chemical counterparts, be easy to handle in the field, 

and are as economically viable (Bruce 1998). However, although this is important, the pressure to adopt sustainable 

forestry methods, for example via the implementation of the UK Woodland Assurance Scheme (UKWAS 2000) is 

leading to a reduction of chemical applications in the forest environment. However, if biological control of storm 

damaged timber is to be considered, more research is needed in the areas outlined above. In the past, many 

biocontrol studies have been laboratory based, and although this is often the cheapest option in terms of time and 

money, it is unlikely to give a true picture of the situation in the field. In particularly greater thought needs to be 

given to climatic and environmental conditions which are likely to cause otherwise successful biocontrol agents to 

fail. 


Anseylmi, N.; Nicolotti, G. 1998: Biological control of Heterobasidion annosum in the forest by non-pathogenic 

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wood destroying fungi. In, 


Delatour, C.; Guillaumin, J.J.; Lung-Escarmant, B.; Marcais, B. (Eds): Root and butt rots of forest trees: 9 th 

International Conference on root and butt rots. INRA, Paris, 421-428. 

Bruce, A. 1992: Biological control of wood decay. International Research Group on Wood Preservation, 

No.IRG/WP/1531- 92. 

Bruce, A.; King, B. 1986: Biological control of decay in creosote treated distribution poles. I. Establishment of 

immunising commensal fungi in poles. Material und Organismen 21: 1-13. 

Brown, A.V. 2003: Biological control of decay fungi in seasoning utility poles. PhD. Thesis, Imperial College, 

London. 

Freitag, M.; Morrell, J.J.; Bruce, A. 1991: Biological protection of wood: status and prospects. Biodeterioration 

Abstracts 5: 2-13. 

Holdenrieder, O.; Greig, B.J.W. 1998: Biological methods of control. In: Woodward, S.; Stenlid, J.; Karjalainen, R.; 

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, 

Wallingford: 235-258 

Gibbs, J. N.; Smith, M.E. 1978: Antagonism during the saprophytic phase of the life cycle of two pathogens of 

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. 

Hulme, M.A.; Shields, J.K. 1970: Biological control of decay fungi in wood by competition for non-structural 

carbohydrates. Nature 227: 300-301. 

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 

a n n o s u m on Norway spruce. Forest Ecology and Management 88: 249-257. 

Palfreyman, J. W.; Smith, G.M.; Bruce, A. 1996: Timber preservation: current status and future trends. Journal of the 

Institute of Wood Science 14: 3-8. 

Rayner, A.D.M,; Boddy, L. 1988: Fungal decomposition of wood: its biology and ecology. John Wiley & Sons, 

Chichester. 

Rayner, A.D.M.; Webber, J.F.W. 1984: Interspecific mycelium interactions - an overview. In: Jennings, D.H.; 

Rayner, A.D.M. (Eds): The ecology and physiology of the fungal mycelium. Symposium of British Mycological 

Society, Cambridge University Press, Cambridge: 384-417. 

Richard, J.; Wilson, M.M.; Bollen, W.B. 1969: Biological control of decay in Douglas Fir poles. Forest Products 

Journal 19: 41-45. 

Schoeman, M.W. 1995: Control of decay fungi in freshly felled pine. PhD. Thesis, Imperial College, London. 

Schoeman, M.W.; Webber, J.F.; Dickinson, D.J. 1994: A rapid method for screening potential biological control 

agents of wood decay. European Journal of Forest Pathology 24: 154-159. 

Schoeman, M.W.; Webber, J.F.; Dickinson, D.J. 1999: The development of ideas in biological control applied to 

forest products. International Biodeterioration and Biodegradation 43; 109-123. 

UKWAS. 2000: Certification for the UK Woodland Assurance Scheme. UKWAS Steering Group, Edinburgh. 

Webber , J.; Gibbs, J. 1996: Water storage of timber: Experience in Britain. Forestry Commission Bulletin 117, 

HSMO, London. 

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Young, E. J.; Eaton, R. A.; Webber, J. F. 2002: Susceptibility of harvested softwoods to infection by sap-staining 

fungi. Int. Res. Group on Wood Pres. IRG/WP 02-10435. pp12. 

3.6.3 Physical wood protection 

End-sealing of hardwood logs 

A well-known method for the protection of Beech-wood is the coating of exposed parts of the wood with a material 

preventing the passage of air and water. The effect of the method is prevention of drying and, probably, an increased 

carbon dioxide concentration within the log. 

Good results were achieved with the end-sealing of Danish Beech logs after the storms in 1967. The idea was to 

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 

parts on the log with a suitable compound. Among the best brands were Permaroof, originally a remedy for leaking 

roofs. This bitumen-based compound is still available on the market. The sealing compound, Allerød Pasta, also 

showed very good results, if it was not damaged by frost. By using Permaroof, the damage during storage were 

reduced by 50% and when used together with a biocide the effect was even greater. If used on the whole area of the 

log, the damages could be reduced by 85 - 90% (Moltesen and Grenaa Kristensen, 1969). Other sealants used 

commercially include wax dispersions, e.g. Anchorseal (Bates Co.) and Mobil-Cer (Mobil Oil). 

A finding of merely historical interest was that spraying of Norway Spruce logs with Santobrite 

(sodiumpentachlorophenate) + Borax + Lindane (HCH) + DDT and/or covered with plastic, showed almost 100% 

protection against insect damage, but the combination seemed to have no significant effect on red top rot (mainly 

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. 

Although chlorinated phenols can no longer be used, these results show that biocides can be very effective and it is 

hoped that safe, environmentally acceptable replacements may become available in the future. 

References: 

Moltesen, P.; Grenaa Kristensen, V. 1969: Afprøvning af kævlesmøringsmidler. Skoven, vol. 3, 1969, pp. 19-21. 

The End 

- 80 -

Version 7, 

10.2.2004 

Annex 1: Terminology/Glossary 


Terminology / Glossary regarding 'Log conservation' Note: The glossary is based mainly on existing English and German terms, which subsequently have been translated to the 

other languages 

Category English (synonym) Definition Remark Français (synonyme) Deutsch (Synonym) Italiano (sinonimo) Español (sinónimo) Portuguese (sinónimo) 

General term wind-blown timber 

(storm-damaged 

timber) 

General term log conservation (log 

storage) 

timber from trees 

damaged by a 

storm (broken, 

thrown or leaning 

trees) 

long-term (several 

months) storage of 

logs with the goal to 

preserve the wood 

quality 

chablis Sturmholz legno proveniente 

da schianti 

conservation des grumes 

(stockage des grumes) 

- 81 - 

Rundholzlagerung 

(Rundholzkonservieru 

ng) 

conservazione dei 

tronchi (stoccaggio 

dei tronchi) 

derribos madeira derrubada pelo 

vento 

conservación de 

trozas 

conservação de toros 

(armazenamento de 

toros) 

General term round timber harvested part of 

tree stem 

prEN844-12 bois rond Rundholz legno tondo madera en rollo rolaria 

General term long pole whole stem prEN844-12 grume Langholz fusto fuste árvore inteira 

General term cut to length stem cut into shorter 

billon Kurzholz (Trämel) toppo madera tronzada, madeira torada 

pieces 

trozas 

General term overcut 

addition in log 

surcote Übermass (Zumass) soprammisura holgura en longitud de medida acima do corte 

(overmeasure) length to account for 

staining in the endgrain 

tronzado 

estabelecido 

General term with bark logs with bark 

avec écorce in Rinde con corteccia con corteza, c/c com casca 

General term without bark logs with bark 

sans écorce entrindet scortecciato sin corteza, s/c sem casca (descascada) 

(debarked) removed 

General term conservation method particular technique 

méthode de conservation Lagerungsmethode metodo di método de 

método de conservação 

to achieve goal of 

log conservation 

conservazione conservación 

General term pile heap of logs pile Polter catasta pila pilha 

General term compact pile heap of closely piled 

logs 

pile compacte Haufenpolter catasta compatta pila compacta pilha compacta 

General term cross-pile heap of logs with 

pile à rangs croisés Lagenpolter catasta con strati pila encastillada pilha com troncos 

perpendicular 

perpendicolari 

cruzados 

intermediate layer of 

single logs allowing 

free ventilation 

transversalmente 

General term standing tree tree in upright 

arbre sur pied (arbre stehender Baum albero in piedi árbol en pie árvore em pé 

position (inclination 

90-60°) 

debout) 

General term leaning tree tree with inclination 

59-30° 

arbre penché angeschobener Baum albero inclinato árbol inclinado árvore inclinada 

General term uprooted tree thrown tree with 

inclination 29-0° 

arbre déraciné geworfener Baum albero sradicato árbol desarraigado árvore arrancada 

General term broken tree tree broken in 2 (or 

arbre cassé gebrochener Baum albero spezzato árbol tronchado árvore partida 

(snapped tree) more) separate

pieces 

Cons. method In-situ storage logs left untouched 

in place in the stand 

Cons. method live-conservation of 

wind-thrown trees 

Cons. method drying by 

transpiration 

in situ storage of 

living, uprooted 

trees with sufficient 

root contact 

in situ storage of 

entire trees (with 

crown) with a crosscut 

at the stem base 

Cons. method wet storage storage under 

(controlled) wet 

conditions keeping 

the wood saturated 

Cons. method compact pile with 

water sprinkling 

Cons. method ponding (immersion 

in water) 

Cons. method storage under drying 

conditions 

Cons. method log pre-drying in 

covered cross-pile 

Cons. method fast log pre-drying in 

open cross-pile 

Cons. method storage under humid 

conditions 

compact pile with 

water sprinkling 

(logs with bark) 

storage of (loating) 

logs in running or 

standing water (logs 

with bark) 

storage under 

(uncontrolled) 

conditions resulting 

in slow or fast 

drying of the logs 

pre-drying of logs in 

covered cross-pile 

(logs debarked) 

fast log pre-drying in 

open cross-pile 

(logs debarked) 

storage under 

(uncontrolled) 

changing conditions 

Cons. method compact pile compact pile (logs 

with bark / 

Cons. method compact pile 

covered with plastic 

sheets 

debarked) 

compact pile 

covered with plastic 

sheets (logs with 


conservation in-situ Lagerung im Bestand stoccaggio in situ almacenamiento in 

situ 

chapter 3.1.1 conservation sur site des 

bois partiellement 

déracinés 

- 82 - 

Lebendkonservierung 

im Bestand 

chapter 3.1.2 séchage par transpiration Physiologische 

Trocknung 

(Ganzbaumlagerung) 

stoccaggio in piedi 

di alberi danneggiati 

dal vento (ma 

ancora radicati) 

Stagionatura per 

traspirazione 

conservación en vivo 

de árboles 

parcialmente 

desarraigados 

secado natural, 

secado al aire 

chapter 3.2 stockage sous eau Nasslagerung stoccaggio in acqua almacenamiento en 

húmedo 

chapter 3.2.1 pile compacte sous 

aspersion d'eau 

Nasslagerung durch 

Beregnung 

chapter 3.2.2 immersion Nasslagerung in 

Gewässern 

chapter 3.3 stockage sous conditions 

asséchantes 

chapter 3.3.1 stockage sous conditions 

sèches 

chapter 3.3.2 pré-séchage rapide des 

grumes stockées en pile 

croisée ouverte 

chapter 3.4 stockage sous conditions 

humides 

Rundholzvortrocknun 

g 


g in gedecktem 

Lagenpolter 

Schnelle 


g in offenem 

Lagenpolter 

Lagerung unter 

feuchten 

Bedingungen 

(Feuchtlagerung) 

catasta compatta 

con aspersione 

d'acqua 

pila compacta bajo 

aspersión 

armazenamento no local 

do povoamento 

conservação em vida de 

árvores derrubadas pelo 

vento 

secagem por evaporação 

conservação com água 

pilhas compactas com 

sistemas de expressão de 

água 

immersione inmersión conservação de toros por 

imersão 

stoccaggio al riparo 

dagli agenti 

atmosferici 

pre-essiccazione in 

cataste, con strati 

perpendicolari, 

coperte 

pre-essiccazione 

veloce in cataste, 

con strati 

perpendicolari, non 

coperte 

stoccaggio 

all'aperto 

almacenamiento en 

condiciones de 

secado al aire 

pre-secado de trozas 

en pilas encastilladas 

bajo cubierta 

pre-secado de trozas 

en pilas encastilladas 

descubiertas 


condiciones húmedas 

no controladas 

armazenamento de toros 

ao ar livre 

pré-secagem dos troncos 

em pilhas cobertas 

pré-secagem de pilhas ao 

ar livre com troncos 

cruzados 

armazenamento em 

condições humidas 

chapter 3.4.1 pile compacte Haufenpolter catasta compatta pila compacta pilha compacta 

chapter 3.4.2 pile compacte recouverte 

d'une bâche plastique 

Haufenpolter mit 

Folien-Abdeckung 


coperta da teli di 

plastica 

pila compacta 

recubierta con 

plástico 

pilha compacta coberta 

com plásticos

ark / debarked) 

Cons. method 'special' methods conservation 

methods with 

protection 

mechanisms not 

fitting into main 

Cons. method log conservation 

under oxygen 

exclusion, compact 

pile wrapped in 



covered with geo 

textile fabric 


covered with a 

mineralic suspension 

categories 

compact pile 

wrapped and sealed 

in plastic sheets 

resulting in oxygen 

free conservation 

atmosphere (logs 

with bark) 

compact pile 

covered with geo 

textile fabric (logs 

with bark) 

compact pile 

covered with a thin 

layer of mineralic 

suspension 

(protection against 

insects) 

Cons. method storage in gravel pits compact pile buried 

in a hole in the 

ground or on level 

ground covered with 

thick layer of 

clay/soil 

Cons. method storage in mines storage in unused 

Cons. method compact pile above 

timberline 

mine tunnels 

compact pile above 

timberline (logs with 

bark) 

Cons. method storage in snow compact pile 

covered with snow 


covered with organic 

material 

Cons. method supplementary 

conservation 

measures 

compact pile 

covered with bark 

chips, wood chips, 

sawdust etc. 

conservation 

measures 

supplementary to 

main methods 

('integrated 

methods') 


chapter 3.5 méthodes spéciales Spezialverfahren metodi particolari métodos especiales métodos especiais 

chapter 3.5.1 conservation en 

atmosphère confiné, pile 

compacte enroulée dans 

une bâche en plastique 

scellée 

chapter 3.5.2 pile compact recouverte 

d'une feuille de géotextile 

chapter 3.5.3 pile compacte recouverte 

d'une suspension 

minérale 

- 83 - 

Rundholzkonservierun 

g durch 

Sauerstoffentzug 


Geovlies-Abdeckung 


mineralischer 

Schutzhülle 

stoccaggio del 

legno in assenza di 

ossigeno, cataste 

compatte avvolte da 

teli di plastica 


coperta con tessuto 

geotessile 


trattata con una 

sospensione 

minerale 

chapter 3.5.4 stockage sous terre Erdlagerung stoccaggio per 

interramento 

chapter 3.5.5 stockage dans des mines Lagerung in 

Bergwerken 

chapter 3.5.6 pile compacte stockée au- Haufenpolter oberhalb 

dessus de la limite Waldgrenze 

supérieure des forêts 

chapter 3.5.7 stockage sous la neige Lagerung unter 

Schnee 

chapter 3.5.8 pile compacte couverte de 

matière organique 

chapter 3.6 mesures supplémentaires 

de conservation 


Abdeckung aus 

organischem Material 

zusätzliche 

Schutzmassnahme 

stoccaggio in 

miniera 

stoccaggio in 

altitudine 

stoccaggio sotto la 

neve 

stoccaggio con 

materiale organico 

misure 

supplementari di 

conservazione 

conservación en 

atmósfera pobre en 

oxígeno de pilas 

compactas bajo 

plástico hermético 

pila compacta 

cubierta por tejido 

geotextil 

pila compacta 

cubierta por una 

suspensión mineral 

almacenamiento de 

pilas enterradas 


minas 

Pila compacta bajo el 

límitealtitudial del 

bosque 

almacenamiento bajo 

la nieve 

Pila compacta 

cubierta por materia 

orgánica 

medidas 

suplementarias de 

conservación 

conservação de troncos 

em pilhas seladas sem 

entrada de oxigénio 

cobertas com plásticos 


com tela têxtil 


com uma folha de mineral 

em suspenção 


subterrâneos ou ou pilhas 

cobertas com barro 


minas 

pilha compacta em zonas 

de montanha, acima da 

linha de crescimento da 

vegetação 

armazenamento na neve 


com material orgânico 

medidas suplementares 

de conservação

Cons. method chemical protection wood protection by 

chemical 

agents 

Cons. method biological protection wood protection by 

biological agents 

Cons. method physical protection wood protection by 

physical measures 

(e.g. end-grain 

sealing) 

Processes input process of building 

up a log storage 

Processes removal process of 

extracting logs from 

a log storage 

Material sprinkler device to produce 

artificial rain 


chapter 3.6.1 protection chimique chemischer 

Holzschutz 

chapter 3.6.2 protection biologique biologischer 

Holzschutz 

chapter 3.6.3 protection physique physikalischer 

Holzschutz 

- 84 - 

protezione chimica protección química protecção química 

protezione biologica protección biológica protecção biológica 

protezione con 

mezzi fisici 

mise en place Einlagerung inizio (del processo 

di stoccaggio dei 

tronchi) 

reprise Auslagerung interruzione (del 

processo di 

stoccaggio dei 

tronchi) 

Protección fisica protecção física 

montaje entrada 

retirada remoção dos troncos do 

armazenamento 

arroseur Kreis-/Sektorregner aspersore aspersor aspersor

STODAFOR - Ctba

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