Download Full PDF - 28.09 MB - The Society of Irish Foresters
Download Full PDF - 28.09 MB - The Society of Irish Foresters Download Full PDF - 28.09 MB - The Society of Irish Foresters
Crop Structure and Productivity for Unthinned Sitka Spruce 35Plot Distribution40no.Age Classesyrs20,12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 4240Height Classes m20Fig. 1.7 8 9 10 II 12 13 14 15 16 17 18 19 20 21Distribution of unthinned Sitka spruce plots by age and top height.height (D.B.H.) and over were girthed (with a steel tape). Treeswere grouped in assortments of 3cm. and over and 7cm and over.Heights of dominant trees were measured by a Blume Leiss hypsometer.A sample of dominant trees (defined as the 100 largestgirthed trees per ha.) were felled and analysed for height agepatterns. A sample in the 7cm. D.B.H. and over assortment werefelled and measured in sections for volume.A wide range of site conditions was encountered; elevationsvaried from 30-500 m., soils from brown earths to peaty podsols andgleys. Topographical features included flat sites and slopes in excessof 20°.The distribution of height and age categories is g.iven in Figure l.
36VARIABLESThese are defined in Table 1.Irish ForestryCOMPUTATION AND ANALYSISData were analysed with the aid of the LB.M. 360 computer.Three stages were involved.(i) Calculation of crop volumes.(ii) Correlation of crop and site variables.(iii) Explanation in detail of the relationship of some of the cropvariables.TABLE 1PLOT VARIABLES PER HECTAREVariableVs (m 3 )Vt (rna)A (Yrs.)S (No.)Hd (m)H (m)Dd (cm)i5 (cm)G (m')Sdd ( %)Gdd ( % )Alt (m)h (ratio)v (ratio)SIp (0)AspFDefinitionVol. ofAll * stems to 8cm. top diameterVol. ofAll * stems 3cm. D .B.H. and over to tipAgeSince plantingNumber ofAll * stems 3cm. D.B.H. and overMean Height of100 largest diameter stemsMean Heightof 240 volume sample stemsDiameter of100 largest diameter stemsMean Diameter ofall trees 3cm. and overBasal area of all * stems3cm. D .B.H. and overStems dead x 100SBasal area dead x 100GHeight above sea levelHeight at 6 yrs./6V s/B.F.C + . vol. from 'b' curveSlope in degreesAspect N-NW clockwise coded 1-8V 8 Form factorG x HMean23225621381611.39.920.313.040.03.90.9265.9 I1.04StandardDeviation747565102.11.62.81.27.06.42.196.10.290.286.32.6.037* Living and deat trees.+ British Forestry Commission Management Table (1971).
- Page 1 and 2: IRISH FORESTRYJournal of the Societ
- Page 3: Control weedsin forestryplantations
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- Page 12 and 13: IRISH FORESTRYVolume 29 1972 No.2Ed
- Page 14 and 15: Some Forestry Problems in the Europ
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- Page 24 and 25: The Response of Sitka Spruce to Sul
- Page 26 and 27: The R esponse of Sitka Spruce to Su
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- Page 36 and 37: The Response 0 fSitka Spruce to Sul
- Page 38 and 39: Labour Cost Trends in ForestNurseri
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- Page 72 and 73: Reviews 63includes an Appendix VI b
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Crop Structure and Productivity for Unthinned Sitka Spruce 35Plot Distribution40no.Age Classesyrs20,12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 4240Height Classes m20Fig. 1.7 8 9 10 II 12 13 14 15 16 17 18 19 20 21Distribution <strong>of</strong> unthinned Sitka spruce plots by age and top height.height (D.B.H.) and over were girthed (with a steel tape). Treeswere grouped in assortments <strong>of</strong> 3cm. and over and 7cm and over.Heights <strong>of</strong> dominant trees were measured by a Blume Leiss hypsometer.A sample <strong>of</strong> dominant trees (defined as the 100 largestgirthed trees per ha.) were felled and analysed for height agepatterns. A sample in the 7cm. D.B.H. and over assortment werefelled and measured in sections for volume.A wide range <strong>of</strong> site conditions was encountered; elevationsvaried from 30-500 m., soils from brown earths to peaty podsols andgleys. Topographical features included flat sites and slopes in excess<strong>of</strong> 20°.<strong>The</strong> distribution <strong>of</strong> height and age categories is g.iven in Figure l.
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