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The Thinning of Sitka spruce - Two Experiments 15 TABLE 6 Coolgreany. Effect of thinning type on basal area (square feet Hoppusjacre) and mean diamter (inches) Eclectic Significance Basal area; After 1st thinning Increment Year 1 2 3 4 Increment Qears 1-4 After 2nd thinning Increment Year 5 Increment Years 1- 5 111.05 12.47 11.78 9.89 13.48 47.62 121.28 11.87 58.49 110.17 13.38 11.74 12.53 14.39 51.75 10 ~~ 120.35 12.24 63.99 20% Diameter; After 1st thinning J ncrement Year 1 2 3 4 Increment Qears 1-4 Increment Year 5 Increment Years 1- 5 4.65 .25 .25 .20 .25 .95 .25 1.20 5.00 .30 25 % .20 25% .25 25% .30 1.05 25% .30 1.35 10%
16 Irish Forestry small stems were ignvred at thinning. The distribution in low thinned plots is more normal (Table 9). Thinnings Table 10 shows thinning data from both types of thinning. In eclectically thinned plots a smaller number of larger trees resulted in about 100 cubic feet extra removed at first thinning. In the second thinning volumes were much the same, though the average size of trees removed in eclectically thinned plots was still larger. The size of these trees may be more attractive to timber merchants resulting possibly in a slight price difference. Conclusions The results to date indicate that thinning intensity does effect increment to some extent and also the size of trees within the stand. Type of thinning also seems, though less conclusively, to influence increment and stand structure somewhat. It is obvious that Sitka spruce is a very flexible and tolerant crop as regards thinning intensity and that first thinnings can be q;.rite heavy without adverse repercussions, though at greater than 40°/) volume removal, increment loss is likely to occur. Recovery appears ·~o be quite rapid-within four years. The removal of 30'/0 by volume or basal area is quite safe. This is encouraging in the light of recent developments 111 systematic thinning trends and at present experiments are being set TABLE 7 Coolgreany. Effect of thinning type on volume to 3 inches top diameter, and total stemwood (cubic feet Hoppus/acre). Eclectic Low Periodic annual volume increment Mean annual volume increment Increase in mean annual volume increment since first thinning Periodic annual stemwood increment Mean annual stemwood increment Increase in mean annual stem wood increment since first thinning 349 403 162 168 44 ss 348 404 176 187 44 ss
Page 1: IRISH FORESTRY Journal of the Socie
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Page 6 and 7: The wide range of Danarm Chai n Saw
Page 8 and 9: IRISH FORESTRY CONTENTS (Authors al
Page 10 and 11: IRISH FORESTRY Volume 26 SPRING 196
Page 12 and 13: The Thinning of Sitka spruce - Two
Page 20 and 21: Thinnings The Thinning of Sitka spr
Page 24 and 25: The Thinning oj Sitka spruce - Two
Page 28 and 29: 21 The Wellingtonia in Ireland By A
Page 30 and 31: The Wellingtonia in Ireland 110 ft.
Page 32 and 33: Notes and News 25 FOREST LAND V ALU
Page 34 and 35: 27 Abstract Extraction Damage as a
Page 36 and 37: Fore'st Service 29 held on to its y
Page 38 and 39: forest Serz'ice 31 The author faith
Page 40 and 41: Timber Pests and Diseases 33 attack
Page 42 and 43: Society Activities 35 Other Publica
Page 44 and 45: Control weeds in forestry plantatio
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Page 48 and 49: BEFORE PLANTING TREES consult an ex
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