tailieunhanh - Báo cáo khoa học: "Wood density traits in Norway spruce understorey: effects of growth rate and birch shelterwood densit"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Wood density traits in Norway spruce understorey: effects of growth rate and birch shelterwood density. | Ann. Sci. For. 55 1998 809-821 Inra Elsevier Paris 809 Original article Wood density traits in Norway spruce understorey effects of growth rate and birch shelterwood density Goran Bergqvist SLU Department of Silviculture 90183 Umeâ Sweden Received 4 June 1997 accepted 27 April 1998 Abstract - Effects of growth rate and birch shelterwood density 0 300 and 600 trees ha 1 on wood density traits in Norway spruce Picea abies L. Karst understorey were evaluated for a trial in the boreal coniferous forest 56 years after establishment of the stand and 19 years after establishment of the trial. Wood density traits were measured by micro-densitometry for annual rings 21-30 extracted at breast height. In addition ring width and mean density were measured for all annual rings. Growth rate was generally low with a mean ring width of mm. Radial variations in ring width and density depended more on calendar year than on cambial age. The shelterwoods had moderate d fluctuations in ring width but not in wood density. For annual rings 21-30 the mean density was 12 higher in trees of the lowest growth rate compared to trees of the highest growth rate. Also minimum density and latewood percentage were higher in trees with the lowest growth rate compared to all other trees while there were no significant effects due to shcltcrwood treatment for any of the wood density traits tested. An increase in ring width from 1 to 2 mm resulted in an 18 decrease in wood density. Latewood percentage explained 84 of the variation in wood density. Inra Elsevier Paris. Norway spruce understorey birch shelterwood wood density growth suppression latewood percentage Resume - Caractéristiques de la densité du peuplement dans le sous-étage de sapin de Norvège effets du taux de croissance et de la densité du peuplement de bouleaux resultant de la regeneration par coupes progressives. Les effets du taux de croissance et de la densité du peuplement de bouleau resultant de la regeneration par coupe .

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