造林密度对湿地松人工林木材性质的影响效应

湿地松4种初植密度（900、1350、1800、2700株/hm^2)林分间树高、胸径、材积、蓄积量和单位面积上1-2级优势木数理等因子存在着显著的差异。初植密度对其人工林木材管胞解剖特征、化学成份含量、干缩性状和木材力学性能有一定的影响，但没有达到显著的程度。稀植的林分木材纵向干缩大、差异干缩大。1800、1350株/hm^2的林分，其木材管胞长、长宽比大、微纤丝角小，干缩特性适中，力学强度较高，适于培养建筑结构用材。1800株/hm^2林分单位蓄积量大，管胞长、长宽比大、纤丝角小，纤维纱与综纤维素含量高，木素含量低，适于培育纸浆材。

Effects of Initial Densities on Wood Quality of Exotic Slash Pine Plantation

trees wood were collected from four kinds of initial stand densities (900, 1 350, 1 800 and 2 700 N/hm 2) for 17-year-old slash pine plantation in this paper. There were significant differences in tree height, diameter at breast height, tree volume, volume per hectare and number of large diameter wood in stands among these initial stand densities. There are some effects of initial densities on wood tracheid formal features (tracheid length, tracheid length-width ratio, tracheid dull wall thickness-diameter ratio, tracheid diameter-width ratio and MFA in S 2 layer of tracheid), wood chemical constitute content (extractives, cellulose, lignin, pentsans, helocellulose), wood shrinkage properties in air-dried condition and wood mechanical properties (compressing strength along grain of wood, MOE and MOR), but these effects were not distinct at 0.05 level. In stand of 900 N/hm 2, wood possessed the largest axial shrinkage and biggest ratio of tangential to radial direction. Wood from two stands of 1 350 and 1 800 N/hm 2 initial densities had features of longer tracheid length, larger ratio of tracheid length-width, smaller MFA in S 2 layer of tracheid, middling shrinkage properties and higher mechanical properties of wood. These two initial densities of slash pine were suitable for culturing construction timber. In 1 800 N/hm 2 initial density of slash pine, volume per hectare was the largest. Its wood possessed the longest tracheid length, largest length-width ratio of tracheid, smallest MFA in S 2 layer of tracheid, highest contents of cellulose and helocellulose and the lowest content of lignin. The initial density of slash pine is suitable for culturing pulpwood.