抚育间伐强度对兴安落叶松中龄林测树因子的影响

The Effects of Different Thinning Intensities on Tree-measurement Factors of Middle-aged Larch gmelinii Seedlings

为更好的了解抚育间伐对天然兴安落叶松中龄林树高、胸径和冠幅等因子的影响,充分掌握林分消长动态,为森林更好的经营提供理论依据。本文以大兴安岭新林林业局平均林龄在52 a的落叶松天然次生中龄林为研究对象,在林地内设置4块(20 m×30 m)不同抚育间伐强度的样地,依次为对照样地(CK,0%)、低强度间伐样地(Z1,16.75%)、中强度间伐样地(Z2,25.48%)、高强度间伐样地(Z3,34.38%)。分别对各样地进行每木检尺,调查样地中所有乔木,包含树种、株数、树高、胸径和冠幅等测树因子。采用通径分析的方法分析不同抚育间伐强度下测树因子的变化规律及其相关性。结果表明:在中等强度间伐下,冠幅主要分布在1.5~4.0m之间,平均冠幅2.5m;冠高率主要分布在0.3~0.8之间,平均冠高率为0.54;胸径对冠幅和冠高率促进作用最大,胸径对冠形率抑制作用较小;树高对冠幅和冠高率抑制作用最小,树高对冠形率促进作用较大。因此,在中强度间伐Z2(25.48%)时,树高、胸径和冠幅等均达到最大。

In order to better understand the effects of thinning on the tree height, DBH, and crown width in middle-aged Larch gmelinii of natural forests, the dynamics of growth and decline of the stands are fully grasped to provide a theoretical basis for better forest management. The natural secondary Larch gmelinii middle-aged forests with an average age of 52 years in the Xinlin Forestry Bureau of Daxing’ an Mountains was studied in this paper, and set up 4 plots （20m X 30m） with different thinning intensities including the control plot （CK, 0%）, the low-intensity thinning plot （Zl, 16.75%）, the medium-intensity thinning plot （Z2, 25.48%）, and the high-intensity thinning plots （Z3, 34.38%）. Each wooden plot was measured for each plot and all trees in the plot were surveyed, including tree species, tree numbers, tree height, DBH, and crown width. The path analysis method was used to analyze the variation and correlation of tree-making factors under different tending intensities. The results showed that when the mid-intensity thinning was used, the crown width was mainly distributed between 1.5 and 4.0m with an average crown width of 2.5m; the crown rate was between 0.3 and 0.8, and the average crown rate was 0.54; The DBH had the largest promoting effect on the crown width and crown height, and the DBH had a smaller inhibition effect on the crown rate. The tree height had the least inhibition effect on the crown and crown height, and the tree height had a greater promoting effect on the crown rate; Therefore, the tree height, DBH, and crown width reached the maximum on the thinning Z2 （25.48%）.