关帝山华北落叶松林林分因子及其对林下草本多样性的影响

The Stand Factors of Larix principis-rupprechtii forest in Guandi Mountain and Their Effects on the Understory Herbaceous Diversity

以关帝山华北落叶松林为研究对象,采用典型抽样方法,调查其林分密度、平均树高、平均胸径、平均冠幅、平均林龄和平均枝下高6个林分因子和林下草本层物种多样性指数,探究林分因子对林下草本物种多样性指数和林分结构的影响。结果显示:(1)除林分密度、平均冠幅和平均胸径外,其他林分因子都有显著性差异;林分密度的变异程度最高,平均林龄变异程度最低。(2)4种草本多样性指数在各样地之间均存在显著性差异,其中物种丰富度指数变异性最大,Simpson指数变异程度最低。(3)物种丰富度指数在6个林分因子的影响下有较明显波动,整体上呈减小的趋势,而其余3种指数无明显变化。(4)由相关性和线性拟合分析得出林分密度主要影响林下草本层物种丰富度指数和Shannon指数,平均树高和平均枝下高主要影响林下草本层物种丰富度指数,各林分因子对Simpson指数和Pielou指数均无显著影响。(5)林分密度为150株/hm^(2),平均树高为17.34 m,平均胸径为30.53 cm,平均枝下高为2.95 m,平均冠幅为5.68 m,平均年龄为53年时,华北落叶松林林下草本层物种多样性达到最大。结果表明:适当对华北落叶松进行间伐和修枝,栽植其他树种和灌木,可以提高华北落叶松人工林林下草本层物种多样性。

This study took the L.principis-rupprechtii as the research object,and adopted the method of field survey,six forest stand factors including stand density,average tree height,average diameter at breast height,average crown width,average forest age and average undershoot height,and the species diversity index of the understory herb layer were analyzed to understand the impact of stand factors on understory herb species diversity index and stand structure.The results show that except stand density,average crown width and average breast diameter,the other stand factors have significant differences;the variation degree of stand density is the highest,and the variation degree of average stand age is the lowest.There are significant differences between the four herbaceous diversity indexes in each plot.Among them,the species richness index has the largest variability and the Simpson index has the lowest variability.The species richness index fluctuates obviously under the influence of the six stand factors,and shows a decreasing trend as a whole,while the other three indexes have no obvious changes.From correlation and linear fitting analysis,the forest density mainly affects the understory herb layer species richness index and Shannon index,the average tree height and average undershoot height mainly affect the understory herb layer species richness index,and each stand factor has no significant effect on the Simpson index and Pielou index.When the stand density is 150 trees/hm^(2),the average tree height is 17.34 m,the average diameter at breast height is 30.53 cm,the average undershoot height is 2.95m,the average crown width is 5.68m,and the average age is 53 years,the species diversity of the herb layer of L.principis-rupprechtii reaches the maximum.The thinning and pruning of L.principis-rupprechtii,and the planting of other tree species and shrubs,could appropriately increase the species diversity of the understory herbaceous layer of the L.principis-rupprechtii plantation.