间伐后环境的改变对植物多样性的影响

以河北省围场县境内华北落叶松人工林为研究对象,通过对其间伐林分和未间伐林分林下灌草的调查以及林下光照条件、土壤理化性质的测定,分析其测定指标的相关关系对林下灌草生长的影响。结果表明,间伐后2年,Shannon多样性指数的提高与林冠覆盖度与土壤毛管空隙度存在极显著相关性。林冠覆盖度与土壤总孔隙度、毛管孔隙度及土壤容重存在显著相关性(P<0.05)。而总孔隙度与毛管孔隙度及土壤容重存在极显著相关性(P<0.01),与土壤非毛管孔隙度则存在显著相关(P<0.05)。针对主成分分析而言,光照及其土壤孔隙度与土壤的营养元素共同影响着林下草本的多样性,但是根据之前对各项指标的方差分析中发现,土壤中的营养元素含量之间并不存在显著性差异,因此,对林下草本多样性短期影响的主要因素为光照(林冠覆盖度、林冠均匀度)和水分(土壤毛管含量)。

Effects of environment change on plant diversity after thinning

The research on the plantation of Larixprincipis-rupprechtii at Weichang County of Hebei Province was conducted through determination of the shrub and grass, understory light conditions and soil properties, and analysis of correlation of the indicators on the growth of the shrub and grass at thinned and not thinned stands. The results showed that Shannon-Wiener index increase has the extremely remarkable correlation with the canopy coverage and soil capillary porosity. Canopy coverage degree, soil total porosity, capillary porosity and soil bulk density were significantly correlated （P〈0.05）. The total porosity, capillary porosity and bulk density of the soil has the extremely remarkable correlation （P〈0.01）, The total soil porosity and soil non-capillary porosity is significantly related（P〈0. 05）. According to principal component analysis, the light, soil porosity and soil nutrient elements affect the understory diversity together, but according to the prior analysis of variance of the indicators, the content of soil nutrient elements shows insignificant differences. Therefore, it can be concluded that the main factors of short-term effects on the understory diversity are supposed to be light （canopy coverage degree, canopy uniformity）, water （soil water con- tent）.