湖南栎类天然次生林林分空间结构对灌木物种多样性的影响

林分空间结构会显著影响其林下植被多样性,为明确其影响灌木物种多样性的关键因子,以栎类天然次生林为研究对象,利用Pearson简单相关分析、多元线性逐步回归法与典型相关分析探索乔木层空间结构与林下灌木物种多样性的相关关系,为保护林下植被多样性提供生态经营建议。以混交度、聚集指数和开敞度表达林分空间结构,以Margalef指数、Pielou指数和AuclairGoff指数作为灌木物种多样性评价指标,利用3种统计分析方法分析两者之间的相关关系,研究结果表明:(1)Pearson相关分析结果显示混交度对灌木层Pielou指数和AuclairGoff指数影响显著(P0.05),其余指数均不显著;(2)多元线性逐步回归分析结果显示林下灌木物种多样性受到多个林分空间指标的综合影响,其中Pielou指数受到混交度、聚集指数和开敞度的显著影响,AuclairGoff指数受到混交度与开敞度的显著影响;(3)典型相关分析结果显示,第一对典型相关变量通过显著性检验,典型相关系数为0.5427,林分空间结构与灌木层多样性指标两组变量在整体上相关性较强,其中混交度是影响力最大的变量。因此,欲提高栎类天然次生林下灌木物种多样性,应选择以调整树种结构为主,综合考虑林木空间分布格局的调整方案。

Effects of stand spatial structure on species diversity of shrubs in Quercus spp. natural secondary forests in Hunan Province

It is noted that forest spatial structure significantly affects the understory species diversity. In the present study, for identifying the spatial structure factors that affect understory shrub species diversity in the Quercus secondary forest, Pearson''s correlation analysis, step-wise multiple linear regression models, and canonical correlation analysis (CCA) were used to explore the relationships between spatial structure and shrub species diversity. The forest spatial structure was expressed by the mingling index, aggregation index, and opening degree index. Margalef index, Auclair & Goff index, and Pielou''s index were used to describe shrub biodiversity. Results showed that:(1) The mingling index had significant influence on the Pielou and Auclair & Goff index of the shrub layer (P < 0.05) according to the Pearson''s correlation analysis. In contrast, the Margalef index was not significant (P > 0.05). (2) Shrub species diversity was influenced by several spatial structure indices at the same time through multiple linear regression analysis. Pielou''s index was affected by the mingling index, aggregation index, and opening degree index. The Auclair & Goff index was affected by the mingling index and opening degree index. (3) Given the linear combination of spatial structure indices and understory shrub diversity indices, the canonical correlation coefficient was 0.5427. Especially, the mingling index was the most important variable affecting the shrub species diversity. Therefore, to improve the shrub species diversity of the Quercus secondary forests, it is necessary to focus on regulating the forest species structures, and following by forest spatial distributions.