河北省森林草原区草本植物物种多样性和功能多样性

理解物种多样性和功能多样性之间的关系以及分析它们对环境变化的响应,有利于揭示生物多样性的影响因素。本研究以塞罕坝地区不同植被类型(草地、灌木林和天然次生林)的草本群落为研究对象,分析了物种多样性(物种丰富度、Shannon-Wiener多样性和Pielou均匀度)和功能多样性测度指标(功能丰富度、功能均匀度和功能离散度)之间的相互关系,并采用相似性分析检验(ANOSIM)和冗余度(RDA)分析等方法研究了它们随植被类型和环境因子的变化规律。结果表明,草地中草本植物物种丰富度、Shannon-Wiener多样性指数显著高于灌木林和天然次生林中的草本群落(P<0.05),而功能丰富度指数在草地中最低(P<0.05),功能均匀度和功能离散度在灌木林中最低(P<0.05),Pielou均匀度指数在不同植被类型间差异不显著(P>0.05);功能丰富度与物种丰富度、Shannon-Wiener多样性指数显著负相关(P<0.01),功能离散度与物种均匀度显著正相关(P<0.01),而功能均匀度与所有物种多样性指数均不相关(P>0.05);影响物种多样性的主要因子有土壤含水量、土壤有机质、土壤pH值、土壤全氮含量和坡向,影响功能多样性的主要因子有土壤有机质、土层深度、土壤含水量和海拔。物种多样性和功能多样性分布主要受土壤因子的影响,分别占到总解释变异的29.1%和29.8%。本研究结果表明研究区草本植物物种多样性和功能多样性变化相对独立,物种多样性可能主要是由资源可利用程度决定,而功能多样性可能是生态位分化即环境筛选和物种间相互作用共同决定。

Herbaceous plant species diversity and functional diversity in the forest-steppe zone of Hebei,China

Understanding the relationships between environmental/soil factors and plant species diversity and functional diversity is useful for identifying which factors have the strongest effects on plant communities.In this study,we first studied the relationships between different components of herbaceous plant species diversity (species richness,Shannon-Wiener diversity,and Pielou evenness) and functional diversity indices (functional richness,functional evenness,and functional dispersion).Then,we used methods of analysis of similarities (ANOSIM) and redundancy analysis to explore their variation across three vegetation types (grassland,shrub,and natural secondary forest) and different environmental gradients.The results showed that species richness and Shannon-Wiener diversity were significantly higher in grassland than in shrub and natural secondary forest (P＜0.05);however,the lowest functional richness was in grassland (P＜0.05) and the lowest functional evenness and functional dispersion were in shrub forests (P＜0.05).There was no significant difference in Pielou evenness among the three vegetation types (P＞0.05).Functional richness was negatively related to species richness and Shannon-Wiener diversity (P＜0.01).Functional dispersion was significantly positively correlated with species evenness (P＜0.01),whereas functional evenness had a non-significant correlation with all species diversity indices (P＞0.05).The main factors affecting species diversity were soil water content,soil organic matter,soil pH,soil total nitrogen content,and aspect.The main factors correlated with functional diversity were soil organic matter,soil depth,soil water content,and altitude.Consequently,soil factors were the vital determinants of plant species diversity and functional diversity in the study area,and accounted for 29.1％ and 29.8％ of the total variance explained by environmental factors,respectively.The results showed that herbaceous plant species diversity and functional diversity varied independently in the study area.Species diversity was mainly determined by resource availability,whereas functional diversity was mainly related to niche differentiation (the effects of both environmental filters and species interactions).