基于植物多度的群落物种组成与环境关联性分析

Analysis of plant abundance-based association between community species composition and environmental properties

揭示群落物种组成与环境的关联性对于理解物种共存机制具有重要意义。传统生态种组划分不仅带有主观性,且难以定量种组–环境的关联程度。本研究以浙江天童31个处于不同生境的植物群落为研究材料,以群落实际物种组成作为研究对象,利用物种多度分别构建了各群落的最大、实际和相对环境选择性指数,并以随机模拟的群落环境关联性作为零假设,通过与实际群落相比较来揭示群落物种组成的环境关联程度;最后,利用环境选择指数(environmental dependence index)与群落生境马氏距离(Mahalanobis distance)的相关分析来确认群落物种组成与环境的关联性。结果表明:最大环境选择指数反映的是现有生境在理论上的最优群落配置组合的环境选择性,实际选择指数可反映群落物种组成对现状生境的选择性,相对环境选择指数可综合反映群落物种组成与环境间的关联性;相对环境选择指数与单独生境因子的相关性不显著,而与表征综合环境特征的Mahalanobis距离显著正相关;随生境异质性增大,群落物种组成的环境专一性更强。此结果为天童常绿阔叶林的群落物种组成与生境关联性提供了新证据,也为如何完善物种与环境之间关系的定量化研究提供了借鉴。

Revealing associations between species composition and environmental characteristics is crucial for understanding species coexistence. In past studies, traditional ecological species groups have been classified subjectively, and the associations between species groups and environment characteristics were not determined quantitatively. In this study, we evaluated environmental relationships of plant species composition among 31 plant communities within different habitats in Tiantong region, Zhejiang Province. Maximum, actual, and relative environmental dependence indices were defined respectively on the basis of plant abundance. We tested the actual association between species composition and environment using a random null hypothesis. The community type–environmental association was confirmed by Pearson correlation between relative environmental dependence index and Mahalanobis distance. The results showed that： （1） the maximum environmental dependence index is an idex of premium community type’s combination from randomization under current conditions and actual environmental dependence, which may be used to indicate preference of species composition to actual habitat conditions. The association between species composition and environmental characteristics may be denoted effectively by the relative environmental dependence index; （2） the relative environmental dependence index did not correlate with most single environmental variables, but significantly correlated with Mahalanobis distance; and （3） if habitat properties were more heterogeneous, species composition–environment association was more unique. These findings provide new evidence for relationships between plant species composition and environment characteristics in the evergreen broad-leaved forests in Tiantong region and an ameliorative reference for how to quantitatively determine species–environmental associations.