千岛湖被子植物枝叶性状分化及其与种多度的关系

摘要

种间生态位分化是物种共存的重要原因,了解种间生态位分化特征对于推测物种多样性维持机制具有重要意义.植物的种间功能性状分化在一定程度上能够反映其生态位分化,进而导致植物在群落内的适合度差异.据此,本研究针对千岛湖地区75种常见木本被子植物,分析了8个与水分输导、资源获取和利用策略相关的功能性状分化,及其与物种多度的关系.主成分分析表明,种间功能性状的分化主要发生在比叶面积、叶绿素含量以及叶气孔密度上.8个性状中有5个,即叶绿素含量、叶片厚度、叶面积、比叶面积和最大树高具有一定程度的系统发育保守性(即Blomberg`s K的p<0.05).功能性状间的相关性广泛存在,且在使用系统发育独立对比方法(phylogenetic independent contrast, PIC)控制系统发育的影响后,相关性大多仍然显著.单个性状以及所有性状的主成分1和主成分2与物种多度间均没有显著相关性.结果表明:千岛湖地区片段化次生马尾松林内木本被子植物的功能性状分化受系统发育和进化历史共同影响;且性状分化发生在主要的环境资源梯度 (即光照和水分)上;但性状对处于演替过程中的片段化森林群落内的物种多度不一定会产生重要影响.%Niche differentiation is a major determinant of species coexistence, and hence understanding how species niche differentiates is beneficial to our understanding of the mechanisms underlying species diversity maintenance.Since interspecific plant functional trait differentiation represents the niche differentiation to some extent, we have studied the differentiation of eight functional traits related to water conductance, resource acquisition and utilization in 75 common woody angiosperm species in the Thousand Island Lake Region.We find that the overall interspecific functional trait differentiation is mainly associated with interspecific differentiation in specific leaf area (SLA), chloroplast concentration (Chl) and stomata density (StoD) by principle component analysis (PCA).Five traits (i.e., chloroplast concentration (Chl), leaf thickness (LT), leaf area (LA), specific leaf area (SLA) and maximum height (MaxH) are constrained by phylogeny (i.e., p<0.05 for Blomberg`s K) to some extent.A great number of significant pairwise trait correlations are detected, and after PIC adjustment, these significant correlations mostly remaine.We also find that the single trait and the principle component 1 (PC1) and principle component 2 (PC2) values of all traits are not related to species abundance.Our results suggest that the functional trait differentiation of angiosperm species in the fragmented successional Masson pine forest of the Thousand Island Lake Region are constrained by both phylogeny and evolutionary history;And, the functional traits differentiate in major environmental resource axes (i.e., irradiance and water);But they may not relate to species abundance in the successional stage of fragmented forests.