浙江遂昌马尾松林物种和谱系β多样性驱动因子分析

Analysis of species and phylogenetic β diversity drivers in the Masson pine forests in Suichang, Zhejiang Province

关键词:  马尾松林, 扩散限制, β多样性, 谱系结构, 物种组成

Key words:  Masson pine forest, dispersal limitation, beta diversity, phylogenetic structure, species composition

摘要:

生境过滤和扩散限制是影响森林群落间物种组成差异(β多样性)的主要生态过程。为了探究生境过滤和扩散限制对亚热带马尾松(Pinus massoniana)群落物种和谱系β多样性的相对贡献,该文以浙江省遂昌县37个马尾松林样地为研究对象,结合物种和谱系β多样性分析,探讨了影响群落间物种组成差异主要生态机制; 通过计算群落内物种β多样性指数(Bray-Curtis指数)和谱系β多样性指数(Dnn指数和Dpw指数),分析土壤、地形等生境因子和地理距离与物种和谱系β多样性之间的相关性,并通过方差分解分析生境因子和地理距离对物种和谱系β多样性的相对作用大小; 此外,还进行了不同径级和生长型的上述相关性分析和方差分解。结果表明:(1)Bray-Curtis指数与土壤、地形因子和地理距离均显著正相关,Dnn指数仅与地理距离显著正相关,Dpw指数与土壤因子和地理距离均显著正相关。(2)环境因子对Bray-Curtis指数和Dpw指数的解释度均高于地理距离的解释度。(3)从物种多样性角度来说,生境因子对不同生长阶段Bray-Curtis指数的解释度均高于地理距离的解释度; 从谱系多样性角度来说,地理距离对幼树阶段的Dnn指数和Dpw指数的解释度更高,生境因子则对成树阶段的Dpw指数的解释度更高。由此可以推论,生境过滤是驱动该地区马尾松林物种和谱系β多样性的主要生态机制,扩散限制仅在幼树阶段对马尾松林谱系β多样性起主导作用。

Abstract:

Habitat filtering and dispersal limitation are the main ecological processes affecting species composition variation(β diversity)in forest communities, but their relative importance in subtropical Masson pine(Pinus massoniana)forests remains unclear. Jointly analysis of how phylogenetic and species β diversity varies with habitat factors and geographic distance is critical to understand the roles played by historical and current ecological processes in shaping the regional biodiversity. In this study, 37 Masson pine forest plots in Suichang County, Zhejiang Province were selected to analyze the species and phylogenetic β diversities, and the main ecological mechanisms driving the differences of species composition among communities were explored. Species β diversity index(Bray-Curtis)and phylogenetic β diversity index(the mean phylogenetic dissimilarity, Dnn; the mean nearest taxon distance, Dpw)were calculated, and their correlation with habitat factors including soil and topography, as well as geographical distance were analyzed. The relative importance of habitat factors and geographical distance on species and phylogenetic β diversity was analyzed by variance partitioning. In addition, two life stages(divided by diameter class)and growth form were for the same analyses. The results were as follows:(1)Bray-Curtis index significantly correlated with soil factors, topographic factors and geographical distance. Dnn correlated with geographical distance only. Dpw correlated with soil factors and geographical distance.(2)The explanatory degree of habitat factors to Bray-Curtis and Dpw was higher than that of geographical distance.(3)For species diversity, habitat factors could better explain Bray-Curtis of both life stages than geographical distance. For phylogenetic diversity, geographical distance could better explain Dnn and Dpw of seedling stage, while habitat factors were more likely to explain Dpw of adult stage. To conclude, The results show that habitat filtering is the main ecological mechanism driving species and phylogenetic β diversity of Masson pine forests in this region. Dispersal limitation plays a dominant role in the β diversity of Masson pine forests only at the sapling stage. The most important finding of this research is that the main mechanism drives species and phylogenetic β diversity in Masson pine forests is different, which highlights the necessity of joint analysis of species and phylogenetic β diversity. This research also suggests that the main ecological mechanism drives β diversity may change as plants shift across different growth stages.