Assembly Mechanism Of Community Based On Phylogeny And Functional Traits

The research of community assembly mechanism is a main problems in ecology,and the method based on the phylogeny and functions traits of species can quantify the role of habitat filtering,competitive exclusion and neutral assembly in the process of community assembly,and help people to understand the mechanism of community assembly and accurately judge the main ecological processes that drive species co-existence.In this study,seven communities in the Shiyang River basin(from the bottom to the top of the mountain)were studied,including Nitraria tangutorum shrub,Stipa breviflora herb,Reaumuria songarica shrub,Potentilla fruticosa shrub(under the forest boundary),Picea crassifolia forest,Potentilla fruticosa shrub(on the forest boundary),alpine meadow.The leaf thickness,leaf dry mass,leaf area,and specific leaf area were used for phylogenetic signal,to determine the conserved or convergent of traits.Calculate the net relative index,the nearest taxon index and the diversity of species to explore the mechanism of community assembly.The main findings are as follows:(1)Along the rise of the altitude,the community of the Shannon Weiner index and the Simpson index are showing an upward trend,and the pielou index do not show a significant trend of change.The Shannon Weiner index has a significant positive correlation with the Simpson index.(2)The analysis results based on traits show that the leaf thickness of the woody plant shows the phylogenetic signal,which is obviously influenced by the phylogenetic history.The leaf dry mass,the leaf area and the specific leaf area of the woody plant leaves do not shows the phylogenetic signal.The traits of the herb plant do not show the phylogenetic signal,and it can be considered that the traits of the Shiyang River basin show the convergence pattern.(3)The analysis results based on phylogenetic show that the community assembly mechanism does not have obvious variation trend in the community of Shiyang River basin from bottom to top.whether the overall analysis or the hierarchical analysis of the community,the community assembly mechanism supports the ecological niche hypothesis.The mechanism of shrub community assembly tends to be competitive exclusive,the forest community assembly mechanism tends to be environmental filtering,and the mechanism of herb community aeesmbly is driven by environmental filtering and competition exclusion.(4)The results of multiple linear regressions linking of species abundance and environmental factors show that the main environmental factors affecting species richness in the Shiyang River basin are the annual mean precipitation,soil water content,soil nitrogen and soil phosphorus,of which the annual mean precipitation has a greater impact on species richness.Comprehensively,the assembly of plant communities in the Shiyang River basin is a deterministic process that supports the ecological niche hypothesis.Along the altitude gradient,the mechanism of community assembly does not show the change regularity,the same type of community assembly mechanism tends to be the same.The annual mean precipitation affects the community composition of the region,the traits of the plant are the convergence pattern.The results of the phylogenetic structure show that the construction of the shrub community tends to be competitive excluded,the construction of the forest community is environmental filtering and the construction of grassland community is combined by environmental filtration and competition exclusion.