The Community Assembly And Influencing Factors Of Phylogeny And Traits Of Coniferous And Broad-leaved Mixed Forest In Jiaohe Jilin Province

The community assembly mechanism is a hot issue in ecological research.The ecological process affecting community assembly through functional trait structure and phylogenetic structure has become an important means to study community assembly.This paper takes 21 hectares of temperate coniferous and broad-leaved mixed forestin Jiaohe,Jilin Province.The subjects collected and measured six different functional traits of 34 woody plants in the plot,through the mean pairwise trait distance index(PW)and the mean nearest neighbor trait distance index.(NN)to calculate Trait structure;calculates the phylogenetic structure of the community by net relatedness index(NRI)and nearest taxon index(NTI),comprehensively analyzes the distribution pattern of traits and phylogenetic in the community,and uses regression with topographic factors.The method of analysis explores the response of functional trait distribution patterns of community to local habitat changes,and aims to explore the main ecological processes affecting community assembly in the Jiaohe.The specific research results are as follows:1.The six functional traits measured in this study are all lineage conserved,indicating that the functional traits of the study area are affected by the evolutionary history.2.At the scale of 20m×20m,the results based on the mean pairwise trait distance index(PW)show that except for the leaf area,the distribution pattern of all traits is more than the discrete area;based on the mean nearest neighbor index(NN)the results showed that except for leaf area and maximum tree height,the distribution pattern of other traits was more than the discrete area;the results based on net relatedness index(NRI)and nearest taxon index(NTI)It shows that the phylogenetic structure of the community is aggregated.This result indicates that the non-random process plays an important role in community assembly,and the environmental filtration effect is the most significant.3.Based on the results of regression analysis,the distribution pattern of functional traits in forest communities is significantly affected by the elevation,slope and aspect of the plot,while the unevenness of the plots has no significant effect on the distribution pattern of functional traits,and the altitude is high.It is the most significant environmental factor in the region,and it dominates the pattern change of the coniferous and broad-leaved community in the temperate zone of the Jiaohe in Jilin Province.4.The community structure of different traits is different,and there will be changes in different spatial scales.The leaf nitrogen,leaf carbon,carbon-nitrogen ratio and specific leaf area trait structure increase with spatial scale,and the aggregation distribution is significant;leaf area with space The increase of scale showed a discrete distribution trend,indicating that the ecological processes affecting the distribution of traits were different.Among them,environmental filtration had the most significant effect on maintaining the stable distribution of traits.5.The distribution structure and functional trait structure of the study area are different under different algorithms.The results calculated by NN(NTI)show that the functional trait structure or phylogenetic structure of the community shows a significant aggregation distribution in the plot,but by PW(NRI)showed that the community structure was aggregated,but the degree of aggregation was not significant.In view of the pedigree conservation of all traits,two calculation methods were combined.The study concluded that the community structure calculated by NN(NTI)is stable and convergent.consistent,so it is best to use the nearest neighbor distance(NN/NTI)to calculate the community structure in the experiment.Determining the mechanisms affecting the construction of plant communities and the driving factors affecting plant diversity and community function changes play an important role in the management and restoration of plant resources in the region,and help to understand the corresponding types of communities under the global change pattern.And based on this,targeted protection or response measures are essential to predicting the future distribution and dynamics of biodiversity.