Habitat Association Of Community Structure And Functional Diversity In Subtropical Forests

Under the background of global warming,this paper studied the habitat association of subtropical forest community structure and functional diversity,analysed the spatial heterogeneity of forest community composition and structure,and revealed the response of plant communities to environmental gradients,which plays an important role in explaining the maintenance mechanism of biodiversity and the geographical gradient pattern of plant communities,and can provide reference for biodiversity protection.In this study,two 1-hm~2subtropical evergreen broad-leaved forest community were studied in Ruyuan sampling area,Dongyuan sampling area and Dongguan sampling area,respectively.The trees(DBH≥3 cm)in 20 m×20 m square as the primary sampling unit wereinvestigated,a small sample sides(2 m×2 m)was set up at the center of each square and the four points of the diagonal to investigate the undergrowth plants,and the site environment factor data of each sample unit were measured.The functional diversity of plant communities was calculated by taking the distribution type of the genus of trees and undergrowth,and the growth of undergrowth plants as the functional indices.On this basis,the relationship between community structure and functional diversity and habitat of subtropical forest was studied by element statistical analysis and multivariate statistical analysis,and the spatial variation of species diversity and functional diversity of plant communities in regional scale and sample scale was analyzed,and the response of community composition and structure to environmental gradients was revealed.The indicator species analysis method was used to reveal the response of species level to environmental gradient,to reveal the role of geo-gradient filtration,and to predict the change of plant community composition and structure under the background of global climate warming and its response to environmental changes.The results of the paper are as follows:(1)At the regional scale,the individual number,species number,Shannon-Wiener index and Menhinick index of trees and undergrowth plants of different geographical gradients(sampling area)were statistically significant(P<0.001).There were significant statistical differences in the Berger-parker dominance index in different sampling areas(P<0.01),but there was no statistical difference in the evenness of undergrowth plants in different sampling areas(P=0.2554),and there was a critical statistically significant difference in trees evenness at different sampling intervals(P=0.0149).(2)In the sample land scale,the common species,rare species and dominant species of canopy plants and undergrowth plants of different communities in the same sampling area have some differences,but there are also a certain number of common populations among different communities.Within the same geographical area,whether it is a canopy plant or a undergrowth plant,the number of individuals,species number,Shannon-Wiener index,evenness,the Berger-parker dominance index and Menhinick index have some degree of difference under different sample scale,and its numerical value has certain fluctuation range,but it is not necessarily statistically significant.(3)In different geographical gradients(sampling area),the effects of site environmental factors on species diversity and functional diversity of canopy plants and undergrowth plants were different,and the diversity of plant communities varied with environmental factors.In addition,both canopy plant and undergrowth plant,the functional diversity index of plant community has significant correlation with the number of species,and the functional richness of canopy plants has significant correlation with the number of individual plants.The difference of functional diversity index of plant community is probably caused by the difference of plant community structure and species,which depends to a large extent on the number and composition of species.The site environment factor may indirectly affect the plant functional diversity by influencing the species composition and quantity of plant communities,and then affect the ecosystem function.(4)Canopy plants and undergrowth plant communities have different responses to environmental gradients.Detrended correspondence analysis(DCA)and nonparametric multivariate variance analysiswas to found that there were significant differences in the composition and structure of canopy plants and undergrowth plants in different geographical gradients(sampling area)(P<0.001);however,there was no significant difference in the composition and structure of canopy plants and undergrowth in different communities in the same sampling area(P>0.05),revealing the species composition and structure are similar,and the spatial heterogeneity of canopy plant is small.(5)Different species have different response strategies to environmental gradients,the indicator species analysis reflects the plant’s indication to the habitat,and the difference of the composition and quantity of the common species,rare species and total species of different geographical gradients reflects the adaptation of the species to the heterogeneous habitats,and is the result of the interaction of habitat filtration and species to resource utilization strategy.These results indicate that forest community composition and structure have different responses to different geographical gradients,it is revealed that the spatial distribution pattern of plant community composition and diversity pattern in regional scale and sample square scale,and revealed the influence of habitat heterogeneity on community composition and diversity,and can provide scientific basis for conservation and maintenance of biodiversity.