Spatial-temporal Changes Of Forest Community Functional Traits And Biodiversity In Northeast China

The spatiotemporally patterns of species diversity and plant functional traits have always been the core of ecological research.Previous studies on plant functional traits were mainly based on small area scale.However,there was no significant difference in climate factors,soil factors and other environmental factors at small scales,so it is difficult to summarize the overall situation of functional traits and quantify the impact of environmental factors on plant functional traits at large scales.In the past,the researches always ignored the multiple effects of time and space on the relationship between biodiversity and functional traits.In this paper,the forest of different latitudes in northeast China was taken as the research object,and the characteristics of functional traits and biodiversity with latitudes under community level and species level were discussed,and the differences between the characteristics of functional traits of forest in northeast China and the average level of China and the world were compared.At the same time,using the method of space instead of time commonly used in ecology,taking the forest of different ages of broad-leaved Korean pine forest of Changbai Mountain system as the research object,the changes of functional traits and biodiversity with time?succession stage?were discussed.We used the methods of variance decomposition,enhanced regression tree and multiple regression to systematically evaluate the role of climate factors,soil factors and terrain factors in the temporal and spatial changes of functional traits and biodiversity.The results show that,?1?There are significant differences in some functional characters?such as specific leaf area,nutrient element content of leaves?between Northeast China and China and the world average,but there is no regional difference in dry matter content of leaves and N_mass/P_mass.The specific leaf area and dry matter content of leaves showed significant differences in life style,while the nutrient element content of leaves did not show significant differences in life style.Most of the functional characters of coniferous tree species and broad-leaved tree species show some differences,reflecting different life history strategies.There is a significant trade-off relationship between the content of nutrient elements in leaves,and the correlation between the content of nutrient elements in leaves and the functional properties related to photosynthesis is more significant.?2?Although there are significant differences in latitude and succession progress of leaf functional traits at community level and species level,the degree of explanation of latitude and succession stage for leaf functional traits at community level is higher than that at species level.?3?Different biodiversity indexes?such as species diversity,functional diversity and pedigree diversity?all show the same latitude and succession change law,and the forest pedigree structure shows the characteristics of aggregation and distribution,indicating that habitat filtration dominates community construction on the latitude scale.The results show that in the early stage of succession,habitat filtration dominates community construction,while in the middle and late stage of succession,habitat filtration and competitive exclusion jointly maintain community construction.?4?Cluster analysis of species composition in different latitudes and different forest types shows that the similarity of species composition in the same forest type is higher,indicating that the community construction mechanism is similar in the same forest type.The forest species composition of broad-leaved Korean pine forest,which is the top community in different succession stages of Changbai Mountain system,is also quite different,indicating that the community construction mechanism is also different in different succession stages.?5?Under the influence of the same environmental factors,the change trend of functional traits of different living species is the same.It shows that in a specific community,different living plants are affected by the same environmental sieve.The ability of climate factors to shape the latitudinal?succession?change pattern of functional traits is stronger than that of soil factors.Habitat filtration significantly affected the latitudinal pattern of functional traits.Through a large number of field experimental data,this study quantifies the overall characteristics of plant functional traits and biodiversity in northeast China,explores the temporal and spatial variation rules of the two and the controlled environmental factors,reveals the mechanism of community construction on the temporal and spatial scale,and provides a theoretical basis for forest management and biodiversity protection in northeast China.