Community Assembly And Diversity Patterns Based On Functional Traits And Phylogeny In Artificial Coniferous Forests

Artificial forests are important part of the forest ecosystem and provide many ecosystem services.However,the diversity level and the formation and maintenance mechanism(community assembly)of near-natural restoration artificial forest communities relative to those of natural forest communities have always been controversial.Therefore,it is necessary to combine environmental factors to conduct a comparative study on the similarities and differences of the diversity patterns between artificial and natural forests along environmental gradients to determine the main driving factors affecting the diversity patterns.In this study,we selected 696 artificial and natural forest plots in North China based on community survey data,and analyzed the phylogenetic diversity pattern and phylogenetic structure of coniferous artificial and natural forest communities.At the same time,18 coniferous artificial plots were established on Loess Plateau of Shaanxi province,and the functional differences of community weighted average character value(CWM),functional structure and functional diversity index of coniferous artificial forests were studied on the hydrothermal gradient,so as to infer the assembly process of artificial coniferous forest communities.The results showed that annual precipitation(AP)and mean annual temperature(MAT)are important factors affecting the community assembly of the artificial and natural forest communities in North China,and the impact of AP is greater.The diversity patterns of the artificial and natural forests along the hydrothermal gradient are different,and the species and phylogenetic diversities of the natural forests are higher than that of the artificial forests.It found that there are no significant difference in the weighted mean value of functional traits in coniferous artificials forests,and the plant functional traits in artificial coniferous forests were relatively conservative.The changes of plant functional traits along annual precipitation(AP)are more significant than those along annual temperature(AMT),which may be the result of adaptation to drought.Functional diversity increases with hydrothermal gradient,that is,from the Pinus tabulaeformis communities on the southern Loess Plateau to the Larix principis communities on the southern Loess Plateau,the environmental filtering is indeed obvious.Among the 8 functional traits in this study,some of the functional traits showed converge patterrn,indicating that environmental filtering drove the community assembly process of artificial coniferous forests.However,some traits showed diverging patterns in areas with higher MAT,suggesting that similarity limitation(exclusion of competition among species)also contributed to the community assembly process of coniferous artificial forests.All in all,the above results showed that the main driving and limiting factors for the assembly of forest communities in North China are temperature and precipitation.Furthermore,due to the lack of succession processes in artificial forests,the preferential effects of introduced species led to inconsistencies in the diversity and assembly pattern between artificial and natural forests.The process of coniferous artificial forest assembly is subject to obvious environmental filtering.Combining taxonomic,phylogenetic and functional traits,the study on community assembly of coniferous artificial forests can not only systematically understand the maintenance mechanism of community diversity,but also provides a reference for returning farmland to forests and for vegetation restoration management in North China.