Community Assembly Patterns Based On Hydraulic Traits In Two Different Water Availability Quercus Wutaishanica Forests

The process of species colonization and the assemblage of plant communities at a regional scale has been the topic of ecology study.Trait-based approaches have made progress in understanding the driving factors that underlie the community assembly process.However,the assembly process of plant community based on hydraulic traits has not been studied in detail.Here,this study aimed to explore determine key traits that may reflect community assembly patterns of the same forests type but within different water availability.Natural Quercus wutaishanica forests were choosed as a suitable study system to test the role of economic and hydraulic traits on understanding the assembly processes between the Loess Plateau and Qinling mountains of China with different water availability.Total 75 plots were established separately in two sites,and 12 functional traits（7 hydraulic traits and,5 economic traits）of 167species were focused.Community-weighted mean traits and functional diversity indices were compared between the two sites,and canonical component analysis was performed to infer whether the changes of community traits and their relationships are driven by intraspecific variation or species turnover.Evidence for likely community assembly processes was tested using the null model to determine whether functional structure among 7 hydraulic traits and 5economic traits was clustered,random,or divergent between two sites.We found that Quercus wutaishanica forests in the Loess Plateau（LP）and Qinling mountains（QL）showed entirely different hydraulic and economic traits values,which was primarily driven by species turnover.Functional traits(LMA,LDMC,P_max,SD,VD,SL)comprised a key group that are important for understanding the community assembly process in different water availability and community functional structure for most hydraulic traits（except for SD）showed an increasing clustering pattern from in LP than that in QL.Our results suggest a strong environment filtering in hydraulic traits that drives community assembly in forest with low water availability;Emphasize the critical role of multi-dimensional traits selecting like hydraulic traits in community assembly;Revealing the relationship of hydraulic and economic traits at the community level along the water availability gradient at temperate regions such as the Loess Plateau and the Qinling mountains.These results are helpful to provide a new perspective for comprehensively understanding and explaining the mechanisms of biodiversity maintenance and species coexistence in Quercus wutaishanica community.Besides,these results have significant consequences for predicting plant species’response to changes in the hydraulic traits due to drought caused by human disturbance or climate change.