Leaf Functional Trait Variations Of Desert Plants Respond To Different Soil Moisture And Salinity In The Ebinur Lake Area

The response mechanism and adaptation strategies of plants to the environment have been the core of ecological research.Leaves are the largest and most sensitive organ for plants responding to the environmental changes.They are the main place for photosynthesis and material production.It is an important basis for understanding plant environmental adaptation mechanisms and predicting community structure changes.However,there were currently few relevant studies in desert areas.This experiment was conducted in Ebinur Lake National Wetland Nature Reserve in Xinjiang.We established three transects perpendicular to the Aqikesu River channel.The plant composition,leaf functional traits and soil factors in each plot were investgated.At species and community levels,principal component analysis(PCA),variance decomposition,one-way ANOVA,redundancy analysis(RDA),correlation analysis and linear mixed-effect models were used to explore the inter-and intraspecific variations in leaf functional trait under high and low water-salt environments.Then we quantified the relative contribution of inter-and intraspecific variations to community trait variation,and comprehensively discuss the driving mechanism of interspecific and intraspecific variation of desert plant leaf traits from the perspective of soil property and species' own attributes.The results were as below:(1)According to PCA method combining soil water with salt contents,30 soil sampling points could be divided into high(n=11)and low moisture and salinity habitats(n=19).The soil water and salt contents in high and low moisture and salinity environments were 9.51%,13.33g/kg and 4.76%,5.58g/kg,respectively.There was a significant difference between the soil water and salt contents of the two habitats(P<0.01).Average soil SOC,total N,and total P contents in salt stress habitats were higher than those in drought stress habitats,and the soil total N and total P contents differed between groups(P <0.01);(2)At the species level,except for the leaf P content in the high water and salt content environment,the other leaf functional traits differered among eight species(P <0.05).In general,the interspecific trait variations were greater than the intraspecific variations.Among them,the interspecific variation of leaf N: P was the largest,and the C variation was the smallest.The interspecific variations of leaf P,C: P,N:P and leaf thickness in low moisture and salinity environment were significantly higher than that in high moisture and salinity environment,while there was no significant difference in intraspecific variation.In high water-salt content environment,the intraspecific variation of herbaceous plants was generally higher,while the intraspecific variation of shrubs in low water-salt content environment was higher than that of trees and herbs;(3)At the community level,the leaf functional traits respond differently to two water-salt content environments.Leaf C,N,C: P,N: P contents in the high water-salt environment were higher than those in the low.However,leaf P,C: N,leaf thickness,and chlorophyll content were lower than the low water-salt environment.Besides,there were significant differences in leaf C,N,C: N and leaf thickness between two environments;(4)The community level trait variations in two habitats were mainly driven by intraspecific variation.However,interspecific variation only dominated leaf N variation in high moisture and salinity environment.The contributions of intraspecific variation increased with the decrease of soil water and salt content(except N: P),and the contributions of interspecific variation were also higher in the drought stress environment(except leaf thickness).There were significant differences in intraspecific variation of N and interspecific variation of leaf C and leaf thickness between two habitats.Besides,positive covariations between inter-and intraspecific variations occurred in the high moisture and salinity environment and negative covariations occurred in low water-salt environment;(5)At the species level,soil moisture,SOC,and total N contents had effects on the interspecific trait variation,but the explanations were generally low.At the community level,soil water,salt and SOC contents affected the interspecific variation and soil salinity,water and nutrient content were closely related to intraspecific variation in the high water and salt content environment.In the low water-salt environment,soil SOC,total N,total P had strong correlations with interspecific trait variation and soil moisture and nutrient content were closely related to intraspecific variation.In addition,compared with the species level,we also found that the plant's own attributes(species richness here)had a significant impact on the inter-and intraspecific variation in the community level.