Variation In Functional Traits Of Woody Plants In Aquatic-terrestrial Ecotone,Lijiang River

The variation in plant functional traits mainly reflect not only the differences between the physiological processes of plant itself and its adaptation strategies to the external environment,but also can effectively integrate the species adaptation strategy,community assembly and ecosystem processes.Also,it can mirror the interactions between organisms,and between organisms and the environment at different levels,reveal the impact of biology and environment on the processes and functions of ecosystems.Therefore,the research on the variation pattern and correlation of plant functional traits at different scales will help us understand the relative roles of habitat filtering and niche differentiation in community assembly,as well as provides a new way to reveal the adaptation strategies of plants to the environment,species coexistence and community assembly mechanism.In addition,it can accurately reflect the changes in the processes and functions of ecosystems,which have important theoretical implications for scientifically predicting the distribution of vegetation and their response to global change.The vegetation zone in aquatic-terrestrial ecotone of Lijiang River is the unique vegetation area of the Lijiang River,has a unique ecosystem structure and service function,and it plays an extremely important role in maintaining the health of Lijiang River Basin ecosystem.However,there was few research report on the plant functional traits in aquatic-terrestrial ecotone of Lijiang River.In view of this,the main woody plants in aquatic-terrestrial ecotone of Lijiang River was taken as the research object.First,we have performed a linear mixed model and‘varcomp'function to partition the variance in four key functional traits?SLA:specific leaf area,LA:leaf area,LTH:leaf thickness,CHL:leaf chlorophyll content?from 5418 individuals of 51 species across four nested ecological scales?plot,species,individual,leaf?in riparian plant communities of Lijiang River.Secondly,the trait gradient analysis and correlation analysis method were used to explore the functional trait?leaf area,specific leaf area and wood density?variation pattern of the woody plants in different reaches?upstream,midstream and downstream?in aquatic-terre-strial ecotone of Lijiang River,and to reveal whether there are differences in the adaptation strategies of coexisting species in the community and the response mechanisms of species to changing environmental conditions.The main conclusions of this study are as follows:There are significant differences in the explanation variance of the key functional traits of main woody plants on the four nested ecological scales in the aquatic-terrestrial ecotone of Lijiang River.However,the relative contribution of all traits are similar,that was species?0.51–0.70?>individual?0.21–0.27?>leaf&error?0.09–0.20?>plot?0–0.07?.For all traits,interspecific variability?for specific leaf area,leaf area,leaf thickness and leaf chlorophyll content were 64%,70%,51%and 56%,respectively?was higher than the intraspecific variability and the plot level accounted for only a minute percentage of the total variance despite relatively high species turnover between plots.These results suggest that variation of leaf functional traits is dominated by interspecific variation but also showed a substantial amount of intraspecific trait variability.Thus,intraspecific variation of functional traits should be taken into account if we want to be better understand the assembly rules in plant communities.The lowest or even the lack of the functional traits variance at the community level provide substantial support for the idea that trait-based habitat filtering could play an important role in plant community assembly.When the plant communities were changing along the longitudinal gradient,the mean community leaf area decreases first and then increases slightly,and the mean community specific leaf area increases first and then decreases,while the mean community wood density gradually decreases.The dispersion of alpha components of the three functional traits was greater than that of beta components,it implies that plant functional trait variation within communities is greater than the variation among communities.For the species functional traits,there was no significant correlation between leaf area and specific leaf area,and between leaf area and wood density,while there was extremely significant negative correlation between specific leaf area and wood density.For the alpha component of functional traits,there was a weak correlation between?_LA and?_SLA,and there were extremely significant negative correlation and significant negative correlation between?_SLALA and?_WD and between?_LA and?_WD,respectively.For the plot average functional trait value,the correlation between leaf area and specific leaf area was weak,and the specific leaf area was extremely significantly negatively correlated with wood density,while leaf area was significantly negatively correlated with wood density.For the beta component of functional traits,?_LA and?_SLALA were not related,and there were extremely significant negative correlation and significant negative correlation between?_SLA and?_WD and between?_LA and?_WD,respectively.Results indicate that the species within and among communities adopted different strategies to adapt to changing habitats in aquatic-terrestrial ecotone of Lijiang River,Guilin,Southwest China.