| The invasion of alien species has caused harm to biodiversity,ecosystem function and human welfare,particularly in mountain ecosystems,which are unique and serve as the cradle and refuge of biodiversity.Due to climate change and intensification of human activities,alien species are increasingly invading high elevations.To better understand this phenomenon,it is important to study the elevational diversity pattern and trait variation of native and invasive plants.We conducted our study in the Mountain Tianmu National Nature Reserve in Zhejiang Province,a rich and diverse area that has been impacted by human activity and is located in the economically developed region in the east of China.We established 39 herbaceous plots along an elevational gradient of 300-1500 m to conduct vegetation surveys and collect plant leaf traits and environmental data,including microclimate,soil characteristics,topography,and canopy cover.In this thesis,we analyzed the elevational pattern of diversity and trait variation of native and invasive plants,as well as the factors that influence them.We also compared and studied the intraspecific trait variation patterns of two typically invasive plants in this region Solidago canadensis and Erigeron canadensis.Our main research findings are as follows:(1)The species richness and phylogenetic diversity of invasive plants significantly decreased along the elevational gradient,while we did not observe a significant trend for native plants.The functional diversity of both native and invasive plants decreased along the elevational gradient.Microenvironmental factors such as canopy cover,slope and soil nutrients were identified as the main factors that influence diversity patterns of both native and invasive plants.The phylogenetic and functional trait community structure of invasive plant species showed a tendency to overdispersion at low elevations and clustering at high elevations,but overall showed a trend towards clustering.While we did not observe a significant change in native plant community structure.Canopy cover and soil nutrient were identified as the main factors that affect community structure.(2)The functional traits of both native and invasive plants showed multiple variation patterns with elevation,including decreasing,increasing,and U-shaped patterns.However,native plant traits showed greater variation across the elevational gradient than invasive plant traits.Canopy cover,soil silt content,p H,and soil nutrient were identified as the main driving factors that affect the elevational variation of native plant traits.For invasive plant traits,canopy cover,plot vegetation cover,soil silt content,p H,soil nutrient,and soil temperature were identified as the main driving factors.(3)The elevational gradient variation of intraspecific traits differed between the invasive plants S.canadensis and E.canadensis,with E.canadensis showing greater overall variation.For S.canadensis,the main explanatory factors for the intraspecific trait variation were plot vegetation cover,soil nutrients,soil silt content,and p H.For E.canadensis,the main explanatory factors for the intraspecific trait variation were canopy cover,plot vegetation coverage,soil nutrients,soil silt content,and p H.In conclusion,this research illustrated the elevational gradient pattern of diversity and trait variation in both native and invasive plants,as well as the elevational gradient variation patterns of intraspecific traits in invasive plants S.canadensis and E.canadensis and its influencing factors.The study has emphasized the significant effects of microenvironmental and light conditions,as well as vegetation factors,on the elevational pattern of plant diversity and trait variation.It provides a scientific basis for understanding plant invasion mechanisms and biodiversity conservation in mountain areas. |
