拉萨河谷植物物种丰富度空间分布格局及其环境解释

Spatial distribution patterns and environmental interpretation of plant species richness in the Lhasa Valley,Tibet

为研究拉萨河谷植物物种丰富度的空间分布格局,按不同植被类型设置47个样地,每个样地随机设置3个样方,共141个样方。记录维管植物247种,隶属47科、134属。运用基于距离的Moran特征向量图(MEM)和方差分解,分析环境因子和空间变量对植物物种丰富度空间分布的影响;运用广义可加模型(GAM)对各环境因子与转换物种丰富度(TSR)进行回归分析,同时对各环境因子之间进行相关分析;运用除趋势对应分析(DCA)对样地和物种进行非约束排序,并将环境因子与排序轴之间进行相关分析。结果表明空间结构对拉萨河谷植物物种丰富度分布具有重要作用,而环境因子的空间格局是影响物种丰富度空间分布格局的重要因素;各环境因子与TSR的GAM拟合结果发现气候因子、经纬度和海拔对TSR存在显著的影响;DCA排序结果表明干扰可能是影响物种丰富度空间格局的未测环境因子,DCA第二轴反映了湿度梯度。干扰和湿度可能是拉萨河谷植物物种丰富度空间分布格局的主要影响因素。

Spatial distribution patterns of species richness and potential influencing factors are important aspects of species diversity research and biodiversity conservation.However,little biodiversity research has been carried out in the Lhasa valley.Based on vegetation types,47 plots with 141 quadrats were established to investigate the spatial distribution of species richness and its relationship with environmental factors.The study showed that a total of 247 species of vascular plant species,belonging to 47 Families and 134 different Genus,were recorded in this study.Climatic data for each plot was calculated using the Cokriging method.Moran＇s eigenvector maps（MEM）and variation partitioning were generated to explore the influence of spatial structures and environmental factors on the distribution of species richness,and generalized additive model analyses（GAM）were performed to examine the influence of environmental factors and vegetation cover on species richness.De-trended correspondence analysis（DCA）was utilised to detect and analyze the distribution of species richness and its relationships with environment.The results of MEM and variation partitioning indicated thatspatial structure was important to the distribution of species richness but environmental factors also played an important role in spatial structure.GAM of environmental factors and transformed species richness（TSR）suggested that distribution patterns of plant species richness are significantly related to longitude,latitude,altitude,AP（annual precipitation）,AET（actual evapotranspiration）,MAT（mean annual temperature）,PET（potential evapotranspiration）,MI（moisture index）.DCA also supported this result,indicating that these environmental factors influenced the distribution patterns of species richness.Other important factors influencing biodiversity include disturbance and humidity.