中国温带荒漠植物群落生态特异性格局及其影响因素

The ecological uniqueness of plant communities and their determinants acrossthe temperate deserts of China

局域取样单元对beta多样性的贡献可用于测度每个局域群落物种组成的生态特异性(ecological uniqueness)。温带荒漠生态系统广泛分布于全球干旱和极端干旱区域,极易受到气候变化和人类活动的影响。然而目前温带荒漠植物群落生态特异性大尺度地理分布格局及其形成机制的系统研究还很缺乏,制约着我们对荒漠植物群落多样性维持机制的认知。本文在温带灌木、矮半乔木及草原化灌木荒漠等6个中国温带荒漠区的主要地带性植被类型中设置了948个样方,通过开展系统的野外调查采样和室内分析,以及量化每个取样单元对beta多样性的贡献,并结合土壤和气候变量等环境数据,探讨了中国荒漠植物群落生态特异性大尺度地理分布格局及其影响因素。结果表明:(1)温带荒漠植物群落生态特异性存在显著的经度、纬度和海拔分布格局,随着经度增加显著降低,但随着纬度或海拔的升高呈现出先下降后增加的变化趋势;(2)土壤、气候、群落特征(植物物种丰富度和群落盖度)对植物群落生态特异性都有着显著的单独影响,植物群落生态特异性随着物种丰富度增加呈先下降后上升的变化趋势;经度、土壤、气候和植物群落特征共同解释了温带荒漠植物群落生态特异性33.5%的空间变异,其中气候因子有着更强的单独解释率。上述结果说明环境过滤和中性过程以及其他未知过程共同调控了温带荒漠植物群落的生态特异性大尺度分布格局的形成,且气候和土壤因素的过滤作用有着重要影响。

Aims:Overall beta diversity can be partitioned into the relative contributions of its individual sampling units,which represent comparative indicators of the ecological uniqueness of each local community within the sampling units.Temperate desert ecosystems are widely distributed primarily in arid and extremely arid regions and are especially sensitive to influence by climate change and human activities.However,distribution patterns of unique desert plant ecologies and their determining factors have yet to be studied extensively,which has hindered our understanding of mechanism for maintaining desert biodiversity in these regions.Therefore,this study aims to explore the ecological uniqueness of plant communities and identify their determinants in temperate deserts of China.Methods:In this study,we selected 948 plots(10 m×10 m)at 316 sites in the temperate deserts of China.We computed beta diversity as the total variation within the community data and used a plotting-based approach to determine if ecological uniqueness is related to the local environmental conditions and/or community characteristics.Stepwise multiple regressions and variation partitioning analyses were performed to further infer the mechanisms driving the geographic patterns of desert plant ecological uniqueness.Results:The ecological uniqueness of desert plants exhibited significant variations based on longitudinal,latitudinal,and elevational patterns.Plant ecological uniqueness significantly decreased with longitude but displayed a U-shaped relationship with latitude and elevation.In addition,we observed a U-shaped relationship between plant ecological uniqueness and plant species richness.The soil,climate,and community characteristics(i.e.,plant species richness and community coverage)significantly influenced the ecological uniqueness of plant communities.Longitude,soil,climate,and community characteristics taken together explained 33.5%of the total variation in the ecological uniqueness of plant communities.In addition,climatic factors demonstrated a more significant influence on the ecological uniqueness of the plant communities when compared to the soil and community characteristics.Conclusions:Taken together,we propose that the ecological uniqueness of desert plant communities is regulated by environment filtering,neutral processes,and other unknown processes,where the soil and climate are primary drivers of uniqueness.