不同纬度植物群落系统发育与功能性状结构研究

研究植物群落系统发育和功能性状结构有助于了解植物多样性维持机制及物种间的亲缘关系。甘肃省地理环境复杂，显著而多变的气候梯度形成了区域植被和环境差异，丰富了栖息地类型，具有显著的纵向连通性和纬度隔离性，以甘肃省典型纬度梯度植物群落为研究对象，通过对其进行群落学调查和功能性状测定，计算净亲缘关系指数(Net relatedness index, NRI)和平均成对性状距离(Mean pairwise trait distance, PW)来分析植物群落系统发育结构和功能性状格局对不同纬度的响应。结果表明：(1) Shannon-Weiner多样性指数，物种丰富度，谱系α多样性指数表现出随纬度增加而显著降低的变化趋势(P<0.05),Pielou均匀度指数随纬度的升高没有显著的变化趋势；(2)系统发育结构在高、低纬度上趋于发散状态(NRI<0),在中纬度上又表现出聚集(NRI>0)的谱系结构，表明种间竞争作用减弱，环境过滤作用逐渐增强，随纬度继续升高相似性限制作用在物种聚集过程中占优势；而群落的功能性状结构随着纬度增加表现出与谱系结构相反的状态，因此植物群落的系统发育和功能...

Studies on phylogeny and functional traits structure of plant communities at different latitudes

The study of phylogeny and the functional trait structure of plant communities is useful for understanding the maintenance mechanism of plant diversity and the relation between species. The geographical environment of Gansu Province is complex. The remarkable and changeable climate gradient has formed regional vegetation and environmental differences, enriched habitat types, and has significant vertical connectivity and latitude isolation. Taking typical plant community of latitude gradient in Gansu Province as the research object, through community investigation and functional traits determination, the net relatedness index (NRI) and mean paired trait distance (PW) were calculated to analyze the response of plant community phylogenetic structure and functional trait pattern to different latitudes. The results showed that:(1) Shannon-Weiner diversity index, species richness, and phylogenetic alpha diversity index presented a significant decrease trend with the increase of latitude (P<0.05), while the Pielou evenness index had no significant change trend with the increase of latitude. (2) The phylogenetic structure tended to be divergent at high and low latitudes (NRI<0), and then showed a spectral structure of aggregation at mid-latitudes (NRI>0). It indicates that interspecific competition weakens, environmental filtering gradually increases, and similarity limitation prevails in the process of species aggregation as latitude continues to increase. However, the functional trait structure of the community showed the opposite of the spectral structure as latitude increased, so the phylogenetic and functional trait structures of the plant community are not consistent. (3) Plant height showed weak phylogenetic signals (P<0.05) and other traits showed no significantly phylogenetic signals, indicating that plant functional traits were greatly affected by environmental factors and had little relationship with phylogeny. In general, the maintenance mechanism of species diversity of typical latitude gradient plant community in Gansu Province was dominated by a deterministic process, which supported the ecological niche theory. Among them, environmental filtering and competitive exclusion played a dominant role in the process of species aggregation in most communities. Environmental factors such as soil moisture content, soil pH, and mean annual temperature had a significant impact on the pattern of plant traits. This study contributes to understanding of the geographic distribution patterns and potential ecological maintenance mechanisms of plant diversity in different climatic zones.