Pattern of species richness along an altitudinal gradient on Gaoligong Mountains,Southwest China
高黎贡山种子植物物种丰富度沿海拔梯度的变化

Patterns of species richness along altitudinal gradients have become a focus of ecological research. We explored the patterns of seed plants richness along an altitudinal gradient on Gaoligong Mountains, Southwest China. Information on seed plants and their distribution ranges was collected from Flora of Gaoligong Mountains, and the DEM (Digital Elevation Model) was derived from a topographical map of this region. Using these datasets, altitudinal patterns of richness and species density of all seed plant species and plants of three different life forms (trees, shrubs and herbaceous plants), as well as their relationship with topographic parameters were studied. The results are summarized as follows: (1) the species richness increased rapidly first and then decreased with increasing elevation, peaking at the altitudes of between 1500 m and 2000 m; (2) similar to the altitudinal pattern of species richness, species, genus and family densities (number of taxa per unit area) also showed a humped pattern along the altitudinal gradient. Species density reached a maximum between 1500 m and 2000 m, with an average of 1653 m, while genus and family densities peaked between 900-1500 m, with an average of 1089 m,and (3) energy and moisture represented by elevation, as well as hard boundaries of species distribution were possible factors determining the patterns of species richness and density.