The climatic control of plant species richness along altitudinal gradients in different climate zones, southwest China

This article presented an analysis of plant species richness and its association with climatic factors along altitudinal gradients of five mountains in different climate zones, southwest China. The climate zones of the mountains range from tropical zone to subtropical zone. Plant diversity was weight in family, genus and species levels. According to the elevation dimensional gradient of the mountains, species richness and the value of climatic factors were calculated in every 100m band. The pattern of species richness along altitudinal gradients was not uniform and it could be divided to two types. Species richness decreased monotonically with increasing elevation for tropical mountain and showed a unimodal pattern with a bias towards high values in the lower half of the elevation gradient for subtropical mountains. There was a strong relationship between species richness and the ambient available energy. Annual potential evapotranspiration (PET, a measure of ambient or atmospheric energy) and annual actual evapotranspiration (AET, a measure of water-energy balance) were used to explain the pattern of species richness. Species richness of seed plants was more strongly correlated with AET than with PET. Rainfall was not a restrictive factor for tropical mountain and the spatial difference of rainfall resulted in different pattern of species richness.