Abstract:

The mechanisms underlying elevational patterns of species diversity remain one of the most important questions in biogeography and macroecology. We studied the effects of area, mid-domain effect (MDE) and contemporary climate on elevational patterns in species richness and species density for native seed plants in Xishuangbanna, for which we used plant monograph, digital elevation model, and large-scale climatic data. We found that: (1) area, MDE, and climate explained 81.9%, 17.5%, and 60.0-69.3% of the unimodal pattern in species richness; (2) when species richness calculated using the species-area hypothesis showed a decreasing pattern along the elevational gradient. Moreover, richness was not correlated to MDE and the explanatory power of climate decreased to 32.6-40.6%; (3) species richness calculated using equal-area elevational bands showed a hump-shaped pattern but was not correlated to MDE; the explanatory power of climate was 81.6-89.9%. Our results provides comprehensive insights into the theoretical mechanisms underlying elevational patterns in species diversity and also provide practical guidance for the biodiversity conservation in Xishuangbanna.

Key words: species richness, species density, species-area relationship, mid-domain effect, elevation