Climatic control of plant species richness along elevation gradients in the Longitudinal Range-Gorge Region

Abstract

To explore the elevation gradients in species richness in the Longitudinal Range-Gorge Region (LRGR) and evaluate how climatic variables and area may explain the patterns of species richness, 5 mountains are selected. According to the elevation dimensional gradients of the mountains, species richness, the values of area and climatic variables are calculated in each 100 m zone. The relationships between seed plant species richness and climatic variables and area along elevation gradients are analyzed. The results have shown that: (1) Elevational patterns of species richness are not uniform and can be divided in to two types. The values of species richness are higher in the lowlands and then decrease monotonically with increasing elevation in the tropical mountains. Species richness has unimodal patterns with a bias towards high values in the lower half of the elevation gradients in the subtropical mountains. (2) The patterns of species density are the same as that in species richness along elevation gradients. (3) Among the climate variables, actual evapotranspiration (AET) as a measurement of water-energy balance has strong relationships with species richness. The decline in species richness is due to the higher temperature and less precipitation in the lowlands of the subtropical mountains.