Richness of Seed Plants in Relation with Topography in Hunan Province

To explore relationship between species richness and topography at a regional scale, topographical features, patterns of taxa (family, genus and species) richness and species density along elevational gradients, and relationships between degree of topographical variation, expressed as coefficient of variation(CV) of elevation, and species richness and species density in Hunan Province were studied by using provincial flora list and DEM (Digital Elevation Model) data. The results indicate that: (1) With an increase of elevation, taxa richness and species density increased first and then decreased, showing a unimodal pattern along an elevational gradient; and (2) with increasing CV of altitude, species richness and species density increased first and then decreased, namely, higher species richness and species density occurred at habitats with a moderate CV value.