Spatial heterogeneity and diversity analysis of macrovegetation in the Xilingol region, Inner Mongolia, China, using the beta distribution

摘要

The extensive natural grassland areas of the Xilingol region provide the most nutritive livestock forage in Inner Mongolia, China. We used the beta distribution to examine the characteristics of macrovegetation diversity and spatial variation by selecting four representative 100-cm~2 regions (actual area = 22,500 km~2) from a vegetation map of Xilingol: a dry western region, a southern region with mixed dry, sandy, and humid land, a semiarid central region, and a semiarid eastern region. We divided each region into 100 1 × 1-cm cells and measured the cover area of each vegetation type in each cell, using a point-grid film. The dry western region was the least variable in annual overland water flow distribution, as well as soil type and land use, resulting in the simplest vegetation composition and lowest spatial heterogeneity. In the southern region, overland water flow and soil type varied greatly, resulting in various land-use types, very complex vegetation composition, and very high spatial heterogeneity. In the central and eastern regions, the number of macrovegetation types was intermediate, whereas the spatial heterogeneity of vegetation was relatively high. Human activities in these two regions have disturbed the grassland vegetation continuously over the past several centuries, and these high levels of anthropogenic stress of varying intensity have resulted in high spatial heterogeneity values.