Spatial patterns of vegetation and soil fertility along a grazing gradient in a desert steppe in Inner Mongolia, China.

摘要

Spatial heterogeneities of vegetation and soil can strongly affect ecological processes in arid and semi-arid ecosystems. However, little is known about how those spatial patterns respond to grazing intensity in such systems. I studied how grazing intensity affect the spatial patterns of vegetation and soil nutrients at scales ranging from 0.1 to 18.7 m in a desert steppe in Inner Mongolia, China. Vegetation patches were more fragmented and homogeneous under higher grazing pressure. Heavy grazing also destroyed the spatial aggregation of plant species richness. Spatial heterogeneity of soil water and organic matter contents decreased along the gradient of increasing grazing intensity, while that of soil mineral N was first increased and then decreased along the grazing gradient. Both percent plant cover and power-law modeling could be used to indicate the risk of desertification associated with increasing grazing pressure.