Analysis of sheep grazing behavior and interaction with grassland environment in desert steppes using 3S

The study of the spatial and temporal distribution of grazing behavior of sheep can lay the scientific basis for livestock management and rational use of grassland resources. In this paper, the spatial-temporal distribution of fine-wool sheep were determined by attaching GPS collars to the sheep in different vegetation zones under different stocking rates. While the vegetation data were obtained by using satellite data of ALOS in 2010 and Landsat in 2002 and 2010, GIS-based spatial analysis and Ivlev’s electivity index (E_i) of terrain and vegetation coverage of sheep were used to determine the relationship between the temporal and spatial distribution of sheep and the environment. The results showed that sheep walked longer distances for search of feed in summer than in autumn. The distance covered by sheep for search of feed increased with increasing stocking rate. The order of the walking distance of sheep in different stocking rate zones was lightly grazed zones < moderately grazed zones < heavily grazed zones. Terrain was the main environment factor affecting sheep grazing behavior. In the experiment area, though the sheep normally grazed even in slopes with the max gradient (5°~15°), they preferred low gradient terrain. The order of terrain E_i of sheep was flat land > gentle slope > ramp. The difference in E_i of different terrains was smaller in summer than in autumn. Sheep active areas in the morning was different from that in the afternoon. Between 5:308:30 am, sheep were active in northern areas far away from ranch gate, where sheep drunk water. Then from 16:00 to 17:30 pm, sheep were active in southern area near ranch gate. This was related with grazing management — drinking water before and after grazing. Although vegetation coverage had no significant effect on grazing behavior of sheep, sheep avoided grazing in very low vegetation coverage zones with exposed soil surface. Vegetation coverage in desert steppe decreased with increasing stocking rate. Therefore livestock management should take into account different terrains and seasons for different water and grazing management strategies. This can change the spatial and temporal distribution of sheep and reduce the grazing frequency of degraded grasslands.