基于3S技术的绵羊牧食行为与草地环境相互作用研究

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

  • 摘要: 研究绵羊牧食的时空分布特征可为草畜管理及合理利用草地资源提供科学依据。本文以内蒙古典型荒漠化草原区的主要牲畜细毛绵羊为研究对象, 通过GPS项圈获取不同载畜率条件下绵羊的时空分布信息和遥感获取的植被数据, 利用空间分析技术和选择性指数方法, 研究绵羊牧食行为的时空分布特征及其与草地环境间的关系。研究结果表明: 绵羊行走距离夏季大于秋季, 且不同载畜率条件下行走距离呈现轻度放牧<中度放牧<重度放牧的特征。地形对绵羊牧食的影响表现为, 选择性指数平地>斜缓坡>斜坡, 不同地形选择性指数之间的差异夏季小于秋季。在上午5:30—8:30和下午16:00—17:30时间段内, 绵羊的活动区域有差异, 上午集中在样地北半部活动, 而下午在南半部即归牧地附近活动。植被盖度对绵羊行为没有显著影响, 只有在植被盖度非常低、地表裸露的区域, 绵羊才会有避食行为产生。在长期不同载畜率绵羊放牧影响下, 荒漠草原植被盖度随着载畜率的增加呈递减趋势。因此, 在放牧管理时, 可以考虑因地形和季节的不同调整饮水及收牧管理, 这可以改变绵羊的时空分布, 减少在退化草地的牧食频率。

     

    Abstract: 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 (Ei) 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 Ei of sheep was flat land > gentle slope > ramp. The difference in Ei 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.

     

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