Jinghe river，originated from the Liupan Mountain in Shannxi Province, is one of the secondary tributaries of the Yellow River. For the local residents of this basin, stockbreeding is one of the main economic income resource. Along with the economic development in Northwest China, overstocking became more and more severe in the basin, and came to the most crucial cause for grassland degradation and environmental deterioration. To the livestock carrying capacity of Jinghe River basin, what the present condition is and how to reach to a reasonable condition is the main purpose of this paper.
According to relationship among precipitation-vegetation-livestock numbers, in this study, the authors have collected the even monthly precipitation of 16 meteorological base stations and 200 rainfall stations and the even annual county-leveled livestock number data in this basin from 19712000, in addition to the vegetation classification data and the DEM(100m×100m) data of the basin.
Using the DEM model, the spacial distribution of the annual precipitation of the basin was interpolated with the DEM data in this paper, and intersected with the vegetation classification data; the spatial distribution of grassland NPP were made based on the Thorthwaite model in which the model parameter was estimated. Through the relationship between annual precipitation and estimated grassland NPP, livestock carrying capacity of the grassland in the basin was evaluated employing the method proposed by Oesterheld. And then, we figured out spatial and temporal pattern of the stocking rate index (SRI), radio of the actual livestock numbers and estimated stock carrying capacity of the grassland considered with climatic factors in the level of county. And the index denoted the livestock pressure.
The results showed as following: The grassland livestock carrying capacity exhibited a decreasing tendency as the fall-down of the precipitation in the basin. But the livestock pressure showed a contrary tendency. To the SRI based on the whole land areas, only five counties were less than 1, such as Huanxian, Wuqi, Dingbian, Yanchi, and Wuzhong. However, based on the grassland areas, except the relative developed cities such as Xifeng, Xianyang, and Xingping, the SRI of most other counties all exceeded 1, especially Huanxian, and Wuqi, in the north of the basin with a developing economic condition showed a dangerous condition. At the same time, the northern part of the basin transported most sediments to the river，and even to the whole Loess Plateau. The results could propose appropriate plan for the return from the farmland to grassland project in Jinghe River basin. To the planning project in the basin, we should strengthen the ecological education in those areas with a higher SRI value. At the end, the comparison of SRI showed that (data) based on grassland areas could give a more scientific explanation than the one based on whole areas.