Remote sensing monitoring on dynamic status of grassland productivity and animal loading balance in Northern China

The study region includes 312 counties of 11 provinces and autonomous regions in Northern China. The methodology is mainly the combination of remote sensing, geographic information system and spatial database technology with field investigation of the grassland. The main conclusions are as follows. (1) the monitoring indicates that grass production of the major grasslands in Northern China is decreasing in recent decades, at a rate of 10-40%. (2) Compared with the grass production, over-grazing is a common phenomenon in grazing region. Among the 153 counties in the grazing region, over 50% is with over-loading of herd. Similar phenomenon is also observed in semi-grazing region where over 80% of the 159 counties have various degrees of herd over-loading. (3) Over-loading is severe in semi-grazing area than in grazing area. Comparison has been done to the loading balance between grazing and semi-grazing regions by the end of 1990´s. In grazing region. there were 12 counties (banners) with extreme over-loading, accounting for 7.79% of total county numbers in this region. In semi-grazing region, there were 82 counties showing sign of overloading, accounting for 51.5% of total county numbers in this region. The proportion of extreme over-loading grazing region to the total regions occupies 4.82% in grazing region. This proportion is 34.85% in semi-grazing. Obviously, the severity of extreme overloading in semi-grazing highly surpasses that in grazing region. Understanding this animal loading difference among various types of region may help to facilitate proper administration of grazing for sustainable development of the grassland.