The Analysis of Human Factors on Grassland Productivity in Western Songnen Plain

West Songnen Plain is ecologically fragile area and degrading ecosystem. Over the past 50 years, interfered by the natural factors and human activities, the quality of grassland and the carrying capacity declined. It is important for the rational utilization of grassland resources and the carbon cycle study of terrestrial ecosystem by analyzing human factors on the grassland productivity. The studying sites were divided into 8 land units with relatively homogeneous natural conditions. Then identify the grassland areas interfered and those not interfered by human activities. The sum NDVI of each land unit were obtained by using satellite remote sensing data. The effects of human factors on grassland productivity were got through calculating the relative degradation index of grassland. It showed that the productivity of grassland without anthropogenic interference was much higher than that of anthropogenic interference in the growing season. The impact of human factors on grassland was smaller in west of Songnen Plain in 2002 and 2005, but bigger in 2004. There is no obvious correlativity between the climatic factors and grassland relative degradation index in west of Songnen Plain. The relative degradation index can reflect the human factors on the grassland productivity.