Regional Degraded Trend through Assessing of Steppe NPP on Remotely-Sensed Images in China

The ecological crisis derived from NPP decline in grassland region not only endangers the regional stockbreeding development, but also aggravates the contradiction between ecological environment and social economy development. This paper developed a methodology to estimate the degradation process of grass-lands at large scale based on the assessment of regional NPP on TM/ETM images. The improved CASA Model was used to simulate regional NPP in the short grassland (typical steppe) region on account of NPP frequently considered to indicate the degrees of grassland degradation in China. The results displayed that the average regional NPP gradually decreased from 1991 to 2000, 2005 due to impacts of climatic change and the grazing manners. Image analysis showed that the ecosystem had been in an incompetent environment over the past decades. Continued degradation will be intense unless grazing activities are changed.