Evaluating effects of national key eco-environment conservation projects by vegetation change on the Loess Plateau of China

In order to combat the developing trend of ecoenvironment degradation, a serious of national key projects of ecological environment construction have been carried out in the Loess Plateau since 1998. The construction measures include handing farmland back forestland or grass land, protecting native forestry from deforestation, planting sheltering forest, and taking conservation measures of soil and water. To evaluate the effects of the projects on eco-environments, SPOT VGT data were used to derive the vegetation changes indices in the region over the period of 1999-2004. As NDVI is widely used parameter to effectively assess and monitor the vegetation vigor and changes, the trend in NDVI change were simulate with the years; to monitor vegetation cover changes. On,I regional scale, the vegetation is strongly sensitive to climate variations, so the rainfall surfaces derived from climatic data with the same resolution as NDVI also were used to discriminate the project affected vegetation variation from the influence of climate change by simulating spatial correlation between annual rainfall and NDVI changes.