Temporal variation and spatial distribution of NDVI in northeastern China.

Based on the highresolution remote sensing NDVI data during the first stage of the Natural Forest Protection Project, using the mathematical method such as statistics and correlation analysis, we calculated the temporal variation and spatial distribution of NDVI in northeastern China to analyze the effects of human activities, such as the Natural Forest Protection Project and climate change, on the vegetation of northeastern China. Results showed that the distribution of annual NDVI in the northeastern China had obvious regional differences, the key factor affecting the stability of vegetation change was human activities; the annual mean NDVI was significantly increased by the combine effects of Natural Forest Protection Project and climate change, it was dominant by the increase of forest NDVI(it was mainly caused by the increase of NDVI in forest regions); the spatial distribution of seasonal NDVI was similar to the annual NDVI in northeastern China, and seasonal change was similar to the biological characteristics and phenological changes of vegetation, the seasonal NDVI in summer was increased very significant. It shows that the Natural Forest Protection Project promotes the renewed growth of vegetation in northeastern China.