Spatial Differences of Changes in Spring Vegetation activities across Eastern China during 1982-2006

To understand the spatial differences of changes in spring vegetation activities across eastern China during 1982-2006, we analysed the mean spatial pattern of Normalized Differences Vegetation Index in spring and spatial pattern of linear trend of changes in spring NDVI, identified the models of spring vegetation activities changes through the clustering analysis and calculated the correlations coefficients between spring NDVI and temperature and precipitation variations. It was found that vegetation activities decreased from south to north with an abrupt decrease at 34°-39° N. The transition belt was derived from natural vegetation distribution, but the south-north grads in the transition belt were enhanced by anthropogenic cropland. Across eastern China, spring vegetation activities had trends of significant increase in the North China Plain, Hulun Buir area and Dongting Lake Plain, and the North China Plain had the greatest rate of 0.03 NDVI per decade (r2 = 0.52; p 0.001); while, spring vegetation activities had trends of significant decrease in the Yangtze River Delta and Pearl River Delta, and Yangtze River Delta had the greatest rate of -0.02NDVI per decade (r2 = 0.24; p = 0.014). The vegetation activities variations across eastern China had evident spatial heterogeneities. The spatial heterogeneities were primarily featured by differences between a decreasing trend in the Yangtze River Delta and Pearl River Delta and an increasing trend in other areas. The secondary differences were the differences between persistent increasing trend during 1982-2006 in the North China Plain, Hulun Buir area and south of Yangtze River to South China and breaking increase after 1997-1998 in Northeast China, eastern part of Inner Mongolia Plateau and lower reaches of the Yangtze River. The third and lower level differences were interannual variabilities differences among the regions.