Vegetation Index Trends for the Northern Part of China at the Beginning of the 21st Century

Moderate-resolution Imaging Spectroradiometer (MODIS)-Enhanced Vegetation Index (EVI) data reported during 2000-2009 have been analyzed to study recent trends in vegetation greenness over the northern part of China at the beginning of the 21st century. The results showed that the afforestation area was larger than the degraded area in the northern part of China during the last 10 years, and the regional total mean annual EVI increased by 5.97%. Seasonal EVI increased significantly, and trends in summer and winter were larger than those in spring and autumn. The sparsely vegetated area declined, unit area EVI increased, and vegetation activity rose during the study period. In addition, EVI changes in the northern part of China exhibited relatively large spatial heterogeneity. The Northeast China Plain, North China Plain, Loess Plateau, and Xinjiang agriculture regions experienced marked increases, and part of Northeast China and West China experienced declining trends. Such patterns are attributed primarily to regional climate changes and human activities such as ecological construction and urbanization.