Impacts Prediction of Climatic Change on Distribution and Production of Grassland in Inner Mongolia The Determination of Ecotone and the Characteristics of Biome on Ordos Plateau The Potential Evapotranspiration (PE) Index for Vegetation and Vegetation-Climatic Classification (III)——An Introduction of Main Methods and PEP Program Temporal and spatial distribution and movement tendency of mean center of the Holdridge life zones in China Application of Landform-based Desert Vegetation-Climate Model in Xinjiang Uygur Autonomous Region