Spatial Heterogeneity of Vegetation and Its Causes in Southern Yunnan Province

The research on relationships among terrain, climate and vegetation is a main topic of ecological geography. Taking the moderate resolution imaging spectroradiometer based enhanced vegetation index (MODIS-EVI) and Parameter elevation Regressions on Independent Slopes Model (PRISM) data as the indices, we analyzed the spatial heterogeneity of vegetation in southern Yunnan province of China and its causes by ArcGIS9.3 and SPSS. The results show that the regional difference of EVI is remarkbale with apparent topographical effect. The effect of longitudinal mountains on the reallocating of heat and moistrure factors is the main cause of EVI regional difference. Especially, the effect of Ailao and Wuliang mountains on rainfall intercept in rainy season and cold wave block in dry season is even more obvious. By counting statistics data of points at altitudes between 1400 and 1500 m in a cross-section, the annual precipitations in five sub-areas are 1244.67, 1081.44, 1111.41, 1033, and 807.11mm respectively in rainy seasons, while the annual mean minimum temperatures are 7.93, 7.46, 7.28, 8.44, and 9.16°C respectively in dry season.