The Trend of NDVI during the Past 30 Years in Linzhi Area,Tibet Autonomous Region

Based on the significant correlations between Global Inventory Modeling and Mapping Studies(GIMMS) and SPOT-Normalized Difference Vegetation Index(NDVI) across different vegetation types in Linzhi Area,nearly 30-year NDVI data of main vegetation types were interpolated.The results showed that,driven by the increasing temperature in spring,the growing seasons of all vegetation types began earlier and the NDVI increased significantly in the past 30 years.Following the ascending of temperature,the NDVI of alpine shrub-grasslands and meadows increased in summer/autumn,but the evergreen vegetations demonstrated no clear trend in autumn/winter,when the NDVI values arrived at their maximum.In general,during the past 30 years,the air temperature increased and the vegetation showed the trend of getting better in the study area.