Vegetation dynamics and their responses to climate factors in the Qinghai-Tibet plateau: insights from the terrestrial ecosystems

This study examined the structural changes of vegetation ecosystems, multi-scale cyclical variations of normalized difference vegetation index (NDVI), as well as their responses to climate factors in the QTP during 2001-2018. Results showed the annual increment of NDVI in forest ecosystem was the largest, followed by grassland, and the increment of NDVI in desert ecosystem was the smallest. Vegetation activities showed a steady upward trend in forest, grassland and desert ecosystems, a fluctuating upward trend in the wetland ecosystem, and a slow downward trend in the farmland ecosystem. The intra-annual cycles of vegetation activities in these ecosystems were between 28 and 42 days, and only the forest ecosystem had a clear inter-annual cycle of 2.1 years. The responses of NDVI to precipitation and temperature in grassland, wetland, and farmland ecosystems all had a lag time of 16 days, while those in desert and forest ecosystems were weak.