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

Abstract

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.