Asynchronous changes in precipitation and soil water content decelerate vegetation greening on the Qinghai-Tibetan Plateau

Climate warming and precipitation generally enhance greening on the Qinghai-Tibetan Plateau (QTP). However, recent studies suggested that the greening trend is decelerating, while its underlying driving mechanisms remain unclear. We speculate that this may be related to an asynchrony between precipitation and soil water content in certain regions, but this is poorly understood. To fill this gap, we studied vegetation greening on the QTP using time series satellite-derived AVHRR NDVI (normalized difference vegetation index) data of climate and soil water content for the past 39 years. NDVI increased over the whole period; however, it displayed a downward trend after the year 2000 compared with the previous 19 years. Asynchronous changes in precipitation and soil water content decelerated vegetation greening. Non-woody species responded stronger to asynchrony than woody species, with meadows being most affected and forests the least. We concluded that with global warming, soil water content may decrease in areas on the Qinghai-Tibetan Plateau, and that vegetation greening may decelerate in the future. • Vegetation greening does not increase consistently with warming and wetting in the Qinghai-Tibetan Plateau. • Vegetation greening was limited by precipitation and soil water content asynchrony. • Woody species were less affected by asynchrony than non-woody species. • Greening deceleration hidden in overall vegetation greening.