China’s Greening Modulated the Reallocation of the Evapotranspiration Components during 2001–2020

Abstract

Increasing numbers of observations and research studies have detected widespread vegetation greening across China since the 1980s. The dynamics of vegetation can influence the process of terrestrial evapotranspiration (ET) and its components (vegetation transpiration (Ec), soil evaporation (Es), and intercepted precipitation evaporation (Ei)). However, it is still not clear how the ET components responded to China’s greening. This work investigated the characteristics and dynamics of ET components for different climate zones and moisture regions and the dominant ecosystems over China using PML ET products during 2001–2020. The results showed that ET increased by 9%, Ec and Ec/ET increased by 18.7% and 4.4%, respectively, contributing to more than 90% of the ET increment across China. The increment in Ec generally increased from north to south with the most obvious change of Ec/ET having occurred in the temperate zone and semi-humid regions. Es increased in arid, semi-arid and plateau climate regions but decreased in the remaining climate zones. As a result, Es only decreased by 2.7% on average, while Es/ET decreased by 5.7%. Ei increased by 26.6% across China, while Ei/ET changed slightly due to the little contribution of Ei to ET. The agricultural ecosystem presented the most obvious change of Ec and Es among the dominant ecosystems, and the most obvious change of Ei occurred in the forest ecosystem. Vegetation greening altered biophysical factors that govern heat and vapor exchange in the soil-plant-atmosphere continuum, thus modulating the reallocation of ET components.