Ecosystem Water Use Efficiency Response to Drought Over Southwest China

Drought is showing an increasing trend as a result of the significant variation in precipitation and temperature in China. This study investigated the impacts of drought on ecosystem water use efficiency (WUE) in southwest China. The spatiotemporal distribution of drought and ecosystem WUE were analysed through integrated approaches based on observed climate and satellite remote sensing datasets to understand the response of ecosystem WUE to drought. Also, the impacts of climatic variables on gross primary productivity (GPP), evapotranspiration (ET) and WUE have been discussed. More than 30% of the total area can be categorized as suffering moderate drought. Six drought events (autumn 2006, autumn 2009, winter 2010, summer 2011, autumn 2011 and winter 2013) were identified during the period of 2001–2016. The average monthly WUE was 2.37 gC/kgH2O, showing a decreasing trend under the combined effects of drought and other environmental factors. Autumn 2006 exhibited the highest significant positive effect of drought on WUE on more than 80% of the total area that concentrated in the forest, shrubland, savanna and agriculture ecosystems. The results of this study have implications for ecosystem management and climate policy making that could allow implementing feasible water use strategies under a warming climate.