The complex drought effects associated with the regulation of water-use efficiency in a temperate water-limited basin

Abstract

Study regionYellow River basin, China. Study focusDrought, whose intensity and frequency are projected to increase under climate change, profoundly affects terrestrial carbon and water cycles. In the study, we explored the ecological response to long-term meteorological drought, with a focus on gross primary production (GPP), transpiration (Tr) and water-use efficiency (WUE) by a linear fitted model in the Yellow River basin (YRB), a temperate water-limited basin. New hydrological insightsThe onset and conclusion of a long-term meteorological drought event were 1990 and 2001, which were used to subdividing pre-drought, drought and recovery periods to reflect hydrological response stages. GPP, Tr and WUE increased between 1982–2010, which presented different trends in the three periods (e.g., WUE decreased in the YRB and increased in the Loess Plateau region (LPR) during the drought period). The sensitivity of GPP to P and Tr varied under different hydrological response stages (e.g., GPP was most sensitive to Tr during the drought period). That is, drought can profoundly alter terrestrial carbon uptake (i.e., GPP) and water loss (i.e., Tr) that effectually alters WUE, which differs in different hydro-climatic conditions. To a certain extent, the expansive revegetation has altered the water balance of the region, subsequently increasing drought risks. This study enhances our understanding of the effects of long-term drought on carbon and water cycles in water-limited ecosystems.