Assessing water use efficiency reactivity to meteorological, hydrological, and agricultural droughts on the Mongolian Plateau

Abstract

Water use efficiency (WUE) is an important metric for assessing regional sustainability and the carbon-water balance of ecosystems. Drought is a significant stressor affecting the carbon-water cycle. Nevertheless, the response of WUE to different types of droughts remains poorly understood. This study analyzed the variability characteristics of WUE, meteorological (SPEI), hydrological (SRI), and agricultural (SSMI) droughts. Additionally, it investigated the response of WUE to these three types of droughts over the Mongolian Plateau (1982–2021). The results indicated a non-significant decreasing trend in WUE, and a remarkable drying trend in SPEI, SRI, and SSMI. WUE was positively correlated with three drought indices, with average R (WUE, SPEI), R (WUE, SRI), and R (WUE, SSMI) at 0.060, 0.051, and 0.028, respectively; this indicated that WUE decreased as drought intensified. Regional WUE proved most sensitive to SPEI and was observed in coniferous forests, broadleaf forests, meadow steppes, typical steppes, and alpine grasslands. Sand land vegetation and desert steppes showed the highest sensitivity to SRI, whereas shrubs and croplands exhibited the highest sensitivity to SSMI. More importantly, SRI caused more severe losses in WUE than SSMI and SPEI. These findings offer valuable insights for future carbon sink management and drought risk assessment.

Keywords

• Water use efficiency
• meteorological drought
• hydrological drought
• agricultural drought
• sensitivity