Spatiotemporal variations and driving factors of China's ecosystem water use efficiency. (April 2023)

• Record Type: Journal Article
• Authors: Ji, Yongyue; Zeng, Sidong; Tang, QingQing; Yan, Lingyun; Wu, Shengjun; Fan, Yuanchao; Chen, Jilong
• Is Part Of: Ecological indicators. Volume 148(2023)
• Publication Date: 2023-04
• Subjects: Ecosystem water use efficiency -- Climate change -- Vegetation factors -- Drought index -- China; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2023.110077
• Languages: English
• ISSNs: 1470-160X

Abstract

Graphical abstract: Highlights: WUEe showed a significantly increasing trend, especially in humid areas. LAI and VPD contributed mostly to WUEe increase. TEM contributed mostly to WUEe decrease. The main contributors to WUEe varied noticeably in different regions of China. Abstract: Ecosystem water use efficiency (WUEe) is a key metric of the coupled carbon and water cycles. Understanding WUEe variations along the climate gradient (arid to humid) and across different vegetation ecosystems is crucial for assessing the impacts of climate variability on these ecosystems. Based on the Penman-Monteith-Leuning version 2 (PML-V2) dataset from a coupled diagnostic biophysical model, this study investigated the spatiotemporal variations and driving factors of WUEe under different aridity conditions and across vegetation types in China from 2001 to 2020. The results showed that the annual mean WUEe was 1.36 ± 0.07 g C kg −1 H2 O in China, and humid regions had higher WUEe than other arid regions except for the extremely arid regions (the top level of aridity classification). Annual WUEe showed an increasing trend of 0.084 g C kg −1 H2 O/10a in China, which mainly occurred in humid areas. The forest ecosystem had the highest WUEe (2.48 g C kg −1 H2 O), followed by shrubland (2.11 g C kg −1 H2 O) and cropland (1.99 g C kg −1 H2 O) ecosystems. Leaf Area Index (LAI) and vapor pressure deficit (VPD) contributed the most to increases in WUEe, which accounted for areal proportions of 63.82% and 77.36% of China, and average relative contributions of 31.80% and 14.73%, respectively. In contrast, air temperature (TEM) contributed the most to WUEe decreases, with an areal proportion of 61.73% and an average relative contribution of 12.42%. Normalized Difference Vegetation Index (NDVI), precipitation (PRE) and downward short-wave radiation (SSRD) showed little differences in the proportions of land area where they either promoted and suppressed WUEe and their respective relative contributions were 16.99%, 14.32% and 8.61%.