How is water-use efficiency of terrestrial ecosystems distributed and changing on Earth?

Abstract

A better understanding of ecosystem water-use efficiency (WUE) will help us improve ecosystem management for mitigation as well as adaption to global hydrological change. Here, long-term flux tower observations of productivity and evapotranspiration allow us to detect a consistent latitudinal trend in WUE, rising from the subtropics to the northern high-latitudes. The trend peaks at approximately 51°N, and then declines toward higher latitudes. These ground-based observations are consistent with global-scale estimates of WUE. Global analysis of WUE reveals existence of strong regional variations that correspond to global climate patterns. The latitudinal trends of global WUE for Earth's major plant functional types reveal two peaks in the Northern Hemisphere not detected by ground-based measurements. One peak is located at 20° ~ 30°N and the other extends a little farther north than 51°N. Finally, long-term spatiotemporal trend analysis using satellite-based remote sensing data reveals that land-cover and land-use change in recent years has led to a decline in global WUE. Our study provides a new framework for global research on the interactions between carbon and water cycles as well as responses to natural and human impacts.

Characterizing ecosystem water-use efficiency of croplands with eddy covariance measurements and MODIS products

“…Currently, NASA TERRA and AQUA MODIS-based estimates of GPP and ET have been developed and improved greatly during the past decade which can also be obtained to quantify large-scale WUE (Lu and Zhuang, 2010;Tang et al, 2014). Zhao et al (2005) rectified the GPP products by improving the data processing methods and modifying parameters in the algorithm used, which generated the improved Collection 5 MOD17 estimates.…”

“…By combining these fluxes with satellite-based remote sensing, it has become possible to upscale the spatiotemporal variability of land-surface exchanges at regional to global scales (Zhao et al, 2005;Jung et al, 2010;Tang et al, 2012). Although Tang et al (2014) using MODIS products on annual time scale, the consistencies with tower-based WUE at short time scales remain unclear. Meanwhile, it is important to understand how management practices affect the agriculture.…”

Numerical Evaluation of JULES Surface Tiling Scheme with High-Resolution Atmospheric Forcing and Land Cover Data

“…Field studies have also reported on the mixture effects caused by BL and NL PFTs on both the SWC and productivity (Falge et al 2002;Pretzsch et al 2015;Tang et al 2014). However, the assumption of complete soil water mixing can result in erroneous flux estimation (Hartmann 2016;Rihani et al 2010;Wagener and Gupta 2005).…”

Bamboo Forest Water Use Efficiency in the Yangtze River Delta Region, China

“…Carbon and water cycles are closely related in the terrestrial ecosystem because the exchange of carbon dioxide and water vapor between the biosphere and atmosphere are both controlled by stomata (Beer et al 2009). Water use efficiency (WUE), the ratio of gross primary productivity (GPP) to evapotranspiration (ET), can be used to quantify this coupling relationship (Yu et al 2004;Tang et al 2014;Wang et al 2015;Zhu et al 2015). A better understanding of WUE will provide an alternative approach for carbon budget assessment (Beer et al 2007(Beer et al , 2010.…”