Contributors: Department of Physics; ProdInra, Archive Ouverte; Nanjing Institute of Geography and Limnology (Niglas); Chinese Academy of Sciences Beijing (CAS); Department of Atmospheric and Oceanic Sciences Madison; University of Wisconsin-Madison; MTA-SZIE Plant Ecology Research Group; Szent István University; Northern Arizona University Flagstaff; Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH); Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE); School of Geographical Science Changchun; Northeast Normal University; Institute of Climate-Smart Agriculture; Johann Heinrich von Thünen-Institut = Thünen Institute; ICOS Headoffice, Department of Physics; Department of Chemical and Biochemical Engineering (IVC-SEP); Danmarks Tekniske Universitet = Technical University of Denmark (DTU); Institute of Hydrology and Meteorology Dresden; Technische Universität Dresden = Dresden University of Technology (TU Dresden); Climate and Air PollutionGroup; Agroscope; This study was jointly supported by the National Natural Science Foundation of China (41030745, 41401221, 41271500), the Key Research Program of the Chinese Academy of Sciences (KZZD-EW-10-04), and the Natural Science Foundation of Jiangsu Province, China (BK20141058)
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.
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