Water use efficiency and its influential factor over Horqin Meadow

At ecosystem level, water use efficiency (WUE, defined as the net carbon uptake per amount of water lost from the ecosystem) reflects the coupling of carbon and water cycles. Continuous observation of carbon and water fluxes was made over Horqin Meadow with eddy covariance system in growing season of 2012. This paper calculated the water use efficiency, WUE[subCPP], defined as the ratio of gross primary productivity, GPP, to evapotranspiration, ET. Comparison of WUE in different ecosystems found that leaf area index was the dominant factor of WUE magnitude because that leaf area index was a comprehensive reflection of air temperature and precipitation, while air temperature or precipitation alone can not determine the WUE of an ecosystem.