Assessment on water use efficiency under climate change and heterogeneous carbon dioxide in China terrestrial ecosystems

AbstractAssessing the effects of climate change on water use efficiency (WUE) is critical for policymaking and adaptation. The influences of heterogeneous distribution of atmospheric carbon dioxide (CO2) concentration on WUE have not considered in China. In this study, we used a spatial-temporal distribution of CO2 constructed from remote sensing data and ground-based observations, to quantify the heterogeneity of CO2 concentrations. Based on the initial conditions, the spatial patterns of WUE in history and future were estimated using the Integrated Biosphere Simulator (IBIS). Results showed that the geographical distributions of the averaged WUE have significant difference under the heterogeneous surface CO2 fertilization condition during 1951-2006. Partial correlation analysis indicated that the cold temperate zones are strong associated with the spatial heterogeneity of CO2, suggesting the special relationship of carbon-water cycle coupling with the interannual variations of CO2. WUE showed high negative correlations with temperature in subtropical zones and positive correlations in Tibet Plateau. The correlation between WUE and precipitation exhibits high positive in wet temperate zones, where the cropland is mainly located. Our estimates of WUE and its covariation with major climate variables can improve understanding of carbon-water cycle coupling under climate change