Dynamic Response of Terrestrial Hydrological Cycles and Plant Water Stress to Climate Change in China

Rising atmospheric CO2 concentration CO2 and climate change are expected to have a major effect on terrestrial ecosystem hydrological cycles and plant water stress in the coming decades. The present study investigates the potential responses of terrestrial ecosystem hydrological cycles and plant water stress across China to elevated CO2 and climate change in the twentieth and twenty-first centuries using the calibrated and validated Lund-Potsdam-Jena dynamic global vegetation model (LPJ-DGVM) and eight climate change scenarios. The spatiotemporal change patterns of estimated evapotranspiration (ET), soil moisture, runoff, and plant water stress due to climate change and elevated CO2 are plotted singly and in combination. Positive future trends in ET, soil moisture, and runoff-although differing greatly among regions-are projected. Resultant plant water stress over China's terrestrial ecosystem generally could be eased substantially through the twenty-first century under the climate scenarios driven by emission scenarios that consider economic concerns. By contrast, under the climate scenarios driven by emission scenarios that consider environmental concerns, plant water stress could be eased until 2060, then begin to fluctuate until 2100. The net impact of physiological and structural vegetation responses to elevated CO2 could result in an increasing trend in runoff in southern and northeastern China, and a decreasing trend in runoff in northern and northwestern China in the twentieth century. It is projected to reduce ET by 1.5 x 10(9) to 6.5 x 10(9) m(3) yr(-1) on average, and increase runoff by 1.0 x 10(9) to 5.4 x 10(9) m(3) yr(-1) during 2001-2100 across China's terrestrial ecosystems, although the spatial change pattern could be quite diverse. These findings, in partial contradiction to previous results, present an improved understanding of transient responses of China's terrestrial ecosystem hydrological cycles and plant water stress to climate change and elevated CO2 in the twentieth and twenty-first centuries.