Evaluating the effects of future climate change and elevated CO2 on the water use
efficiency in terrestrial ecosystems of China
Qiuan Zhua, b, Hong Jianga, c, , , , Changhui Pengb, Jinxun Liud, Xiaohua Weie,
Xiuqin Fangf, Shirong Liug, Guomo Zhouc and Shuquan Yuc
a
International Institute for Earth System Science, Nanjing University, Hankou Road 22, Nanjing 210093, China
Institute of Environment Sciences, University of Quebec at Montreal, Case Postale 8888, Succursale Centre-Ville, Montreal,
QC, Canada H3C 3P8
c International Research Center of Spatial Ecology, Zhejiang Forestry University, Linan 311300, China
d Stinger Ghaffarian Technologies (SGT, Inc.), Contractor to the U.S. Geological Survey (USGS) Earth Resources Observation
and Science (EROS) Center, 47914 252nd St., Sioux Falls, SD 57198, United States 1
e Department of Earth and Environmental Sciences, University of British Columbia (Okanagan), 3333 University Way, Kelowna,
BC, Canada V1V 1V7
f State Key Laboratory of Hydrology, Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
g Institute of Forest Ecology and Environment, Chinese Academy of Forestry, Beijing 100091, China
Received 22 February 2010;
revised 26 September 2010;
accepted 28 September 2010.
Available online 23 October 2010.
b
Abstract
Water use efficiency (WUE) is an important variable used in climate change and hydrological
studies in relation to how it links ecosystem carbon cycles and hydrological cycles together.
However, obtaining reliable WUE results based on site-level flux data remains a great challenge
when scaling up to larger regional zones. Biophysical, process-based ecosystem models are
powerful tools to study WUE at large spatial and temporal scales. The Integrated BIosphere
Simulator (IBIS) was used to evaluate the effects of climate change and elevated CO2
concentrations on ecosystem-level WUE (defined as the ratio of gross primary production (GPP)
to evapotranspiration (ET)) in relation to terrestrial ecosystems in China for 2009–2099. Climate
scenario data (IPCC SRES A2 and SRES B1) generated from the Third Generation Coupled
Global Climate Model (CGCM3) was used in the simulations. Seven simulations were
implemented according to the assemblage of different elevated CO2 concentrations scenarios and
different climate change scenarios. Analysis suggests that (1) further elevated CO2
concentrations will significantly enhance the WUE over China by the end of the twenty-first
century, especially in forest areas; (2) effects of climate change on WUE will vary for different
geographical regions in China with negative effects occurring primarily in southern regions and
positive effects occurring primarily in high latitude and altitude regions (Tibetan Plateau); (3)
WUE will maintain the current levels for 2009–2099 under the constant climate scenario (i.e.
using mean climate condition of 1951–2006 and CO2 concentrations of the 2008 level); and (4)
WUE will decrease with the increase of water resource restriction (expressed as evaporation
ratio) among different ecosystems.
Keywords: Water use efficiency; WUE; Climate change; Ecosystem level; IBIS; DGVM; China