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Title: Global patterns and climate drivers of water-use efficiency in terrestrial ecosystems deduced from satellite-based datasets and carbon cycle models

Our aim is to investigate how ecosystem water-use efficiency (WUE) varies spatially under different climate conditions, and how spatial variations in WUE differ from those of transpiration-based water-use efficiency (WUE t) and transpiration-based inherent water-use efficiency (IWUE t). LocationGlobal terrestrial ecosystems. We investigated spatial patterns of WUE using two datasets of gross primary productivity (GPP) and evapotranspiration (ET) and four biosphere model estimates of GPP and ET. Spatial relationships between WUE and climate variables were further explored through regression analyses. Global WUE estimated by two satellite-based datasets is 1.9 ± 0.1 and 1.8 ± 0.6g C m -2mm -1 lower than the simulations from four process-based models (2.0 ± 0.3g C m -2mm -1) but comparable within the uncertainty of both approaches. In both satellite-based datasets and process models, precipitation is more strongly associated with spatial gradients of WUE for temperate and tropical regions, but temperature dominates north of 50 degrees N. WUE also increases with increasing solar radiation at high latitudes. The values of WUE from datasets and process-based models are systematically higher in wet regions (with higher GPP) than in dry regions. WUE t shows a lower precipitation sensitivity than WUE, which is contrary to leaf- and plant-levelmore » observations. IWUE t, the product of WUE t and water vapour deficit, is found to be rather conservative with spatially increasing precipitation, in agreement with leaf- and plant-level measurements. In conclusion, WUE, WUE t and IWUE t produce different spatial relationships with climate variables. In dry ecosystems, water losses from evaporation from bare soil, uncorrelated with productivity, tend to make WUE lower than in wetter regions. Yet canopy conductance is intrinsically efficient in those ecosystems and maintains a higher IWUEt. This suggests that the responses of each component flux of evapotranspiration should be analysed separately when investigating regional gradients in WUE, its temporal variability and its trends.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [5] ;  [3] ;  [3] ;  [6] ;  [7] ;  [8] ;  [6] ;  [3] ;  [9] ;  [10]
  1. Peking Univ., Beijing (China). Sino-French Inst. for Earth System Science, College of Urban and Environmental Sciences
  2. Peking Univ., Beijing (China). Sino-French Inst. for Earth System Science, College of Urban and Environmental Sciences; Chinese Academy of Sciences (CAS), Beijing (China). Key Lab. of Alpine Ecology and Biodiversity, Inst. of Tibetan Plateau Research; Chinese Academy of Sciences (CAS), Beijing (China). Center for Excellence in Tibetan Plateau Earth Sciences
  3. Peking Univ., Beijing (China). Sino-French Inst. for Earth System Science, College of Urban and Environmental Sciences
  4. Lab. des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette (France)
  5. CSIRO Land and Water Flagship, Canberra, ACT (Australia)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst., Environmental Sciences Division
  7. Peking Univ., Beijing (China). Sino-French Inst. for Earth System Science, College of Urban and Environmental Sciences; Lab. des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette (France)
  8. Montana State Univ., Bozeman, MT (United States). Inst. on Ecosystems, Dept. of Ecology
  9. CSIRO Oceans and Atmosphere Flagship,Aspendale, Vic.(Australia)
  10. Peking Univ., Shenzhen (China). Shenzhen Graduate School
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 41530528; 2013CB956303
Type:
Accepted Manuscript
Journal Name:
Global Ecology and Biogeography
Additional Journal Information:
Journal Volume: 25; Journal Issue: 3; Journal ID: ISSN 1466-822X
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Climate drivers; inherent water-use efficiency; process-based model; satellite-based datasets; transpiration-based water-use efficiency; water-use efficiency
OSTI Identifier:
1348319