1982–2010 Trends of Light Use Efficiency and Inherent Water Use Efficiency in African vegetation: Sensitivity to Climate and Atmospheric CO2 Concentrations

Remote Sensing

Abdoul Khadre Traore¹  Philippe Ciais¹  Nicolas Vuichard¹  Natasha MacBean¹  Cecile Dardel⁵  Benjamin Poulter²  Shilong Piao⁴  Joshua B. Fisher⁶  Nicolas Viovy¹  Martin Jung³ 

[1] Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL-CEA-CNRS-UVQS, F-91191, Gif sur Yvette, France; E-Mails:;Department of Ecology, Montana State University, P.O. Box 173460Bozeman, MT 59717-3460, USA; E-Mail:;Max Planck Institute for Biogeochemistry, 07745Jena, Germany; E-Mail:;Department of Ecology, College of Urban and Environmental Science, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China; E-Mail:;Geosciences Environnement Toulouse (GET), Observatoire Midi-Pyrénées, UMR 5563 (CNRS/UPS/IRD/CNES), 14 Avenue Edouard Belin, 31400Toulouse, France; E-Mail:;Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA; E-Mail:

关键词: inherent water use efficiency;    light use efficiency;    Africa;    trend analysis;    atmospheric CO₂ effect and climate effects on vegetation;   

DOI  :  10.3390/rs6098923

来源: mdpi

【 摘 要 】

Light and water use by vegetation at the ecosystem level, are key components for understanding the carbon and water cycles particularly in regions with high climate variability and dry climates such as Africa. The objective of this study is to examine recent trends over the last 30 years in Light Use Efficiency (LUE) and inherent Water Use Efficiency (iWUE*) for the major biomes of Africa, including their sensitivities to climate and CO₂. LUE and iWUE* trends are analyzed using a combination of NOAA-AVHRR NDVI3g and fAPAR3g, and a data-driven model of monthly evapotranspiration and Gross Primary Productivity (based on flux tower measurements and remote sensing fAPAR, yet with no flux tower data in Africa) and the ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms) process-based land surface model driven by variable CO₂ and two different gridded climate fields. The iWUE* data product increases by 10%–20% per decade during the 1982–2010 period over the northern savannas (due to positive trend of vegetation productivity) and the central African forest (due to positive trend of vapor pressure deficit). In contrast to the iWUE*, the LUE trends are not statistically significant. The process-based model simulations only show a positive linear trend in iWUE* and LUE over the central African forest. Additionally, factorial model simulations were conducted to attribute trends in iWUE and LUE to climate change and rising CO₂ concentrations. We found that the increase of atmospheric CO₂ by 52.8 ppm during the period of study explains 30%–50% of the increase in iWUE* and >90% of the LUE trend over the central African forest. The modeled iWUE* trend exhibits a high sensitivity to the climate forcing and environmental conditions, whereas the LUE trend has a smaller sensitivity to the selected climate forcing.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland