Weakening temperature control on the interannual variations of spring carbon uptake across northern lands
Piao, Shilong (Zhongguo ke xue yuan. Institute of Tibetan Plateau Research)
Wang, Tao (Zhongguo ke xue yuan. Institute of Tibetan Plateau Research)
Liu, Zhuou (Zhongguo ke xue yuan. Institute of Tibetan Plateau Research)
Peng, Shushi (Zhongguo ke xue yuan. Institute of Tibetan Plateau Research)
Ciais, Philippe (Laboratoire des Sciences du Climat et de l'Environnement)
Huang, Mengtian (Sino-French Institute for Earth System Science)
Ahlstrom, Anders (Stanford University. School of Earth, Energy and Environmental Sciences)
Burkhart, John F. (Universitetet i Oslo. Department of Geosciences)
Chevallier, Frédéric (Laboratoire des Sciences du Climat et de l'Environnement)
Janssens, Ivan (University of Antwerp (Bèlgica))
Jeong, Su-Jong (South University of Science and Technology of China. School of Environmental Science and Engineering)
Lin, Xin (Laboratoire des Sciences du Climat et de l'Environnement)
Mao, Jiafu (Oak Ridge National Laboratory. Climate Change Science Institute and Environmental Sciences Division)
Miller, John (National Oceanic and Atmospheric Administration Earth Systems Research Laboratory)
Mohammat, Anwar (Zhongguo ke xue yuan. Xinjiang Institute of Ecology and Geography)
Myneni, Ranga B. (Boston University. Department of Earth and Environment)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Shi, Xiaoying (Oak Ridge National Laboratory. Climate Change Science Institute and Environmental Sciences Division)
Stohl, Andreas (Norwegian Institute for Air Research)
Yao, Yitong (Sino-French Institute for Earth System Science)
Zhu, Zaichun (Sino-French Institute for Earth System Science)

Data:	2017
Resum:	Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems1, 2, 3. Here we use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. We use two indicators: the spring zero-crossing date of atmospheric CO2 (SZC) and the magnitude of CO2 drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model4 coupled to a terrestrial ecosystem model5 suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. Our results thus challenge the 'warmer spring-bigger sink' mechanism.
Ajuts:	European Commission 610028
Nota:	Imbalance-P paper contact with Josep Peñuelas: j.penuelas@uab.cat
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Biogeochemistry ; Ecological modelling
Publicat a:	Nature climate change, Vol. 7 (2017) , p. 359-363, ISSN 1758-6798

DOI: 10.1038/nclimate3277

Post-print 26 p, 865.0 KB

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