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Regional atmospheric CO 2 inversion reveals seasonal and geographic differences in Amazon net biome exchange
Author(s) -
Alden Caroline B.,
Miller John B.,
Gatti Luciana V.,
Gloor Manuel M.,
Guan Kaiyu,
Michalak Anna M.,
LaanLuijkx Ingrid T.,
Touma Danielle,
Andrews Arlyn,
Basso Luana S.,
Correia Caio S. C.,
Domingues Lucas G.,
Joiner Joanna,
Krol Maarten C.,
Lyapustin Alexei I.,
Peters Wouter,
Shiga Yoichi P.,
Thoning Kirk,
Velde Ivar R.,
Leeuwen Thijs T.,
Yadav Vineet,
Diffenbaugh Noah S.
Publication year - 2016
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13305
Subject(s) - biosphere , biome , environmental science , amazon rainforest , carbon cycle , primary production , atmospheric sciences , climatology , climate change , rainforest , ecosystem , ecology , geology , biology
Abstract Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate–carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO 2 with the atmosphere ( NBE ), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub‐Basin Amazon NBE estimates have relied heavily on process‐based biosphere models, despite lack of model agreement with plot‐scale observations. We present a new analysis of airborne measurements that reveals monthly, regional‐scale (~1–8 × 10 6 km 2 ) NBE variations. We develop a regional atmospheric CO 2 inversion that provides the first analysis of geographic and temporal variability in Amazon biosphere–atmosphere carbon exchange and that is minimally influenced by biosphere model‐based first guesses of seasonal and annual mean fluxes. We find little evidence for a clear seasonal cycle in Amazon NBE but do find NBE sensitivity to aberrations from long‐term mean climate. In particular, we observe increased NBE (more carbon emitted to the atmosphere) associated with heat and drought in 2010, and correlations between wet season NBE and precipitation (negative correlation) and temperature (positive correlation). In the eastern Amazon, pulses of increased NBE persisted through 2011, suggesting legacy effects of 2010 heat and drought. We also identify regional differences in postdrought NBE that appear related to long‐term water availability. We examine satellite proxies and find evidence for higher gross primary productivity ( GPP ) during a pulse of increased carbon uptake in 2011, and lower GPP during a period of increased NBE in the 2010 dry season drought, but links between GPP and NBE changes are not conclusive. These results provide novel evidence of NBE sensitivity to short‐term temperature and moisture extremes in the Amazon, where monthly and sub‐Basin estimates have not been previously available.