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Land use change and nitrogen feedbacks constrain the trajectory of the land carbon sink
Author(s) -
Gerber Stefan,
Hedin Lars O.,
Keel Sonja G.,
Pacala Stephen W.,
Shevliakova Elena
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50957
Subject(s) - sink (geography) , carbon sink , environmental science , carbon cycle , land use, land use change and forestry , nitrogen , greenhouse gas , land use , nitrogen cycle , atmospheric sciences , carbon sequestration , global change , climate change , deforestation (computer science) , carbon dioxide in earth's atmosphere , ecology , ecosystem , geography , geology , chemistry , cartography , organic chemistry , computer science , biology , programming language
Our understanding of Earth's carbon climate system depends critically upon interactions between rising atmospheric CO 2 , changing land use, and nitrogen limitation on vegetation growth. Using a global land model, we show how these factors interact locally to generate the global land carbon sink over the past 200 years. Nitrogen constraints were alleviated by N 2 fixation in the tropics and by atmospheric nitrogen deposition in extratropical regions. Nonlinear interactions between land use change and land carbon and nitrogen cycling originated from three major mechanisms: (i) a sink foregone that would have occurred without land use conversion; (ii) an accelerated response of secondary vegetation to CO 2 and nitrogen, and (iii) a compounded clearance loss from deforestation. Over time, these nonlinear effects have become increasingly important and reduce the present‐day net carbon sink by ~40% or 0.4 PgC yr −1 .