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Carbon cycling under 300 years of land use change: Importance of the secondary vegetation sink
Author(s) -
Shevliakova Elena,
Pacala Stephen W.,
Malyshev Sergey,
Hurtt George C.,
Milly P. C. D.,
Caspersen John P.,
Sentman Lori T.,
Fisk Justin P.,
Wirth Christian,
Crevoisier Cyril
Publication year - 2009
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2007gb003176
Subject(s) - environmental science , sink (geography) , carbon sink , carbon cycle , primary production , land use, land use change and forestry , vegetation (pathology) , land use , atmospheric sciences , deforestation (computer science) , ecosystem , hydrology (agriculture) , precipitation , pasture , ecology , forestry , geography , meteorology , geology , computer science , medicine , cartography , geotechnical engineering , pathology , biology , programming language
We have developed a dynamic land model (LM3V) able to simulate ecosystem dynamics and exchanges of water, energy, and CO 2 between land and atmosphere. LM3V is specifically designed to address the consequences of land use and land management changes including cropland and pasture dynamics, shifting cultivation, logging, fire, and resulting patterns of secondary regrowth. Here we analyze the behavior of LM3V, forced with the output from the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model AM2, observed precipitation data, and four historic scenarios of land use change for 1700–2000. Our analysis suggests a net terrestrial carbon source due to land use activities from 1.1 to 1.3 GtC/a during the 1990s, where the range is due to the difference in the historic cropland distribution. This magnitude is substantially smaller than previous estimates from other models, largely due to our estimates of a secondary vegetation sink of 0.35 to 0.6 GtC/a in the 1990s and decelerating agricultural land clearing since the 1960s. For the 1990s, our estimates for the pastures' carbon flux vary from a source of 0.37 to a sink of 0.15 GtC/a, and for the croplands our model shows a carbon source of 0.6 to 0.9 GtC/a. Our process‐based model suggests a smaller net deforestation source than earlier bookkeeping models because it accounts for decelerated net conversion of primary forest to agriculture and for stronger secondary vegetation regrowth in tropical regions. The overall uncertainty is likely to be higher than the range reported here because of uncertainty in the biomass recovery under changing ambient conditions, including atmospheric CO 2 concentration, nutrients availability, and climate.