A new study on agricultural land use calls into question conclusions made by previous studies that recent land-use changes have caused the United States to take up more carbon than it emits.
The conclusions from the study arose after the authors reconstructed the U.S. land use history data and used it to model how farmland expansion and contraction influence how much carbon is stored in the soil and plants, said Chaoqun Lu, an assistant professor of ecology, evolution and organismal biology at Iowa State University and author of the study, published in the scientific journal Global Change Biology.
“There’s large uncertainty with land conversion and to what it extent it affected carbon,” Lu said. Pep Canadell, the executive director of the Global Carbon Project and one of the coauthors of the study, said the analysis suggests that the land carbon sink in the Unites States may have been overestimated owing to the use of a commonly used global land use database that overestimates recent cropland abandonment and forest recovery.
“Land use and land cover changes, globally and in many countries, particularly in tropical ones, result in large net CO2 emissions, but in the U.S. there is more recovery than loss resulting in a net carbons sink. However, we show that net sink seems to be smaller than estimated,” Canadell said.
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Image via Hongli Feng, Iowa State University
