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Edited by Susan E. Trumbore, Max Planck Institute for Biogeochemistry, Jena, Germany, and approved October 9, 2012 (received for review July 4, 2012)
Abstract
Carbon exchange associated with accelerated erosion following land cover change is an important component of the global C cycle. In current assessments, however, this component is not accounted for. Here, we integrate the effects of accelerated C erosion across point, hillslope, and catchment scale for the 780-km2 Dijle River catchment over the period 4000 B.C. to A.D. 2000 to demonstrate that accelerated erosion results in a net C sink. We found this long-term C sink to be equivalent to 43% of the eroded C and to have offset 39% (17–66%) of the C emissions due to anthropogenic land cover change since the advent of agriculture. Nevertheless, the erosion-induced C sink strength is limited by a significant loss of buried C in terrestrial depositional stores, which lagged the burial. The time lag between burial and subsequent loss at this study site implies that the C buried in eroded terrestrial deposits during the agricultural expansion of the last 150 y cannot be assumed to be inert to further destabilization, and indeed might become a significant C source. Our analysis exemplifies that accounting for the non–steady-state C dynamics in geomorphic active systems is pertinent to understanding both past and future anthropogenic global change.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: kristof.vanoost{at}uclouvain.be.
↵2Present address: Swiss Federal Institute of Technology Zürich, Department of Environmental Systems Science, Institute of Agricultural Sciences, Sustainable Agroecosystems Group, Universitätstrasse 2, 8092 Zürich, Switzerland.
Author contributions: K.V.O. and G.V. designed research; K.V.O., G.V., S.D., B.N., F.W., and N.B. performed research; K.V.O., G.V., S.D., B.N., and J.S. analyzed data; and K.V.O., G.V., and J.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1211162109/-/DCSupplemental.
Soil erosion and C cycling
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