Reconciling the paradox of soil organic carbon erosion by water

[摘要] The acceleration of erosion, transport, and burial of soil organic carbon(OC) by water in response to agricultural expansion represents a significantperturbation of the terrestrial C cycle. Recent model advances now enableimproved representation of the relationships between sedimentary processesand OC cycling, and this has led to substantially revised assessments ofchanges in land OC as a result of land cover and climate change. However,surprisingly a consensus on both the direction and magnitude of theerosion-induced land–atmosphere OC exchange is still lacking. Here, we showthat the apparent soil OC erosion paradox, i.e., whether agriculturalerosion results in an OC sink or source, can be reconciled whencomprehensively considering the range of temporal and spatial scales atwhich erosional effects on the C cycle operate. We developed a frameworkthat describes erosion-induced OC sink and source terms across scales. Weconclude that erosion induces a source for atmospheric CO 2 whenconsidering only small temporal and spatial scales, while both sinks andsources appear when multi-scaled approaches are used. We emphasize the needfor erosion control for the benefits it brings for the delivery of ecosystem services, but cross-scale approaches are essential to accurately represent erosion effects on the global C cycle.

[学科分类] 大气科学