As one of the primary medium for ecosystem energy flow and biogeochemical cycling, grassland carbon (C) cycling is the most fundamental process for maintaining ecosystem services. Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide. Grassland is one of the largest terrestrial biomes, providing critical ecosystem services such as food production, biodiversity conservation, and climate change mitigation. The thick green and cyan lines represent the response curves for colluvial and alluvial burial using the median values for α and τ. The thin cyan lines represent the non-linear regression models for five alluvial studies (n=273, see Table 2). The green boxplots represent oxidation in colluvial settings (bur, n=255, see Table 2). For the feedback scenario, we assumed a negative feedback that ranged randomly between 3 to 5% yield loss for each 10 cm of cumulative erosion (Bakker et al., 2004). Erosion rates were allowed to vary randomly between 0.1 415 and 0.2 mm yr-1 and soil C residence time for the top layer between 2 yr. We use the model for cropland presented by (Quinton et al., 2010). The fine red lines represent the results of 100 model runs covering a range of typical erosion and C turnover rates representative for global agricultural land. The bold blue line denotes a fit of a non-linear regression model through the reported SOC recovery data points. The error bars denote the reported uncertainty range. We emphasize the need for erosion control for the benefits it brings for the delivery of ecosystem services, particularly in low-input systems, but our analysis clearly demonstrates that cross-scale approaches are essential to accurately represent erosion effects on the global C cycle.įraction of eroded C replaced by atmospheric CO2 (rec) as a function of time since start of agricultural erosion based on studies using mass-balance (circles) and model (triangle) approaches. Based on this framework, we conclude that erosion is a source for atmospheric CO2 when considering only small temporal and spatial scales, while both sinks and sources appear when multi-scaled approaches are used. Based on the currently available data (74 studies), we developed a framework that describes erosion-induced C sink and source terms across scales. Here, we show that the apparent soil C erosion paradox, i.e., whether agricultural erosion results in a C sink or source, can be reconciled when comprehensively considering the range of temporal (from seconds to millennia) and spatial scales (from soil microaggregates to the Land Ocean Aquatic Continuum (LOAC)) at which erosional effects on the C cycle operate. However, surprisingly a consensus on both the direction and magnitude of the erosion-induced land-atmosphere C exchange is still lacking. Recent model advances now enable improved representation of the relationships between sedimentary processes and C cycling and this has led to substantially revised assessments of changes in land C as a result of land cover and climate change. The acceleration of erosion, transport and burial of soil organic carbon (C) in response to agricultural expansion represents a significant perturbation of the terrestrial C cycle.
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