Response of erosion-induced carbon loss to rainfall characteristics is forest type dependent

The paucity of studies on the response of erosion-induced carbon (C) loss to rainfall characteristics hinders our ability to estimate how changes in rainfall regime may affect C budget of forests, particularly in regions prone to water erosion. In the current study, we monitored the losses of dissolved organic carbon (DOC) and particulate organic carbon (POC) in relation to rainfall depth, average intensity, maximum 5 min intensity (I5), erosivity (EI30), and vegetation cover in three young forests during the first three years of reforestation. The three forest types include an assisted naturally regenerated (ANR) forest, a young Castanopsis carlessi plantation (YCP), and a young Cunninghamia lanceolata (Chinese fir) plantation (YCF). Our results indicate that POC was the dominant form of C loss, and erosion-induced C loss was lower in the ANR than the two plantations, likely due to its high vegetation cover. Erosion-induced C loss decreased through time across forest types as vegetation cover increased, highlighting the role of vegetation cover in mitigating C loss. The response of C loss to rainfall characteristics varied among different forest types. Vegetation cover and rainfall depth had similar contributions in predicting DOC flux in the ANR, while rainfall depth was more important in the YCP and vegetation cover was more important in the YCF. The most important factor predicting POC loss was vegetation cover in the ANR, I5 in the YCP, while in the YCF vegetation cover and I5 were of similar importance. Overall, DOC loss was mainly driven by rainfall depth, while POC loss was more related to I5. Our results suggest that projected increases in storm intensity associated with climate change are likely to increase erosion-induced C loss. And ANR should be widely promoted as an effective management practice of C conservation.