University of California International and Area Studies

Soil erosion and terrestrial sedimentation are important variables in global change science. Erosion is estimated to transport more than 100 Gt soil yr-1; 70 to 90-percent of which is deposited in depositional basins within the same or adjacent toposequence. Terrestrial sedimentation may constitute a sink of up to 1 Gt C yr-1 (missing Carbon (C)-sink = 1.8 (+/- 1.2) Gt C yr-1), which would offset up to 15-percent of global fossil fuel emissions. Our study characterized the rates of input, storage and stability of soil organic matter in three positions of an eroding hillslope and two types of depositional basins of an undisturbed zero-order watershed in Tennessee Valley, CA. Our study provided experimental evidence that in this small, undisturbed watershed photosynthesis is able to replace eroded C and that the depositional basins contain twice as much C, with preliminary findings of three times longer turnover time, compared to the eroding hillslopes. Here we show that burial of eroded-C can promote a significant, formerly unaccounted, terrestrial C-sink in undisturbed landscapes that are not experiencing anthropogenically accelerated erosion.