Bedrock outcrops promote rather than inhibit soil carbon sequestration after vegetation restoration

Herein, we selected 362 fixed locations to investigate the magnitude and mechanisms underlying soil organic carbon (SOC) sequestration before and after croplands restoration in a karst catchment with varying bedrock exposure ratios and initial soil C pools prior to restoration.

Active vegetation restoration (i.e., cropland converted to forage grass, plantation forest, and a combination of grass and forest) and natural regeneration (cropland abandoned) was compared, with cropland maintained with no change as a control. Compared with unrestored croplands 10 years ago, the SOC density substantially increased in the four vegetation restoration types, but remained unchanged in croplands. The SOC accumulation rate was higher for natural regeneration (39 g C m–2 yr–1) than for the three active restoration strategies (18–27 g C m–2 yr–1).