Response of soil organic carbon to land-use change after farmland abandonment in the karst desertification control

Land-use change caused by vegetation restoration in karst areas plays an active role in soil carbon sink. However, the response of soil organic carbon (SOC) accumulation and turnover to land-use change after farmland abandonment is still poorly understood.

In this study, we investigated the impacts of converting farmland (maize) (FL) to economic forests [Juglans regia L. (walnut) plantation (JP), and Rosa roxburghii Tratt plantation (RP)], artificial grassland (AG), or natural grassland (NG) on the distribution of SOC and δ¹³C in the karst desertification control.

The SOC stock in the 0–40 cm profile was 67%, 59%, 14%, and 8% higher in RP, JP, AG, and NG than in FL (control). The δ¹³C values in AG, RP, and JP were significantly lower than those in NG and FL at the 0–5 cm depth. It was observed that the δ¹³C increased with soil depth. However, the SOC content decreased. The β values ranged from − 6.94 to -3.88 and increased in the order of RP < AG < FL < JP < NG. Redundancy analysis (RDA) showed that total nitrogen content and soil C/N ratio accounted for significant differences in soil δ¹³C and SOC levels.

Our results suggested that economic forests triggered higher SOC accumulation than artificial grassland and natural revegetation after farmland abandonment, but the rate of soil C turnover following afforestation was still higher than that followed by natural revegetation in the short term.