Response of soil productivity to rehabilitation time in debris flow deposits behind check dams in Hunshui Gully, southwestern China

Soil productivity is a primary determinant of vegetation restoration and land resources utilization in debris flow deposits. However, little is known on the soil productivity change process of debris flow deposits behind check dams during rehabilitation. To investigate the change process of soil productivity at debris flow deposits behind check dams, soil physicochemical properties were measured in different time of rehabilitation (0, 2, 4, 5, 16, 23, 28, 33, 39, 45 years) in Hunshui gully (HSG). Modified Productivity Index (MPI) model was used to evaluate soil productivity. The results showed that soil organic matter (OM), total nitrogen, total phosphorus, available potassium and clay increased with rehabilitation time, while total potassium, pH and bulk density decreased. OM and MPI exponentially increased with the increase of rehabilitation time from 0.1% to 1.7% and 0.0006 to 0.1423, respectively. The rehabilitation time of 23 years was most likely a threshold time for the restoration of soil productivity at debris flow deposits. The trend of MPI indicated that soil productivity increased slowly in the early stage of ecosystem restoration, followed by a rapid with the increase of vegetation and OM. Our results can provide scientific bases for the effective utilization and restoration of debris flow deposits.

Automated summary

Soil productivity change in debris flow deposits behind check dams during rehabilitation was investigated in this study. The results showed that soil organic matter, total nitrogen, total phosphorus, available potassium and clay increased with rehabilitation time, while total potassium, pH and bulk density decreased. The trend of Modified Productivity Index (MPI) indicated that soil productivity increased slowly in the early stage of ecosystem restoration and then rapidly increased with the increase of vegetation and organic matter. The results can provide scientific bases for the effective utilization and restoration of debris flow deposits.