Response of soil enzyme activity to long-term restoration of desertified land

• 50 years' restoration enhanced microsite soil nutrients and enzyme activities.
• Microsite soil was improved to 35 cm depth under crust.
• Incremental rates with years were much bigger in crust and 0–5 cm soil layer.
• Desertification can be mitigated to a certain extent if human controls pressure.

Low extracellular enzyme activity in desert soil can be recovered during the succession of re-vegetation, especially in soils forming under shrubs (microsite soil), which closely reflects desert restoration conditions. However, not much is known about the restoration of soil enzyme activity at these microsites. By using the space-for-time substitution method, soils on moving sand dunes that had been stabilized at different dates over a fifty year period at the southeastern fringe of the Tengger Desert were selected to investigate the enzyme activities in the surface soil crust and three other soil depths at microsites to demonstrate the evolution of enzymatic activity at different stages from bare soil to complex vegetation over a fifty year sequence. The results showed that organic C and total and available N, P, and enzyme activities (dehydrogenase, catalase, α- and β-glucosidase, protease, and phosphatase) were progressively enhanced in each microsite soil in the 50-year chronosequence and had effect down to 35 cm depth. Soil enzyme activities of the crust and the 0–5 cm soil layer were higher than in deeper soil layers. The observed increase over time of the values of the measured soil properties, such as organic C, total and available N, was much larger in the crust and the 0–5 cm soil layer in comparison to the deeper layers. The improvement of desert soil quality indicated that desertification can be mitigated to a certain extent under human controls.