Restoration effects of reseeding and enclosure on the vegetation of different degraded desert steppes

In this study, we investigated moderately and severely degraded desert steppes in Ningxia in order to compare how reseeding and enclosure affect vegetation restoration in different degraded desert steppes. We performed both enclosure and reseeding in two degraded desert steppes and adopted a severely degraded steppe with grazing as a control. We explored vegetation community characteristics and above-ground ecological multi-function (EMF) upon different treatments. In the case of the severely degraded desert steppe, compared with the control grazing steppe, reseeding simultaneously increased species number, coverage, and aboveground biomass as well as enhanced important values of grasses and legumes. However, enclosure increased only the species number, coverage, and above-ground biomass of the severely degraded steppe, while it reduced the Shannon-Wiener, Pielou, Simpson, and Patrick indices. Concerning the moderately degraded desert steppe, both enclosure and reseeding increased the species number, coverage, aboveground biomass, and enhanced important values of grasses and legumes. Our ecological multi-function (EMF) analysis indicated that, compared with the EMF of the control (−0.629), enclosure did not affect EMF in the severely degraded steppe (−0.970; P > 0.05). However, both enclosure and reseeding significantly increased EMF in the moderately degraded steppe (0.471 and 0.851; P < 0.05), and enclosure displayed higher potential than reseeding in promoting the EMF of the moderately degraded steppe. Therefore, the results of this study indicate that reseeding is superior to enclosure in restoring severely degraded desert steppes, while enclosure is superior to reseeding in restoring moderately degraded desert steppes.