Soil seed bank is pivotal for vegetation regeneration in degraded desert steppes. However, there is limited information on the dynamic changes of aboveground vegetation and soil seed banks across different degradation stages of desert steppe following removal of grazing. Influence of 2-year fenced enclosure treatment and precipitation on changes of soil seed banks and aboveground vegetation of different degraded grasslands in west Ordos of North China were studied. The climax community of desert steppe was dominated by Stipa breviflora. As degree of degradation increased due to intensified grazing, the dominant species were S. breviflora → Artemisia scoparia → Eragrostis minor → Peganum harmala. In addition, as degree of degradation increased aboveground species richness and density decreased, belowground richness declined, but seed bank density increased. Species similarity first decreased and then increased. In the starting year of enclosure (2021), Sorensen similarity index of aboveground and belowground vegetation of moderately and intensely grazed areas was lower than that of the control. After 1–2 years, the similarity index increased, showing that enclosure (fencing) increased the number of species in both enclosures. After 1 to 2 years of fencing, soil seed bank density continued to increase while diversity did not change, driven by increased seed production of E. minor and that of P. harmala decreasing. Growing-season precipitation increased in the above-average year of 2022 and a slightly below-average year of 2023, and it was significantly associated with increasing seed bank species density and aboveground species richness. Thus, seed bank community structure was altered by a reduction in P. harmala and an increase in E. minor but without a change in richness. The combined effects of 2-year short-term enclosure and increased natural precipitation enhanced aboveground species density and seed bank capacity and facilitated the early natural restoration of degraded grasslands.
Chen et al. (Wed,) studied this question.