关键词: 适应性放牧, 半干旱草原, 土壤种子库, 群落组成, 物种多样性

Abstract: Soil seed banks (SSBs) play an important role in the recovery and renewal of plant ecosystems. Numerous studies have explored the effects of grazing on the density, diversity, and composition of SSBs in grasslands. However, information on how different livestock species affect SSBs in semi-arid grasslands remains limited. Here we examined shift in species diversity, plant density, and community structure in both SSBs and aboveground vegetation in grasslands grazed by three livestock species under adaptive grazing management. We found that (i) Grazing by three livestock species increased plant density and species richness in both SSB and aboveground vegetation, with cattle grazing increased the most. (ii) Grazing leads to a notable increase in the seed density of annual and biennial plants while decreasing that of perennial plants in the upper 5 cm of soil; grazing also increases burial depth of seeds, with cattle and goat grazing significantly increasing the seed density of annual and biennial plants in the 5-10 cm soil layer, as well as that of perennial forbs in the 0-10 cm layer. (iii) The species composition of aboveground vegetation and SSB differed, but cattle grazing significantly increased the similarity between the two. Our results provide significant insights into SSB responses to three livestock species, and indicate that adaptive grazing management, which maintains grassland residual height above a certain level, may benefit the SSB and support vegetation regeneration.

Key words: adaptive grazing,  semi-arid steppe, soil seed bank, community composition, species diversity