Moderate Grazing Disturbance Can Promote the <i>Leymus chinensis</i> Grasslands’ Recovery through the Existing Bud Banks in Northern China

The Leymus chinensis grassland is one of the most widely distributed associations in the warm temperate grassland and due to overgrazing in recent years, it has experienced varying degrees of degradation. Vegetative regeneration via bud banks serves as the primary way of vegetation reproduction in the L. chinensis grassland ecosystem. However, the role of the bud bank in the vegetation regeneration of grazing grassland remains unclear. Based on the relationship between the under-ground bud bank and above-ground vegetation of L. chinensis grassland under different grazing stages, this study aimed to explore whether the grazing grassland could self-recover through the existing bud bank. The findings revealed that the bud density initially increased and then decreased with increasing grazing intensity, indicating that appropriate grazing promoted vegetation renewal. Moreover, grazing significantly influenced the composition of the bud bank: during the early grazing stage, the rhizome buds accounted for the main part, and tiller buds dominated during the mid-stage grazing; while during the late-stage grazing, root-sprouting buds prevailed. The meristem restriction index for light, moderate, and heavy grazing grasslands was close to one; conversely, overgrazing and extreme overgrazing grasslands exhibited the higher meristem restriction index (2.00, 3.19), suggesting that plant regeneration was constrained by bud banks under light-grazing conditions where regenerate rates failed to meet above-ground modular’s recovery requirements following overgrazing and extreme overgrazing events. Consequently, moderate grazing grasslands could achieve natural community recovery by continuously adjusting their vegetative regeneration strategies. Understanding the role of bud banks in vegetative regeneration in grazing grassland will not only supply theoretical support for the ecological succession process of degraded grassland but also provide practical experience for the sustainable management of the L. chinensis grassland ecosystem.