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Aims <p>Soil seed banks (SSB) in alpine grasslands are vertically stratified into transient (0–5&#xa0;cm) and persistent (5–10&#xa0;cm) layers, but how livestock combinations regulate vertical SSB differentiation and its mechanisms remains unclear.</p> Methods <p>A 2014-initiated long-term moderate grazing experiment was conducted in a Qinghai–Tibet Plateau alpine meadow, with treatments including yak-only, sheep-only, mixed yak-sheep grazing (1:2, 1:4, 1:6), and an ungrazed control. Germinable SSB in two soil layers were quantified via greenhouse germination assays. Plant community, soil physicochemical, and untargeted soil metabolomic data were integrated using mixed-effects models and structural equation modeling (SEM).</p> Results <p>Soil depth × grazing interactions drove most variation in SSB density and diversity. Moderate grazing reduced total SSB density but promoted vertical redistribution (lower transient-layer density, higher persistent-layer contribution/richness). We propose the "seed escape hypothesis": continuous grazing and trampling redistribute seeds to deeper soil layers, reducing stress exposure and enhancing survival to form a persistent seed bank. Our results support this hypothesis. Soil carbon and aboveground plant diversity were key positive predictors of SSB, and roseotoxin A was identified as a potential mediator linking grazing, soil carbon, and SSB regulation.</p> Conclusions <p>Under moderate grazing regimes, livestock combinations can regulate the alpine soil seed bank by modifying seed bank distribution across soil depths and through plant mediated coupling pathways linking soil and metabolites. Mixed grazing at yak sheep ratios of 1:2–1:4 showed comparatively favorable outcomes for maintaining plant diversity and stabilizing seed bank structure, informing grazing management and grassland restoration.</p>

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Grazing affects the soil seed bank of alpine meadows by altering soil carbon and plant diversity

  • 期刊论文

  • 发表日期：

    2026年4月13日

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  • Qinyuan Zhou,
  • Quanmin Dong,
  • Yuzhen Liu,
  • Xiaoxia Yang,
  • Weidong Lv,
  • Wenting Liu

摘要

Aims

Soil seed banks (SSB) in alpine grasslands are vertically stratified into transient (0–5 cm) and persistent (5–10 cm) layers, but how livestock combinations regulate vertical SSB differentiation and its mechanisms remains unclear.

Methods

A 2014-initiated long-term moderate grazing experiment was conducted in a Qinghai–Tibet Plateau alpine meadow, with treatments including yak-only, sheep-only, mixed yak-sheep grazing (1:2, 1:4, 1:6), and an ungrazed control. Germinable SSB in two soil layers were quantified via greenhouse germination assays. Plant community, soil physicochemical, and untargeted soil metabolomic data were integrated using mixed-effects models and structural equation modeling (SEM).

Results

Soil depth × grazing interactions drove most variation in SSB density and diversity. Moderate grazing reduced total SSB density but promoted vertical redistribution (lower transient-layer density, higher persistent-layer contribution/richness). We propose the "seed escape hypothesis": continuous grazing and trampling redistribute seeds to deeper soil layers, reducing stress exposure and enhancing survival to form a persistent seed bank. Our results support this hypothesis. Soil carbon and aboveground plant diversity were key positive predictors of SSB, and roseotoxin A was identified as a potential mediator linking grazing, soil carbon, and SSB regulation.

Conclusions

Under moderate grazing regimes, livestock combinations can regulate the alpine soil seed bank by modifying seed bank distribution across soil depths and through plant mediated coupling pathways linking soil and metabolites. Mixed grazing at yak sheep ratios of 1:2–1:4 showed comparatively favorable outcomes for maintaining plant diversity and stabilizing seed bank structure, informing grazing management and grassland restoration.