Abstract: Soil physical structure plays a crucial role in maintaining grassland ecosystem functions and its formation is intimately linked with plant root systems. However， it remains unclear how different management practices affect soil structure and water retention throughout the profile by regulating belowground biomass （BGB）. This study compared the effects of four management practices—fencing， continuous grazing， rest grazing， and mowing—on soil physical structure （bulk density， pore distribution， aggregate composition）， water retention， and BGB in the 0-10， 10-30， 30-60， and 60-100 cm soil layers. The results showed that the response of soil structure to management was primarily concentrated in the surface layer. In the 0-10 cm layer， continuous grazing significantly reduced BGB， leading to increasing bulk density， decreasing porosity， and a reduction in macroaggregates. In contrast， rest grazing effectively mitigated soil compaction and maintained soil structure by sustaining higher BGB. Macroaggregates were the most sensitive indicator of management， with impacts extending to a depth of 60 cm. Furthermore， both pore structure and water-holding capacity were significantly and positively correlated with BGB. In conclusion， BGB is a key driver of soil structural changes， and rest grazing， by promoting root development， helps to enhance soil structural stability and water storage capacity.

Key words: Grassland management, Belowground biomass, Soil physical structure, Water retention, Profile differentiation, Temperate meadow steppe

摘要： 土壤物理结构在维持草地生态系统功能中具有关键作用，其形成与植物根系密切相关。然而，不同管理方式如何通过调控地下生物量影响全剖面土壤结构及持水性仍不明确。本研究比较了围封、持续放牧、休牧和刈割4种管理方式对0~10，10~30，30~60和60~100 cm土层下土壤物理结构（容重、孔隙分布、团聚体组成）、持水性及地下生物量的影响。结果表明：土壤结构对管理的响应主要集中于表层。在0~10 cm土层，持续放牧显著降低地下生物量，导致容重增加、孔隙率下降及大团聚体减少。相比之下，休牧通过维持较高地下生物量，有效缓解土壤压实并维持土壤结构。大团聚体对管理方式最为敏感，其影响深度可达60 cm。此外，孔隙结构与持水能力均与地下生物量显著正相关。综上，地下生物量是驱动土壤结构变化的关键因子，休牧通过促进根系发育，有助于提升土壤结构稳定性和蓄水能力。

关键词: 草地管理, 地下生物量, 土壤物理结构, 持水性, 剖面分异, 温带草甸草原