Topography-driven spatial differentiation in soft capping: vegetation–soil dynamics at Liangzhu earthen sites

Soft capping is widely used to protect earthen archaeological sites, yet its long-term stability mechanisms remain unclear. This study examines how slope aspect and elevation shape soil and vegetation patterns in a Trifolium repens soft-capping system at Damojiao Hill. Field surveys quantified vegetation cover and density, soil physicochemical properties, and nutrient distribution across topographic gradients. Results show that slope aspect controls horizontal heterogeneity of vegetation and soil, while elevation regulates systematic spatial differentiation of water and heat. Northern and eastern slopes exhibited higher vegetation cover and soil organic matter with lower nutrient depletion, whereas southern and western slopes showed sparse cover, phosphorus and potassium deficits, and increased bulk density. These patterns reflect enhanced nutrient leaching on north-facing slopes and accelerated organic-matter mineralization on south-facing slopes. Overall, the study identifies topography as a key driver of spatial heterogeneity, providing a diagnostic basis for site-specific assessment of soft-capping systems in humid regions.