Grassland restoration measures influence soil water-holding capacity by altering soil and vegetation properties composition

The Tibetan plateau, referred to as the “Water Tower of Asia”, is dominated by alpine meadows. The ability of these meadows to support water source supply is directly influenced by soil water capacity; however, their soil and vegetation degradation may reduce the water-holding capacity. Although many restoration projects have been implemented on the Tibetan plateau to improve water retention on the degraded meadows, their effectiveness and the underlying mechanisms remain unclear and are debated. This study focused on degraded alpine meadows in the upper reaches of the Yellow River, a crucial water source region on the Tibetan plateau. We investigated plant community characteristics, soil physicochemical properties, and soil water-holding capacity—comprising a total of 20 parameters—under three main restoration measures, involving grazing prohibition, composted organic fertilizer combined with reseeding, and a combined measure of grazing prohibition, composted organic fertilizer, and reseeding. The effects of these restoration measures on soil water-holding capacity were analyzed using subset regression analysis and structural equation modeling. The results revealed that all three restoration measures increased the height, coverage, and biomass of plant communities. Additionally, soil physicochemical properties and water-holding capacity improved, with increases in soil organic carbon, total phosphorus, total nitrogen, porosity, and soil infiltration rate. Restoration measures explained 98% of the variation in soil water-holding capacity through changes in plant community height, soil moisture, soil organic carbon, and total phosphorus content. Our findings provide scientific insights and comprehensive evaluations to understanding soil water-holding capacity through several dominant restoration measures on the Tibetan plateau.