Response of soil aggregate stability to plant diversity loss along an inundation stress gradient in a reservoir riparian zone

Abstract

Dam-triggered periodic wetting and drying has increased the disintegration of soil particles in riparian areas. Most studies in this field have primarily explored the effects of vegetational characteristics on soil stability. However, the impact of plant diversity loss on the soil aggregate stability under periodic inundation stress remains unclear. This study investigated the relevant plant characteristics, root traits, and soil physicochemical properties in a typical riparian ecosystem along a hydrological stress gradient. Data-driven models were used to quantify the paths influencing soil aggregate stability through root traits under heterogeneous inundation stress. The findings showed that as inundation stress intensified, there was an overall decline in plant community diversity and soil aggregate stability in this riparian zone. Perennial herbs with fibrous root systems, as the dominant species, played an essential role in the subsurface soil aggregate stability under intense inundation stress, in contrast to the critical role of plant diversity under weak inundation stress. Moreover, the results revealed that root volume density and macroaggregate carbon content mediated the effects of plant diversity on riparian soil stability. Overall, the results suggest that suitable plants with high root volume density benefit essential soil aggregate stability under well-documented inundation effects in riparian zones.