Study region This research was carried out in the Zhifanggou small watershed on the Chinese Loess Plateau. Gully slopes in this area feature fragile ecological condition and serve as the primary source of soil erosion and nutrient loss. Study focus Clarifying multi-pathway nutrient loss characteristics is essential for soil erosion and nutrient management. Current research lacks systematic understanding of the contribution and driving mechanisms of multi-pathway nutrient loss on gully slopes. So we conducted a comprehensive study based on eight natural rainfall events in 2021. Runoff plots (3 m × 1 m) were installed on six typical plant communities and one bare land (BL), to monitor carbon (C), nitrogen (N), and phosphorus (P) losses via runoff, sediment and litter export pathway, and key environmental factors were quantified. New hydrological insights for the region Plant communities produced runoff, sediment yield, and litter export mass ranges of 1.94–7.31 L m - ², 2.57–5.18 g m - ², and 0.26–0.78 g m - ², respectively. Grasslands had higher C, N and P losses through runoff and sediment than shrublands, and litter-related nutrient losses in grasslands ranked as AG > CL > AS > BI. Sediment was the dominant nutrient loss pathway for BL, while shrublands mainly lost nutrients via litter export (43.66%-84.76%) rather than sediment pathway (3.85%-14.36%). Dominant nutrient loss pathways differed greatly among grassland communities. Soil total carbon (STC) and soil organic carbon (SOC) content significantly inhibited sediment-mediated C, N, and P loss ( p < 0.05), while STC content significantly enhancing litter-mediated total C and P loss ( p < 0.05). Runoff reduced nutrient loss via runoff and litter pathways, while significantly promoted sediment-mediated C, N, and P loss ( p < 0.05). Overall, grassland communities exhibited better performance in reducing total nutrient loss across all three pathways. Soil surface carbon content and runoff were the main drivers of the loss pathways. The findings provide critical insights for designing soil conservation and nutrient loss control strategies.
Wang et al. (Tue,) studied this question.