Soil C, N and P contents and their stoichiometry as affected by typical plant communities on steep gully slopes of the Loess Plateau, China

The contents and stoichiometric characteristics of soil carbon, nitrogen and phosphorus greatly influence the structures and functions of the ecological system. The steep gully slope is the main source of erosion sediment in the small watershed on the Loess Plateau, China. It is vital to fully quantify the potential effects of vegetation restoration on soil nutrients and their stoichiometry under such harsh standing environments. To investigate the effects of plant communities on soil C, N, P contents and their stoichiometry on steep gully slopes. Two shrubs (Hippophae rhamnoides Linn., Caragana korshinskii Kom.), four typical grasses (Carex lanceolata Boott., Artemisia giraldii Pamp., Bothriochloa ischcemum (Linn.) Keng. and Artemisia sacrorum Ledeb.), and one slope farmland planted with Zea mays (as control) were chosen as the testing sites. Soil samples were collected from seven layers (0-10, 10-20, 20-30, 30-40, 40-60, 60-80, and 80-120 cm). The results showed that grassland had higher soil total carbon, soil total nitrogen, soil total phosphorus, and stoichiometries than shrubland on steep gully slopes. The C/N ratio had the minimum variation between different communities, while N/P and C/P ratios gradually decreased with soil depth. Both N and P were scarce on steep gully slopes. Soil C, N, P contents and their stoichiometry were closely related to bulk density, plant litter density and root mass density. The results are helpful to understand the spatial variation of soil nutrients and their stoichiometry and vegetation management on steep gully slopes in arid and semi-arid regions.