Grassland management strategies influence soil C, N, and P sequestration through shifting plant community composition in a semi-arid grasslands of northern China

Current studies regarding the effects of grassland management strategies on the soil nutrient cycle have mostly focused on soil organic carbon (SOC). Less is known about the responses of SOC, total nitrogen (TN), and total phosphorous (TP) stocks to grassland management strategies at different soil depths. We therefore quantified vertical variations in SOC, TN, and TP stocks as well as controlling factors under three grassland management strategies (i.e., enclosure control, grazing twice a year, grazing combined with mowing) in 2014 and 2017 in a semi-arid grassland of northern China. We found that grazing twice a year and grazing combined with mowing led to an increase in plant production as well as soil C and N sequestration during 2014 to 2017. Changes in plant aboveground biomass (AGB), belowground biomass (BGB), and root-to-shoot ratio (R:S) all exerted significant positive effects on changes in soil C and N sequestration in the surface soil layer (0-30 cm), while changes in AGB and plant community composition played a more important role in mediating soil C, N, and P sequestration in response to grassland management strategies in the subsoil layer (30-100 cm). Specifically, grassland management strategies influence soil C, N, and P sequestration capacity by altering plant community composition. The results of this study provide new insights into the response mechanisms of plants and soils to grassland management practices and offer a range of new possible strategies that might be applied to the effective management of semi-arid grasslands.