Changes in soil organic carbon and nitrogen stocks following revegetation in a semi-arid grassland of North China

Abstract

Long-term restoration practices have been often reported to enhance soil organic carbon (SOC) and nitrogen (N) stocks in grassland ecosystems. However, there is a limited understanding of how vegetation restoration affects SOC and N stocks at different soil depths over short timescales in semi-arid grassland of North China. To address this problem, we conducted a field study to investigate the effects of plant properties on the SOC and N stock changes during a nine-year period of grassland restoration practices (natural recovery; shallow ploughing; harrowing) in a semi-arid grassland of North China. The results revealed that three restoration practices had a positive contribution to SOC and N stocks following nine years of recovery, however, the rates of SOC and N stock changes under mechanical disturbance were lower across the 0–60 cm soil depth when compared with the natural recovery. The biomass of litter, roots, and dominant plant species were the major factors contributing to SOC and N stock changes. Our findings from the nine-year restoration experiment suggested that short-duration natural recovery is likely to be a beneficial strategy for the restoration of both the plant community and the soil nutrients. Our findings elucidate the regulatory mechanisms of dominant plant species on SOC and N stock changes following revegetation and suggest that the overcompensatory growth of dominant species should be fully considered in grassland restoration.