Revegetation type affected soil C, N, P stocks and stoichiometry in a reclaimed mine area in Shanxi province, China

Abstract

Soil stoichiometry serves as an indicator for balance of soil C, N, P pools and for the maintenance of ecosystem stability and function. Especially in seriously degraded lands, it can also reflect the status of soil recovery. However, the response of soil elements and stoichiometry to patterns of plant restoration remains unclear. In this study, soil organic C, N, P stocks and stoichiometry along a succession gradient of vegetation types were investigated in a reclaimed post-mining area in Shanxi province. Soil C and N stocks varied significantly with revegetation types while soil P stock showed no significant difference. Revegetation type significantly influenced soil C, N stocks and stoichiometry by affecting litter and fine root inputs, and consequently modifying the rates of C sequestration and nutrient release. The maximum of C and N stocks occurred in a naturally-restored shrub land with largest fine root biomass, resulting mainly from its diverse species including some legumes. Although soil C and N stocks increased significantly with succession gradient after twenty years of restoration, they were still lower than those of a nearby undisturbed site. Furthermore, soil C:N and C:P values varied among revegetation types, and the mean soil C:P (11.63) and N:P (1.03) values were significantly lower than the average level across China, indicating serious soil C and N shortage. Our result implied that shrubs with diverse species might be the most efficient plant type to rebuild soil C and N stocks, and consequently would promote restoration process of degraded lands.