Ecological stoichiometric characteristics of plants and soil in grassland under different restoration types in Yunwu Mountain, China

Abstract

Carbon (C), nitrogen (N) and phosphorus (P) stoichiometry from the aboveground parts of plants, roots, plant litter and soils, as well as their relationships were studied in grassland under four distinct types of vegetation recovery including natural grassland, grassland with shrubs, grassland after grazing exclusion, and abandoned cropland in Yunwu Mountain, China. The results showed that there was significant correlation among the ecological stoichiometric characteristics of soils with the aboveground parts and roots. The relation between the aboveground parts and roots was closer in P concentration than in N concentration. The linkage of plants and soils was closer in N concentration than in P concentration. The ecological stoichiometric relationships between soils and litter as well as between roots and litter were weak. There was no significant difference between the aboveground parts and roots in total C and N storages among four distinct recovery methods. How-ever, the P storage differed greatly among the four recovery types with the maximum of 0.49 g·m-2 in the abandoned cropland and the minimum value of 0.29 g·m-2 in the grassland after grazing exclusion. Grazing prohibition duration had minor effects on ecological stoichiometric characteristics. The 12-year-abandoned cropland had lower soil organic C and total N concentration (9.98 and 1.07 g·kg-1, respectively) compared with natural grasslands (14.27 and 1.55 g·kg-1, respectively), and this difference of ecological stoichiometric characteristics was caused by the high P concentration in abandoned cropland. The roots N and P concentrations were the lowest in natural grassland with 6.25 and 0.57 g·kg-1, respectively, due to the greatest amount of root biomass. The N and P concentrations in the grassland with shrubs were relatively lower in the aboveground parts(12.77 and 0.98 g·kg-1,respectively) while relatively higher in roots (9.30 and 0.77 g·kg-1, respectively). Overall, the plant composition was the key factor that influenced the ecological stoichiome-tric characteristics of plant communities. The distinctions of the ecological stoichiometric characteristics among different restoration types decreased with the increasing Sorensen index.