Ecological stoichiometry of plant leaves, litter and soils in a secondary forest on China's Loess Plateau

Ecological stoichiometry can reveal nutrient cycles in soil and plant ecosystems and their interactions. However, the ecological stoichiometry characteristics of leaf-littersoil system of dominant grasses, shrubs and trees are still unclear as are their intrinsic relationship during vegetation restoration. This study selected three dominant plant types of grasses (Imperata cylindrica (I. cylindrica) and Artemisiasacrorum (A.sacrorum)), shrubs (Sophora viciifolia (S. viciifolia) and Hippophae rhamnoides (H. rhamnoides)) and trees (Quercus liaotungensis (Q. liaotungensis) and Betula platyphylla (B. platyphylla)) in secondary forest areas of the Chinese Loess Plateau to investigate ecological stoichiometric characteristics and their intrinsic relationships in leaf-litter-soil systems. The results indicated that N concentration and N:P ratios in leaf and litter were highest in shrubland; leaf P concentration in grassland was highest and litter in forestland had the highest P concentration. Soil C, N and P concentrations were highest in forestland (P < 0.05) and declined with soil depth. Based on the theory that leaf N:P ratio indicates nutritional limitation of plant growth, this study concluded that grass and shrub growth was limited by N and P element, respectively, and forest growth was limited by both of N and P elements. The relationships between the N concentration in soil, leaf and litter was not significant (P >0.5), but the soil P concentration was significantly correlated with litter P concentration (P < 0.05). These finding enhance understanding of nutrient limitations in different plant communities during vegetation restoration and provide insights for better management of vegetation restoration.