Changes in Carbon, Nitrogen and Phosphorus Stoichiometry of Leaf-Litter-Soil in Differently Stands Under ‘Plain Afforestation Program’ in China

Abstract

Changes in land use might affect the combined C, N, and P stoichiometry in soil. The Plain Afforestation Program, which converts low-yield croplands or abandoned lands into forest, shrub, and/or grassland, was a famous land reforestation project in Beijing. To clarify the spatial distribution, stoichiometric characteristics, and controlling factors of carbon (C), nitrogen (N), and phosphorus (P), four typical Plain Afforestation forests including Robinia pseudoacacia, Pinus tabuliformis, Ailanthus altissima, and Salix matsudana plantations were selected in Yongding River plain afforestation area, Beijing. Leaf, litter, and soil C, N, and P concentrations and their stoichiometric relationships were analyzed. The results showed that the concentrations of N and P in the four plantations were in order of R. pseudoacacia>A. altissima>S. matsudana >P. tabuliformis in leaf and litter. Compared with leaves, the concentrations of C for P. tabuliformis were highest. The concentrations of N and P, as well as N:P for R. pseudoacacia plantation, were significantly higher than those for the other plantations. C and N concentrations were the highest in surface soil (0-10 cm), and C:N and C:P both demonstrated the trend of litter>soil in the plantations with the exception of S. matsudana. The total N concentration of leaf was positively correlated with that of litter in the four plantations. Overall, our findings suggested the growth of R. pseudoacacia, P. tabuliformis, and S. matsudana was mainly restricted by P, while that of A. altissima was constrained by N. In addition, it is a feasible method that uses nitrogen fertilizer when tending the artificial forest in the plain area.