[Ecological stoichiometry characteristics of leaf-litter-soil in different plantations on the Loess Plateau, China].

In order to research into the influence of Grain to Green Project in Ziwuling forest region, this paper took three typical plantations which were Robinia pseudoacacia plantation, Pinus tabuliformis plantation, and Platycladus orientalis plantation in the Ziwuling forest region of Shaanxi Province as research objects and analyzed the carbon, nitrogen and phosphorus contents of leaf, litter and soil among the three plantations. The results showed that the contents of C, N and P in the three plantations were in order of leaf > litter > soil, the contents of N and P in leaf of R. pseu-doacacia plantation were significantly higher than that of P. tabuliformis plantation and P. orientalis. Leaf N:P was 12.21, 5.36 and 6.09 in R. pseudoacacia plantation, P. tabuliformis plantation and P. orientalis plantation, respectively. It was indicated that the three species were all subject to N deficiency. C:N and C:P showed the trend of litter > leaf > soil, and N:P demonstrated the trend of leaf > litter > soil. There were highly significant positive relationships in C:N between leaf and litter in P. tabuliformis plantation. N and P in the leaf development process of R. pseu-doacacia plantation were proportionally absorbed, and proportionally remained in the litter after N and P resorption. R. pseudoacacia was the better plantation species than P. tabuliformis and P. orientalis in the south fo-rest zone on the Loess Plateau.