Effects of N addition on nutrient resorption efficiency and C:N:P stoichiometric characteristics in Stipa bungeana of steppe grasslands in the Loess Plateau,China
氮素添加对黄土高原典型草原长芒草氮磷重吸收率及C:N:P化学计量特征的影响

Aims Our purpose was to study the effects of deposition of nitrogen (N) on plant carbon (C), N, phosphorus (P), N and P nutrient resorption efficiencies, C : N : P stoichiometry and their internal relations on Stipa bungeana of Loess Plateau natural grassland. Methods Deposition of N was simulated by N fertilization at four levels. Changes of C, N and P contents were detected, and C : N : P and the N and P nutrient resorption efficiencies were estimated for S. bungeana. Important findings The C and N contents of leaves and N and P contents of standing litter increased significantly with N addition. However, the P content of leaves and C content of standing litter did not response to N addition. The N and P resorption efficiencies of S. bungeana decreased significantly with N addition. When there was no N addition, N and P resorption efficiencies were highest (60.35% and 71.75%, respectively). Meanwhile, the P resorption efficiency was greater than that of N in same treatment. The C : N of S. bungeana decreased gradually with N addition, but the N : P and C : P increased with N addition. Values of the N : P were 18.25–29.01. The results showed the Loess Plateau natural grassland was mainly limited by P, and the strength of P limitation was enhanced with N deposition. Higher N and P resorption efficiencies were an important strategy for S. bungeana to survive soil infertility.