关键词: 氮沉降, 生态化学计量, 氮磷可塑性, 高山苔原生态系统, 长白山

Abstract: Nitrogen (N) is a major limiting element for plant growth and net primary productivity in tundra. However, the effects of exogenous N input on plant nutrient concentrations of tundra in Changbai Mountain remain unclear. In this study, we examined the effects of short-term N (as NH₄NO₃) input on foliar N and P concentrations of Vaccinium uliginosum and Rhododendron chrysanthum, two dominant species of tundra in Changbai Mountain, under four treatments \[control (N0, 0 kg·hm^-2), low N (N1, 25 kg·hm^-2), medium N (N2, 50 kg·hm^-2), and high N (N3, 100 kg·hm^-2)\]. Low N input increased foliar N concentration ofR. chrysanthum, but did not affect N and P concentrations in V. uliginosum. However, a higher N input promoted the growth ofV. uliginosum and increased its ability to acquire N and P. With increased nitrogen input, the plasticity index (PI) of N and P concentrations in V. uliginosum (deciduous shrub) decreased first and then increased, while that ofR. chrysanthum (evergreen shrub) always decreased. The stress resistance of R. chrysanthum was higher than that of V. uliginosum. Under the scenario of increasing N deposition, V. uliginosum will have more growth advantages in the tundra zone of Changbai Mountain.

Key words: nitrogen deposition, ecological stoichiometry, plasticity of N and P content, alpine tundra ecosystem, Changbai Mountain.