大兴安岭不同退化阶段土壤和植物C、N、P浓度及其化学计量特征

在大兴安岭加格达奇地区,选择处于不同退化阶段的蒙古栎林、灌丛、灌草丛和草丛,进行土壤和植物叶片C、N、P浓度及其化学计量比分析。结果表明,土壤全N、全P浓度随植被退化逐渐下降,而土壤全C浓度在灌丛达到最高。随着植被退化,各退化阶段植物群落的叶片C、N、P浓度逐渐降低,而N/P比值则逐渐增加。蒙古栎林、灌丛、灌草丛和草丛植物群落的叶片N/P比值分别为：7.35、8.04、9.36和13.61,均小于14。各退化阶段9个共有物种的叶片N/P比值,在蒙古栎林和灌丛群落中均小于14;在灌草丛群落中小于14的共有物种8个,在14～16之间的共有物种1个;在草丛群落中小于14的共有物种7个,大于16的共有物种2个。根据以往对N/P临界值的确定,可以认为该区各退化阶段的植物生长主要受N素的限制。

Concentrations of C, N, P and Stoichiometry of Soil and Plant at Different Vegetation Degradation Stages in Great Xing＇an Mountains

Abstract： The C, N, P concentrations and stoichiometry of soil and plant at different vegetation degradation stages （Quercus mongolica forest, shrub, shrub-grass, and grassland）in Great Xing＇an mountains were studied. Results showed that, soil total N and total P concentrations decreased with degradation, while soil total C concentration was highest in shrub. The C, N, P concentrations of plant communities at different degradation stages decreased with degradation. The N/P ratios of plant communities in Quercus mon- golica forest, shrub, shrub-grass, and grassland were 7.35, 8. 04, 9. 36, and 13.61, respectively, which increased with degrada- tion. The N/P ratios of all common species in Quercus mongolica forest and shrub were below 14, while the N/P ratios of 8 common species in shrub-grass were below 14 and one was 14 - 16. The N/P ratios of 7 common specie in grassland were below 14, the other two were above 16. These results indicated that the vegetation growth at different vegetation degradation stages in Great Xing＇an mountains is generally N-limited.