中文摘要：

为了探究青藏高原东部窄叶鲜卑花（Sibiraea angustata）灌木不同器官碳（C）、氮（N）、磷（P）含量的分配格局及其生态化学计量特征,该文采用分层随机抽样方法布设样地,选择16个窄叶鲜卑花灌丛样地,分别采集窄叶鲜卑花灌木根、茎、叶、当年枝和果等植物器官样品,并分析样品C、N、P含量及其计量比。结果表明：C、N、P在不同器官中的含量分别表现为茎〉当年枝〉果〉根〉叶,叶〉果〉当年枝〉茎〉根,果〉叶〉当年枝〉根〉茎。窄叶鲜卑花各器官中C含量相对稳定,N、P含量变异系数较大,在根部的变异系数最大。在不同器官中N：P的范围为7.12–12.41,其值变化不大,N：P变异系数的最小值在当年枝中,说明N：P在当年枝中的内稳性较高。在该灌木植物体中C与N之间、C与P之间呈极显著的负相关关系,C对N、P具有稀释作用;N与P呈极显著正相关关系,N与P间具有较好的耦合协同性。分析发现：窄叶鲜卑花不同器官C、N、P化学计量特征在一定程度上符合内稳态理论和生长速率理论,其元素分配与器官所执行的功能密切相关;同时指出在物种水平上应当谨慎使用生态化学计量比来判断养分的限制情况。

英文摘要：

Aims Little is known about the stoichiometric characteristics of carbon （C）, nitrogen （N） and phosphorus （P） in plateau shrubs across China. Sibiraea angustata is a typical and representative shrub species on the eastern Qinghai-Xizang Plateau, and exploring its C, N and P distribution patterns and stoichiometric properties in different organs （including root, shoot, leaf, twig and fruit） would help us better understand the mechanisms of C, N and P cycling and balance in the S. angustata dominated shrub ecosystem. Methods Sixteen sampling sites were selected on the eastern Qinghai-Xizang Plateau by the stratified sampling method. The height and coverage of the dominant shrubs, latitude, longitude and altitude of the sites were recorded. Three 5 m × 5 m plots were selected at each site. At least 128 biological samples of plant organs of S. angustata were collected and measured, respectively. The C and N concentrations of plant samples were analyzed using an elemental analyzer （2400 II CHNS）. The P concentration was analyzed using the molydate/ascorbic acid method after H2SO4-H2O2 digestion. Important findings The C, N and P concentrations of different organs followed the order of： shoot （495.07 g·kg^-1） 〉 twig （483.37 g·kg^-1） 〉 fruit （480.35 g·kg^-1） 〉 root （468.47 g·kg^-1） 〉 leaf （466.33 g·kg^-1）; leaf （22.27 g·kg^-1） 〉 fruit （19.74 g·kg^-1） 〉 twig （7.98 g·kg^-1） 〉 shoot （4.54 g·kg^-1） 〉 root （4.00 g·kg^-1） and fruit （2.85 g·kg^-1） 〉 leaf （1.92 g·kg^-1） 〉 twig （0.96 g·kg^-1） 〉 root （0.52 g·kg^-1） 〉 shoot （0.45 g·kg^-1）, respectively. The ranges of the coefficient of variation （CV） for C, N and P concentrations were 1.71%–4.44%, 14.49%–25.50% and 11.46%–46.15%, respectively. Specifically, the C concentration was relatively high and stable, and the maximum CV values for N and P were found in roots. The N：P value of different organs varied from 7.12–12.41 and the minimum CV for N