Abstract: To examine patterns of nutrient concentrations in different organs, stoichiometry of various nutrients, and the relation of nutrient concentrations with species and the environment, the concentrations of total non-structural carbohydrate (TNC), nitrogen (N), and phosphorus (P) among leaves, stems, tap roots, and first order roots in Asian white birch (Betula platyphylla) and Meyer spruce (Picea meyeri) were studied. The two species were located in the southeastern edge of Inner Mongolia. For TNC, leaves had the highest and first order roots had the lowest concentrations ; the largest difference between them was less than 53%. For N and P, however, there were much higher concentrations in leaves and first order roots than that in stems and the tap roots; the largest difference between them was about 98%. These patterns were determined by the physiological roles (carbohydrate production, nutrient uptake and storage, etc.) that different organs play. In addition, both TNC∶ N and TNC∶ P of Meyer spruce were higher than those of Asian whiter birch, reflecting the physiology of different species and variations in soil nutrient conditions.

Key words: non-structural carbohydrate, nitrogen, phosphorus, Betula platyphylla, Picea meyeri, organs, semi-arid

摘要： 为探讨半干旱区树木各器官中养分浓度的分配格局、养分之间的化学计量关系，以及植物器官养分浓度与树种、土壤养分条件之间的关系，选取内蒙古东南缘的两种天然的典型树种（白桦和白杄），对其叶片、树干、基部最粗根以及根尖中的总非结构性碳水化合物（TNC）、氮（N）和磷（P）浓度进行分析。结果表明：TNC浓度在叶片中最高，在根尖中最低，两者的浓度差异在53％以内；而N和P浓度在叶片和根尖中最高，树干和基部最粗根中最低，不同器官最大差异达98％。这种分配格局与各器官的生理功能（碳水化合物的生产、养分的吸收和储藏）密切相关。此外，白杄的TNC∶N和TNC∶P均大于白桦，这些格局不仅和树种本身的生理特性有关，而且反应了土壤的养分状况。

关键词: 非结构性碳水化合物, 氮, 磷, 白桦, 白杄?, 植物器官, 半干旱