Abstract: Natural close distribution of different functional group plants provides natural experimental conditions for comparing the differences of their physiological characteristics. In this study,we selected Hongsipu District and the Ningxia Habahu National Nature Reserve as research area locating in the ecotone,and used the Continuous Component Method to determine the calcium oxalate content in leaf blade of constructive species of plant communities from different ecosystems and different successional stages with close distribution (within 30 m intervals),and of different canopy positions as well as different growth stages. The results showed that,the calcium oxalate content of the constructive species in desert was significantly higher than that of the constructive species in typical steppe,and there was no significant difference between the late successional stage and the middle-late successional stage, the calcium oxalate content in the bottom was significantly higher than the canopy top for three leguminous bushes;and the calcium oxalate content in adult stage was significantly lower than young and old stages for Artemisia ordosica. Thus,plant calcium oxalate content is the result of long-term adaptation to environment,and is also related to the canopy position and age stage of plants.

Key words: Steppe, Desert, Ecotone of arid and semi-arid regions, Calcium oxalate, Close distribution

摘要： 不同功能群植物天然近距离同地分布时有利于比较它们生理特性之间的差异。本文以地处过渡带的宁夏回族自治区境内的红寺堡区和宁夏哈巴湖国家级自然保护区为研究区，用连续组分法测定了近距离分布（间隔在30 m内）的不同生态系统和不同演替阶段的建群种以及同种不同冠层高度和不同生长阶段叶片草酸钙含量。结果表明：荒漠植物群落建群种叶片草酸钙含量显著高于典型草原建群种，演替后期阶段与演替中后期阶段植物叶片草酸钙含量之间差异不显著，3种豆科灌木冠层底部叶片草酸钙含量均显著高于顶部；油蒿（Artemisia ordosica）成龄阶段叶片草酸钙含量显著低于幼龄和老龄阶段。上述研究表明，植物体内草酸钙含量是其对环境长期适应的结果，也与冠层高度和年龄阶段有关。

关键词: 草原, 荒漠, 过渡带, 草酸钙, 同地分布