【摘要】 本研究以科尔沁沙地典型固沙植物小叶锦鸡儿(Caragana microphylla)为对象,采用氧稳定同位素技术,比较了小叶锦鸡儿群落内3、5和9年生小叶锦鸡儿生长季内土壤水、降雨与植株木质部水的δ18O值关系,并利用多元线性混合模型定量研究了不同树龄小叶锦鸡儿用水来源;结合不同树龄小叶锦鸡儿土壤水分季节特征和根系分布分析用水来源变化原因;通过评价不同树龄小叶锦鸡儿与地区水分条件适应性,分析3种树龄小叶锦鸡儿的水分竞争关系,判断群落稳定性。结果表明:根系的分布决定了不同树龄小叶锦鸡儿对水分利用的范围和选择何种用水策略的可能性,水分的分布也一定程度上影响了小叶锦鸡儿的主要用水来源。生长季内30～80 cm土层是3年生小叶锦鸡儿主要水分利用层位;30～100 cm土层是5年生小叶锦鸡儿主要水分利用层位,其中80～100 cm土层贡献率所占较大; 0～30和100～160 cm土层是9年生小叶锦鸡儿主要水分利用层位。小叶锦鸡儿群落内,不同树龄植株之间不存在强烈的水分竞争,该地区小叶锦鸡儿群落较为稳定。更多还原

【Abstract】 Caragana microphylla is a typical sand-fixing species in Horqin sandy land. Using oxygen stable isotope technique,the relationships of δ¹⁸O of soil water,precipitation and xylem water were compared among 3-,5-and 9-year-old C. microphylla individuals in the C. microphylla community during growing season. Water source of C. microphyllas with different tree ages was quantified using multiple linear mixing model. The water source of C. microphylla was analyzed according to the seasonal pattern of soil moisture and root distribution. By evaluating the adaptability of three aged C. microphylla individuals to regional water conditions,water competition of different aged individuals was analyzed to assess community stability. The results showed that root distribution determined the range of soil water use and water use strategy of different aged C. microphylla individuals,and soil water distribution also affected the main water sources of C. microphylla individuals. During the growing season,water in 30-80 cm soil layer was the main water source of three years old C. microphylla. The water in 30-100 cm soil layer was the main water source of five years old C. microphylla,with a larger contribution rate from 80-100 cm soil layer.For nine years old C. microphylla,0-30 and 100-160 cm soil layers was the main water source.There was no strong water competition among different aged C. microphylla individuals,suggesting the community is stable.更多还原