中文摘要：

本研究运用简单竞争指数（CI）、生长空间竞争指数（GSCI）和生长空间指数（GSI）对浑善达克沙地不同立地类型下天然榆树的种内竞争关系进行分析。结果表明，反映个体竞争能力的指数（GSCI、GSI）以及生长状况的指标（平均株高、平均胸径）的趋势为：迎风坡〉丘间地〉背风坡，植物个体生长状况直接影响种内竞争的强弱，因此不同立地类型下种内竞争强度关系为背风坡〉丘间地〉迎风坡；将对象木胸径和简单竞争指数（CI）进行回归分析，结果表明两者之间的最佳回归模型为指数模型即：Y=Ae—B，不同立地类型下简单竞争指数（CI）随着对象木胸径的增大呈现减小的趋势，但当对象木胸径大于30cm时简单竞争指数（CI）的变化趋于平缓。

英文摘要：

This research was to investigate the individual competition characteristics of Elm which grow in different site types using 3 variables including CI （ Competition index）, GSCI （ Growth space competition index ） and GSI （ Growth space index ）, The results showed that the Elm which growing in the lee slope of sand have the highest ability in competition, the ability in competition of the Elm which growing in the fiat between sand dunes is less than growing in the Leeward slope of sand, and the Elm which growing in the Windward have the lowest ability in competition, but the GSCI.GSI.average height and average BDH showed the opposite trend; Re- gression analysis showed that the best regression model between CI and BDH is exponential model, the individual competitions strength of Elm reduces gradually along with the diameter increases, but when the BDH is Large than 30cm the change of CI Becomes Insignificant.