不同沙地生境下黄柳(Salix gordejevii)的根系分布和冠层结构特征

对分布于3种不同沙地生境（半固定沙丘、固定沙丘、丘间低地）黄柳灌丛的根系分布（根的数目与深度分布）和冠层结构特征（叶面积指数、平均叶倾角以及当年枝长度分布）进行了研究。半固定沙丘上的黄柳根系最发达（根系分布深，数量大），固定沙丘的黄柳明显不及前者，而丘间低地的黄柳根系最不发达。粗根（Φ≥5mm）的分布与土壤水分和土壤容重呈显著相关性，细根（Φ<5mm）的分布与土壤容重和紧实度呈极显著相关。不同程度的根系发育导致地上部分的繁茂程度不同分布于半固定沙丘上的黄柳灌丛叶面积指数较大，当年枝平均长度较大，枝长频度分布趋于正态分布；丘间低地的黄柳灌丛叶面积指数较小，当年枝平均长度较小，枝长频度分布趋于对数正态分布；固定沙丘上灌丛的上述特征大致介于二者之间，而其当年枝长度频度符合Weibull分布。

Root distribution and canopy structure of Salix gordejevii in different sandy land habitats

Root distribution and canopy structure parameters of S. gordejevii in semi fixed sand dunes, fixed sand dunes and inter dunes lowland were investigated. The population in the semi fixed sand dunes had the most developed root systems, followed by the population in the fixed sand dunes, and that in the inter dunes lowland was the last. The number of thick roots was closely related to the soil water content and volume weight of the soil, while that of fine roots closely related to the soil compactness and volume weight. The population in the semi fixed sand dunes had a greater leaf area index and longer first year shoots whose frequency distribution followed a Normal Distribution Model. The population in the inter dunes lowland had a lower leaf area index and shorter first year shoots, whose frequency distribution tended to follow a Logarithmic Normal Distribution Model. The population in fixed sand dunes was rather intermediary between the above two and the frequency distribution of the first year shoot lengths followed a Weibull Distribution Model.