中文摘要：

在毛乌素沙地选设3个样地，系统研究2种密集型克隆植物白沙蒿和黑沙蒿根围丛枝菌根真菌的多样性、分布及共生体结构特征。结果艟示，AM真菌的分布及多样性与宿主植物和土壤条件密切相关，黑沙蒿根围AM真菌的孢子密度高于白沙蒿，水肥条件较好的榆林样地黑沙蒿根围孢子密度最高。本试验共分离出AM真菌6属20种，其中地球囊霉（Glomus geosporum）是黑沙蒿根围的优势菌种，光壁无梗囊霉（Acaulospora laevis）为白沙蒿根围的优势菌种。2种沙蒿根围孢子密度在3个样地均与土壤深度显著负相关，最大值出现在0～20cm表层土。菌丝侵染率与泡囊侵染率呈显著正相关，丛枝侵染率与菌丝圈百分率显著正相关。丛枝侵染率与宿主植物须根在土壤中的分布变化密切相关。分析表明，2种沙蒿均为典型的丛枝菌根植物，其优异吲沙性能的主要原因之一是特化根系与丛枝菌根真菌共牛互补的结果。同时，荒漠土壤植物-菌根最佳组合的优势菌种的筛选，可为毛乌素沙地植被恢复提供材料和依据。

英文摘要：

Three typical sites were chosen in the Mu Us sandland： A Research Station （110°11′22＂E, 39°29′40＂ N）, Yuling （109°42′54＂E,38°20′07＂N）, and Wuhai （106°48′76＂E , 39°46′47＂N）. Six colonization indexes （hypha, vesicular, arbuscular, hyphal coils, colonization Arternisia ordosica and A. sphaerocephala in Auguest soil and dep soil pot 07. ential, and spore density ） were used on roots of Colonizations of AM fungi were correlated with and sites. The species, distribution, and activity of AM fungi were affected by both the host plant factors. Spore density in the rhizosphere of A. ordosica was higher then in that of A. sphaerocephala, and had a maximum value at the Yuling site. In Pearson＇s correlation analysis, spore density was significantly negatively correlated with soil depth. Hyphal colonization was significantly positively correlated with vesicular colonization, but not with arbuscular colonization. The percentage of hyphal coils was significantly correlated with arbuscular colonization. The relativity of arbuscular in different sites and fine roots of host plant was re- markable. Both A. ordosica and A. sphaerocephala were excellent sand fixation plants which benefited from the mutualistic arbuscular-mycorrhizal symbiosis.