中文摘要：

在腾格里沙漠东南缘的沙坡头地区设立样地,于2007年4、7和10月从白沙蒿（Artemisia sphaerocephala）根围0～10、10～20、20～30、30～40和40～50cm土层采集土样,分离其丛枝菌根（arbuscular mycorrhiza,AM）真菌并测定相关土壤因子,研究了白沙蒿根围AM真菌的时空分布。结果表明：AM真菌在白沙蒿根系菌丝定殖率达90.5%,其根围AM真菌孢子密度平均5.4ind.g-1土,随季节变化有明显的时空差异,并与土壤微环境显著相关;共分离鉴定出5属21种AM真菌,白沙蒿根围优势菌种为光壁无梗囊霉（Acaulospora laevis）,7月AM真菌物种丰富度最大;AM真菌孢子密度与土壤有机质呈极显著正相关;AM真菌种的丰富度与土壤速效磷呈极显著负相关,与土壤温度和孢子密度呈极显著正相关,与菌丝定殖率呈显著正相关。分析表明,白沙蒿与AM真菌有良好的共生关系,AM真菌增强了白沙蒿对恶劣沙生环境的抵抗力,有助于维护荒漠土壤生态系统的完整性和稳定性。

英文摘要：

In April,July,and October 2007,soil samples （0-10,10-20,20-30,30-40,and 40-50 cm layers） were collected from the rhizosphere of Artemisia sphaerocephala in Shapotou area,the southeastern edge of Tenger desert,aimed to investigate the spatiotemporal variation and diversity of arbuscular mycorrhizal （AM） fungi in the rhizosphere. The hyphal colonization rate of AM fungi in the rhizosphere was 90.5%,with the spore density averaged by 5.4 ind·g-1 soil. There was an obvious spatiotemporal variation in the colonization among seasons,which was significantly correlated with soil microenvironment. A total of 21 AM fungi taxa belonging to 5 genera were isolated and identified,and the dominant species was Acaulospora laevis. Most species were found in July. The spore density was significantly positively correlated with soil organic matter content,and the species richness was significantly negatively correlated with soil available P content but positively correlated with soil temperature,spore density,and hyphal colonization rate. A. sphaerocephala could establish well symbiosis with AM fungi under natural conditions,which was the main reason for the enhancement of the endurance capability of A. sphaerocephala in rigorous circumstance and for the maintenance of the integrity and stability of desert ecosystem.