西藏高原针茅草地土壤因子对丛枝菌根真菌物种多样性的影响

在对西藏高原北部针茅草地根围土壤中的丛枝菌根(AM)真菌种类分离鉴定基础上，研究了藏北针茅草地的土壤质地、pH、有机质和有效磷含量对AM真菌孢子密度、分离频度、相对多度、重要值、物种多样性指数和均匀度的影响.结果表明: 针茅草地根围土壤中共分离鉴定出AM真菌3属15种，其中,球囊霉属9种、无梗囊霉属6种、盾巨孢囊霉属1种.球囊霉属和无梗囊霉属为藏北针茅草地AM真菌的优势属；近明球囊霉和光壁无梗囊霉为藏北高寒草原针茅属植物根围AM真菌的优势种.不同质地土壤中AM真菌孢子密度、分离频度、相对多度和重要值均表现出球囊霉属＞无梗囊霉属＞盾巨孢囊霉属的趋势；土壤pH值对AM真菌种群组成无明显影响，球囊霉属和无梗囊霉属真菌分离频度、相对多度和重要值随土壤pH升高而增加，盾巨孢囊霉属则呈现相反趋势；不同土壤有机质含量范围内，AM真菌孢子密度等各项指标均呈球囊霉属＞无梗囊霉属＞盾巨孢囊霉属,而AM真菌属的分布没有明显规律；土壤有效磷含量对AM真菌种丰度和孢子密度影响较小.研究区域内AM真菌物种多样性指数和均匀度随着土壤有效磷含量升高而增加.

Influence of soil factors on species diversity of arbuscular mycorrhizal(AM)fungi in Stipa steppe of Tibet Plateau

This study was based on the isolation and identification of arbuscular mycorrhizal (AM) fungi collected from the alpine Stipa steppe of north Tibet, and focused on the influence of soil texture, pH, organic matter, and available P on the spore density, isolation frequency, relative abundance, importance value, species diversity, and species evenness of the AM fungi. In the rhizosphere soil of the steppe, a total of 15 species AM fungi were isolated and identified, including 9 species of Glomus, 6 species of Acaulospora, and 1 species of Scutellospora. Among them, Glomus and Acaulospora were the dominant genera, and Glomus claroideum and Acaulospora laevis were the dominant species. In the soils with different texture, the spore density, isolation frequency, relative abundance, and importance value of the AM fungi all showed a trend of Glomus > Acaulospora > Scutellospora. Soil pH value had no significant effects on the species composition of AM fungi. However, the isolation frequency, relative abundance, and importance value of Glomus and Acaulospora showed an increasing trend with increasing soil pH, while Scutellospora showed the contrary trend. In the soils with different organic matter content, the spore density of AM fungi all showed a trend of Glomus > Acaulospora > Scutellospora, while the distribution of AM fungi had no definite pattern. The species richness and spore density of AM fungi were less affected by the soil available P content, but the species diversity and evenness showed an increasing trend with the increasing content of soil available P.