Diversity of AM fungi associated with the common tropical tree species in Wuzhi Mountain of Hainan Island, China

Arbuscular mycorrhizal (AM) status and diversity of AM fungi were investigated on 10 indigenous tropical tree species at Wuzhi Mountain, central Hainan Island, China. All 10 plant taxa investigated were colonized by AM fungi, while the infective rates varied from 21.8 % to 90.5 % with a mean of 51.5 %. Arbuscules and vesicles were observed in all collected tree samples. A total of thirty-six AM fungi belonging to 4 genera, Acaulospora, Glomus, Gigaspora and Scutellospora were isolated from the rhizosphere of trees. Glomus was the most popular and dominant genus, closely followed by Acaulospora, and then Scutellospora. The highest spore density (7.32) was found in the soils of Swietenia macrophylla, while soils from the rhizosphere of Machilus namu were highest in species richness (5.37) and diversity index (1.6548) of AM fungi. A relationship between the frequency of occurrence and diversity of AM fungi and the elevation of the sampling sites for Swietenia macrophylla was observed. The elevation significantly affected the frequency of occurrence and diversity of Gigaspora and Scutellospora, but showed no significant influence to Glomus and Acaulospora.