Relationship Between Ectomycorrhizal Fungi And Subtropical Forest Succession In Gutianshan

Ectomycorrhizas (ECM) are symbiont formed between soil fungi and plant roots. ECMfungi, as a main component in ecosystems, are widely distributed and play important roles innutrient transfer, inter-or intra-specific interactions, and maintenance of biodiversity in naturalecosystems.Subtropical evergreen broad-leaved forest is one of essential forest ecosystems in China,with rich plant and ECM fungal diversity. This study was carried out in Comparative StudyPlots (CSP) from three successional stage (10-20,40-50,>70years) in Gutianshan subtropicalforest ecosystem of Zhejiang province. The ECM fungi were investigated usingmorphological characters, pyrosequencing and ITS barcoding.1) Investigation of the ECM sporocarp specimens in CSP plot.A total of235ECM sporocarp specimens were collected from the CSP and identifiedinto95taxa according to morphological characters. Of these taxa,31belonged to Boletacea,21to Amanitacea,19to Russulacea, and24to other families. Boletacea was species rich.2) The ECM fungal sporocarp diversity changed during the forest succession.With the forest succession from early, middle to late stage, Boletacea species diversitydecreased (from17,15to14taxa), but Amanitaceae species diversity increased (from7,9to12taxa). In three age classes, Russulacea species diversity was7,8and5taxa in the early,middle to late forest successional stages. Result shows that the forest successinal stages hadlittle effect on ECM fungal diversity but significant effect on ECM fungal communitycomposition. Spatial analysis demonstrated that ECM fungal sporpcarps preferred to appear inmid-altitude ridges and avoid valleys, indicating the important role of habitat types indetermining distribution of ECM fungal sporocarps, including inclination, soil moisture andplant composition.3) Investigation and sequence analysis of the underground ECM fungi in CSP.A totle of59741ITS sequences were obtained by pyrosequencing from CSPs, of thesesequences,23357were recovered from early stage,16747from middle stage and14169fromlate stage. These sequences were grouped into4361OTUs (operational taxonomic units)based on97%sequence similarity. The numbers of OTUs increased in the early and middlestages and decreased in the late stage. Based on the phylogeny analysis of ITS sequence data,the4361OTUs were grouped into36monophyletic lineages, i.e./amanita,/amphinema-tylospora,/austropaxillus,/boletus,/byssocorticium,/cantharellus,/cenococcum,/ceratobasidium,/clavulina,/coltricia,/cortinarius,/elaphomyces,/entoloma, /hebeloma-alnicola,/helotiales,/hydnellum-sarcodon,/hygrophorus,/hysterangium,/inocybe,/laccaria,/marcelleina-peziza,/paxillus-gyrodon,/phellodon-bankera,/piloderma,/pisolithus-scleroderma,/pseudotomentella,/sebacina,/ramaria-gautieria,/russula-lactarius,/sordariales,/suillus-rhizopogon,/tomentella-thelephora,/tomentellopsis,/tricholoma,/tuber-helvella,/tulasnella.4) Analysis between ECM diversity and community and the forest succession.There were34monophyletic lineages in early stage,28monophyletic lineages in middlestage and29monophyletic lineages in late stage. On these fungi,23monophyletic lineagesshared in all the three stages. In the early and middle age classes,/boletus was the dominantlineage, but tomentella-thelephora was the dominant lineage in late age class.The forest successional stages had significant effect on ECM fungal dicersity andcommunity composition. Diversity and composition of ECM fungi were also significantlyaffected by plant species composition, proportion of ECM plant genus diversity, slope, aspect,altitude and rainfall. The result suggested that plant community structure and ecological factoris the main factor in determining the ECM fungal diversity.