Shift of soil fungal communities under afforestation in Nanliu River Basin, southwest China.

Although soil fungi play a pivotal role in determining soil ecosystematic feedbacks to afforestation, there remains a big knowledge gap in the effects of afforestation on soil fungal communities, especially at a watershed scale. In this study, the variations of soil fungal diversity and community structures under afforestation were investigated in Nanliu River Basin, where paddy field and dry farmland were converted to eucalyptus plantation at an unprecedented speed. Spatial distance along the upper, middle and lower reaches of the Basin were also considered to analyze the dominant sources of the variations. The results demonstrated that eucalyptus afforestation had little effect on soil fungal diversity but could significantly influence fungal community structures. As paddy field and dry farmland converted to eucalyptus plantation, dominant fungal phylum shifted from Ascomycota to Ascomycota and Basidiomycota. Compared with afforestation from dry farmland, much bigger variation of fungal community structures was found in afforestation from paddy field. In addition, the significant change of fungal community structures exhibited in the upper reaches was from dry farmland, while presented in the middle reaches was from paddy field. However, afforestation comprised a larger source of variation than spatial distance within the soil fungal community structures, and Fusarium, Westerdykella,Zopfiella and Scleroderma were the most sensitive genera affected by afforestation. These results showed that afforestation did not always cause soil fungal diversity change and the heterogeneity of fungal community structures under afforestation was mainly controlled by original land use practices, while spatial distance partly decided the results.