Afforestation of cropland fundamentally alters the soil fungal community

Aims The objective of this study was to analyze the responses of the soil fungal community to the afforestation of cropland with single and mixed tree species. Methods We investigated changes in soil fungal community composition, diversity, structure and functional groups in the topsoil (0–20 cm) following afforestation. Six forest types were analyzed in this study: Robinia pseudoacacia (RP), Platycladus orientalis (PO), Pinus tabuliformis (PT), Robinia pseudoacacia + Platycladus orientalis (RPPO), Robinia pseudoacacia + Pinus tabuliformis (RPPT), and Platycladus orientalis + Pinus tabuliformis (POPT). Results Soil fungal community composition and diversity significantly varied among cropland and forestland samples. Afforestation generally reduced soil fungal diversity and altered functional groups, and these variations were mainly mediated by tree species. Rare genera play an important role in the soil fungal network among cropland and forestland samples. Soil available phosphorus (AP) explained the largest portion of the variance in the soil fungal community. Soil available nutrients and microclimate were significantly associated with soil fungal diversity and richness. Conclusions Our observations indicate that afforestation of cropland fundamentally restructures soil fungal community composition, structure, diversity and functional groups. Nutrient availability was a principal factor regulating fungal community composition following afforestation.