Historical logging alters soil fungal community composition and network in a tropical rainforest

The effects of logging on forest ecosystems are severe and long-lasting. In addition, these effects are often paralleled with shifts in soil fungal community composition and functional guilds with potential feedbacks on ecosystem functioning. Clarifying how soil fungal communities are linked to the effects of historical logging could help us better understand the ecological consequences of logging. Here, we collected soils from 61 25 m × 25 m quadrats across a 160-km2 tropical rainforest in Hainan Island, China, which had been partially clear cut or selectively harvested and left to recover for up to 50 years. Soil fungal community composition and species co-variation networks were investigated in the selectively harvested (select cut) and clear cut forest stands and were compared to data from the primary stands without a history of logging. Historical logging shifted fungal community composition from Zygomycota towards Basidiomycota domination mainly through modifying vegetation composition and soil properties. The relative abundance of root associated fungi (i.e., ectomycorrhizal and ericoid mycorrhizal), animal pathogens and wood saprotrophs increased 50 years after logging, while the relative abundance of undefined saprotrophs decreased. In select cut stands, the fungal community was better organized with higher numbers of functionally interrelated operational taxonomic units (OTUs) and more generalist OTUs. In contrast, the number of functionally interrelated OTUs was lowest in the fungal network in clear cut stands. By comparing the topological roles of the shared OTUs among the three types of forest stands, we found role-shifts among fungal members from the specialists in the primary stands to the generalists in the select cut stands. Ascomycota and Basidiomycota were the major phyla involved in the role-shifts. Moreover, the fungal network in primary stands was positively associated with litter nutrients, while that in select cut stands was positively related to soil nutrients content. This indicated that the major drivers of fungal community organization shifted from litter nutrients content in the primary forest towards soil nutrients content in the selectively harvested forest. In the clear cut stands, however, the associations between fungal network and both litter and soil nutrients content decreased when compared with those in the primary and select cut stands. More than 60% of the total links among fungal members in clear cut stands were negative, implying a trend of niche partitioning among fungal groups with a half-century recovery after clearcutting in the tropical rainforest.