Land-Use Shapes Soil Fungal Communities and Functional Guilds in Tropical Forest Ecosystems

Land-use change is a major driver of biodiversity loss and soil degradation in tropical ecosystems, yet its impacts on soil fungal communities, particularly arbuscular mycorrhizal fungi (AMF), remain poorly understood. Here, we investigated how fungal diversity and community composition differed between three land use types (cropland, disturbed, and undisturbed forest vegetation) in two forest reserves in southwestern Nigeria. We hypothesized that intact forests harbor the most diverse fungal communities, while croplands would be dominated by a less diverse community of more disturbance-tolerant fungi. Using high-throughput sequencing of the Internal Transcribed Spacer (ITS) and Small Subunit (SSU) regions, we detected 9240 fungal operational taxonomic units (OTUs) and 738 AMF amplicon sequence variants. Fungal communities were dominated by Ascomycota, while AMF communities were primarily represented by the genus Glomus, followed by Paraglomus, Diversispora, Acaulospora, and Claroideoglomus. Contrary to expectations, we found no significant differences in AMF communities between land-use types (F = 1.1, p = 0.351). Total fungal, saprotrophic and plant pathogenic fungal communities, on the other hand, clearly differed between land-use types. Furthermore, indicator species analysis identified a greater number of unique fungal OTUs in undisturbed forests, suggesting that while generalists persist, specialist fungal taxa are lost in disturbed sites. Overall, our findings indicate that agroforestry, where perennial crops maintain host root continuity, may buffer mycorrhizal fungal assemblages against the negative effects of deforestation, but at the same time highlight the importance of conserving multiple forest habitats to protect site-specific belowground biodiversity.