Land use change in the Amazon rain forest favours generalist fungi

Summary Land use change is a significant threat to biodiversity, particularly within tropical ecosystems, but the responses of microbial communities remain poorly understood. We used long‐term plots established in multiple land use types in the Brazilian Amazon to examine the effect of land use change on soil fungal communities. We measured fungal richness and composition and identified factors associated with shifts in community composition across multiple land use types, including primary forest, two secondary forests and a chronosequence of differently aged pastures. Additionally, we used distribution patterns to estimate the niche breadth of fungal taxa in order to quantify changes in the relative abundance of generalists, or fungi with broad environmental tolerance, in response to land use change. Conversion of primary forest to pasture resulted in large reductions in fungal richness coupled with substantial changes in community composition. Generalist fungi were strongly favoured in all pasture sites, regardless of time since conversion. Distance to primary forests was the strongest correlate of community composition in pastures, indicating that primary forests can act as reservoirs for recolonization by forest‐associated fungi. The two secondary forests showed variable patterns of richness, composition and the overall abundance of generalist fungi, suggesting that community recovery is stochastic. Fungal community response to land use change mirrors patterns observed in macroscopic organisms, which indicates that the increased prevalence of generalist taxa is a consistent response to disturbance across broad taxonomic groups. A lay summary is available for this article.