Drivers of Fungal Succession in Three Different Woody Species in a Tropical Forest Fragment

Wood-inhabiting fungi are important in forest ecosystems and play an essential role in nutrient and carbon recycling. However, the drivers of fungal succession are poorly understood. We assessed the fungal succession of three tree species in a fragment of Atlantic forest in the state of São Paulo, Brazil. Decomposing branches from different locations were sampled every four months for two years. This study identified 2 309 Operational Taxonomic Units (OTUs), predominantly from the phyla Ascomycota and Basidiomycota, in freshly cut branch fragments of tropical angiosperm trees. The richness exceeded comparable studies in non-tropical ecosystems, attributed to the unique substrate and sequencing methodology. Despite variations in OTU abundance across time points, no significant differences were observed between the three tree species studied. Decomposition rates exhibited temporal variations, with more intense activity during summer and reduced rates in winter. Nitrogen content increased over time, associated with microbial action. Cellulose degradation predominated, followed by hemicelluloses and lignin. Fungal community structure showed a shift from Ascomycota to Basidiomycota, indicative of a natural decomposition pattern. Factors influencing decomposition included substrate specificity, individual branch history, and the fungal community's resilience and competitiveness. The study emphasizes the complex interplay between biotic and abiotic factors in shaping fungal communities during wood decomposition in tropical forests. Overall, the findings contribute to understanding the intricate dynamics of fungal succession, nutrient cycling, and substrate specificity in tropical wood decay processes.