Fungal community succession on decomposing leaf litter across five phylogenetically related tree species in a subtropical forest

Abstract

Fungi are an essential component of the ecosystem. They play an integral role in the decomposition of leaf litter and return nutrients to the ecosystem through nutrient cycling. They are considered as the “key players” in leaf litter decomposition, because of their ability to produce a wide range of extracellular enzymes. Time-related changes of fungal communities during leaf litter decomposition have been relatively well-investigated. However, it has not been established how the tree species, tree phylogeny, and leaf litter chemistry influence fungal communities during decomposition. Using direct observations and a culturing approach, this study compiles fungi found in freshly collected leaf litter from five phylogenetically related, native tree species in Taiwan: Celtis formosana (CF), Ficus ampelas (FA), Ficus septica (FS), Macaranga tanarius (MT), and Morus australis (MA). We investigated (i) the effects of tree species (including tree phylogeny) and leaf litter chemistry on fungal community succession, and (ii) specific patterns of fungal succession (including diversity and taxonomic community assembly) on decomposing leaf litter across the selected tree species. We hypothesized that host species and leaf litter chemistry significantly affect fungal community succession. A total of 1325 leaves (CF: 275, FA: 275, FS: 275, MT: 275 and MA: 225) were collected and 236 fungal taxa were recorded (CF: 48, FA: 46, FS: 64, MT: 42 and MA: 36). Tree species relationships had variable associations on the fungal communities, as even closely related tree species had strongly differing communities during decomposition. A high number of species were unique to a single tree species and may indicate ‘host-specificity’ to a particular leaf litter. The overlap of microfungal species in pair wise comparisons of tree species was low (7–16%), and only 1–2% of microfungal species were observed in leaves of all tree species. The percentage of occurrences of fungal communities using Hierarchical Cluster Analyses (HCA) showed that there were at least four succession stages in each tree species during decomposition. Fungal diversity increased at the beginning of each tree species leaf decay, reached peaks, and declined at the final stages. Overall, our findings demonstrate that tree species and leaf litter chemistry are important variables in determining fungal diversity and community composition in leaf litter. Referring to the establishment of fungal discoveries from this experimental design, two new families, two new genera, 40 new species and 56 new host records were reported. This study provides a host-fungus database for future studies on these hosts and increases the knowledge of fungal diversity in leaf litter.