Exploring Fungal Communities in the Needles of Marginal Conifer Tree Populations

In Montenegro, coniferous forests play a key ecological role in maintaining ecosystem stability. Root-associated mycorrhizal fungi and saprotrophic fungi inhabiting forest soils are well known for their roles in nutrient cycling, organic matter decomposition, and supporting host tree health. In contrast, the fungal communities residing within conifer needles, despite potentially important ecological functions, remain largely underexplored, particularly in natural and marginal forest ecosystems such as those in the Balkans. This study aimed to investigate the diversity and community composition of needle-associated fungi in three native conifers: Picea abies and Abies alba (at the edge of their native range), and the endemic Pinus heldreichii, from different mountainous regions in Montenegro. High-throughput sequencing was conducted to assess fungal diversity and community composition. Dothideomycetes dominated fungal communities in all three tree species, followed by Leotiomycetes and Tremellomycetes. Multivariate analysis revealed distinct fungal communities in P. heldreichii, whereas fungal communities in A. alba and P. abies were partially overlapping. Functional classification showed a dominance of saprotrophic, pathogenic, and endophytic fungi, with P. heldreichii exhibiting the highest proportion of saprotrophs, while A. alba and P. abies showed a considerable proportion of pathogens. The findings highlight strong host specificity, biogeographical influences, and the ecological importance of fungal communities in coniferous forests. This study provides new insights into the diversity and functional roles of needle-associated fungi, emphasizing the need for conservation efforts to maintain microbial biodiversity in native forests of Montenegro.