Abstract

The mycorrhizal type of dominant trees ( "mycorrhizal dominance ") likely affects other non-mycorrhizal fungal guilds by means of soil resource partitioning and/or competition (i.e., by niche overlap between saprotrophic and ectomycorrhizal fungi). Chilean temperate rainforests, located in two mountain systems (Andes and Coast), offer a model system with contrasting geological histories and forest mycorrhizal dominance: Nothofagus spp. forests (dominated by ectomycorrhizal (EM) trees), Valdivian forests and coniferous forests (both dominated by arbuscular mycorrhizal (AM) trees). This study aimed to test the effects of mountain system, forest mycorrhizal dominance, and edaphic conditions on soil fungal communities of southern Chile's temperate rainforests. Here, we describe soil fungal communities using ITS2 Illumina sequencing and implemented standard soil chemical analyses. The Andes and Coast mountain systems differed in terms of community composition of total, saprotrophic, EM, and plant pathogenic fungi. Forest mycorrhizal dominance was related to the fungal community composition of total, saprotrophic, and EM fungi. Among soil conditions, only pH affected the total fungi community composition (also affecting EM and plant pathogens), while redox potential was related to saprotrophic (also affected by available P) and EM fungal communities. The composition of plant pathogenic fungal communities was also related to soil C and N. EM fungal richness/abundance was higher in Andean EM tree-dominated forests, while saprotrophic fungi richness and abundance were higher in AM tree-dominated forests. Overall, we found that co-occurring soil fungal groups are affected differently by abiotic (edaphic) and biotic (forest mycorrhizal dominance) factors-possibly including interguild fungal interactions.