Ectomycorrhizal (EcM) fungi are key forest symbionts, yet the extent to which environmental factors and host identity interact to shape EcM communities remains unclear. We examined EcM fungi biodiversity changes associated with three co-occurring Nothofagus species across two sites along a precipitation gradient in northern Patagonia. Specifically, we hypothesized that (i) environmental context modulates host-specific effects on EcM fungal biodiversity, and (ii) the distribution of exploration types, as key functional traits, is primarily structured by precipitation-driven abiotic conditions (e.g., soil moisture and related edaphic factors). Fine roots of Nothofagus alpina , N. obliqua , and N. dombeyi were sampled in mixed forests at two sites with different precipitation levels (humid vs. mesic). EcM colonization was determined and EcM fungi identified by morphotyping and Sanger sequencing (ITS). We compared EcM colonization, taxonomic α- and β-diversity, and functional diversity based on the characterization of EcM exploration types across sites and hosts, and assessed soil properties (moisture, pH, electrical conductivity, and nutrient content). Site was the principal driver of EcM abundance and of both taxonomic and functional diversity. While EcM colonization and taxonomic α-diversity responded exclusively to site, taxonomic β-diversity revealed a site-dependent host effect; communities differed among Nothofagus species only at the mesic site. Functional diversity was determined solely by site. Site, representing environmental context, especially determined by precipitation level, generally overrides host effects on EcM communities, with host identity influencing β-diversity only under specific conditions. Our findings provide new insight into EcM ecology in temperate Patagonian forests and underscore the value of integrating functional and taxonomic perspectives to understand plant-fungal interactions across environmental gradients, particularly under ongoing climate change. This information is critical for informing climate-adaptive forest management.
Floriani et al. (Thu,) studied this question.