Temperature niche position and breadth of ectomycorrhizal fungi: Reduced diversity under warming predicted by a nested community structure

Abstract

Species with narrow niche breadths are assumed to be more susceptible to environmental changes than those with wide niche breadths. Although information on niche properties is necessary for predicting biological responses to environmental changes, such information is largely missing for soil microbes. In this study, we present the temperature niche positions and breadths of a functionally important group of eukaryotic soil microbes, ectomycorrhizal (EM) fungi. We compiled high-quality EM fungal sequence data from 26 forested sites in Japan (with mean annual temperatures ranging from 1.6 to 23.6°C) to create temperature niche profiles for each individual fungal species. Nested theory and a newly developed weighted-randomization null model were applied to 75 fungal operational taxonomic units (OTUs) with high occurrence records to examine potential preferences for certain temperature positions and breadths. Our analyses revealed that (a) many EM fungal OTUs were restricted to habitats with low mean annual temperatures, (b) fungal OTUs observed at colder sites exhibited narrower temperature breadths than expected by chance, (c) the composition of EM fungal OTUs exhibited a nested pattern along the temperature gradient, and (d) EM fungal richness was highest at colder sites, where the greatest degree of overlap in OTU occurrence was observed. These findings imply that future warming may limit the distribution of many EM fungal species that are currently adapted to only cold climates. This could eventually reduce EM fungal biodiversity, which is linked to forest function through symbiotic associations with trees. This study demonstrates the distribution and environmental ranges of various EM fungal species and can contribute to develop species distribution models with the aim of conserving microbes in the face of climate change.

Regional-Scale In-Depth Analysis of Soil Fungal Diversity Reveals Strong pH and Plant Species Effects in Northern Europe

“…The lineage-level taxonomic composition of EcM fungi is consistent with previous comprehensive root-tip-based surveys in temperate Eurasia and North America, where forests of Pinaceae or Fagales dominate (Tedersoo et al, 2012a;Miyamoto et al, 2018;van der Linde et al, 2018). The overall commonness of/inocybe lineage and low abundance of/cortinarius, the rhizomorph-forming group and most species-rich EcM fungal genus in the Nordic countries (Knudsen and Vesterhold, 2012), is somewhat unexpected.…”

Community Assembly of Endophytic Fungi in Ectomycorrhizae of Betulaceae Plants at a Regional Scale

“…For example, some fungal taxa preferred to nutrient-rich habitats, while some taxa could grow well in nutrient-poor habitats (Cox et al, 2010;Mundra et al, 2016). In addition, some fungi only distributed in habitats with lower MAT and exhibited narrower temperature breadths, while some fungi were detected across wider temperature ranges and in warmer habitats (Miyamoto et al, 2018).…”

“…different niche properties including nutrients and climate (Cox et al, 2010;Mcguire et al, 2010;Mundra et al, 2016;Barnes et al, 2018;Miyamoto et al, 2018). For example, some fungal taxa preferred to nutrient-rich habitats, while some taxa could grow well in nutrient-poor habitats (Cox et al, 2010;Mundra et al, 2016).…”

“…In addition, with increasing nitrogen (N) addition, the abundance of fungal species changed (Cox et al, 2010). This could be ascribable to the fact that fungal taxa commonly prefer to certain niche properties and differ in response to environmental changes (Cox et al, 2010;Mcguire et al, 2010;Mundra et al, 2016;Barnes et al, 2018;Miyamoto et al, 2018).…”

Ectomycorrhizal Fungi: Participation in Nutrient Turnover and Community Assembly Pattern in Forest Ecosystems

“…The richness of EcMF communities decreases with increasing atmospheric temperature [113,114]. Analysis of the EcMF temperature niche position on the Japanese archipelago revealed that the richness and diversity of the EcMF community are highest in cold regions; this further indicates that climate warming might limit the distribution of EcMF only adapted to the cold climate and thus reduce EcMF diversity [113]. However, there exist considerable differences in the temperature sensitivity and temperature adaptability among various EcMF taxa.…”