Data from: Species turnover (β diversity) in ectomycorrhizal fungi linked to NH4+ uptake capacity

AbstractEctomycorrhizal (EcM) fungal communities may be shaped by both deterministic and stochastic processes, potentially influencing ecosystem development and function. We evaluated community assembly processes for EcM fungi of Pseudotsuga menziesii among 12 sites up to 400 km apart in southwest British Columbia (Canada) by investigating species turnover (β diversity) in relation to soil nitrogen (N) availability and physical distance. We then examined functional traits for an N-related niche by quantifying net fluxes of NH4+, NO3- and protons on excised root tips from three contrasting sites using a microelectrode ion flux measurement system. EcM fungal communities were well aligned with soil N availability and pH, with no effect of site proximity (distance-decay curve) on species assemblages. Species turnover was significant (β1/2 = 1.48) along soil N gradients, with many more Tomentella species on high-N than low-N soils, in contrast to Cortinarius species. Ammonium uptake was greatest in the spring on the medium and rich sites, and averaged over 190 nmol m−2 s−1 for Tomentella species. The lowest uptake rates of NH4+ were by non-mycorrhizal roots of axenically grown seedlings (10 nmol m−2 s−1), followed by Cortinarius species (60 nmol m−2 s−1). EcM roots from all sites displayed only marginal uptake of nitrate (8.3 nmol m−2 s−1). These results suggest NH4+ uptake capacity is an important functional trait influencing the assembly of EcM fungal communities. The diversity of EcM fungal species across the region arguably provides critical belowground adaptations to organic and inorganic N supply that are integral to temperate rainforest ecology., Usage notesIon flux resultsNet fluxes of H+, NH4+ and NO3- measured on ectomycorrhizal root tips using a microelectrode ion flux measurement system (MIFE). Roots were retrieved from three sites of contrasting soil fertility, both in the spring and fall of 2014. Non-mycorrhizal roots taken from axenically raised seedlings.Dryad file.xlsxcommunity similarity and distance measuresPair-wise comparisons of test sites for community similarity (Sorensen Bray-Curtis) with distance measures of mineralizable nitrogen and physical distance (km)