Untangling the fungal niche: the trait-based approach

Abstract

Fungi are prominent components of most terrestrial ecosystems, both in terms of biomass and ecosystem functioning, but the hyper-diverse nature of most communities has obscured the search for unifying principles governing community organization. In particular, unlike plants and animals, observational studies provide little evidence for the existence of niche processes in structuring fungal communities at broad spatial scales. This limits our capacity to predict how communities, and their functioning, vary across landscapes. We outline how a shift in focus, from taxonomy toward functional traits, might prove to be valuable in the search for general patterns in fungal ecology. We build on theoretical advances in plant and animal ecology to provide an empirical framework for a trait-based approach in fungal community ecology. Drawing upon specific characteristics of the fungal system, we highlight the significance of drought stress and combat in structuring free-living fungal communities. We propose a conceptual model to formalize how trade-offs between stress-tolerance and combative dominance are likely to organize communities across environmental gradients. Given that the survival of a fungus in a given environment is contingent on its ability to tolerate antagonistic competitors, measuring variation in combat trait expression along environmental gradients provides a means of elucidating realized, from fundamental niche spaces. We conclude that, using a trait-based understanding of how niche processes structure fungal communities across time and space, we can ultimately link communities with ecosystem functioning. Our trait-based framework highlights fundamental uncertainties that require testing in the fungal system, given their potential to uncover general mechanisms in fungal ecology.

Fungal Traits That Drive Ecosystem Dynamics on Land

“…Accordingly, our findings support the trade-off between these two fungal groups as theorized by Crowther and colleagues (227). These functional groups can form distinct feedbacks on ecosystem function owing to their possession of different response and effect traits.…”

“…In Grime's framework, competitors are characterized as species that can outcompete other species by more effectively exploiting available resources or by directly interfering with competitors. Recently, Crowther and colleagues (227) specifically addressed how this framework applies to fungi, especially with respect to drought tolerance versus combative ability. In fact, they reanalyzed data from a previously published study of fungal competition (228), and they found that strong competitors tended to display less tolerance for low water availability than did weaker competitors.…”

Combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition

“…Dry stress tolerance is governed by the coordinated response of multiple functional traits such as cellwall thickness or production of intracellular osmolyte and/or heat-shock proteins (Crowther et al, 2014). Response to drying stress is energetically expensive and occurs at the cost of other metabolic processes (Schimel et al, 2007).…”

Biotic interactions mediate soil microbial feedbacks to climate change

“…Soil carbon dynamics are particularly sensitive to climate change in forest ecosystems (3), which contain ∼40% (787 Pg carbon) of the global soil carbon pool (2). These soils are generally dominated by basidiomycete fungi (4), which govern the ratelimiting steps in organic matter decomposition via the production of various hydrolytic and oxidative enzymes (5,6). Elevated temperature is expected to stimulate growth and enzyme production of large, cord-forming basidiomycetes (7,8), driving functional shifts in soil decomposer communities (9) and enhancing carbon losses from forest sinks (10).…”