Energy and physiological tolerance explain multi‐trophic soil diversity in temperate mountains

Abstract

Aim Although soil biodiversity is extremely rich and spatially variable, both in terms of species and trophic groups, we still know little about its main drivers. Here, we contrast four long‐standing hypotheses to explain the spatial variation of soil multi‐trophic diversity: energy, physiological tolerance, habitat heterogeneity and resource heterogeneity. Location French Alps. Methods We built on a large‐scale observatory across the French Alps (Orchamp) made of seventeen elevational gradients (~90 plots) ranging from low to very high altitude (280–3,160 m), and encompassing large variations in climate, vegetation and pedological conditions. Biodiversity measurements of 36 soil trophic groups were obtained through environmental DNA metabarcoding. Using a machine learning approach, we assessed (1) the relative importance of predictors linked to different ecological hypotheses in explaining overall multi‐trophic soil biodiversity and (2) the consistency of the response curves across trophic groups. Results We showed that predictors associated with the four hypotheses had a statistically significant influence on soil multi‐trophic diversity, with the strongest support for the energy and physiological tolerance hypotheses. Physiological tolerance explained spatial variation in soil diversity consistently across trophic groups, and was an especially strong predictor for bacteria, protists and microfauna. The effect of energy was more group‐specific, with energy input through soil organic matter strongly affecting groups related to the detritus channel. Habitat and resource heterogeneity had overall weaker and more specific impacts on biodiversity with habitat heterogeneity affecting mostly autotrophs, and resource heterogeneity affecting bacterivores, phytophagous insects, enchytraeids and saprotrophic fungi. Main Conclusions Despite the variability of responses to the environmental drivers found across soil trophic groups, major commonalities on the ecological processes structuring soil biodiversity emerged. We conclude that among the major ecological hypotheses traditionally applied to aboveground organisms, some are particularly relevant to predict the spatial variation in soil biodiversity across the major soil trophic groups.

A Practical Approach to Constructing a Knowledge Graph for Soil Ecological Research

“…Large trait databases have the potential to address this trade-off between feasibility and completeness. By supporting the assignment of species (or higher taxonomic ranks) to trophic and/or functional groups, they reduce the dimensionality of ecological communities without biasing studies toward a single trophic level or taxonomic group [30, 15]. Yet, challenges remain: although we have trait databases available for some of them, our trait knowledge is limited for most groups of soil organisms.…”

“…The difficulty of integrating data distributed across heterogeneous sources remains. As a result, integrative analyses of soil communities that span several taxonomic groups and integrate multitrophic interactions are scarce — see [15] for an example — although essential to improve our understanding of the links between soil biodiversity and ecosystem functioning [16].…”

Towards all-inclusive community ecology via DNA metabarcoding

“…(Bloor, Si-Moussi, Taberlet, Carrère, & Hedde, 2021;Calderón-Sanou et al, 2022;Guerrieri et al, 2022). This approach has the advantage of providing a reasonable representation of biodiversity, with good information on selected key taxa and few taxa completely missing, and might thus allow exploring complex relationships between multiple taxonomic groups (Bloor et al, 2021;Calderón-Sanou et al, 2022). Nevertheless, similarly to approach 2.1, it remains costly and labor-intensive.…”

“…One decade of advances on eDNA metabarcoding has fostered our ability to obtain biodiversity data, filling long-standing gaps on many components of both terrestrial and aquatic environments. Nevertheless, just a few studies have taken the challenge of attempting analyses covering multiple taxonomic groups, and trying to identify the complex multi-trophic interactions between them (but see Bloor et al, 2021;Calderón-Sanou et al, 2021;Calderón-Sanou et al, 2022;Martinez-Almoyna et al, 2019). Several approaches can now allow an all-inclusive community ecology, potentially allowing unprecedented understanding of patterns and processes underlying biodiversity variation, but both technical and conceptual developments will be required for a more widespread application of the all-inclusive ecology, and some challenges are shared by most approaches.…”

New progress in exploring the mechanisms underlying extraordinarily high biodiversity in global hotspots and their implications for conservation

“…Moving up from single taxa to multi‐trophic assemblages, Calderón‐Sanou et al (2022) tested the role of energy, physiological tolerance, habitat heterogeneity and resource heterogeneity on the spatial variation of soil multi‐trophic diversity across the French Alps. Using an environmentally stratified sampling design together with soil environmental DNA and a machine learning algorithm, the authors found the strongest support for the energy and physiological tolerance hypotheses across the 36 analysed soil trophic groups, while the other two hypotheses were important only for some specific ones.…”