Biology subjects

Chomel, M.

Publications and source records attributed to Chomel, M..

3 recordsLinked to original sources

bioRxiv2026

Maximum entropy networks predict fluctuations and stability of food web energetics

A central goal of ecology is understanding how the architecture of food webs, which represent the structural backbone of ecosystems, affects their stability. The analysis of stability in the classical sense of population dynamics (i.e. return to equilibrium) can be successful for a single instance of an empirical food web but ignores the multiplicity of alternative states in which the system could be found as a result of intrinsic variability and fluctuations. Here we propose and test a new methodology to reconstruct, from single empirical observations of a food web, the viable ensemble of alternative realizations respecting the observed resource-consumer linkages and empirical ener-getics. The reconstruction can be handled analytically within a maximum-entropy framework which predicts how empirical food webs access a multitude of alternative states with comparable stability and reactivity. The (measurable) entropy of the reconstructed ensemble directly quantifies this multiplicity and serves as a novel proxy of system resilience, that is the rate of return to equilibrium in response to an external perturbation. We show that the associated ensemble fluctuations provide explicit predictions for the expected response of food webs to external perturbations, such as anthropogenic or climate-induced stresses. We do that by validating the proposed fluctuation-response relation on empirical soil food webs subjected to experimentally controlled perturbations, confirming that intrinsic fluctuations in the unperturbed state predict responses to subsequent stresses. The perturbed states are associated with higher entropy, indicating less likely spontaneous recovery.

ecology↗

bioRxiv2025

Litter biota and quality as drivers of litter decomposition in mature oak forests subject to drought or elevated CO2

1.) Increasing atmospheric CO2 concentrations alongside more frequent and severe droughts are key global change factors impacting litter decomposition and global carbon cycles. Yet, we have a poor understanding of how these perturbations impact interactions between initial litter chemical properties and the abiotic and biotic properties of the decomposition environment, especially under field conditions. 2.) We tested how drought and elevated atmospheric CO2 concentrations modify litter decomposition via litter properties and decomposition environment using two separate, long-term manipulative drought or elevated CO2 field experiments in mature oak woodlands. Litterbags were deployed in a reciprocal transplant design within each experiment, where we measured litter mass loss, carbon-biochemistry, C:N ratios, moisture content, and microbial and mesofaunal properties. 3.) We found that litter placed in droughted plots decomposed slower than in control plots and experimental litter derived from elevated CO2 plots decomposed slower over the first three harvests compared to control litter. Under drought, litter mass loss rates and C:N ratio was regulated by initial litter properties and the decomposition environment, while elevated CO2 impacted mass loss via changes in initial litter properties. 4.) Synthesis: We show that drought and elevated atmospheric CO2 can modify the decomposability of litter prior to litterfall and during the subsequent decomposition, highlighting the need to disentangle their individual and interactive effects to better predict how global change factors influence decomposition.

ecology↗

bioRxiv2022

Globally invariant metabolism but density-diversity mismatch in springtails

Soil life supports the functioning and biodiversity of terrestrial ecosystems1, 2. Springtails (Collembola) are among the most abundant soil animals regulating soil fertility and flow of energy through above- and belowground food webs3-5. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset collected from 2,470 sites, we estimate total soil springtail biomass at 29 Mt carbon (threefold higher than wild terrestrial vertebrates6) and record peak densities up to 2 million individuals per m{superscript 2} in the Arctic. Despite a 20-fold biomass difference between tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the increase in temperature. Neither springtail density nor community metabolism were predicted by local species richness, which was highest in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation7, 8, and resource limitation7, 9, 10 in soil communities. Contrasting temperature responses of biomass, diversity and activity of springtail communities suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting major soil functions.

ecology↗