Applying population and community ecology theory to advance understanding of belowground biogeochemistry

Abstract

Approaches to quantifying and predicting soil biogeochemical cycles mostly consider microbial biomass and community composition as products of the abiotic environment. Current numerical approaches then primarily emphasise the importance of microbe-environment interactions and physiology as controls on biogeochemical cycles. Decidedly less attention has been paid to understanding control exerted by community dynamics and biotic interactions. Yet a rich literature of theoretical and empirical contributions highlights the importance of considering how variation in microbial population ecology, especially biotic interactions, is related to variation in key biogeochemical processes like soil carbon formation. We demonstrate how a population and community ecology perspective can be used to (1) understand the impact of microbial communities on biogeochemical cycles and (2) reframe current theory and models to include more detailed microbial ecology. Through a series of simulations we illustrate how density dependence and key biotic interactions, such as competition and predation, can determine the degree to which microbes regulate soil biogeochemical cycles. The ecological perspective and model simulations we present lay the foundation for developing empirical research and complementary models that explore the diversity of ecological mechanisms that operate in microbial communities to regulate biogeochemical processes.

Dispersal-Based Microbial Community Assembly Decreases Biogeochemical Function

“…As ecosystem process models become more sophisticated (e.g., [44][45][46]), there is a need to improve these models by better understanding the linkages among community assembly processes and ecosystem function. Here, we used an ecological simulation model to highlight the importance of dispersal-based microbial community assembly for biogeochemical function.…”

“…The cumulative impacts of ecological processes through time and how they relate to ecosystem-level processes is an emerging research frontier in ecosystem science [2,44,52,68,69]. We reveal how dispersal-based community assembly can decrease adaptation to local environments and, in turn, decrease biogeochemical function.…”

Animal‐mediated organic matter transformation: Aquatic insects as a source of microbially bioavailable organic nutrients and energy

“…Our data suggest that animal‐mediated transformation of ingested organic matter (detritus, prey, primary producers) provides a significant flux of labile energy (DOC) and nutrients (DON) to heterotrophic microbes. Recent biogeochemical models describe the coupled dynamics between organic matter resources and microbial communities by separating organic matter pools based on their chemical composition or biological reactivity (e.g., Buchkowski, Bradford, Grandy, Schmitz, & Wieder, ; Guenet, Danger, Abbadie, & Lacroix, ). While conceptual and numerical food web models capture animal waste fluxes as sources of detritus and nutrients (particulate organic matter; e.g., Carpenter, Cole, Pace, & Wilkinson, ; Moore et al, ; Zou et al, ), few models represent the production of labile dissolved organic nutrients and energy, which are readily available to heterotrophic microbes.…”

Nitrogen recycling in coupled green and brown food webs: Weak effects of herbivory and detritivory when nitrogen passes through soil

“…We developed a dynamical systems model to track the flow of nitrogen and our 15 N tracer through the experimental ecosystems. Our model is based on previous ecosystem models and includes all the total nitrogen and 15 N pools measured in our experiment: litter, soil, isopods, soil microbes, and plants (Figure a,b; Zou et al, ; Buchkowski, Bradford, Grandy, Schmitz, & Wieder, ). Details of the model equations and example simulations are presented in the supporting information (SI: Section ).…”