Predicting coexistence of plants subject to a tolerance-competition trade-off

TL;DR

This paper introduces a mathematical model for plant community coexistence based on a stress-tolerance and competitive ability trade-off, providing explicit coexistence conditions and graphical illustrations.

Contribution

The paper presents a novel discrete-time dynamical system model that explicitly characterizes coexistence conditions in terms of a stress-tolerance and competition trade-off.

Findings

Coexistence conditions are graphically represented.

The model generalizes a continuous-time tolerance-fecundity trade-off model.

Conditions for stable coexistence are explicitly derived.

Abstract

Ecological trade-offs between species are often invoked to explain species coexistence in ecological communities. However, few mathematical models have been proposed for which coexistence conditions can be characterized explicitly in terms of a trade-off. Here we present a model of a plant community which allows such a characterization. In the model plant species compete for sites where each site has a fixed stress condition. Species differ both in stress tolerance and competitive ability. Stress tolerance is quantified as the fraction of sites with stress conditions low enough to allow establishment. Competitive ability is quantified as the propensity to win the competition for empty sites. We derive the deterministic, discrete-time dynamical system for the species abundances. We prove the conditions under which plant species can coexist in a stable equilibrium. We show that the coexistence conditions can be characterized graphically, clearly illustrating the trade-off between stress tolerance and competitive ability. We compare our model with a recently proposed, continuous-time dynamical system for a tolerance-fecundity trade-off in plant communities, and we show that this model is a special case of the continuous-time version of our model.