AUTHOR=Finotello Alvise , D’Alpaos Andrea , Marani Marco , Bertuzzo Enrico 

TITLE=A Minimalist Model of Salt-Marsh Vegetation Dynamics Driven by Species Competition and Dispersal

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.866570

DOI=10.3389/fmars.2022.866570

ISSN=2296-7745

ABSTRACT=We present a new bi-dimensional, spatially explicit ecological model aimed at simulating the dynamics of halophytic vegetation in tidal saline wetlands. Vegetation dynamics are treated more realistically compared to previous modelling attempts, which employed relatively simple deterministic or stochastic mechanisms, dictated only by the ability of different species to adapt to different topographic elevations. In the proposed model, in contrast, spatial vegetation dynamics depend not only on the marsh local habitat quality but also on spatially explicit mechanisms of dispersal and competition among multiple interacting species. Habitat quality, here determined by the local elevation relative to the mean sea level as a proxy for environmental conditions, is mathematically modeled by a logistic function that represents the fundamental (theoretical) niche of each halophytic species. In this way, our model does not impose any constrain to the upper elevational limit of vegetation performance across marsh topographic gradients. 
We qualitatively test our model against field data based on a suitable assemblage of focus species, and perform a sensitivity analysis aimed at determining how dynamic equilibria in vegetation distributions are affected by changes in model input parameters. Results indicate that the model is robust and can predict realistic vegetation distributions and species-richness patterns. More importantly, the model is also able to effectively reproduce the outcomes of classical ecological experiments, wherein a species is transplanted to an area outside its realized niche. A direct comparison shows that previous models not accounting for dispersal and interspecific competitions are unable to reproduce such dynamics. Our model can be easily integrated into virtually any existing morphodynamic model, thereby strengthening our ability to simulate the coupled biotic and abiotic evolution of salt marshes under changing climate forcings.