Unlocking ensemble ecosystem modelling for large and complex networks

TL;DR

This paper introduces a fast sequential Monte Carlo method for ensemble ecosystem modelling, enabling the analysis of larger, more complex networks efficiently while maintaining accuracy and ecological insight.

Contribution

A novel sequential Monte Carlo sampling approach that significantly accelerates ensemble generation for large ecosystem networks, making practical analysis feasible.

Findings

Speed-up from 108 days to 6 hours in ensemble generation

Equivalent parameter inferences and model predictions with the new method

Ability to identify key parameter combinations driving stability

Abstract

The potential effects of conservation actions on threatened species can be predicted using ensemble ecosystem models by forecasting populations with and without intervention. These model ensembles commonly assume stable coexistence of species in the absence of available data. However, existing ensemble-generation methods become computationally inefficient as the size of the ecosystem network increases, preventing larger networks from being studied. We present a novel sequential Monte Carlo sampling approach for ensemble generation that is orders of magnitude faster than existing approaches. We demonstrate that the methods produce equivalent parameter inferences, model predictions, and tightly constrained parameter combinations using a novel sensitivity analysis method. For one case study, we demonstrate a speed-up from 108 days to 6 hours, while maintaining equivalent ensembles. Additionally, we demonstrate how to identify the parameter combinations that strongly drive feasibility and stability, drawing ecological insight from the ensembles. Now, for the first time, larger and more realistic networks can be practically simulated and analysed.