Predicting and Prioritising Community Assembly: Learning Outcomes via Experiments

ABSTRACT Community assembly provides the foundation for applications in biodiversity conservation, climate change, invasion, restoration and synthetic ecology. However, predicting and prioritising assembly outcomes remains difficult. We address this challenge via a mechanism‐free approach useful when little data or knowledge exist (LOVE; Learning Outcomes Via Experiments). We carry out assembly experiments (‘actions’, here, random combinations of species additions) potentially in multiple environments, wait, and measure abundance outcomes. We then train a model to predict outcomes of novel actions or prioritise actions that would yield the most desirable outcomes. Across 10 single‐ and multi‐environment datasets, when trained on 89 randomly selected actions, LOVE predicts outcomes with 0.5%–3.4% mean error, and prioritises actions for maximising richness, maximising abundance, or removing unwanted species, with 94%–99% mean true positive rate and 10%–84% mean true negative rate across tasks. LOVE complements existing mechanism‐first approaches for community ecology and may help address numerous applied challenges. Predicting community assembly outcomes is a major challenge for ecological theory, but is necessary for prioritisation applications (e.g. determining what actions to take to yield a given desirable community state). We show that prediction and prioritisation are possible with no mechanistic understanding of the ecological system, so long as a moderate number of assembly actions and outcomes can be observed.