Root Competition: A Game Theory Model Predicts Plant Root Distribution and Carbon Allocation

Plant roots play a crucial role in carbon uptake, survival, and agricultural yield, and constitute a significant portion of the world's vegetation carbon pool. Unlike aboveground competition, the study of belowground competition is hindered by the inability to directly observe roots. This research introduces a consumer-resource model based on game theory that predicts the spatial distribution of individual plant root density. The model's predictions were tested in a greenhouse experiment where plants exhibited behavior consistent with the model's evolutionary stable equilibrium, both overinvesting in nearby roots and reducing their root foraging range in response to neighbors. These findings provide a theoretical foundation for understanding belowground carbon allocation in vegetation, reconciling seemingly contradictory experimental results such as root segregation and the 'tragedy of the commons' in plant roots.