Reconciling Root Segregation and the Tragedy of the Commons: A Theoretical Framework for Belowground Carbon Allocation

This research presents a new theoretical framework that explains how vegetation allocates carbon belowground, effectively resolving seemingly contradictory observations in experimental studies like root segregation and the tragedy of the commons in plant roots.

Root segregation is the phenomenon where different plant species position their roots at varying depths within the soil profile. This behavior is generally attributed to resource partitioning, where plants avoid competition by accessing distinct soil layers. Conversely, the tragedy of the commons in plant roots describes situations where individual plants exploit shared resources, leading to overutilization and depletion.

Our theoretical foundation proposes that belowground carbon allocation in vegetation is driven by a trade-off between acquiring and conserving resources. Plants strategically allocate roots to different depths to efficiently exploit available resources. By segregating their roots, plants access resources not utilized by neighbors, minimizing competition and maximizing their own resource acquisition.

However, our framework also recognizes the crucial importance of resource conservation. Plants must ensure the long-term sustainability of resource availability as overexploitation can lead to resource depletion and detrimental effects on the entire plant community. Consequently, plants allocate a portion of their carbon belowground towards conservation mechanisms like the production of fine roots enhancing nutrient uptake efficiency and the development of mycorrhizal associations facilitating nutrient acquisition.

By incorporating both resource acquisition and conservation, our theoretical framework provides a comprehensive understanding of belowground carbon allocation in vegetation. It explains why root segregation arises as a strategy to minimize competition and maximize resource acquisition while simultaneously addressing the need for resource conservation to prevent the tragedy of the commons. This reconciliation of seemingly contradictory experimental results contributes to a more holistic understanding of plant root dynamics and ecosystem functioning.