Hierarchical responses of plant-soil interactions to climate change: consequences for the global carbon cycle

1. Interactions between plant and soil communities play a major role in determining the impact of climate change on ecosystem functioning and the carbon cycle, and the mechanisms involved operate over a wide range of spatial and temporal scales. 2. We present a framework for understanding the consequences of climate-induced changes in plant-soil feedback for the carbon cycle. The framework describes a hierarchy of mechanisms by which changes in climate impact on ecosystem carbon dynamics at three levels of response, namely individual and community reordering and species immigration and loss. 3. For each level, we identify the mechanisms by which climate change impacts on plant-soil interactions with consequences for the carbon cycle. We also demonstrate that the potential for decoupling of plant-soil interactions increases across the three levels of response, being greatest with species immigration and/or loss, for example, if plants were to undergo a biome shift, but their associated soil communities did not. Such decoupling is a largely unrecognized, but potentially important regulator of the future global carbon cycle. 4. Synthesis. The framework presented here highlights a need for a new approach to the study of climate change impacts on plant-soil interactions and carbon cycling that integrates this hierarchy of responses, and incorporates the decoupling of above-ground and below-ground networks, across a range of temporal and spatial scales, and ecosystems.