Biota-mediated carbon cycling – a synthesis of biotic-interaction controls on blue carbon

Research on biotic interactions has been a core theme of ecology for over a century. However, despite the obvious role that biota play in the global carbon cycle, effects of biotic interactions on carbon pools and fluxes are poorly understood. Here we develop a conceptual framework that illustrates the importance of biotic interactions in regulating carbon cycling based on a literature review and quantitative synthesis by means of meta-analysis. Our study focuses on blue carbon ecosystems, vegetated coastal ecosystems that function as the most effective long-term CO2 sinks of the biosphere. We demonstrate that a multitude of mutualistic, competitive and consumer-resource interactions between plants, animals and microbiota exert strong effects on carbon cycling across various spatial scales ranging from the rhizosphere to the landscape scale. Climate-change sensitive abiotic factors modulate the strength of biotic-interaction effects on carbon fluxes, suggesting that the importance of bi...