Rhizosphere control on peat carbon stability

Living plant roots interact with soil microbial communities in the rhizosphere, influencing the decomposition rate of soil organic carbon (SOC). These interactions, known as rhizosphere priming effects, can either stabilize or destabilize SOC pools, representing a critical feedback mechanism in the soil–climate system. Despite the disproportionate role of peatlands in the global carbon cycle, rhizosphere priming in these ecosystems remains understudied.

We present findings from primary research on rhizosphere priming in coastal and inland peat soils, complemented by a meta-analysis. Our results show that both positive and negative rhizosphere priming effects can be much stronger in peat and other wetland soils compared to upland soils.

We attribute these differences to contrasting redox conditions and carbon preservation mechanisms in peats compared to upland soils. Building on this, we propose a conceptual framework in which wetland vascular plants act as dual regulators of soil redox status. Through root exudation and oxygen loss, they provide both electron donors and acceptors, influencing the stability of peat carbon stocks in opposite directions. Finally, we discuss how these root-driven processes may determine the response of peatland carbon dynamics to climate change.