Vegetation Type and Decomposition Priming Mediate Brackish Marsh Carbon Accumulation Under Interacting Facets of Global Change
Anthony J. Rietl, J. Patrick Megonigal, Ellen R. Herbert, Matthew L. Kirwan
Abstract
Abstract Coastal wetland carbon pools are globally important, but their response to interacting facets of global change remain unclear. Numerical models neglect species‐specific vegetation responses to sea level rise (SLR) and elevated CO 2 ( e CO 2 ) that are observed in field experiments, while field experiments cannot address the long‐term feedbacks between flooding and soil growth that models show are important. Here, we present a novel numerical model of marsh carbon accumulation parameterized with empirical observations from a long‐running e CO 2 experiment in an organic rich, brackish marsh. Model results indicate that e CO 2 and SLR interact synergistically to increase soil carbon burial, driven by shifts in plant community composition and soil volume expansion. However, newly parameterized interactions between plant biomass and decomposition (i.e. soil priming) reduce the impact of e CO 2 on marsh survival, and by inference, the impact of e CO 2 on soil carbon accumulation.