Climate-driven tradeoffs between landscape connectivity and the maintenance of the coastal carbon sink

• Published in: Nature communications Vol. 14; no. 1; p. 1137
• Main Authors: Valentine, Kendall, Herbert, Ellen R., Walters, David C., Chen, Yaping, Smith, Alexander J., Kirwan, Matthew L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 13-03-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/694/2739; 704/158/4016; 704/445/215; Accumulation; Biomass; Carbon; Carbon sequestration; Carbon sinks; Climate change; Climate-change impacts; Coastal ecosystems; Coastal erosion; Ecosystems; ENVIRONMENTAL SCIENCES; Forest biomass; Forests; Geomorphology; Humanities and Social Sciences; Landscape; Marshes; multidisciplinary; Nutrients; Organic carbon; Science; Science & Technology; Science (multidisciplinary); Sea level; Sea level rise; Tradeoffs; Wetlands ecology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36803-7

Ecosystem connectivity tends to increase the resilience and function of ecosystems responding to stressors. Coastal ecosystems sequester disproportionately large amounts of carbon, but rapid exchange of water, nutrients, and sediment makes them vulnerable to sea level rise and coastal erosion. Individual components of the coastal landscape (i.e., marsh, forest, bay) have contrasting responses to sea level rise, making it difficult to forecast the response of the integrated coastal carbon sink. Here we couple a spatially-explicit geomorphic model with a point-based carbon accumulation model, and show that landscape connectivity, in-situ carbon accumulation rates, and the size of the landscape-scale coastal carbon stock all peak at intermediate sea level rise rates despite divergent responses of individual components. Progressive loss of forest biomass under increasing sea level rise leads to a shift from a system dominated by forest biomass carbon towards one dominated by marsh soil carbon that is maintained by substantial recycling of organic carbon between marshes and bays. These results suggest that climate change strengthens connectivity between adjacent coastal ecosystems, but with tradeoffs that include a shift towards more labile carbon, smaller marsh and forest extents, and the accumulation of carbon in portions of the landscape more vulnerable to sea level rise and erosion.
Coastal connectivity between ecosystems increases with sea level rise but fails to maintain landscape carbon storage and marsh extent at extreme rates of sea level rise.