Blue Carbon Soil Stock Development and Estimates Within Northern Florida Wetlands

Abstract

Blue carbon habitats, such as mangroves and salt marshes, have been recognized as carbon burial hotspots; however, methods on measuring blue carbon stocks have varied and thus leave uncertainty in global blue carbon stock estimates. This study analyzes blue carbon stocks in northern Florida wetlands along the Atlantic and Gulf coasts. Carbon measurements within 1–3m length vibracores yield total core stocks of 9.9–21.5 kgC·m−2 and 7.7–10.9 kgC·m−2 for the Atlantic and Gulf coast cores, respectively. Following recent IPCC guidelines, blue carbon stock estimates in the top meter are 7.0 kgC·m−2–8.0 kgC·m−2 and 6.1 kgC·m−2–8.6 kgC·m−2 for the Atlantic and Gulf cores, respectively. Changes in stable isotopic (δ13C, C/N) and lignin biomarker (C/V) indices suggest both coastlines experienced salt marsh and mangrove transgressions into non-blue carbon habitats during the mid- to late-Holocene following relative sea-level rise. These transgressions impact carbon storage within the cores as the presence of carbon-poor soils, characteristic of non-blue carbon habitats, result in lower 1m carbon stocks in north Florida Gulf wetlands, and a deeper extent of carbon-rich soils, characteristic of blue carbon habitats, drive higher 1m and total carbon stocks in north Florida Atlantic wetlands. Future blue carbon research should assess carbon stocks down to bedrock when possible, as land-cover and/or climate change can impact different depths across localities. Ignoring carbon-rich soil below the top meter of soil may underestimate potential carbon emissions based on these changes.

Organic carbon stocks of Great British saltmarshes

“…The Troels-Smith soil descriptions (Troels-Smith, 1955) were used to create soil profiles for the 606 cores (Miller et al, 2022a;Smeaton et al, 2023). The soil profiles highlight that, unlike the saltmarshes of North America and Australia (e.g., Kelleway et al, 2016;Gorham et al, 2021;Vaughn et al, 2021), soils associated with GB marshes rarely extend to a depth of 1 m. The GB systems are characterized by saltmarsh soils overlying sediments deposited in an intertidal flat environment that preceded the development of the saltmarsh (Figure 3). Soil profiles similar to these have been described in other blue carbon (Mueller et al, 2019;Smeaton et al, 2020;Miller et al, 2023) and sea level studies (Teasdale et al, 2011;Barlow et al, 2014;Long et al, 2014;Long et al, 2016) across the United Kingdom and Europe.…”

Sedimentary carbon on the continental shelf: Emerging capabilities and research priorities for Blue Carbon

“…This method was developed for North Sea continental shelf sediments, where phytoplankton primary productivity is the main source of organic matter. It has more recently been applied as part of a study of organic matter in the South Yellow Sea and East China Sea sediments (Chen et al, 2021), and in coastal blue carbon habitats (Vaughn et al, 2021). Recently, compound-specific radiocarbon analysis of amino acids has been proposed as a novel method for improving understanding of food webs and sedimentary organic carbon .…”

Response of Mangrove Development to Air Temperature Variation Over the Past 3000 Years in Qinzhou Bay, Tropical China

“…The world at present is characterized by a rapid sea level rise, rapid warming, frequent extreme climate events, and an increasing population. Therefore, to predict the fate of mangrove ecosystems under this rapidly changing environment, it is imperative to understand how they have changed or disappeared in the past (Valiela et al, 2001), by reconstructing historical mangrove dynamics through useful indicators recorded in sediments (Gonneea et al, 2004;Ellison, 2008;França et al, 2013;Cohen et al, 2016;Meng et al, 2017;Xia et al, 2019;Vaughn et al, 2021).…”