Qualifying C sequestration in the tidal wetlands of conterminous United States
Abstract
Coastal tidal wetlands are largereservoirs of soil carbon (C) as a result of their high C sequestration rates per unit area. Previous studies have provided estimates of the total C storage along the conterminous US (CONUS) tidal wetlands. However, the C sequestration rates in these systems have yet to be spatially estimatedon a large scale. Here we synthesized soils accretion andC accumulation datain 361 sites from 63 references. We grouped all these sites based on their vegetation types (Tidal Freshwater Wetlands, Brackish, Saltmarsh, and Mangroves) watershed regions. Combined with the National Wetland Inventory (NWI) dataset, we upscaled these observed CAR rates to each tidal wetland type in CONUS, and estimated the total annual C sequestration in each region and predicted their trends based on . Our dataindicated that the mean C accumulation rate (CAR) was161.8±6 g C m-2yr-1in tidal wetlands of CONUS. Carbon accumulation rates variedgreatlyamong regions but not among different vegetation types. The lower Mississippi region had the highest C accumulation rate (271.9±18 g C m-2yr-1), followed by Mid-Atlantic region, both of which were significantly higher than the lowest values which occurred in theCalifornia region (103.8±8 g C m-2yr-1). Combined with their largeareal distribution, the tidal wetlands in lower Mississippi region (mainly in Louisiana) sequestrated 2.13 Tg C/yr, which accounted for over 45% of total C sequestration in CONUS tidalwetlands. Further, the average of the sediment accretion rate (SAR) was 4.82 mm/yr. This SAR generally kept pace with local relative sea level rise rate (RSLR) at all regions except for the lower Mississippi, where the SAR (8.89 mm/yr) was lower than the local RSLR. Overall, RSLR greatlyregulated SAR and CAR in these tidal wetlands. We concluded that CONUS tidal wetlands sequestrated over 4.59 Tg C/yr in the last several decades, and this rate can be maintainedor even increased by 2100. Our study compiles the detailedC sequestration rate data from each of the major regions and states within the CONUS, and provides estimates showing that these tidal wetlands will be a significantC sink during this century.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B41C..03W
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES