The impact of late Holocene land-use change, climate variability, and sea-level rise on carbon storage in tidal freshwater wetlands on the southeastern United States Coastal Plain

Journal of Geophysical Research: Biogeosciences
By: , and 

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Abstract

This study examines Holocene impacts of changes in climate, land use, and sea-level rise (SLR) on sediment accretion, carbon accumulation rates (CAR), and vegetation along a transect of tidal freshwater forested wetlands (TFFW) to oligohaline marsh along the Waccamaw River, South Carolina (4 sites) and along the Savannah River, Georgia (4 sites). We use pollen, plant macrofossils, accretion, and CAR from cores, spanning the last 1500-6000 years to test the hypothesis that TFFW have remained stable throughout the late Holocene and that marshes transitioned from TFFW during elevated SLR during the Medieval Climate Anomaly, with further transformation resulting from colonial land-use change. Results show low and stable accretion and CAR through much of the Holocene, despite moderate changes associated with Holocene paleoclimate. In all records, the largest observed change occurred within the last ~400 years, driven by colonial land clearance, shifting terrigenous sediment into riparian wetlands, resulting in order-of-magnitude increases in accretion and C accumulation. The oligohaline marshes transitioned from TFFW ~300-500 years ago, coincident with colonial land clearance. Post-colonial decreases in CAR and accretion occur because of watershed reforestation over the last century. All sites show evidence of recent (decades to century) swamp forest decline due to increasing salinity and tidal inundation from SLR. This study suggests that allochthonous sediment input during colonialization helped maintain TFFW, but that current SLR rates are too high for TFFW to persist, although higher accretion rates in oligohaline marshes increases the resilience of tidal wetlands as they transition from TFFW to marsh.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The impact of late Holocene land-use change, climate variability, and sea-level rise on carbon storage in tidal freshwater wetlands on the southeastern United States Coastal Plain
Series title Journal of Geophysical Research: Biogeosciences
DOI 10.1002/2017JG004015
Volume 122
Issue 12
Year Published 2019
Language English
Publisher Wiley
Contributing office(s) Eastern Geology and Paleoclimate Science Center
Description 16 p.
First page 3126
Last page 3141
Country United States
State Georgia, South Carolina
Other Geospatial Savannah River, Waccamaw River