Carbon accumulation and vertical accretion in a restored vs. historic salt marsh in southern Puget Sound, Washington, United States

Restoration Ecology
By: , and 

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Abstract

Few comparisons exist between vertical accretion (VA) and carbon accumulation rates (CARs), in restored vs. historic (i.e., reference) marshes. Here we compare these processes in a formerly diked, sparsely vegetated, restored salt marsh (Six Gill Slough, SG), whose surface is subsided relative to the tidal frame, to an adjacent, relatively pristine, historic salt marsh (Animal Slough, AS). Six sediment cores were collected at both AS and SG ~six years after restoration. Cores were analyzed for bulk density, % loss of ignition, % organic carbon, and 210Pb. We found that sharp changes in bulk density in surface layers of SG cores were highly reliable markers for the onset of restoration. The mean VA since restoration at SG (0.79 (sd=0.29) cm yr-1) was ~twice that of AS (0.41 (sd=0.16) cm yr-1). In comparison, the VA at AS over 50 years was 0.30 (sd=0.09) cm yr-1. VA consisted almost entirely of inorganic sediment at SG whereas at AS it was ~55%. Mean CARs at SG were somewhat greater than at AS, but the difference was not significant due to high variability (SG: 81 - 210 g C m-2 yr-1; AS: 115 - 168 g C m-2 yr-1). The mean CAR at AS over the past 50 years was 118 (sd=23) g C m-2 yr-1. This study demonstrates that a sparsely vegetated, restored salt marsh can quickly begin to accumulate carbon and that historic and restored marshes can have similar CARs despite highly divergent formation processes.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Carbon accumulation and vertical accretion in a restored vs. historic salt marsh in southern Puget Sound, Washington, United States
Series title Restoration Ecology
DOI 10.1111/rec.12941
Edition Online First
Year Published 2019
Language English
Publisher Society for Ecological Research
Contributing office(s) Western Ecological Research Center, National Research Program - Western Branch, California Water Science Center
Country United States
State Washington
Other Geospatial Puget Sound