Blue carbon stocks in the Siuslaw River Estuary
This study evaluates carbon storage and accumulation in reference, restored, and degraded tidal marshes of Oregon's Siuslaw River Estuary. Findings show high carbon stocks across all marsh types and strong carbon sequestration potential, highlighting the importance of conserving and restoring tidal wetlands as a natural climate solution.
Subject Tags
- Climate resilience
- Carbon storage
- Coastal
Description
Protecting and restoring tidal wetlands is an important natural climate solution because these systems both store carbon and reduce greenhouse gas emissions. This study evaluated sediment carbon in reference, restored, and degraded marshes in the Siuslaw River Estuary and assessed carbon accumulation rates at a reference site. Despite differences in site condition and history, soil organic carbon and other key carbon metrics were similar across all marsh types, although degraded and restored sites had higher bulk density and altered soil processes. Overall carbon stocks in the estuary were relatively high compared to other West Coast marshes, and differences among sites were not statistically significant. Carbon accumulation at the reference marsh indicates substantial annual sequestration, while long-term carbon storage underscores the importance of conserving these systems, as much of this carbon has built up over centuries.
TNC measured sediment carbon and accretion rates in the Siuslaw River Estuary. We found that the top meter of sediment on Cox Island stores carbon equivalent to the yearly electricity use of approximately 150 U.S. homes or 1,100 round‑trip flights from New York to London. Accretion rates on Cox Island are also likely to keep pace with sea level rise.
Suggested Citation
Graves, R., Nuckols, J., Dunn, C., & Carter, J. (2026). Blue carbon stocks in the Siuslaw River Estuary. The Nature Conservancy.
TNC Authors
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Rose Graves
Oregon Conservation and Climate Scientist
The Nature Conservancy
Email: rose.graves@tnc.org -
Jason Nuckols
Oregon Coastal and Freshwater Project Manager
The Nature Conservancy
Email: jnuckols@tnc.org -
Catherine Dunn
Oregon Coast Preserves Manager
The Nature Conservancy
Email: cdunn@tnc.org -
Jena Carter
Oregon Emerald Edge Program Director
The Nature Conservancy
Email: jcarter@tnc.org