Carbon Stocks and Accumulation Rates in Salt Marshes of the Pacific Coast of Canada

Abstract. Tidal salt marshes are known to accumulate blue carbon at high rates relative to their surface area and have been put forth as a potential means for enhanced CO2 sequestration. However, estimates of salt marsh carbon accumulation rates are based on a limited number of marshes globally and the estimation of carbon accumulation rates require detailed dating to provide accurate estimates. We address one data gap along the Pacific Coast of Canada by estimating carbon stocks in 34 sediment cores and estimating carbon accumulation rates using 210Pb dating on four cores from seven salt marshes within the Clayoquot Sound UNESCO Biosphere Reserve and Pacific Rim National Park Reserve of Canada (49.2° N, 125.80° W). Carbon stocks averaged 80.6 ± 43.8 megagrams of carbon per hectare (Mg C ha−1) between the seven salt marshes, and carbon accumulation rates averaged 146 ± 102 grams carbon per square meter per year (g C m−2 yr−1). These rates are comparable to those found in salt marshes further south along the Pacific coast of North America (32.5–38.2° N) and at similar latitudes in Eastern Canada and Northern Europe (43.6–55.5° N). The seven Clayoquot Sound salt marshes currently accumulate carbon at a rate of 54.28 Mg C yr−1 over an area of 46.94 ha, 87 % of which occurs in the high marsh zone. On a per-hectare basis, Clayoquot Sound salt marsh soils accumulate carbon at least one order of magnitude more quickly than the average of global boreal forest soils, and approximately two times larger than rates for forests in British Columbia. However, because of their relatively small area, we suggest that their carbon accumulation rate capacity could best be considered as a climate mitigation co-benefit when conserving for other salt marsh ecosystem services.

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Quantification of Blue Carbon in Salt Marshes of the Pacific Coast of Canada

10.5194/bg-2021-157 ◽

2021 ◽

Author(s):

Stephen G. Chastain ◽

Karen E. Kohfeld ◽

Marlow G. Pellatt ◽

Carolina Olid ◽

Maija Gailis

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Pacific Coast ◽

Peat Layer ◽

Accumulation Rates ◽

The Pacific ◽

C Stocks ◽

Clayoquot Sound ◽

C Stock ◽

Global Estimates

Abstract. Tidal salt marshes are known to accumulate “blue carbon” at high rates relative to their surface area, which render these systems among the Earth’s most efficient carbon (C) sinks. However, the potential for tidal salt marshes to mitigate global warming remains poorly constrained because of the lack of representative sampling of tidal marshes from around the globe, inadequate areal extent estimations, and inappropriate dating methods for accurately estimating C accumulation rates. Here we provide the first estimates of organic C storage and accumulation rates in salt marshes along the Pacific Coast of Canada, within the Clayoquot Sound UNESCO Biosphere Reserve and Pacific Rim National Park Reserve, a region currently underrepresented in global compilations. Within the context of other sites from the Pacific Coast of North America, these young Clayoquot Sound marshes have relatively low C stocks but are accumulating C at rates that are higher than the global average, with pronounced differences between high and low marsh habitats. The average C stock calculated during the past 30 years is 54 ± 5 Mg C ha−1 (mean ± standard error), which accounts for 81 % of the C accumulated to the base of the marsh peat layer (67 ± 9 Mg C ha−1). The total C stock is just under one-third of previous global estimates of salt marsh C stocks, likely due to the shallow depth and young age of the marsh. In contrast, the average C accumulation rate (CAR) (184 ± 50 g C m−2 yr−1 to the base of the peat layer) is higher than both CARs from salt marshes along the Pacific coast (112 ± 12 g C m−2 yr−1) and global estimates (91 ± 7 g C m−2 yr−1). This difference was even more pronounced when we considered individual marsh zones: CARs were significantly greater in high marsh (303 ± 45 g C m−2 yr−1) compared to the low marsh sediments (63 ± 6 g C m−2 yr−1), an observation unique to Clayoquot Sound among NE Pacific Coast marsh studies. We attribute low CARs in the low marsh zones to shallow-rooting vegetation, reduced terrestrial sediment inputs, negative relative sea level rise in the region, and enhanced erosional processes. Per-hectare, CARs in Clayoquot Sound marsh soils are approximately 2–7 times greater than C uptake rates based on net ecosystem productivity in Canadian boreal forests, which highlights their potential importance as C reservoirs and the need to consider their C accumulation capacity as a climate mitigation co-benefit when conserving for other salt marsh ecosystem services.

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Multiple Stressors Influence Salt Marsh Recovery after a Spring Fire at Mugu Lagoon, CA

Wetlands ◽

10.1007/s13157-019-01210-6 ◽

2019 ◽

Vol 40 (4) ◽

pp. 757-769 ◽

Cited By ~ 1

Author(s):

Lauren N. Brown ◽

Jordan A. Rosencranz ◽

Katherine S. Willis ◽

Richard F. Ambrose ◽

Glen M. MacDonald

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Pacific Coast ◽

Multiple Stressors ◽

First Record ◽

Extreme Drought ◽

Percent Cover ◽

Burned Areas ◽

In Situ Data ◽

The Pacific

Abstract This paper presents the first record of fire in Pacific coast salt marshes; the 1993 Green Meadows Fire and the 2013 Camarillo Springs Fire burned an area of Salicornia-dominated salt marsh at Point Mugu, CA. These fires inspire concern about resiliency of ecosystems not adapted to fire, already threatened by sea-level rise (SLR), and under stress from extreme drought. We monitored vegetation percent cover, diversity, and soil organic carbon (SOC) in burned and unburned areas of the salt marsh following the 2013 Camarillo Springs Fire and used remotely sensed Normalized Vegetation Difference Index (NDVI) analysis to verify the in situ data. Two years following the fire, vegetation percent cover in burned areas was significantly lower than in unburned areas, with dominant-species change in recovered areas, and NDVI was lower than pre-fire conditions. Multi-year disturbance, such as fire, presents challenges for salt marsh resilience and dependent species, especially in sites facing multiple stressors. With anticipated higher temperatures, increased aridity, extreme drought, and higher frequency fires becoming a reality for much of the Pacific coast, this study indicates that fire in Salicornia-dominated marshes is a vulnerability that will need to be addressed differently from other grass- or reed-dominated marsh systems.

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Holocene Carbon Stocks and Carbon Accumulation Rates Altered in Soils Undergoing Permafrost Thaw

Ecosystems ◽

10.1007/s10021-011-9500-4 ◽

2011 ◽

Vol 15 (1) ◽

pp. 162-173 ◽

Cited By ~ 57

Author(s):

Caitlin E. Hicks Pries ◽

Edward A. G. Schuur ◽

K. Grace Crummer

Keyword(s):

Carbon Stocks ◽

Carbon Accumulation ◽

Accumulation Rates ◽

Permafrost Thaw ◽

Carbon Accumulation Rates

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Sea Level Rise Explains Changing Carbon Accumulation Rates in a Salt Marsh Over the Past Two Millennia

Journal of Geophysical Research Biogeosciences ◽

10.1029/2019jg005207 ◽

2019 ◽

Vol 124 (10) ◽

pp. 2945-2957 ◽

Cited By ~ 2

Author(s):

Nathan McTigue ◽

Jenny Davis ◽

Antonio B. Rodriguez ◽

Brent McKee ◽

Anna Atencio ◽

...

Keyword(s):

Salt Marsh ◽

Sea Level Rise ◽

Sea Level ◽

Carbon Accumulation ◽

Accumulation Rates ◽

The Past ◽

Carbon Accumulation Rates

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Blue Carbon Stocks and Exchanges Along the Pacific West Coast

10.5194/bg-2021-27 ◽

2021 ◽

Author(s):

Melissa A. Ward ◽

Tessa M. Hill ◽

Chelsey Souza ◽

Tessa Filipczyk ◽

Aurora M. Ricart ◽

...

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Carbon Sources ◽

Carbon Stocks ◽

Blue Carbon ◽

Seagrass Meadows ◽

The Pacific ◽

Terrestrial Habitats ◽

Isotope Mixing Models ◽

Sediment Carbon

Abstract. Salt marshes and seagrass meadows can sequester and store high quantities of organic carbon (OC) in their sediments relative to other marine and terrestrial habitats. Assessing carbon stocks, carbon sources, and the transfer of carbon between habitats within coastal seascapes are each integral in identifying the role of blue carbon habitats in coastal carbon cycling. Here, we quantified carbon stocks, sources, and exchanges in seagrass meadows, salt marshes, and unvegetated sediments in six bays along the Pacific coast of California. The salt marshes studied here contained approximately twice as much OC as did seagrass meadows, 23.51 ± 1.77 kg OC m−3 compared to 11.01 ± 1.18 kg OC m−3, respectively. Both seagrass and salt marsh sediment carbon stocks were higher than previous estimates from this region but lower than global and U.S.-wide averages, respectively. Seagrass-derived carbon was deposited annually into adjacent marshes during fall seagrass senescence. However, isotope mixing models estimate that negligible amounts of this seagrass material were ultimately buried in underlying sediment. Rather, the vast majority of OC in sediment across sites was likely derived from planktonic/benthic diatoms and C3 salt marsh plants.

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Carbon accumulation rates recorded in the last 150 years in tropical high mountain peatlands of the Atlantic Rainforest, SE - Brazil

The Science of The Total Environment ◽

10.1016/j.scitotenv.2016.11.076 ◽

2017 ◽

Vol 579 ◽

pp. 439-446 ◽

Cited By ~ 4

Author(s):

Lúcio F. Lourençato ◽

Pedro P. Caldeira ◽

Marcelo C. Bernardes ◽

Andressa C. Buch ◽

Daniel C. Teixeira ◽

...

Keyword(s):

Carbon Accumulation ◽

Atlantic Rainforest ◽

High Mountain ◽

Accumulation Rates ◽

Se Brazil ◽

Carbon Accumulation Rates ◽

Mountain Peatlands

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Factors Influencing Carbon Stocks and Accumulation Rates in Eelgrass Meadows Across New England, USA

Estuaries and Coasts ◽

10.1007/s12237-020-00754-9 ◽

2020 ◽

Vol 43 (8) ◽

pp. 2076-2091 ◽

Cited By ~ 1

Author(s):

A. B. Novak ◽

M. C. Pelletier ◽

P. Colarusso ◽

J. Simpson ◽

M. N. Gutierrez ◽

...

Keyword(s):

Grain Size ◽

New England ◽

Structural Characteristics ◽

Sediment Cores ◽

Carbon Stocks ◽

Carbon Accumulation ◽

Accumulation Rates ◽

Seagrass Meadows ◽

Terrestrial Habitats ◽

C And N

Abstract Increasing the protection of coastal vegetated ecosystems has been suggested as one strategy to compensate for increasing carbon dioxide (CO2) in the atmosphere as the capacity of these habitats to sequester and store carbon exceeds that of terrestrial habitats. Seagrasses are a group of foundation species that grow in shallow coastal and estuarine systems and have an exceptional ability to sequester and store large quantities of carbon in biomass and, particularly, in sediments. However, carbon stocks (Corg stocks) and carbon accumulation rates (Corg accumulation) in seagrass meadows are highly variable both spatially and temporally, making it difficult to extrapolate this strategy to areas where information is lacking. In this study, Corg stocks and Corg accumulation were determined at 11 eelgrass meadows across New England, representing a range of eutrophication and exposure conditions. In addition, the environmental factors and structural characteristics of meadows related to variation in Corg stocks were identified. The objectives were accomplished by assessing stable isotopes of δ13C and δ15N as well as %C and %N in plant tissues and sediments, measuring grain size and 210Pb of sediment cores, and through assessing site exposure. Variability in Corg stocks in seagrass meadows is well predicted using commonly measured environmental variables such as grain size distribution. This study allows incorporation of data and insights for the northwest Atlantic, where few studies on carbon sequestration by seagrasses have been conducted.

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