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

We estimated carbon stocks and carbon accumulation rates using 34 sediment cores collected 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 Mg C ha-1 between the seven salt marshes, and carbon accumulation rates averaged 146 ± 102 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. This carbon accumulation capacity provides a climate mitigation co-benefit when conserving for other salt marsh ecosystem services.