10.25573/data.10046189.v2 Ronald M. Thom Ronald M. Thom Dataset: Accretion rates of low intertidal salt marshes in the Pacific Northwest The Smithsonian Institution 2019 sea-level rise salt-marsh accretion Pacific Northwest global climate change Soil Science Carbon Sequestration Science 2019-11-13 15:23:14 Dataset https://smithsonian.figshare.com/articles/dataset/Dataset_Accretion_rates_of_low_intertidal_salt_marshes_in_the_Pacific_Northwest/10046189 <div>Salt-marsh accretion rate was investigated at sites that spanned a gradient in relative rate of sea-level rise in Washington and Oregon. Mean accretion rate over all sites was 3.6 mm yr<sup>-1</sup> (95% CI = 2.4 to 4.8 mm yr<sup>-1</sup>), which exceeded present mean sea-level-rise rate (1.3 mm yr<sup>-1</sup>; sd = 0.6). However, a mean rise rate of 5.5 mm yr<sup>-1</sup> (sd = 1.9) predicted by a moderate sea-level-change scenario to occur by the year 2050 exceeds mean accretion rate. Marshes with adequate sediment input seemed to have the capacity to keep pace with an increased sea-level-rise rate. Lowest accretion rates were recorded at sites with the least sediment supply. Accretion rate showed a weak negative correlation with sediment organic matter (measured as volatile solids) and marsh standing stock. The data suggest that moderate and high rise-rate scenarios would threaten the existence of salt marshes in the region in the absence of increased sediment supply. A better understanding is required of marsh accretion and predicted rate of sea-level rise to refine predictions of the effects of sea-level rise on Pacific Northwest salt marshes.</div><div><br></div>