Dataset: Mangrove, tidal wetland and seagrass soil carbon stocks along latitudinal gradients

Coastal and marine ecosystems have the potential to produce and sequester organic carbon at rates that exceed tropical and temperate forests. Recent recognition of the value of these ecosystems as significant carbon sinks has strengthened worldwide interest in their management, conservation, and restoration for the purpose of climate change mitigation. However, many gaps in understanding carbon sequestration in coastal ecosystems remain, creating challenges for the application coastal ecosystem carbon research at local, regional and global scales. A major limitation is the fact that most research on this topic has been conducted in relatively few temperate and tropical ecosystems, despite a tremendous amount of spatial variability in carbon stocks across gradients of climate, hydrology, geomorphology, and tide range. Additionally, a standardized protocol has not been widely utilized, which would enable more rigorous comparison across ecosystems and climates. The main objective of this research was to apply a standardized method for documenting carbon storage in vegetated coastal ecosystems along latitudinal gradients, including mangroves, tidal wetlands, and seagrass beds. Field sites were located in Twin Cays, Belize, three islands in Bocas del Toro, Panama, the Indian River Lagoon, Florida, Wachapreague, Virginia, three sites in San Francisco Bay, California, and three sites in Kachemak Bay, Alaska. At each mangrove and tidal wetland site, six deep soil cores were retrieved using an open faced gouge corer, ranging in depth from 70 to 496 cm and subsampled at set depth ranges. At each seagrass site, a one meter long piston corer was used to retrieve the core and subsampled using syringes. All samples were dried to a constant weight to determine dry bulk density. Samples were ground with a ball grinder and subsamples were burned in a muffle furnace to determine loss on ignition (LOI). For all seagrass samples, organic carbon was determined by differencing the percent carbon from ashed and unashed samples analyzed with an elemental analyzer. A subset of mangrove and tidal wetland samples were analyzed in an elemental analyzer to determine organic carbon and a relationship between LOI and percent carbon was determined and applied to the remaining samples. Total organic carbon was quantified with depth and summed for each core.