Spatiotemporal variation in Oregon salt marsh expansion and contraction (GIS data)

Spatiotemporal patterns of salt marsh lateral change vary along the Oregon coast, reflecting complex drivers of morphodynamics. To identify potential drivers of expansion/contraction, marsh edge position and area were measured from aerial imagery (~10 y resolution over ~80 y) in five Oregon estuaries with variable morphologies, fluvial sediment supplies, and relative sea level variation. In addition to highlighting the combined importance of these forcings, results suggest that intensive timber harvest in the mid-20th century coincident with increased precipitation during the wet phase of the Pacific Decadal Oscillation caused marsh expansion in all estuaries. More recently, rates of expansion decreased, sometimes giving way to net contraction. Although the exact reasons remain unclear, reduced timber harvest and improved logging methods are likely culprits. If these trends persist, continued salt marsh contraction is expected into the future along the Oregon coast especially under accelerated sea level rise.