McKown, J.G.; Burdick, D.M.; Moore, G.E.; Gibson, J.L., and Ferguson, W., 0000. Evaluation of drainage enhancement for vegetation recovery in New England salt marshes using public domain, high-resolution aerial imagery.

Paired stressors of sea-level rise and abandoned ditches and embankments from historic farming practices have exacerbated waterlogging and accelerated replacement of valuable interior high marsh with large pools throughout the United States Atlantic seaboard. High marsh loss has contributed to substantial population declines and the threat of future extinction of the Saltmarsh Sparrow (Ammodramus caudacutus), an endemic species of coastal wetlands. Creation of runnels and selective ditch maintenance has been promoted as short- and medium-term solutions to conserve and restore high marsh habitat and restore natural single-channel hydrology. A comprehensive monitoring program was launched in 2020 to evaluate the effect of runnels and maintenance of selective ditches on the hydrology, vegetation, and elevation of interior marshes across 17 marshes of Maine, Massachusetts, and Rhode Island, with the explicit goal of habitat conservation for the Saltmarsh Sparrow. The marsh surface was classified from 2010–21 with public aerial imagery to document the change in aerial extent of the vegetated marsh surface and unvegetated:vegetated ratio of tidal watersheds (mean size = 2.12 ± 0.18 ha) associated with specific management actions: runnelling, reference healthy marshes, and no-action pannes and pools. Runnels reversed the expansion of pools and pannes with annual declines of −0.037 unvegetated:vegetated ratio and gains of 1.55% vegetated area. Tidal watersheds gained an overall net 2.08 ha vegetated surface post-restoration, despite continued losses in reference and no-action tidal watersheds. Re-establishing hydrologic paths to allow regular tidal flooding and drainage promotes revegetation of shallow waterlogged pools—a first step toward rebuilding marsh elevation and conserving habitat for saltmarsh sparrows.

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