The long-term ecological success of compensatory freshwater wetland projects has come into question based on follow-up monitoring studies over the past few decades. Given that wetland restoration may require many years to decades to converge to desired outcomes, long-term monitoring of successional patterns may increase our ability to fully evaluate success of wetland mitigation projects or guide adaptive management when needed. In Portsmouth, New Hampshire a 4 ha wetland was constructed in an abandoned gravel quarry as off-site compensatory mitigation for impacts to a scrub-shrub swamp associated with property expansion. Building upon prior evaluations from 1992 and 2002, we conducted a floral survey in 2020 to compare results with prior surveys to document vegetation successional trends over time. In addition, we monitored the avian community throughout the growing season as a measure of habitat quality. The plant community mirrored documented successional trends of freshwater wetland restoration projects as native hydrophytes dominated species composition. Plant species composition stabilized as the rate of turnover, the measurement of succession, declined by nearly half after 17 years. Researchers should consider long-term monitoring of specific sites to better understand successional patterns of created wetlands as we documented long time frames required for the development of scrub-shrub swamps, red maple swamps, and sedge meadows. High species richness was attributed to beaver activity, topographic heterogeneity from Carex stricta tussocks, and the seed bank from the application of peat from the original wetland. Habitat heterogeneity of open water, herbaceous cover, and woody vegetation supports a diverse avian community including 11 wetland dependent species. Although the mitigation project has not created the full area of lost scrub-shrub swamp after 35 years, it has developed a structurally complex habitat and diverse avian community that effectively provides the functions and values of the impacted system.

One of the main mechanisms for salt marsh decline across the United States is the inability of the marsh surface to keep pace with sea level rise. The interior platform is especially vulnerable, leading to the encroachment of short form Spartina alterni ora pannes, pool formation, and ultimately runaway pool expansion if recovery is not possible. Coastal ecologists in New England have been implementing a restoration strategy of runnels, or shallow ditches, to enhance drainage of oversaturated and ponding interior marshes. In 2015, runnels were constructed to drain two large and expanding pools in the Great Marsh System of Massachusetts, USA. Vegetation, elevation, and hydrology were monitored using eld sampling and remote sensing analysis pre-and post-restoration over seven growing seasons to document the restoration trajectory of the pools and adjacent salt marsh platforms. Pool drainage improved re ecting tidal cycles after three growing seasons. Substantial colonization of S. alterni ora and S. patens into the previously unvegetated pools required three growing seasons. In the adjacent marsh platform, S. patens and Distichlis spicata increased in abundance with substantial declines in S. alterni ora. The runnel for one pool became partially blocked by vegetation after 2018 and inhibited drainage and recovery of the vegetation community in the pool yet not the platform. Runnels may be a viable solution for restoring interior marshes following vegetation loss yet substantial improvements in vegetation and hydrology may require 3-5 years and complete recovery of the vegetation community in the pool system at least a decade or more.

One of the main mechanisms for salt marsh decline across the United States is the inability of the marsh surface to keep pace with sea level rise. The interior platform is especially vulnerable, leading to the encroachment of short form Spartina alterniflora pannes, pool formation, and ultimately runaway pool expansion if recovery is not possible. Coastal ecologists in New England have been implementing a restoration strategy of runnels, or shallow ditches, to enhance drainage of oversaturated and ponding interior marshes. In 2015, runnels were constructed to drain two large and expanding pools in the Great Marsh System of Massachusetts, USA. Vegetation, elevation, and hydrology were monitored using field sampling and remote sensing analysis pre- and post-restoration over seven growing seasons to document the restoration trajectory of the pools and adjacent salt marsh platforms. Pool drainage improved reflecting tidal cycles after three growing seasons. Substantial colonization of S. alterniflora and S. patens into the previously unvegetated pools required three growing seasons. In the adjacent marsh platform, S. patens and Distichlis spicata increased in abundance with substantial declines in S. alterniflora. The runnel for one pool became partially blocked by vegetation after 2018 and inhibited drainage and recovery of the vegetation community in the pool yet not the platform. Runnels may be a viable solution for restoring interior marshes following vegetation loss yet substantial improvements in vegetation and hydrology may require 3–5 years and complete recovery of the vegetation community in the pool system at least a decade or more.