Wilde, Haley, Clean Water Institute, Lycoming College, 1 College Place, Williamsport, PA, 17701, wilhale@lycoming.edu; Bohlin, Emily, , Clean Water Institute, Lycoming College, 1 College Place, Williamsport, PA, 17701, bohlin@lycoming.edu; Rieck, Leslie, Clean Water Institute Lycoming College 1 College Place Williamsport PA, 17701, rieck@lycoming.edu.
Robert Porter Allen Natural Area (RPANA) is a 227-acre former farmstead in South Williamsport, Pennsylvania, with one of the largest remaining floodplain wetlands on the Susquehanna River’s West Branch. This area underwent dredging in 2024 to restore previous hydrologic patterns. Pre-restoration sampling of vegetation and water depth provided baseline data of the biotic and abiotic conditions of the wetland on eight transects established throughout the area. This year’s study aimed to monitor restoration impacts on the wetland over time. During the summer of 2025, the four transects that were most impacted by restoration practices were resampled to assess recolonization of vegetation communities, measure water depth to track hydrologic changes, and monitor the early stages of restoration impact. Transects ranged from 144 meters to 405 meters, with sampling occurring every 40 meters. Vascular plant species, phenology, wetland indicator status, percent cover, and native or introduced status within a total of 29 1m² plots was determined. Water depth was measured using a Stadia rod. A Wilcoxon Signed-Rank Test compared the change in species richness from 2024 to 2025. The Floristic Quality Index (FQI) was calculated for each plot to compare the ecological quality of the site before and after restoration. A total of 115 vascular plant species were identified, with 71% (82 spp.) native and 29% (33 spp.) introduced. Sixty-six percent of plots showed increased species richness one year after restoration. The Wilcoxon signed-rank test yielded a test statistic of 103.5 and a critical value of 126, indicating a significant positive change in species richness following restoration with a 95% confidence interval (p<0.05). Some plots on transects one and two saw a recolonization of introduced species like Velvetleaf, Wormwood, and Barnyard grass. Fourteen plots achieved a higher average FQI post-restoration, 11 had a lower average FQI, and four plots maintained an FQI of zero. The seven plots with the highest FQI scores supported Green Arrow Arum-Scarlet Smartweed plant associations and experienced an increase in water depth post-restoration. The water depth of the wetland increased an average of 0.33 inches from 2024 to 2025. Restoration of this wetland resulted in increased species richness with native species and wetland obligates being the dominant taxa. Plots with higher FQIs should be closely monitored to protect the ecological integrity, whereas plots in transects one and two experiencing colonization of introduced species should be reseeded with native warm season grasses and perennial forbs. Hydrology should also continue to be monitored due to ongoing agricultural operations adjacent to the wetland. The increased species richness, native and high FQI species, and water depth are promising signs of future success for this wetland restoration project.
Wetland restoration, Wetland vegetation, Ecological monitoring, Hydrology