RESILIENCY OF A RESTORED VALLEY BOTTOM WETLAND ECOSYSTEM AT BIG SPRING RUN, LANCASTER COUNTY, PENNSYLVANIA

Wetlands are threatened globally due to human actions and climate change, and various strategies have been utilized to restore them and maximize the ecosystem services they provide. One such approach is the removal of historic “legacy” sediment that has buried wetlands over several centuries after European settlers arrived in North America. In the mid-Atlantic region, valley bottom wetland burial beneath 1 to 5 m of sediment was widespread, mostly due to the building of tens of thousands of milldams for water power. One of these milldams resulted in the burial of a Holocene valley bottom wetland with ~1.3 m of silty sediment at the headwaters of Big Spring Run (BSR) near Lancaster, PA. Historic sediment was removed in 2011 during a legacy sediment removal (LSR) and aquatic floodplain restoration effort. During a twelve-year post-restoration monitoring period, the newly forming hydric soil was analyzed at multiple sample sites to track carbon accumulation as soil organic matter. Clear similarities exist between rates of carbon accumulation in post-restoration soils at BSR and those of naturally formed wetland soils nearby that are unimpacted by legacy sediment accumulation. This demonstrates that legacy sediment removal and the restoration of a buried wetland ecosystem may be as efficient as natural wetland soils in terms of carbon accumulation and sequestration potential. This research showcases the ecological potential of LSR as a means of restoring future wetlands and tracking soil carbon accumulation on riparian floodplains.