SREL Reprint #3168

Ecological Outcomes and Evaluation of Success in Passively Restored Southeastern Depressional Wetlands

Diane De Steven1, Rebecca R. Sharitz2, and Christopher D. Barton3

1U.S. Forest Service Southern Research Station, Center for Bottomland Hardwoods Research,
P. O. Box 227, Stoneville, MS 38776, USA
2Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA
3Department of Forestry, University of Kentucky, Lexington, KY 40546, USA

Abstract: Depressional wetlands may be restored passively by disrupting prior drainage to recover original hydrology and relying on natural revegetation. Restored hydrology selects for wetland vegetation; however, depression geomorphology constrains the achievable hydroperiod, and plant communities are influenced by hydroperiod and available species pools. Such constraints can complicate assessments of restoration success. Sixteen drained depressions in South Carolina, USA, were restored experimentally by forest clearing and ditch plugging for potential crediting to a mitigation bank. Depressions were assigned to alternate revegetation methods representing desired targets of herbaceous and wet-forest communities. After five years, restoration progress and revegetation methods were evaluated. Restored hydroperiods differed among wetlands, but all sites developed diverse vegetation of native wetland species. Vegetation traits were influenced by hydroperiod and the effects of early drought, rather than by revegetation method. For mitigation banking, individual wetlands were assessed for improvement from pre-restoration condition and similarity to assigned reference type. Most wetlands met goals to increase hydroperiod, herb-species dominance, and wetland-plant composition. Fewer wetlands achieved equivalence to reference types because some vegetation targets were incompatible with depression hydroperiods and improbable without intensive management. The results illustrated a paradox in judging success when vegetation goals may be unsuited to system constraints.

Keywords: Carolina bay, Mitigation bank, Vegetation dynamics, Wetland restoration

SREL Reprint #3168

De Steven, D., R. R. Sharitz, and C. D. Barton. 2010. Ecological Outcomes and Evaluation of Success in Passively Restored Southeastern Depressional Wetlands. Wetlands 2010(30): 1129-1140.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).