Transplanting Native Dominant Plants to Facilitate Community Development in Restored Coastal Plain Wetlands

Transplanting Native Dominant Plants to Facilitate Community Development in Restored Coastal Plain Wetlands

Diane De Steven¹ and Rebecca R. Sharitz²

¹U.S. Forest Service–Southern Research Station,Center for Bottomland Hardwoods Research,
P.O. Box 227, Stoneville, Mississippi, USA 38776
²Savannah River Ecology Laboratory, Drawer E, Aiken, SC, USA 29802

Abstract
Drained depressional wetlands are typically restored by plugging ditches or breaking drainage
tiles to allow recovery of natural ponding regimes, while relying on passive recolonization from seed
banks and dispersal to establish emergent vegetation. However, in restored depressions of the
southeastern United States Coastal Plain, certain characteristic rhizomatous graminoid species may not
recolonize because they are dispersal-limited and uncommon or absent in the seed banks of disturbed
sites. We tested whether selectively planting such wetland dominants could facilitate restoration by
accelerating vegetative cover development and suppressing non-wetland species. In an operational-scale
project in a South Carolina forested landscape, drained depressional wetlands were restored in early 2001
by completely removing woody vegetation and plugging surface ditches. After forest removal, tillers of
two rhizomatous wetland grasses (Panicum hemitomon, Leersia hexandra) were transplanted into singlespecies blocks in 12 restored depressions that otherwise were revegetating passively. Presence and cover of all plant species appearing in planted plots and unplanted control plots were recorded annually. We
analyzed vegetation composition after two and four years, during a severe drought (2002) and after
hydrologic recovery (2004). Most grass plantings established successfully, attaining 15%–85% cover in
two years. Planted plots had fewer total species and fewer wetland species compared to control plots, but
differences were small. Planted plots achieved greater total vegetative cover during the drought and
greater combined cover of wetland species in both years. By 2004, planted grasses appeared to reduce
cover of non-wetland species in some cases, but wetter hydrologic conditions contributed more strongly
to suppression of non-wetland species. Because these two grasses typically form a dominant cover matrix
in herbaceous depressions, our results indicated that planting selected species could supplement passive
restoration by promoting a vegetative structure closer to that of natural wetlands.

Keywords: depressional wetlands, Leersia hexandra, Panicum hemitomon, revegetation, wetland
restoration

SREL Reprint #3056

De Steven, D. and R. R. Sharitz. 2007. Transplanting Native Dominant Plants to Facilitate Community Development in Restored Coastal Plain Wetlands. Wetlands 27(4): 972-978.