The Importance of Hydrology in Restoration of Bottomland Hardwood Wetland Functions

• Published in: Wetlands (Wilmington, N.C.) Vol. 28; no. 3; pp. 605 - 615
• Main Authors: Hunter, Rachael G., Faulkner, Stephen P., Gibson, Kimberly A.
• Format: Journal Article
• Language: English
• Published: 1313 Dolley Madison Boulevard, Suite 402, McLean, Virginia, USA 22101 The Society of Wetland Scientists 01.09.2008; Springer Netherlands; Springer Nature B.V
• Subjects: Biogeochemistry; Biological activity; Biomedical and Life Sciences; Bottomland; bottomland hardwoods, fluorescein diacetate hydrolysis; Carbon; Coastal Sciences; Ditches; Drainage; Drainage ditches; Ecology; Environmental Management; Environmental restoration; Freshwater & Marine Ecology; Hardwoods; heterotrophic microbial activity; Hydrogeology; Hydrology; Landscape Ecology; Life Sciences; Microbial activity; Microorganisms; Nutrient removal; Organic carbon; readily mineralizable carbon; redox potential; REGULAR SUBMISSIONS; Restoration; Risers; Sedimentation rates; Soil moisture; Structure-function relationships; Vegetation; Water table; Water table fluctuations; wetland restoration; Wetlands; Woody plants; heterotrophic microbial activity; redox potential; wetland restoration; bottomland hardwoods; biogeochemistry; fluorescein diacetate hydrolysis; readily mineralizable carbon
• ISSN: 0277-5212; 1943-6246
• DOI: 10.1672/07-139.1

Bottomland hardwood (BLH) forests have important biogeochemical functions and it is well known that certain structural components, including pulsed hydrology, hydric soils, and hydrophytic vegetation, enhance these functions. It is unclear, however, how functions of restored BLH wetlands compare to mature, undisturbed wetlands. We measured a suite of structural and functional attributes in replicated natural BLH wetlands (NAT), restored BLH wetlands with hydrology re-established (RWH), and restored BLH wetlands without hydrology re-established (RWOH) in this study. Trees were replanted in all restored wetlands at least four years prior to the study and those wetlands with hydrology re-established had flashboard risers placed in drainage ditches to allow seasonal surface flooding. Vegetation, soils, and selected biogeochemical functions were characterized at each site. There was a marked difference in woody vegetation among the wetlands that was due primarily to site age. There was also a difference in herbaceous vegetation among the restored sites that may have been related to differences in age or hydrology. Water table fluctuations of the RWH wetlands were comparable to those of the NAT wetlands. Thus, placing flashboard risers in existing drainage ditches, along with proper management, can produce a hydroperiod that is similar to that of a relatively undisturbed BLH. Average length of saturation within the upper 15 cm of soils was 37, 104, and 97 days for RWOH, RWH, and NAT, respectively. Soil moisture, denitrification potential, and soluble organic carbon concentrations differed among wetland sites, but soil carbon and nitrogen concentrations, heterotrophic microbial activity, and readily mineralizable carbon concentrations did not. Significant linear relationships were also found between soil moisture and heterotrophic microbial activity, readily mineralizable carbon, and soluble organic carbon. In addition, sedimentation rates were higher in NAT and RWH wetlands than in RWOH sites. Results of this study suggest that reconnection of bottomland hardwood wetlands to their surrounding watershed through the restoration of surface hydrology is necessary to restore wetland functions important to nutrient and sediment removal.