Urbanization alters stream hydrology, hence flooding frequency and duration in floodplain wetlands. Potential impacts include shifts in species composition and survival, making restoration and selection of wetland species difficult. Cephalanthus occidentalis, Fraxinus pennsylvanica, and Quercus shumardii seedlings were subjected to experimental flooding regimes typical of floodplain forests in rural and urban settings. Treatments included a rural flood regime with three 7-day floods, an Urban-short flood regime with six 4-day floods, and an Urban-long flood regime with six 10-day floods over a growing season. Specific responses, measured by stem length, leaf area, and leaf, stem, and root biomass, varied between species from different wetland indicator classes. C. occidentalis, a wetland obligate, was well adapted to both urban flooding regimes, whereas productivity of F. pennsylvanica, a facultative wetland species, and Q. shumardii, a facultative species, was significantly reduced by the Urban-long treatment. Growth rates also varied over time, indicating the importance of temporal flooding patterns on species productivity. Because urban flooding regimes directly and selectively alter species productivity, proper restoration methods in urbanizing environments should include species selection based on current and potential future hydrologic conditions and use of reference standards from reference sites subjected to similar urban hydrologic regimes.
Bibliographical noteFunding Information:
We appreciate the help of Steve Reagan, Andy Crane, Humberto Perotto, Feng Liu, Paihko Rho, and Vivian Perotto for their assistance with the experimental setup and data collection. This research was supported by the City of Garland, TX, the Texas Water Resources Institute, and the Texas Agricultural Experiment Station. The manuscript also greatly benefited from reviews by Nancy Nicolai, Humberto Perotto, and two anonymous reviewers.
Copyright 2008 Elsevier B.V., All rights reserved.
- Bottomland hardwood forest
- Cephalanthus occidentalis
- Flooding regime
- Fraxinus pennsylvanica
- Quercus shumardii
- Urban hydrology
- Wetland restoration