The AERF was built on the KSU campus in 2001. It includes 10 independently flooded wetland basins (total area: 2000 m 2 ), a 1000 m 2 stream pool habitat and ~2000 m 2 of terrestrial habitat around the perimeter of the wetlands. The wetlands have used since 2002 to conduct population and community-level experiments under natural environmental conditions. Equipment at the AERF includes a weather station (Davis Inc., Hayward, CA), a water chemistry data sonde (YSI, Yellow Springs, Ohio) in the stream pool, and water level loggers (Global Water, Gold River, CA) in each basin. A chain-link fence, electric floodlights and a locked gate provide security for long-term experiments.
The AERF was built in an upland field at the edge of a ~3 acre wooded area. It is surrounded by stands of hardwood trees (e.g., Populus deltoides, Quercus palustris, Acer rubrum, Prunus serotina ), and a field with herbaceous plants and shrubs (e.g., Viburnum recognitum, Cornus amomum, Solidago spp., Andropogon scoparius , Agrostis alba , Poa spp .). Allerton Creek flows through the site; this 2nd-order perennial creek is ~10 cm deep during base flow, 2-4 m wide, with a ~1 km 2 watershed. The soils in the AERF are sandy to clayey loams (Olmstead and Chili series), and the stream bottom is comprised of sand, silt, and gravel with some cobbles. There are small (~0.1-0.3 hectare) natural floodplain wetlands immediately upstream and downstream from the facility. The ten 10 m x 20 m wetland basins are built around the 100 m X 10 m stream pool that was created with a 2-m high concrete dam. The stream pool is the water source for the wetland basins. The sides of the wetland basins are sloped inward at 0.3-m linear fall to 1-m vertical run, and maximum water depth is 1.7 m (volume = ~2.5 X 10 5 l). Each wetland basin has a separate inlet and outlet water control structure, and each basin can be flooded and drained independently from the others.
Because the basins were built with topsoil brought in from off-site, we seeded each wetland with a mix of 20 wetland plant species (Onoclea sensibilis, Carex crinita, C. vulpinoidea, C. lupulina, Eleocharis palustris, Scirpus cyperinus, S. acutus, Cyperus esculentes, Leersia oryzoides, Poa palustris, Elymus riparius, Pontederia cordata, Juncus effusus, Sagittaria latifolia, Sparganium americanum, Solidago patula, Polygonum lapathifolium, P. pennsylvanicum, Bidens cernua, Eupatorium perfoliatum; 5% by weight for each species) in June 2002 (4.5 kg seeds/basin) and March 2003 (2.25 kg seeds/basin). All species are native to Ohio, and species represent a range of flooding tolerances from those in moist-soil habitats to those in permanently flooded areas. Additional wetland plants and animals have colonized from the stream and other nearby aquatic habitats. We surveyed the biota during 2002-2003 and documented >200 invertebrate species, 56 wetland plant species, and 27 vertebrate species (including fish, frogs, turtles, and muskrats) inhabiting the site.
The AERF is an ideal facility to test hypotheses on effects of hydrology on wetland functions. First, we can manipulate the hydrology of 10 large replicated wetland basins along a headwater creek. Therefore, we will conduct our experiments under controlled conditions that eliminate most potential confounding variables that often occur between wetlands (e.g., geomorphology, land use, size). The large size of our wetlands also allows us to test community-level interactions of invertebrates and plants that would not be possible in small-scale experiments (i.e., microcosms). Moreover, many plants, invertebrates, and vertebrates have already colonized from nearby habitats, creating diverse species assemblages that are representative of floodplain wetlands in northeastern Ohio. Therefore, information from experiments at this facility will be applicable to other low-order systems. Future experiments will build on the results of our ongoing projects, and we will gain a comprehensive understanding of how hydrologic factors define community structure, and ultimately, ecosystem-level processes in floodplain wetlands.
Cross-section view along the longitudinal axis of a Static wetland and a Flood pulse wetland at the KSU-AERF:
A. is the outlet water control structure. Note that in the Static wetland, the PVC boards are set to keep water levels at about 80 cm. In the Flood pulse wetland, additional PVC boards allow water levels to rise to about 140 cm, but water drains slowly back down to 80 cm through a 1.3 cm hole in one board.
B. is the inlet water control structure, which has PVC boards set 5 cm above the water level in the stream pool. Arrows show direction of flow during a storm as water spills in the inlet structure and discharges through the outlet structure. See text for explanation of non-flooded zone, intermittently-flooded zone and permanently flooded pool. Dimensions are not drawn exactly to scale.