Emergent macrophyte dynamics of two created wetlands in central Ohio

Background/Question/Methods

Field surveys were conducted during the 2008 and 2009 growing seasons to examine emergent macrophyte characteristics within two created wetlands at the Olentangy River Wetland Research Park (ORWRP), Ohio State University. The goals of this study were to compare emergent macrophyte structure and function between a planted and unplanted wetland, as well as from fifteen to sixteen years after wetland creation. Both wetlands sampled are one hectare in size and receive relatively the same amount of hyrodrologic inputs. Overall, ecological processes within these two wetlands have been shown to be relatively the same. The main difference between the wetlands is that wetland one was originally plant, while wetland two was left to be colonized naturally.  Samples were collected at twenty four locations within the wetlands on a monthly basis from August through September of each year. Data collected included above and belowground biomass (used to determine net primary productivity and rate of productivity), total number of species present, number of plant communities, and area of the dominant plant communities. 

Results/Conclusions Over the course of the study, there was little difference in the number of species between the two wetlands (2008 wetland one = 97, wetland two = 92; 2009 wetland one = 98, wetland two = 92). Additionally, the number of species per wetland remained fairly constant from 2008 to 2009 (wetland one Δ_species = +1; wetland two Δ_species = 0). Aboveground peak productivity was higher for wetland two (2008 = 708±144, 2009 = 877±115 g dw/m²) than wetland one (2008 = 669±97, 2009 = 721±132 g dw/m²) for both years based on sample plots, with the occurrence of aboveground peak productivity differing between the two wetlands. Aboveground peak productivity occurred in August for wetland two, but occurred in July for wetland one in both years. Taking into account area covered by emergent vegetation, as well as the area of open water, wetland one had a slightly higher value for kg of aboveground primary productivity than wetland two (3424 kg and 3317 kg, respectively). Results from this study will be compared to previous studies conducted at the ORWRP. Preliminary findings suggest that there are slight differences between these two wetlands and from one year to the next, but whether or not the differences are significant remains to be seen.