Functional analysis of a two-year-old created in-stream wetland: Hydrology, phosphorus retention, and vegetation survival and growth

Abstract

Planted vegetation survival and growth, hydrology, and phosphorus dynamics were monitored for the first two years of wetland development at a 6-ha created riparian wetland, in Franklin County, Ohio, USA. Herbaceous vegetation developed clear zonation and appeared to reduce the invasion ofTypha spp. Of the 17 species introduced, 8 were among the 18 most commonly encountered species approximately 2 years after the wetland was constructed. Planted saplings generally survived except where they were found in standing water;Liquidambar styraciflua andBetula nigra were less successful because the site is close to their northern range. Simulation models were developed to predict hydrology, phosphorus retention, and tree growth. The site has a rapidly pulsing hydroperiod driven by runoff from storm events. Annual simulated phosphorus loading was 17.8 gP m−2 yr−1 and retention was 2.9 gP m−2 yr−1 (16% of inflow). Fifty years of tree growth simulated for each planted tree species indicated that the site will develop into a forested wetland dominated byQuercus palustris andFraxinus pennsylvanica with basal area comparable to riparian forests but with lower stem density unless seedlings germinate from the planted trees. Lower water levels in the wetland would favor the development of the woody vegetation over herbaceous vegetation and would also favor higher retention of phosphorus.