PARENT SESSION
Poster Session #13: Restoration Ecology.
Tuesday, August 7, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Long-term revegetation of restored prairie pothole wetlands.

Mulhouse, John¹, Galatowitsch, Susan¹, ¹

ABSTRACT- One goal of the widespread restoration of prairie pothole wetlands in the mid-1980's was to provide habitat for endemic flora and fauna and prevent further declines in species that had suffered as a result of large-scale agricultural development. A preliminary study of 68 newly restored basins in Iowa, Minnesota and South Dakota determined that many plant species common to natural wetlands were not recolonizing restorations. In 2000, 43 of these restorations that had not been significantly altered or converted back to farm land were revisited and their floras characterized by cover within distinct zones. While species number had increased on virtually every site, a variety of native wet prairie and sedge meadow species, such as Carex spp., were notable for their absence. Phalaris arundinacea, an invasive perennial, was now present on every site, often at covers approaching 75-100% in the zones in which it occurred. Also, Leersia oryzoides, Typha angustifolia and Cirsium arvense had increased significantly on a number of sites. Further, wetlands of similar floristic composition, even those found to be depauperate or chiefly weedy, tended to occur in regional groups, raising questions about the success of dispersal mechanisms within landscapes that have become fragmented. Without significant seeding, planting and aftercare, such as weeding and localized herbicide application, it is questionable whether wetland restorations in fragmented landscapes will ever have a character similar to those that have occurred historically.

KEY WORDS: wetland restoration, invasive species, prairie potholes, recolonization