The Vegetation of Restored and Natural Prairie Wetlands

Abstract

Thousands of wetland restorations have been done in the glaciated mid‐continent of the United States. Wetlands in this region revegetate by natural recolonization after hydrology is restored. The floristic composition of the vegetation and seed banks of 10 restored wetlands in northern Iowa were compared to those of 10 adjacent natural wetlands to test the hypothesis that communities rapidly develop through natural recolonization. Restoration programs in the prairie pothole region assume that the efficient‐community hypothesis is true: all plant species that can become established and survive under the environmental conditions found at a site will eventually be found growing there and/or will be found in its seed bank. Three years after restoration, natural wetlands had a mean of 46 species compared to 27 species for restored wetlands. Some guilds of species have significantly fewer (e.g., sedge meadow) or more (e.g., submersed aquatics) species in restored than natural wetlands. The distribution and abundance of most species at different elevations were significantly different in natural and restored wetlands. The seed banks of restored wetlands contained fewer species and fewer seeds than those of natural wetlands. There were, however, some similarities between the vegetation of restored and natural wetlands. Emergent species richness in restored wetlands was generally similar to that in natural wetlands, although there were fewer shallow emergent species in restored wetlands. The seed banks of restored wetlands, however, were not similar to those of natural wetlands in composition, mean species richness, or mean total seed density. Submersed aquatic, wet prairie, and sedge meadow species were not present in the seed banks of restored wetlands. These patterns of recolonization seem related to dispersal ability, indicating the efficient‐community hypothesis cannot be completely accepted as a basis for restorations in the prairie pothole region.

Partitioning Vegetation Response to Anthropogenic Stress to Develop Multi‐taxa Wetland Indicators

“…There is mixed evidence about the effect on CALAA productivity of nitrogen fertilization (Aerts et al 1992(Aerts et al , 1995 and water levels (Sala and Nowak 1997, Thormann et al 1998, Steed et al 2002. Galatowitsch and coworkers (2000) reported a decline in CALAA abundance with site impacts and landscape disturbance in a study of 40 wet meadows in southwest Minnesota, and CALAA was absent from restored wetlands in northern Iowa despite being frequently found in natural prairie wetlands within the region (Galatowitsch and van der Valk 1996).…”

Seed bank persistence of clonal weeds in contrasting habitats: implications for control

“…Seeds provide an essential link in the population dynamics of these species allowing the establishment of individuals and founding of new populations via dispersal both in space and time (Rees 1996). The timing of seed germination is also a critical determinant of reproductive success (Donohue et al 2005a) and is often controlled by seed dormancy (i.e., seeds that do not germinate in spite of being placed into conditions generally suitable for germination), which can be lost or acquired in response to environmental stimuli such as temperature (Allen and Meyer 1998;Cavieres and Arroyo 2001;Adondakis and Venable 2004), soil moisture (Murdoch and Ellis 1992; Galatowitsch and van der Valk 1996;Bekker et al 1998c) and nutrient concentration (Bekker et al 1998b). Seed dormancy is thought to have evolved in response to unpredictable environmental variability and might lead to the existence of soil seed banks-populations of viable seeds in the soil (e.g.…”

Grass response to seasonal burns in experimental plantings

“…Hulbert 1986, 1988, Steuter 1987, Anderson 1990, Howe 1994b, the rapid and continuing increases in productivity of C 4 grasses, leading to a sharp increase in total productivity in plots burned in May as compared with those burned in August or left unburned, is unexpected after only 2 alternate-year burns. P. arundinacea is a quickly establishing and extremely vigorous competitor on wet or wet-mesic sites such as this, often forming virtual monocultures (Galatowitsch andvan der Valk 1996, Mergliano andLesica 1998), as it has in a large experiment planted in 1990 at this site (Howe 1999). Early displacement of this species in May-burn plots is particularly interesting because wet soils often favor P. arundinacea.…”