Study

Natural revegetation during restoration of wetlands in the southern prairie pothole region of North America

  • Published source details Galatowitsch S.M. & Van der Valk A.G. (1995) Natural revegetation during restoration of wetlands in the southern prairie pothole region of North America. Pages 129-142 in: B.D. Wheeler, S.C. Shaw, W.J. Fojt & R.A. Robertson (eds.) Restoration of Temperate Wetlands. John Wiley and Sons Ltd., Chichester.

Actions

This study is summarised as evidence for the following.

Action Category

Raise water level to restore/create freshwater marshes from other land uses

Action Link
Marsh and Swamp Conservation

Raise water level to restore/create freshwater marshes from other land uses

Action Link
Marsh and Swamp Conservation
  1. Raise water level to restore/create freshwater marshes from other land uses

    A replicated study in 1989–1991 of 62 prairie potholes in the Midwest USA (Galatowitsch & van der Valk 1995) reported that restored potholes (rewetted and planted with cover crops) developed cover of wetland plant communities within three years of first flooding. This included zones of wet meadow vegetation, emergent wetland vegetation, and aquatic (floating and submerged) vegetation. However, the abundance of each community type depended on how often the potholes were flooded, how they had been drained and for how long they had been drained. For example, potholes flooded in only one of three years were dominated by emergent wetland plants or mudflat annuals. Potholes flooded in three of three years contained these plant communities along with zones of aquatic vegetation. The study also reported data on the abundance of individual plant species (see original chapter). Methods: In 1989, 1990 and 1991, vegetation was surveyed in 62 potholes whose drainage structures had been blocked or removed in 1988, to raise the water table. All potholes had been cultivated for ≥25 years. Some had been planted with upland cover crops before rewetting; the study evaluates the combined effect of these interventions in these potholes. Some of the restored potholes were used in (5), (6), (7) and (8) and were studied at later dates in (11), (12) and (15).

    (Summarised by: Nigel Taylor)

  2. Raise water level to restore/create freshwater marshes from other land uses

    A replicated, site comparison study in 1989–1991 in the Midwest USA (Galatowitsch & van der Valk 1995) reported that restored prairie potholes (rewetted and planted with cover crops) developed some zones of wetland vegetation within three years, but contained fewer plant species than naturally occurring potholes. Of the 22 rewetted potholes, 16 contained an emergent vegetation zone and 13 contained a submerged vegetation zone, but only two contained a sedge meadow or wet prairie zone. After three years, 10 restored potholes contained fewer plant species (17–38 species/pothole; average: 27) than 10 contemporary natural potholes (32–56 species/pothole; average: 46) or historical reports for pristine potholes (57–126 species/pothole). More specifically, the restored potholes contained fewer shallow-emergent, sedge-meadow, wet-prairie and floating aquatic species on average (1–5 species/group/pothole) than contemporary natural potholes (4–17 species/group/pothole), but more submerged aquatic species (6 vs 1 species/pothole). Methods: In 1989, 1990 and 1991, vegetation was surveyed in 22 potholes whose drainage structures had been blocked or removed in 1988, to raise the water table. All of these potholes had been cultivated for ≥25 years, but were flooded every summer since rewetting. Some had been planted with upland cover crops before rewetting: the study evaluates the combined effect of these interventions in these potholes. Vegetation was also surveyed in 10 adjacent natural potholes (never drained, but surrounded by farmland). Species richness of seven pristine potholes (unaffected by surrounding agriculture) was obtained from published records from the 1890s–1980s. This study used a subset of the restored potholes from (4) – but not clearly the same 22 potholes as (6).

    (Summarised by: Nigel Taylor)

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