Evaluation of wetland development and waterbird response at Elk Creek Wildlife management area, Lake Mills, Iowa, 1961 to 1990

Published source details Weller M.W., Kaufmann G.W. & Vohs P.A. (1991) Evaluation of wetland development and waterbird response at Elk Creek Wildlife management area, Lake Mills, Iowa, 1961 to 1990. Wetlands, 11, 245-262.
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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

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

A replicated, paired, before-and-after, site comparison study in 1958–1989 aiming to create marshes along a stream in Iowa, USA (Weller et al. 1991) reported that damming the stream increased the area of open water at the expense of emergent riparian vegetation. Statistical significance was not assessed. Before damming, the 445-ha study area contained 188 ha of emergent herbaceous vegetation, plus 21 ha of open water and 239 ha of upland/forest. Approximately 5–19 years after damming, there was only 78 ha of emergent herbaceous vegetation, plus 157 ha of open water and 213 ha of upland/forest. Over 14–28 years, three riparian transects immediately upstream of dams experienced an increase in open water coverage (before: 1–10%; after: 58–72%) and a decline in coverage of tall wetland grasses (before: 7–14%; after: 0–7%). In contrast, two riparian transects away from dams had stable open water coverage (before: 2%; after: 1–3%) but experienced an increase in coverage of tall wetland grasses (before: 4–5%; after: 18–41%). Other major changes in vegetation cover were mirrored across both types of transect (e.g. decreased cover of tussock sedge Carex stricta; see original paper for data). Methods: Between 1961 and 1975, three impoundments were created by damming Elk Creek, with the aim of creating marshland for waterbirds. Maps of the riparian zone before (1958) and after (1980) damming were drawn from aerial imagery. Vegetation cover was surveyed along five transects crossing the riparian zone, before (early 1960s) and after (1989) damming.

(Summarised by: Nigel Taylor)