Degree Name

Master of Science (MS)

Semester of Degree Completion

1986

Thesis Director

Kipp C. Kruse

Abstract

Faced with increasing costs and decreasing federal funds, wildlife managers are turning towards more energy effecient and economical methods of attracting fall migrating waterfowl. The production of food by natural moist-soil plants can be encouraged in low lying areas by timely dewatering and reflooding. This study was designed to determine which of two drawdown dates would result in the greatest seed production by plants known to be valuable waterfowl foods.

A late July 1984 drawdown in an east-central Illinois subimpoundment produced significantly more smartweed (Polygonum spp.) and pigweed (Amaranthus tamariscinus) seed than did a late March 1985 drawdown. Estimated seed production by Cyperus spp. did not vary significantly with a difference in drawdown date. Beggarticks (Bidens spp.) were more abundant following the early drawdown. Wild millet (Echinochloa crusgalli) occurred on soils exposed early but did occur after the late drawdown.

Seed production between plots was highly variable even within the same year. Interspecific competition and differences in microclimate probably account for the majority of this variability. A drawdown between 15 June and 15 July is recommended to maximize seed production of smartweeds, pigweed, and millets. Drawdowns conducted during the early portion of this period are more likely to result in the germination of non-target problem species like cottonwoods and willows.

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