Date of Award

12-1-1999

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Thomas Bragg

Abstract

A plant community gradient, consisting of Open-water, bulrush, Grass, and Forest Zones, was evaluated both before (1995) and one-year after (1997) restoration-dredging of a wetland along the Missouri River in east-central Nebraska. Species diversity declined significantly (P ≥ 0.05) in both the Bulrush and Grass Zones (-24 and -30 species) but not elsewhere. The Open-water Zone, which increased the most with dredging (+40 meters), was dominated by duckweed (Lemna minor) (53% canopy cover in 1995 and 45% in 1997) and watermeal (Wolddia columbiana) (53% and 61%) both before and after dredging. Coontail (Ceratophylum demersum) increased significantly (7% to 25%). The greatest species decline occurred with river bulrush (Scirpus fluviatilis) (50% to 28%) both due to a substantial reduction in the areal extent of the Bulrush Zone(-14 m width) and a significant decline in canopy cover of bulrush within the zone (55% in 1995 to 29% in 1997). Reed canary grass (Phalaris arundinacea) declined significantly in all terrestrial zones (average decline of 31%). Despite declines in cover in these and other native wetland species, most survived dredging, suggesting that, at least in this one instance, dredging to restore the backwater habitat can be accomplished without a substantive loss of associated plant communities.

Comments

A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 1999 Lisa A. Peterson.

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