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Can habitats be enhanced on native prairie rangelands without ecological costs? Asamoah, Stephen*,1, Bork, Edward1, 1 Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
ABSTRACT- Declining waterfowl in the Canadian Prairies have been associated with expanding crop agriculture, which has contributed to the loss of prairie wetlands and upland nesting habitat. In 1983, Ducks Unlimited Canada initiated wetland development projects within native Dry Mixedgrass Prairie rangelands of southeastern Alberta to enhance breeding and nesting opportunities. Over the last 2 decades, created wetlands have experienced marked community change from ephemeral wetlands to spikerush (Eleocharis palustris L.), and eventually cattail (Typha latifolia L.) dominated communities, the latter of which is less desirable for waterfowl and livestock. Using hydrologic manipulations, we conducted greenhouse and field studies from 2002 to 2005 to evaluate the ability to induce retrogression in cattail dominated wetlands, as well as maintain spikerush. Results from our greenhouse studies indicate that although cattail is resilient to drought, it can be killed with extreme moisture stress. In contrast, spikerush was more susceptible to low soil moisture. Our field study affirmed results from the greenhouse experiment, and indicated spikerush may be compromised during attempts to control cattail with flood cessation. Moreover, declines in soil moisture under field conditions were slow to reach levels capable of causing widespread cattail mortality, a process impeded by stochastic environmental factors (e.g. above-normal rainfall), which prevented moisture values from falling to the minimum threshold needed to control cattail. Based on our observations of spikerush and cattail to moisture levels, we hypothesize that long-term strategies to reduce cattail will include alternating periods of anthropogenic flooding with extended water drawdown coincident with below-normal precipitation.
KEY WORDS: dry mixedgrass prairie, wetland development, cattail control, spikerush
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