Determining effective aspen management strategies for enhancing habitat and biological diversity in Manitoba's Interlake

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Froese, James J.
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Manitoba's Southern Interlake region is located in the Aspen Parkland, a zone of tension that historically experienced frequent fire events and grazing from large bison herds. These were two prominent factors in the historic disturbance regime that shaped and maintained habitat diversity in this dynamic ecosystem. More recently, the lack of frequent fire events, elimination of bison, and variation in precipitation have contributed to increased trembling aspen encroachment onto former grassland and shrubland habitats. Aspen encroachment has resulted in an increasingly homogeneous landscape that has negatively impacted wildlife populations and biological diversity. Effective strategies are needed in order to restore some of the habitat and biological diversity that was historically found in the Narcisse Wildlife Management Area (NWMA). Rolling and scraping of aspen bush and shrubland complexes with a large drum roller and skidder have been used in the Interlake as a technique to eliminate larger vegetation species. However, substantial aspen suckering from the clonal root systems has been evident. This project evaluated the effectiveness of 4 secondary treatments prescribed burning, Glyphosate applied with a wiper, mowing and bark scraping) in reducing trembling aspen density and impacting biological diversity in the plant community. The study was set up in a randomized block design, with each treatment and an untreated control replicated 3 times. Measures of vegetative diversity were also taken in adjacent unrolled bush and shrubland complexes. Treatments were applied during mid-May to mid-June 2000, and surveyed during August 2000 and 2001. A 4 m2 quadrat was used to evaluate trembling aspen stem density and health. A 1 m2 quadrat was used to evaluate the plant community, utilizing the Daubenmire cover class method...