Invasive exotic plant monitoring at Pipestone National Monument: Year 2 (2009)

Young, Craig; Short, Mary; Morrison, Lloyd; Gross, Chad; Haack, Jennifer

During surveys in 2006 and 2009, we documented a total of 20 invasive exotic plant taxa in Pipestone National Monument. All species were previously known to occur in the park. We found three grass species to be widespread and abundant: bluegrass and smooth brome were each estimated to cover at least 21 acres or more on the monument, while reed canarygrass occurred on at least four acres. Of the 18 invasive exotic plants found in 2009, 10 taxa each occurred on less than one acre. Invasive plant species that were targeted with control showed greater relative decreases in frequency than species which that were not directly managed. Of the three species with minimal relative decreases in frequency - bluegrass, Canada thistle, and reed canarygrass – only Canada thistle was treated specifically. All six species that showed greater relative decreases in frequency were specifically targeted with control treatments. Six of the eight more abundant invasive species (minimum abundance>0.4 acres) decreased in frequency between 2006 and 2009, while almost equal numbers of the less abundant species increased or decreased in frequency. The cover of common buckthorn (Rhamnus cathartica), which park staff have treated aggressively, was reduced. In summary, these findings suggest that the park’s control efforts have reduced the distribution and abundance of several invasive exotic plant species. This observation combined with the low abundance of many of the other species suggests that on-going park control efforts are likely to be very effective. The information presented in this report may be used to plan management activities leading to control of exotic plants and the accomplishment of GPRA goal IA1.

Invasive exotic plant monitoring at Pipestone National Monument: Year 2 (2009)

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