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The article explores the innovative restoration in ecological area which were occupied by spotted knapweed, a non-native perennial forb in North America. Topics discussed include use of herbicide treatments, long term restoration for knapweed and establishing a study on the development of native warm-season grasses in Michigan. Other topics include the use of single annual mowing methods and experimental management strategies to prevent knapweed.

Invasive species frequently need to be controlled as part of efforts to reestablish native species on degraded sites. While the effectiveness of differing control methods are often reported, the impacts these methods have on the establishment of a native plant community are often unknown. To determine methods that effectively reduce spotted knapweed (Centaurea stoebe) while enhancing native species establishment, we tested 12 treatment combinations consisting of an initial site preparation (mowing, mowing + clopyralid, or mowing + giyphosate), in factorial combination with annual adult knapweed hand pulling and/or burning. We established 48 plots and applied site preparation treatments during summer 2008, seeded 23 native forbs and grasses during spring 2009, pulled adult knapweed annually from 2009-2012, and burned in the early spring 2012. During July of 2011 and 2012, percent cover of all species was visually estimated. By 2011, seeded species had established in all treatment plots, including plots that retained greater than 50% knapweed cover, indicating that native species successfully established despite knapweed dominance. Mowing alone had no longterm impacts on community development. Clopyralid favored non-native grass establishment, while giyphosate encouraged non-native forbs. Clopyralid had minimal impacts on native forb establishment, but did effectively control knapweed. Pulling reduced knapweed cover, increased non-native grass cover and enhanced native species establishment. Burning had little impact, possibly due to low intensity and unseasonable weather. On the heavily invaded site we studied, combining the use of clopyralid with hand pulling effectively controlled knapweed and favored the establishment of seeded native grasses and forbs. [ABSTRACT FROM AUTHOR]

This article discusses various issues related to the effectiveness of hand-pulling spotted knapweed for grassland restoration in Montana, with specific reference to a study conducted in this regard. The results of a three-year experiment, the article author conducted in Missoula, Montana suggest that hand-pulling can be effective when there is a large pool of volunteer labor and the target plant is a species susceptible to hand-pulling. This study indicates that hand-pulling weeds resulted in a two-fold decrease in knapweed density, but also in a ten-fold increase in cheatgrass abundance. This is important because the goal of controlling invasive plants is not simply to eliminate them, but to stimulate the recovery of the native plant community.