Get access

Mid-Spring Burning Reduces Spotted Knapweed and Increases Native Grasses during a Michigan Experimental Grassland Establishment


  • Neil W. MacDonald,

    Corresponding author
    1. Natural Resources Management Program, Department of Biology, Grand Valley State University, Allendale, MI 49401-9403, U.S.A.
      Address correspondence to N. W. MacDonald, email
    Search for more papers by this author
  • Brian T. Scull,

    1. Annis Water Resources Institute, Grand Valley State University, Muskegon, MI 49441, U.S.A.
    Search for more papers by this author
  • Scott R. Abella

    1. Ecological Restoration Institute, Northern Arizona University, Flagstaff, AZ 86011-5017, U.S.A.
    Search for more papers by this author


This article is corrected by:

  1. Errata: Erratum Volume 15, Issue 2, 362, Article first published online: 14 May 2007

Address correspondence to N. W. MacDonald, email


Infestations of the exotic perennial Spotted knapweed (Centaurea maculosa Lam.) hinder the restoration and management of native ecosystems on droughty, infertile sites throughout the Midwestern United States. We studied the effects of annual burning on knapweed persistence on degraded, knapweed-infested gravel mine spoils in western Michigan. Our experiment included 48, 4-m2 plots seeded to native warm-season grasses in 1999 using a factorial arrangement of initial herbicide and fertility treatments. Beginning in 2003, we incorporated fire as an additional factor and burned half of the plots in late April or May for 3 years (2003–2005). Burning increased the dominance of warm-season grasses and decreased both biomass and dominance of knapweed in most years. Burning reduced adult knapweed densities in all 3 years of the study, reduced seedling densities in the first 2 years, and reduced juvenile densities in the last 2 years. Knapweed density and biomass also declined on the unburned plots through time, suggesting that warm-season grasses may effectively compete with knapweed even in the absence of fire. By the end of the study, mean adult knapweed densities on both burned (0.4-m2) and unburned (1.3-m2) plots were reduced to levels where the seeded grasses should persist with normal management, including the use of prescribed fire. These results support the use of carefully timed burning to help establish and maintain fire-adapted native plant communities on knapweed-infested sites in the Midwest by substantially reducing knapweed density, biomass, and seedling recruitment and by further shifting the competitive balance toward native warm-season grasses.

Get access to the full text of this article