First-Year Responses of Cheatgrass Following Tamarix spp. Control and Restoration-Related Disturbances

Authors

  • Anna A. Sher,

    Corresponding author
    1. Department of Biological Sciences, University of Denver, Denver, CO, 80208, U.S.A.
    2. Research and Conservation, Denver Botanic Gardens, 909 York Street, Denver, CO, 80206, U.S.A.
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  • Stephanie Gieck,

    1. Department of Biological Sciences, University of Denver, Denver, CO, 80208, U.S.A.
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  • Cynthia S. Brown,

    1. Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, 80523, U.S.A.
    2. Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, 80523, U.S.A.
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  • Scott J. Nissen

    1. Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, 80523, U.S.A.
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Address correspondence to A. Sher, email anna.sher@du.edu

Abstract

Current invasion ecology theory predicts that disturbance will stimulate invasion by exotic plant species. Cheatgrass or Downy brome (Bromus tectorum) was surveyed in three sites near Florence, Colorado, U.S.A., immediately following Tamarisk or Saltcedar (Tamarix spp.) control and restoration activities that caused disturbance. Despite predictions to the contrary, neither mowing with heavy machinery nor tilling for seedbed preparation stimulated invasion, with a trend for the opposite pattern such that highest percent cover of B. tectorum was observed in the least disturbed transects. Aerial application of imazapyr for Tamarix spp. control caused mortality of nearly all B. tectorum and other understory plant species in all sites. Mechanical control of Tamarix spp. will not necessarily result in increased abundance of invasive species already present, possibly due to the effects of mulch usually left on-site. Imazapyr will control B. tectorum and other herbaceous understory species when applied aerially for Tamarix spp. control. These results are encouraging for managers of riparian systems who may fear that control of woody invasives will stimulate herbaceous invasions.

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