Invasive, non-native plants are introduced from other parts of the world. The spread of invasive plants is a primary cause of degradation to ecological systems. Invasive plants, also known as weedy or noxious plants, displace native plant and animal populations and reduce habitat and food sources for native insects, birds and other wildlife.

Yosemite has actively controlled invasive plant populations since the 1930s and these efforts continue today. Park staff has aggressively managed highly invasive species over the last several years. This control program includes the use of Geographic Positioning System technology to map plant populations. Crews then remove plants using a variety of techniques, including hand-pulling, lopping, mowing, and herbicide. Treated areas are photographed and re-visited each year to assess results and provide follow-up treatment.

Star Thistle

The Parkwide Invasive Plant Management Plan and Environmental Assessment is now available. See link below.

This plan represents a comprehensive, prioritized program of prevention and early detection, control, systematic monitoring, and research.  Some of the goals are to:

• Prevent new invasions through systematic early detection, equipment inspections, use of certified weed-free pack stock feed, and use of weed-free soil and rock for construction projects.
• Prioritize existing populations and sites for control.
• Eradicating existing infestations to minimize threats to natural and cultural resources and scenic values.
• Preserve plants and sites valued by Native Americans.
• Reconcile potential conflicts between preservation of cultural landscapes and removal of invasive plants.
• Promote restoration of native species and habitats in ecosystems degraded by invasive plants.
• Implement the most appropriate control technique for each species and site.
• Ensure that the invasive plant program is regularly monitored and improved, environmentally safe, and is supported by science and research.
• Promote an understanding of invasive species with park visitors, employees, park partners, and gateway communities.
• Provide information to the public on when, where, and how control efforts will take place.
• Control methods may include hand-pulling, use of mechanical weed removal tools, release of predatory insects or fungi, judicious use of herbicides such as glyphosate and aminopyralid.

Documents pertaining to the Parkwide Invasive Plant Management Plan include:

• 2009 Invasive Plant Work Plan - Posted 4/09 (44 kb PDF)
• Invasive Plant Management Plan Workplan - Spring 2009 - Posted 3/09 (16 kb PDF)
• Invasive Plant Management Plan Workplan - Fall and Winter 2008 - Posted 10/08 (33 kb PDF)
• Finding of No Significant Impact - September 2008 (436 kb PDF)
• Comments and Responses - September 2008 (124 kb PDF)
• Environmental Assessment - June 2008 (2.0 MB PDF)
• Slide Show about Invasive Plan Management Plan
• Fact Sheet - January 2009 (73 kb PDF)
• Participants Guide - June 2008 (280 kb PDF)
• Public Comments (9/08)
• • Comment IPM-S-49 (101 kb PDF)
  • Comment IPM-S-50 (236 kb PDF)
  • Comment IPM-S-52 (158 kb PDF)
  • Comment IPM-S-53 (2.4 mb PDF)
  • Comment IPM-L-54 (166 kb PDF)
  • Comment IPM-Redacted (284 kb PDF)

Learn More about How Park Botanists Manage Invasive Plants

• Invasive species, both plants and animals, are a concern in Yosemite National Park.
• What are invasive plants and why are they a problem?
• How are scientists attempting to manage invasive plants within the park?