Invasive Plant Management Plan and Update

Himalayan blackberry completely covers all the native vegetation in this El Portal location. This bramble forms impenetrable thickets in sensitive habits throughout Yosemite.


In 2008, Yosemite National Park created the Invasive Plant Management Plan (2008 IPMP) to provide a comprehensive, prioritized program of invasive plant prevention, early detection, control, systematic monitoring, and research. The 2009 Big Meadow Fire, and issues related to managing Himalayan blackberry (Rubus armeniacus) and other plants, highlighted the need for a more adaptive, programmatic plan that offers additional tools necessary to address the threat that invasive plants pose to park resources. The spread of invasive species is recognized as one of the major factors contributing to ecosystem change and instability throughout the world. An invasive species is “a non-native species whose introduction does, or is likely to cause, economic or environmental harm or harm to human, animal, or plant health” (Executive Order 13112, 1999). These species have the ability to displace or eradicate native species, alter fire regimes, damage infrastructure, and threaten human livelihoods.

Yosemite has actively controlled invasive plant populations since the 1930s. The 2008 IPMP was created to provide for a comprehensive, prioritized program of invasive plant prevention, early detection, control, systematic monitoring, and research.The 2008 plan uses an integrated pest management (IPM) approach to detect, control, and prevent priority invasive plants from spreading into uninfested areas. The best available scientific and practical information is considered in planning control efforts. Then, a full range of cultural, manual, mechanical and chemical control techniques are considered for use, including preventing the introduction of invasive species, to hand-pulling and mowing, and the judicious use of herbicides to treat established populations.

While the 2008 IPMP provides a foundation for well-developed decision-making and prioritization strategies, an plan was initiated in 2010 to update the original plan. This update outlined a protocol for adaptive management techniques that would provide greater flexibility to respond to present and future threats. For example, following the 2009 Big Meadow Fire in Yosemite, the Interagency Fire Management Team recommended applying a pre-emergent herbicide that has proven to be highly effective in other parts of the West, one which could prevent cheatgrass seeds from sprouting and overtaking the meadow after the late-season fire. Since this specific chemical was not considered and evaluated in the 2008 IPMP, the park was unable to use this new tool.

As new herbicides are developed, tested, and approved for use in the western states, adaptive management would allow the park to select more effective herbicides that have fewer undesirable effects. Working cooperatively with university researchers, the park can continue to test and monitor the various approved IPM treatments, to find the most efficient, effective, and safest tools to protect Yosemite’s biodiversity.

The Invasive Plant Management Plan Update went through an environmental planning process initiated with public scoping and related public meetings. The Invasive Plant Management Plan Update (IPMP Update) Environmental Assessment (EA) was released for a 45-day public review in late 2010. During that review period comments were accepted and public meetings were held. After reviewing comments, a Finding of No Significant Impact (FONSI) was signed in August 2011.

Ultimately this updated plan gives Yosemite National Park resource managers greater flexibility in responding to present and future threats to park resources from non-native invasive species. Successful aspects of the 2008 IPMP, such as annual work plans, prioritization, minimum tool analysis, and education, and outreach, would continue to be implemented.

Additional goals included:

  • Refining monitoring protocols to assess the effectiveness of weed control actions and potential impacts of such actions to non-target species and water quality. These protocols also allow managers to respond more effectively to the uncertainties such as large wildfires and climate change.
  • Identifying safe and effective methods for managing invasive wetland and riparian plant species.
  • Addressing language in the plan that precludes using all existing tools to manage new invasive species populations and also populations in wilderness areas of the park.
  • Assuring cultural resource protection under the National Historic Preservation Act (NHPA), including traditional gathering areas, in consultation with American Indian Tribes.

Last updated: February 10, 2020

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