Invasive Plant Management
Prevention and early detection of invasive plants are the most important and economically feasible means to control the spread of invasive plants, as noted on our general invasive plants webpage. Yosemite National Park Service work crews, park partners and volunteers have been using techniques such as hand-pulling, lopping, and mowing to manage the park's most invasive species as part of a 2008 Invasive Plant Management Plan. Yosemite, in 2008, began using two herbicides--glyphosate and aminopyralid--as additional tools to manage the most threatening plants that manual methods have not effectively controlled.
Yosemite's removal efforts are focused on the control of nine high-priority species: yellow star-thistle; Himalayan blackberry; spotted knapweed; bull thistle; common velvet grass; cheat grass; French broom; Italian thistle; and perennial pepperweed.
In 2009, Yosemite's invasive-plant biological technicians treated 156 gross-infested acres (27 acres in wilderness) and mapped 231 acres of invasives so far this season. On the whole, invasive plant ecologists recorded 805 acres (285 in wilderness) of non-native plant infestations in Yosemite, but there's more to document. Some species, such as cheat grass, are so widespread that it's a challenge to map. Using GIS, the invasive-plant crew mapped 2,664 points, lines and polygons of invasive-plant infestations and treatments in 2009. Invasive-plant managers then incorporated these features into their planning map containing a total of 6,389 GIS features collected since 1995.
2013 Invasive Plant Management Program's Work PlanView the 2013 Invasive Plant Management Plan [1.5 MB PDF] The work plan summarizes the 2012 field season and proposed 2013 treatments. The work plan describes the program's general approach as well as area specific plans.
Thirty-eight maps [14 MB PDF] display invasive plant infestation locations and site-specific details on all proposed treatment actions:
Learn More about the Invasive Plant Management Plan
The park's management of these invasive plants incorporates the following goals:
So, how exactly is Yosemite's invasive plant management one of the highest scientific concerns at Yosemite? In 2009, approximately 30 seasonal NPS crew members were involved in removing invasive plants—25 crew members, for example, removed star-thistle in June of 2009. In addition, Yosemite benefitted from 619 volunteers and 8,763 volunteer hours specific to invasive-plant removal in 2009.
Invasive species not only displace native plants, but they also can have severe negative impacts on many of the cultural and natural features. Invasive species are able to:
The following methods or techniques are commonly used for controlling invasive plants.
Did You Know?
In Yosemite Valley, dropping over 594-foot Nevada Fall and then 317-foot Vernal Fall, the Merced River creates what is known as the “Giant Staircase.” Such exemplary stair-step river morphology is characterized by a large variability in river movement and flow, from quiet pools to the dramatic drops of the waterfalls themselves.