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National Cohesive Wildland Fire Management Strategy Success Story

Early Detection of Highly Invasive Non-Native Plants after Big Meadow Fire
Yosemite National Park, California
Cohesive Strategy - Maintain and Restore Landscapes
2011

Italian thistle.
Italian thistle discovered growing on the edge of the 2009 Big Meadow Fire.

Foresta is a private inholder community enclosed completely within Yosemite National Park. As a result of a wildfire several years ago, Foresta is now surrounded by charred chaparral and towering pine snags. Like many other communities in the foothills of the Sierra Nevada, Foresta's landscape is in a perpetual cycle of vegetation change.

For some community members the natural state of things is insufficient; new plants are introduced that sometimes turn out to be invasive. Oxeye daisy and bachelor buttons now occupy acres of habitat in Yosemite National Park after escaping from Foresta residences. Lush non-native grasses were planted to feed stock animals en route to the grandeurs of Yosemite Valley. Spotted knapweed, bull thistle and cheat grass arrived by accident. The introduced species benefit from the disturbances of the frequent fires. After the 2009 Big Meadow Fire, Burn Area Rehabilitation (BAR) was used to slow or eliminate the spread of the invasives into valuable habitats.

Botanists surveyed the burn area for invasives and made two discoveries that, as compared to the cost of known infestations in the park, represent tens of thousands of dollars in savings had they gone undiscovered. During the first year of surveys, the prolific, wind-dispersed, and very aggressive Italian thistle was found in a graveyard of old washing machines and driers on an inholder’s property. The patch of around 300 individual plants was quickly treated. In 2010 the Italian thistle population was revisited and only 45 individual plants were found and removed. Prior to the BAR survey, Italian thistle was previously unknown in the park. The second equally disturbing discovery was a patch of 15 yellow star thistles growing near a pull-out over 3000 feet in elevation higher and nine air miles away from the next closest patch. Yellow star thistle is considered one of California’s worst invasive plants and they were promptly removed.

Natural resource managers can prevent further spread of well-established invasives. However, the encounters of Italian thistle and yellow star thistle early in their establishment are exemplary examples of the importance of early detection and rapid response programs that BAR helps fund. This program helps ensure that the vegetation communities reenter natural vegetation cycles and recovery is not sidetracked by invasives.

Contact

Garrett Dickman, Biologist
Email: garrett_dickman@nps.gov
Phone: (209) 379-3284