Yosemite National Park Half Dome
Home > Nature & History > Nature > Vegetation

Half Dome

Trip Planning
Yosemite Today
Nature & History
Students & Teachers
Park Management
Working in the Park
Support  Your Park
Experience Your America


Also in this section
Air Resources
Nature Home
Exotic Plants

Yosemite National Park has documented more than 130 non-native plant species within park boundaries. These non-native plants were introduced into Yosemite following the migration of early Euro-American settlers in the late 1850s. Natural and human-caused disturbances, such as wildland fires and construction activities, have contributed to a rapid increase in the spread of non-native plants. A number of these species aggressively invade and displace the native plant communities, resulting in impacts on the park’s resources. Non-native plants can bring about significant changes in park ecosystems by altering the native plant communities and the processes that support them. Some non-native species may cause an increase in the fire frequency of an area or increase the available nitrogen in the soil that may allow more non-native plants to become established. Many non-native species, such as yellow star thistle (Centaurea solstitialis), are able to produce a long tap root that allows them to out-compete the native plants for available water.

Grinning Man Holding An Uprooted Weed
A volunteer removes bull thistle in Sentinal Meadow. Photo by Sue Fritzke/NPS.

Bull thistle (Cirsium vulgare), common mullein (Verbascum thapsus), and Klamath weed (Hypericum perforatum) have been identified as noxious pests in Yosemite since the 1940s. Additional species that have been recognized more recently as aggressive and requiring control are yellow star thistle (Centaurea solstitialis), sweet clovers (Melilotus spp.), Himalayan blackberry (Rubus discolor), cut-leaved blackberry (Rubus laciniatus) and periwinkle (Vinca major).

Yosemite National Park Home Page
http://www.nps.gov /archive/yose/nature/veg_exotics.htm
Last modified Wednesday, 22-Dec-2004 10:15:06 Eastern Standard Time
Yosemite National Park Web Manager