History of the Yosemite area drainages of two river watersheds. Preservation of watersheds was very important to Muir, who said "you cannot save Yosemite Valley without saving its Sierran fountains." The State of California retained control of Yosemite Valley and the Mariposa Grove of Big Trees. Muir and 181 others founded the Sierra Club in 1892, in part to lobby for the transfer of the valley and the grove into the national park. Like Yellowstone National Park before it, Yosemite National Park was at first administered by various units of the United States Army. Captain Abram Wood led the 4th Cavalry Regiment into the new
Yosemite National Park 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