2009 MANAGEMENT STATUS: Yosemite’s invasive plant biological technicians have 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 have recorded 805 acres (285 in wilderness) of non-native plant infestations in Yosemite, but there is more to document. Some species, such as cheat grass, are so widespread that it’s a challenge to map.
http://www.nps.gov/yose/naturescience/invasive-plant-management.htm