Upland vegetation consists of woodlands, shrubland--including sagebrush steppe--and grasslands. These ecosystems are often intermixed in a diverse landscape matrix, which makes them important for biological diversity because they provide a wide range of habitats. They are also important for the ecological functions they provide--the ability to retain soils and nutrients, and absorb and release water, for example. These upland ecosystems are typically easy to disturb and slow to recover. Changes in disturbance factors such as drought and wildfire, livestock grazing, and invasive plants can alter the structure and function of these ecosystems, and these changes may be exacerbated or accelerated by climate change. Ecosystem structure refers to the spatial arrangement of the elements in the ecosystem (such as the shrubs, grasses, and forbs); and ecosystem function refers to the processes of how ecosystems change and interact, for example the frequency of fire, or the ability to recover after a disturbance.