Description and Ecology: Lowland riparian forests border stream systems as they flow out of the foothills onto the eastern plains and into the San Luis Valley and valleys on the Western Slope. The lowland riparian forests on the Western Slope generally consist of Rio Grande cottonwoods with an understory of willows and a mixture of red-osier dogwood, buffaloberry, skunkbrush, greasewood, and other shrubs (Andrews and Righter 1992, Kingery 1998). Salt cedar and Russian-olive are exotics that are now major components of lowland riparian communities. Russian knapweed has become a ubiquitous exotic forb in lowland riparian zones.

Various sources report that riparian forests comprise less than 3% of the total landscape, but up to 80% of the resident bird species use them for some part of their life cycle. Birds use this habitat for nesting, cover, resting, migration stopover areas, and migration corridors. This system has the richest avian species component of any of Colorado's habitats. The most frequently detected species in lowland riparian forests in Physiographic Area 87 include American Kestrel, Western Screech-Owl, Great Horned Owl, Mourning Dove, Northern Flicker, Western Wood-Pewee, Western Kingbird, Eastern Kingbird, House Wren, Black-billed Magpie, American Robin, Yellow Warbler, Blue Grosbeak, and Bullock's Oriole (Andrews and Righter 1992, Krueper 1995, Howe 1996, Kingery 1998).

Importance and Conservation Status: Lowland riparian systems provide dispersal corridors for woodland birds across otherwise treeless terrain. Well-defined, unique, and highly productive, riparian zones areas are sensitive to disturbance (Melton et al. 1984).

Riparian ecosystems are highly important areas for both humans and wildlife. During historic times, humans have used riparian zones intensively for many different purposes. They have been substantially altered to create residential, industrial, and recreational developments and to create highways and gravel mines. Riparian zones are convenient locations for those activities. They are also productive areas for domestic livestock grazing. However, the impacts of domestic livestock are not as dominant as in high elevation riparian zones (Melton et al. 1984, Wozniak 1995).

Unlike the high elevation riparian habitat in Colorado, much of the lowland riparian ecosystem is in private ownership. Consequently it is much more susceptible to loss and degradation by urban and industrial development, mining, road and trail development, and recreational development.

Priority Species Accounts: Two species are identified as high priority in lowland riparian habitats in Physiographic Area 87: Lewis's Woodpecker and Western Kingbird.