Fremont Cottonwood
Populus fremontii
Description: Fremont cottonwoods are a deciduous tree
species that can grow up to 100 feet tall. Male and female flowers
grow on separate trees. Female trees produce fluffy white seeds
that become wind-borne in the spring and give cottonwood its common
name. Cottonwood seeds are typically dispersed as receding spring
floodwater exposes moist scoured zones of sand and gravel, which
are ideal for seed germination.
Wildlife and livestock eat the sweet bark, seedlings, and new
growth of saplings; beavers build dams with the branches. Cottonwoods
host a diverse insect fauna that attracts an abundance of insectivorous
birds. Many birds also use cottonwoods for nesting; notable among
them are bald eagles, common black-hawks, and gray and zone tailed
hawks.
Habitat: This cottonwood grows in western North America along streams and rivers. For early desert travelers they indicated a reliable supply of water within digging depth. Mature cottonwoods along desert streams indicate a water table within 10 feet or so. As groundwater tables decline, suitable habitat for cottonwood growth decreases.
Distribution: Fremont cottonwoods occur (or historically occurred) nearly everywhere in Arizona south of the Mogollon Rim, along streams, in bottomland, and around water holes in from sea level to 6,500 feet elevation. Today some of the most extensive cottonwood-willow groves are found along the San Pedro River in southeastern Arizona, and the Hassayampa River near Wickenburg.
Status: The cottonwood-willow community type is considered one of the most important native habitat types in North America. The decline of this community is primarily due to depletion of groundwater, diversion of stream flow, construction of flood control structures, and livestock grazing. Dams along water systems reduce scouring flood events that create a productive seed bed. Salt cedar, an exotic tree that invades cottonwood habitat, has spread primarily because of these changes.
The Cottonwood in Pima County: Cottonwoods occur in a few locations along the effluent-dominated portion of the Santa Cruz River, in portions of the bank-protected channel of the Rillito and Tanque Verde Creeks, and along Arivaca Creek and the San Pedro River. A large stand of cottonwoods, within the Cienega Creek Natural Preserve, became established in the late 1970's or early 1980's.
References
ADWR, 1994. Arizona Riparian Protection Program Legislative Report. Arizona Department of Water Resources report to the Governor, President of the Senate, and Speaker of the House.
Zarlingo, Wade A. , Non-game Branch, Arizona Game and Fish Department.
8/23/99 website at www.gf.stat.az.us/frames/fishwild/ngame-d/htm
back to Keystone Species