EcoSystems and Habitats Tree Dominated Wildlife Habitats Desert Riparian (DRI) Tamarisk, Mesquite, Fremont Cottonwood Vegetation Desert riparian habitats include dense stands of small, bushy trees or tall shrubs (Küchler 1977) to woodlands of small to medium-sized trees (Cheatham and Haller 1975).
These habitats occur adjacent to permanent water, such as streams and springs, or areas annually flooded or naturally watered from below (Parker and Matyas 1981). This habitat commonly forms a sharp ecotone with adjacent, shorter, more open desert communities.
The height of riparian vegetation varies according to the constituent plant species; willow thickets are between 1 to 3 m (3 to 10 ft) in height (Cheatham and Haller 1975), whereas Fremont cottonwoods may reach over 24 m (80 ft). Tree species vary with each desert river type. The overstory species include tamarisk, velvet ash, mesquite, screwbean mesquite, Fremont cottonwood, and willows such as Gooding, Hinds, and arroyo (Bradley and Deacon 1967, Cheatham and Haller 1975, Küchler 1977, Paysen et al. 1980, Parker and Matyas 1981).
The subcanopy has smaller plants of the canopy species and also includes quailbush, Mojave seablight, desert lavender, seep willow, and arrowweed (Bradley and Deacon 1967, Küchler 1977. Paysen et al. 1980, Parker and Matyas 1981). Other names for Desert Riparian habitat include Cottonwood Series; Arrowweed Series (Payson et al. 1980, Parker and Matyas 1981); Tamarisk Series (Parker and Matyas 1981); Saltcedar Series; Mesquite Series; Willow Series (Payson et al. 1980); Colorado River Bottomland Woodland 6.12; Willow Thickets – 6.24; Southern Alluvial Woodland – 6.31 (Cheatham and Haller 1975), and Alkali Scrub Woodland – 48 (Küchler 1977). Habitat Stages Vegetation Changes– 1;24.S-D. Desert Riparian habitats may exist as a variety of habitat stages ranging from seedlings through tree/shrub to large tree. Canopy development and plant density depend on available water, plant species, and site characteristics. Length of Stages. The duration of successional stages for Desert Riparian is not reported, but likely varies depending on disturbance factors, including fire and floods, as well as groundwater and precipitation patterns. Biological Environment Desert riparian habitats often occur adjacent to other desert habitats, including Desert Wash (DSW), Desert Succulent Shrub (DSS), Desert Scrub (DSC), Joshua Tree (JST), Alkali Scrub (ASC), and Palm Oasis (POS). The taller and denser desert riparian habitats typically form a sharply defined border with the surrounding generally shorter and sparser desert habitats. Wildlife Considerations– The value of these rare desert river areas to animal populations is very high. These habitats have more diversity and numbers of birds and other wildlife than most other desert habitats (England et al. 1981)(No England et al. 1981 in Habitat Lit Cite. I used England et al. 1984 as Lit Cite at end.) with the possible exception of some of the Palm Oasis habitats. The dense shrubs and permanent waters provide food, cover, and water for the other wildlife. Physical Setting Soils range from silty alluvial to rocky, sandy, well-drained types (Bradley and Deacon 1967, Cheatham and Haller 1975). Soils are typically moist but some may be dry on the surface with moisture beginning a few meters below (Cheatham and Haller 1975). Desert Riparian habitats do not occur on saline soils (Parker and Matyas 1981), but often occur along permanent streams in canyons or on river sediments in wider valleys. They can also be found in various landforms where the water table reaches or is very close to the surface. The habitats usually experience hot summers, dry with cool to cold, and wet winters. Highest July temperatures range from 30 to 42 C (86 to 107 F). Lowest January temperatures range between 7 and 6 C (19 and 42 F) (Rowlands et al. 1982, P. G. Rowlands pers. comm.). Most precipitation is in winter, but summer rainfall occurs especially in southeastern California. Total rainfall is between 8 and 25 cm (3.1 to 9.8 in) each year, and possible water loss through evaporation and plant transpiration is 3 to 17 times greater than the rainfall (Rowlands et al. 1982, P. G. Rowlands pers. comm.).
Distribution Desert Riparian habitats occur along permanent streams and at areas where the water emerges from the ground, such as seeps and springs, within Mojave and Sonoran deserts, and within desert canyons of the Peninsular ranges. Habitats usually are found below 900 m (3000 ft) in elevation; however, willow thickets can occur far higher up into the mountainsides—Cheatham and Haller, 1975.
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