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Alnus incana-Cornus sericea

mountain alder–red-osier dogwood

Vegetation Composition: Alnus incana dominates the tall shrub overstory of this community. Betula occidentalis may occasionally be present as a codominant. Cornus sericea forms a dense shrub layer with Salix lutea, S. lasiolepis, Philadelphus lewisii, Crataegus douglasii, and Rosa woodsii. The herbaceous layer is usually sparse, with no species occurring in high abundance (Padgett et al. 1989).

Classification Comments: Includes Crowe and Clausnitzer's (1997) Alnus incana-Cornus sericea/Mesic forb association.

Environment: This plant association occurs immediately adjacent to streams that are subject to seasonal fluvial scouring and deposition. Surface topography is typically undulating and slopes are often 2% or less. Valley bottoms are narrow to moderately wide (Padgett et al. 1989). Elevations range from below 3,000 to nearly 8,000 feet.

Soils: Soils are formed by fluvial deposition and scouring and generally have more than 35% coarse fragments at least in the subsurface horizons. Estimated available water-holding capacity ranges from low to moderate. Water tables are closely related to the height of the community above the water level of adjacent streams. Soils have been classified as Aquic Cryofluvents, Typic Udifluvents, Mollic Xerofluvents, and Typic and Aquaic Cryoborolls (Padgett et al. 1989).

Management Considerations: Because of their rooting structure, the dominant shrub species are capable of holding coarse textured streambank materials in place and can act as filters for upland water and soil movement into channel systems. Livestock grazing is limited because of dense undergrowth (Padgett et al. 1989).

Successional Dynamics: This early seral type occurs adjacent to streams and is frequently subjected to seasonal flooding, scouring and deposition. It appears to be long-lived; succession to other types is probably slow. At lower elevations, this plant association is replaced by the Betula occidentalis-Cornus sericea plant association and in some areas these two communities grade into one another with both Alnus incana and Betula occidentalis present in the overstory. Alnus incana, Cornus sericea, and Betula occidentalis are well adapted to growing immediately adjacent to streams. They appear to withstand periodic flooding and seem to require the more aerated groundwater that flows through the coarse-textured subsurface soils with which they are commonly associated (Padgett et al. 1989; Manning and Padgett 1995).

Wildlife Functions: The low tree/shrub layers provide structural diversity for birds and other animals, while providing shade to the adjacent streams (Padgett et al. 1989).

Distribution: Stands occur in Utah (Padgett et al. 1989), Nevada (Manning and Padgett 1995), Oregon (Crowe and Clausnitzer 1997), and Idaho.

References:

Crowe, E. A., and R. R. Clausnitzer. 1997. Mid-montane wetlands classification of the Malheur, Umatilla, and Wallowa-Whitman National Forests. USDA Forest Service R6-NR-ECOL-TP-22-97. Pacific Northwest Region, Portland, OR. 299 pp.

Manning, M. E., and W. G. Padgett. 1995. Riparian community type classification for the Humboldt and Toiyabe National Forests, Nevada and eastern California. USDA Forest Service R4-ECOL-95-01. Intermountain Region, Ogden, UT. 274 pp.

Padgett, W. G., A. P. Youngblood, and A. H. Winward. 1989. Riparian community type classification of Utah and southeastern Idaho. USDA Forest Service R4-ECOL-89-01. Intermountain Region, Ogden, UT. 191 pp.

Author/Date(Update): R. K. Moseley/1997-12-31()