Print Report
A3772 Betula occidentalis Wet Shrubland Alliance
Type Concept Sentence: This riparian shrubland alliance occurs on moderately wide stream benches and floodplains. It may also occur on hillside seeps in the mountains and foothills. Sites are relatively flat (1-5% slope) stream benches and often extend away from the channel edge. The substrate is usually exposed, but surface water can be present for variable periods without detectable seasonal periodicity. Betula occidentalis forms a dense, closed canopy with cover up to 95%. It occurs in the Rocky Mountains, intermountain ranges of Nevada and Sierra Nevada of California.
Common (Translated Scientific) Name: Water Birch Wet Shrubland Alliance
Colloquial Name: Western Water Birch Wet Shrubland
Hierarchy Level: Alliance
Type Concept: In this alliance, Betula occidentalis forms a dense, closed canopy with cover up to 95%. The shrub layer may also include Alnus incana, Artemisia tridentata ssp. vaseyana, Cornus sericea, Crataegus douglasii, Dasiphora fruticosa ssp. floribunda, Juniperus horizontalis, Purshia tridentata, Purshia tridentata, Rosa woodsii, and Salix spp. Due to the dense shrub canopy, herbaceous undergrowth is usually limited. Forb species include Aquilegia formosa, Maianthemum stellatum, and Urtica dioica. Graminoid cover is usually low and is typically composed of introduced hay grasses. This riparian shrubland alliance occurs in the Rocky Mountains, intermountain ranges of Nevada and Sierra Nevada of California on moderately wide stream benches and floodplains. It may also occur on hillside seeps in the mountains and foothills. Sites are relatively flat (1-5% slope) stream benches and often extend away from the channel edge. The substrate is usually exposed, but surface water can be present for variable periods without detectable seasonal periodicity. Inundation is not predictable to a given season and is dependent upon highly localized rainstorms (e.g., summer thunderstorms in eastern Oregon and Idaho). Soils are derived from alluvium and are fairly shallow, ranging from 30 cm to greater than 60 cm. Substrates are typically alluvial and range from fairly shallow, finer-textured soils to gravel and boulders. Soils usually have signs of saturation (mottles).
Diagnostic Characteristics: Tall (>1.5 m) shrubland dominated by Betula occidentalis.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Tall riparian shrublands may be mixed with other tall riparian shrubland alliances such as Alnus- and Salix-dominated communities.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: The tall-shrub layer is dominated by broad-leaved deciduous shrubs or small trees reaching heights of up to 8-9 m. The tree canopy is dominated by conifers of variable density. The tall-shrub stratum is dense with up to 98% cover. The short-shrub layer (1-2 m tall) is sparse to dense with 25-60% cover. The graminoid layer consists of mainly introduced hay grasses and constitutes up to 35% cover. The forb layer has 0-40% cover depending on the overstory canopy cover.
Floristics: Plant associations within this alliance are classified as intermittently flooded, cold-deciduous shrublands. Betula occidentalis forms a dense, closed canopy with cover up to 95%. The shrub layer may also include Alnus incana, Artemisia tridentata ssp. vaseyana, Cornus sericea, Crataegus douglasii, Dasiphora fruticosa ssp. floribunda (= Pentaphylloides floribunda), Juniperus horizontalis, Purshia tridentata, Purshia tridentata, Rosa woodsii, and Salix spp. The tree canopy has a moderate cover and includes any of the following species: Abies lasiocarpa, Acer negundo, Alnus rhombifolia, Picea pungens, Populus angustifolia, Populus tremuloides, Pseudotsuga menziesii, and Thuja occidentalis. Due to the dense shrub canopy, herbaceous undergrowth is usually limited. Forb species include Aquilegia formosa, Maianthemum stellatum (= Smilacina stellata), and Urtica dioica. Graminoid cover is usually low and includes Carex utriculata, Carex pellita (= Carex lanuginosa), Carex microptera, Carex nebrascensis, Glyceria spp., Juncus balticus, and introduced hay grasses.
Dynamics: Betula occidentalis is highly adapted to most forms of disturbance. However, heavy grazing may eliminate the more palatable native graminoids, thereby replacing them with introduced species or nonpalatable native species in the understory (Hansen et al. 1995).
Environmental Description: Plant associations within this alliance occupy moderately wide stream benches and floodplains in moderately wide valleys and on hillside seeps in the mountains and foothills. Sites are relatively flat (1-5% slope) stream benches and often extend away from the channel edge. Elevation ranges up to 2700 m in Idaho. The substrate is usually exposed, but surface water can be present for variable periods without detectable seasonal periodicity. Inundation is not predictable to a given season and is dependent upon highly localized rainstorms e.g., summer thunderstorms in eastern Oregon and Idaho. Soils derived from alluvium are fairly shallow, ranging from 30 to greater than 60 cm.
Geographic Range: This alliance is found in the Rocky Mountains of eastern Oregon and Washington, Idaho, British Columbia, Alberta, Montana, Wyoming, Colorado, New Mexico, and Utah, as well as intermountain ranges of Nevada and Sierra Nevada of California.
Nations: CA,US
States/Provinces: AB, AZ, BC, CA, CO, ID, MT, NM, NV, OR, SD, UT, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.899824
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: ? Betula occidentalis (Water birch thicket) Alliance (Sawyer et al. 2009) [63.610.00]
- Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
- Hansen, P. L., R. D. Pfister, K. Boggs, B. J. Cook, J. Joy, and D. K. Hinckley. 1995. Classification and management of Montana''s riparian and wetland sites. Miscellaneous Publication No. 54. Montana Forest and Conservation Experiment Station, School of Forestry, University of Montana. 646 pp. plus posters.
- Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.