Print Report
A3974 Crataegus douglasii / Symphoricarpos albus Wet Shrubland Alliance
Type Concept Sentence: This deciduous broad-leaved shrubland alliance is dominated by Crataegus douglasii, often forming dense thickets, and is found in the lower montane and foothill regions around the Columbia Basin, and north and east into the Central Rockies in Idaho and northwestern Wyoming.
Common (Translated Scientific) Name: Black Hawthorn / Common Snowberry Wet Shrubland Alliance
Colloquial Name: Valley Bottom Black Hawthorn / Common Snowberry Wet Shrubland
Hierarchy Level: Alliance
Type Concept: The shrub canopy of this deciduous broad-leaved shrubland alliance is dominated by Crataegus douglasii, often forming dense thickets. Occasional the broad-leaved deciduous trees Populus tremuloides or Populus balsamifera ssp. trichocarpa may codominate the tree layer for a period of years before dying back from heart rot. Other trees are occasionally present with low cover. The understory is dominated by short shrubs or herbaceous species. Common shrubs include Rosa nutkana, Rosa woodsii, Spiraea betulifolia, and Symphoricarpos albus. The sparse to moderately dense herbaceous layer is composed of perennial graminoids, such as Deschampsia cespitosa, Elymus glaucus, and Leymus cinereus, and diverse forbs The herbaceous layer is relatively depauperate if Heracleum maximum is abundant due to the extreme shading. Many weedy introduced grasses are common, such as the perennial forage species Bromus inermis, Phleum pratense, Poa pratensis, and invasive annual grass Bromus tectorum. This alliance is found in the lower montane and foothill regions around the Columbia Basin, and north and east into the Central Rockies in Idaho and northwestern Wyoming. Stands occur on relatively moist sites on deep soils within flat valleys on low-gradient streams with broad floodplains that flood seasonally. Elevations range between 400 and 850 m. Stands often extend up adjacent north-facing toeslopes where seepage provides constant moisture. Soils are typically deep and fine-textured.
Diagnostic Characteristics: The alliance is characterized by dominance of diagnostic species Crataegus douglasii, often forming dense thickets 3-8 m tall. Broad-leaved deciduous trees Populus tremuloides and Populus balsamifera ssp. trichocarpa may codominate the tree layer for a period of years before dying back and Crataegus douglasii becoming dominant again. Occasional individuals of Alnus incana, Betula occidentalis, or Celtis laevigata var. reticulata may be present with low cover. The understory is dominated by short shrubs or herbaceous species. If present the shrub layer is composed of associated species Amelanchier alnifolia, Cornus sericea, Rosa nutkana, Rosa woodsii, Salix exigua, Spiraea betulifolia, or Symphoricarpos albus. A sparse to moderately dense herbaceous layer may be present, typically composed of mesic perennial graminoids and forbs. Associated species include grasses Deschampsia cespitosa, Elymus glaucus, Leymus cinereus, and many forbs such as Geum macrophyllum, Heracleum maximum, Hydrophyllum fendleri, Iris missouriensis, Lithophragma parviflorum, Pteridium aquilinum, and Urtica dioica.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Associations within this alliance are often degraded and poorly described. Characteristics which differentiate this alliance from the moister Crataegus douglasii alliances are not clearly quantified.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Associations in this alliance generally support a dense thicket of tall (2-8 m) cold-deciduous woody shrubs with a secondary canopy of low shrubs. The herbaceous layer is usually well-developed and diverse, ranging from low-statured graminoids to coarse forbs approaching 2 m in height. A phase described by Daubenmire (1970) has an emergent open tree canopy of cold-deciduous trees, but this does not occur in all stands.
Floristics: The shrub canopy of this deciduous broad-leaved shrubland alliance is dominated by Crataegus douglasii, often forming dense thickets 3-7 m tall. Occasionally the broad-leaved deciduous trees Populus tremuloides or Populus balsamifera ssp. trichocarpa may codominate the tree layer for a period of years before dying back from heart rot (Daubenmire 1970). These Populus-codominated phases may repeat periodically when Populus stems sprout from roots. The process is described by Daubenmire (1970). Other trees occasionally present with low cover are Alnus incana, Betula occidentalis, or Celtis laevigata var. reticulata, but they never dominate the stand. The understory is dominated by short shrubs or herbaceous species. Shrubs may include Amelanchier alnifolia, Cornus sericea, Rosa nutkana, Rosa woodsii, Salix exigua, Spiraea betulifolia, and Symphoricarpos albus. The sparse to moderately dense herbaceous layer is composed of perennial graminoids, such as Carex spp., Deschampsia cespitosa, Elymus glaucus, and Leymus cinereus (= Elymus cinereus), and forbs such as Achillea millefolium, Besseya rubra, Galium boreale, Geranium viscosissimum, Geum macrophyllum, Heracleum maximum, Hydrophyllum fendleri, Iris missouriensis, Lithophragma parviflorum, Osmorhiza berteroi, Potentilla arguta, Potentilla gracilis, Pteridium aquilinum, and Urtica dioica. The herbaceous layer is relatively depauperate if Heracleum maximum is abundant due to extreme shading. Many weedy introduced grasses are common in the understories of most Crataegus stands. These can include perennial forage species Bromus inermis, Phleum pratense, Poa pratensis, invasive annual grass Bromus tectorum, and many others.
Dynamics: Historically, fire appears to have been important in maintaining the open nature of Crataegus shrublands (Daubenmire 1970). Fire may also have been somewhat influential in maintaining the much branched morphology of the dominant shrubs. Most stands have been severely degraded by livestock grazing. Livestock browse all accessible parts of Crataegus douglasii, and can eliminate entire stands (Daubenmire 1970).A
Environmental Description: This alliance is found in the lower montane and foothill regions around the Columbia Basin, and north and east into the Central Rockies in Idaho and northwestern Wyoming. Elevations range between 400 and 850 m. The climate of the region is characterized by a mix of continental and maritime influences. It is in the rainshadow of the Cascades, with annual precipitation between 23 and 51 cm (9-20 inches). Between 55 and 75% of the precipitation falls as snow during October through March, and summers are typically dry. Summer temperatures can be hot, and winters are typically cold. Stands occur on relatively moist sites on deep soils within flat valleys on low-gradient streams with broad floodplains that flood seasonally. This alliance is typically found on aggraded valley floors which border intermittent or permanent streams and have dependable soil moisture through the growing season (Daubenmire 1970). These sites may be flooded seasonally, but due to the low gradients are rarely scoured. Soils are generally accumulated glacial outwash composed of fine silts and clays of moderate to deep depths. Stands of this alliance often extend up adjacent north-facing toeslopes where seepage provides constant moisture. Adjacent vegetation is usually Artemisia steppe or Pseudoroegneria - Festuca grassland.
Geographic Range: This deciduous broadleaf shrubland alliance is found in the lower montane and foothill regions around the Columbia Basin, and north and east into the Central Rockies in Idaho and northwestern Wyoming.
Nations: US
States/Provinces: CA?, ID, OR, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.900025
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
Concept Lineage: A.917 and A.937. This new alliance is composed of associations from Old Alliance III.B.2.N.a. Crataegus douglasii Shrubland Alliance (A.917) and Old Alliance III.B.2.N.c. Crataegus douglasii Intermittently Flooded Shrubland Alliance (A.937).
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: > Crataegus douglasii / Heracleum lanatum Association Habitat types (Daubenmire 1970)
> Crataegus douglasii / Symphoricarpos albus Association Habitat types (Daubenmire 1970)
> Crataegus douglasii / Symphoricarpos albus Association Habitat types (Daubenmire 1970)
- Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
- Crowe, E. A., and R. R. Clausnitzer. 1997. Mid-montane wetland plant associations of the Malheur, Umatilla, and Wallowa-Whitman national forests. Technical Paper R6-NR-ECOL-TP-22-97. USDA Forest Service, Pacific Northwest Region, Portland, OR.
- Daubenmire, R. F. 1970. Steppe vegetation of Washington. Washington State University Agricultural Experiment Station Technical Bulletin No. 62. 131 pp.
- Evans, S. 1989a. Riparian survey of Washington''s Columbia Basin. Unpublished report prepared for The Nature Conservancy Washington Natural Heritage Program, Olympia, Washington.
- 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.
- Kovalchik, B. L. 1987. Riparian zone associations - Deschutes, Ochoco, Fremont, and Winema national forests. Technical Paper 279-87. USDA Forest Service, Pacific Northwest Region, Portland, OR. 171 pp.
- ORNHP [Oregon Natural Heritage Program]. No date. Unpublished data files. Oregon Natural Heritage Program, The Nature Conservancy, Portland, OR.
- Reid, M. S., L. S. Engelking, and P. S. Bourgeron. 1994. Rare plant communities of the conterminous United States, Western Region. Pages 305-620 in: D. H. Grossman, K. L. Goodin, and C. L. Reuss, editors. Rare plant communities of the conterminous United States, an initial survey. The Nature Conservancy, Arlington, VA.