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CEGL000634 Alnus rhombifolia / Philadelphus lewisii Riparian Forest

Type Concept Sentence: No Data Available


Common (Translated Scientific) Name: White Alder / Lewis'' Mock Orange Riparian Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This riparian plant association is known from data collected in the Snake and Salmon river corridors, within the Blue Mountains ecoregional section. The association occurs on unstable stream channels within an elevational band of 275-850 m (900-2800 feet), in the deeply incised terrain of the Snake River Canyon. Stands of this forest plant association are dominated by broad-leaved, deciduous tree species. Alnus rhombifolia is dominant, and occurs with high cover. The understory broad-leaved deciduous shrub layer is dominated by Philadelphus lewisii. Other deciduous shrub species commonly present, include Crataegus douglasii, Prunus virginiana, Ribes oxyacanthoides ssp. irriguum, and Salix exigua. Occasional colonies of the introduced shrub Rubus armeniacus are present. The herbaceous component of this association is composed of species indicative of disturbance. No other information is available on species composition.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: No Data Available

Similar NVC Types: No Data Available
note: No Data Available

Physiognomy and Structure: No Data Available

Floristics: This forest association is dominated by broad-leaved deciduous woody species. The tree Alnus rhombifolia dominates, with high cover. The shrub layer, also broad-leaved deciduous, is dominated by Philadelphus lewisii, from 1.5-2.5 m tall. Several other shrub species are commonly present, including the taller Crataegus douglasii, and Prunus virginiana, and the shorter Ribes oxyacanthoides ssp. irriguum (= Ribes irriguum), and Salix exigua. Occasional colonies of the introduced shrub Rubus armeniacus (= Rubus discolor) can be found, as well as the native liana Clematis ligusticifolia and the introduced Solanum dulcamara. The rare deciduous shrub Rubus bartonianus was found in one stand of this association; it is endemic to the canyons of the Snake River. Information on canopy cover is not available. The herbaceous component of this association is composed of species indicative of disturbance. No other information is available on species composition.

Dynamics:  No Data Available

Environmental Description:  This association is found in a mountainous region dissected by major river canyons and tributary streams. There are elevational extremes in this region, from subalpine summits over 2740 m (9000 feet), to canyon bottoms below 610 m (2000 feet). Topography is characterized by precipitous canyon walls along the rivers, steep upland slopes, and smaller tributary streams with cliffs, rocky slopes and mass-wasting features such as slumps and mud-rock flows. The soils of the region are especially prone to erosion and slippage. Slopes often exceed the angle of repose, and periodic severe thunderstorms with intense rains will supersaturate the soil mantle. The resulting slumping and mud-rock flows often deposit materials into stream channels and can destroy streambanks.

The climatic conditions in these deep canyon bottoms are strikingly different from surrounding uplands and mountains. In the canyons, summers are hot and dry, and winters mild, with only limited and ephemeral snows. Precipitation is variable, but generally the higher elevation reaches have higher precipitation. Annual precipitation is approximately 33 cm (13 inches) at 225 m (740 feet), and about 46 cm (18 inches) at 610 m (2000 feet). However, a rainshadow effect occurs farther to the east, in upstream reaches, and annual precipitation is less than 25 cm (10 inches).

This association occurs on riparian sites in canyon bottoms, from 275 to 850 m (900-2800 feet) elevation along the Snake River and its tributaries. It is associated with very poor stream channel stability ratings, indicating it occupies sites frequently disturbed by flooding and deposition of mud-rock flow materials.

Geographic Range: Miller (1976) described the association as occurring in the Snake River Canyon and its tributaries. Mancuso and Moseley (1994) observed the association in upper Eagle Creek, a tributary of the Salmon River near its confluence with the Snake.

Nations: US

States/Provinces:  CA?, ID, OR, WA




Confidence Level: Low

Confidence Level Comments: No Data Available

Grank: G1

Greasons: No Data Available


Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available

Synonomy: = Alnus rhombifolia / Philadelphus lewisii Temporarily Flooded Forest (Crawford 2003)
= Alnus rhombifolia / Philadelphus lewisii (Moseley 1998)
= Alnus rhombifolia / Philadelphus lewisii (Jankovsky-Jones et al. 2001)
= Alnus rhombifolia / Philadelphus lewisii Association (Crowe et al. 2004)
= Alnus rhombifolia Dominance Type (Evans 1989b) [(10)]

Concept Author(s): M.S. Reid

Author of Description: M.S. Reid and S.K. Rust

Acknowledgements: No Data Available

Version Date: 11-11-93

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