Natural Resources
Conservation Service
Ecological site R010XY011OR
Cottonwood-Willow-Riparian
Last updated: 12/13/2023
Accessed: 11/13/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 010X–Central Rocky and Blue Mountain Foothills
This MLRA is characterized by gently rolling to steep hills, plateaus, and low mountains at the foothills of the Blue Mountains in Oregon and the Central Rocky Mountains in Idaho. The geology of this area is highly varied and ranges from Holocene volcanics to Cretaceous sedimentary rocks. Mollisols are the dominant soil order and the soil climate is typified by mesic or frigid soil temperature regimes, and xeric or aridic soil moisture regimes. Elevation ranges from 1,300 to 6,600 feet (395 to 2,010 meters), increasing from west to east. The climate is characterized by dry summers and snow dominated winters with precipitation averaging 8 to 16 inches (205 to 405 millimeters) and increasing from west to east. These factors support plant communities with shrub-grass associations with considerable acreage of sagebrush grassland. Big sagebrush, bluebunch wheatgrass, and Idaho fescue are the dominant species. Stiff sagebrush, low sagebrush, and Sandberg bluegrass are often dominant on sites with shallow restrictive layers. Western juniper is one of the few common tree species and since European settlement has greatly expanded its extent in Oregon. Nearly half of the MLRA is federally owned and managed by the Bureau of Land Management. Most of the area is used for livestock grazing with areas accessible by irrigation often used for irrigated agriculture.
Classification relationships
This site may encompass many of the warmer, low elevation plant associations that include an overstory dominated by black cottonwood. These may include:
Riparian and Wetland Vegetation of Central and Eastern Oregon (Crowe, Kovalchik and Kerr 2004):
Populus balsamerifera ssp. trichocarpa – Alluvial Bar Association
Populus balsamerifera ssp. trichocarpa-Alnus rhombifolia Association - CEGL000668
Populus balsamerifera ssp. trichocarpa/Crataegus douglasii Association - CEGL000673
Populus balsamerifera ssp. trichocarpa/Betula occidentalis Association
Populus balsamerifera ssp. trichocarpa/Philadelphus lewisii Association
Ecological site concept
This is a riparian site dominated by a plant community that includes black cottonwood (Populus balsamifera ssp. trichocarpa) and a shrub and herbaceous layer dominated by willow (Salix spp.) and great basin wildrye (Leymus cinereus). Occupying floodplains along rivers and streams, this site has gentle slopes of 0 to 3 percent. In contrast to other sites occupying bottomland areas and supporting few woody species, this site has gravelly soils and higher water tables. The soil temperature regime of this site is mesic. Historically, the prominence of riparian woody species would have helped to anchor and stabilize stream banks from excessive erosion. Lateral stream movement, and erosion/deposition processes would have been within a historical range of variation according to hydrologic disturbances such as floods, vegetation and channel alterations by beaver, and climate patterns that influence seasonal flows. This site may be vulnerable to the effects of long-term improper grazing management leading to loss of woody vegetation and resulting stream bank instability. Additionally, much of this site has been impacted by alterations to associated streams resulting in geomorphic changes to sinuosity, gradient and stream width to depth ratio as well as reduced stream shading and loss of native vegetation.
This is a provisional ecological site whose accelerated development from a draft site was undertaken with little to no field verification and is subject to extensive review and revision before final approval. All data herein was developed using existing information and literature and should be considered provisional and contingent upon field validation prior to use in conservation planning.
Associated sites
R010XY003OR |
Wet Meadow Wet Meadow (hydric soil, long duration seasonal water table at or near the surface, mesic to frigid near mesic soil temperature, anaerobic conditions, different composition - CAREX-DECE association) |
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R010XY004OR |
Meadow Meadow (hydric soil, shorter duration seasonal water table near the surface, mesic to frigid near mesic soil temperature, anaerobic conditions, different composition - DECE-CAREX-JUNCU association) |
R010XY005OR |
Loamy Bottom Loamy Bottom (greater depth to water table, higher terrace, mesic to frigid near mesic soil temperature, different composition – basin wildrye strongly dominant, basin big sagebrush present) |
Similar sites
R010XY010OR |
Coyote Willow Riparian Narrowleaf willow dominant, cottonwood absent |
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R010XY012OR |
Booth-Yellow Willow Riparian Booth and yellow willow dominant, mesic to frigid near mesic soil temperature regime |
R010XY013OR |
Booth-Geyer-Yellow Willow Riparian Booth, yellow and geyer willow dominant, mesic near frigid soil temperature regime |
Table 1. Dominant plant species
Tree |
(1) Populus balsamifera ssp. trichocarpa |
---|---|
Shrub |
(1) Salix |
Herbaceous |
(1) Leymus cinereus |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Invasion of reed canarygrass |
---|---|---|
T2A | - | Improperly managed grazing during times of year when willow is most vulnerable to decline or most susceptible to overuse. |
T2B | - | Alteration of hydrologic function |
R3A | - | Restoration of hydrologic and biotic process and function |
T3A | - | Alteration of hydrologic function |
R4A | - | Restoration of hydrologic and biotic process and function |
T4A | - | Time elapsed in the presence of sufficient sediment loads |