Natural Resources
Conservation Service
Ecological site F043CY608OR
Cool Dry Conifer Foothills and Mountains (PIPO/FEID-PSSPS)
Last updated: 9/08/2023
Accessed: 11/21/2024
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): 043C–Blue and Seven Devils Mountains
This MLRA covers the Blue and Seven Devils Mountains of Oregon, Washington and Idaho. The area is characterized by thrust and block-faulted mountains and deep canyons composed of sedimentary, metasedimentary, and volcanic rocks. Elevations range from 1,300 to 9,800 feet (395 to 2,990 meters). The climate is characterized by cold, wet winters and cool, dry summers. Annual precipitation, mostly in the form of snow, averages 12 to 43 inches (305 to 1,090 millimeters) yet ranges as high as 82 inches (2,085 millimeters) at upper elevations. Soil temperature regimes are predominately Frigid to Cryic and soil moisture regimes are predominately Xeric to Udic. Mollisols and Andisols are the dominant soil orders. Ecologically, forests dominate but shrub and grass communities may occur on south aspects and lower elevations as well as in alpine meadow environments. Forest composition follows moisture, temperature and elevational gradients and typically ranges from ponderosa pine and Douglas-fir plant associations at lower elevations, grand fir at middle elevations and subalpine fir and Engelman spruce at upper elevations. Historical fire regimes associated with these forest types range from frequent surface fires in ponderosa pine - Douglas Fir forest types to mixed and stand replacing fire regimes in grand fir and subalpine fir types. A large percentage of the MLRA is federally owned and managed by the U.S. Forest Service for multiple uses.
Classification relationships
Plant Assoc. of Blue and Ochoco Mountains (R6 E TP-036-92)
Ponderosa pine/bluebunch wheatgrass - CPG111 (modal)
Ponderosa pine/Idaho fescue - CPG112 (modal)
Ponderosa pine/bitterbrush/Idaho fescue-bluebunch wheatgrass - CPS226
Ponderosa pine/mountain big sagebrush/Idaho fescue-bluebunch wheatgrass - CPS131
Ponderosa pine/mountain mahogany/Idaho fescue-bluebunch wheatgrass - CPS234
Ponderosa pine/mountain mahogany/Wheeler bluegrass - CPS233
Ponderosa pine/mountain snowberry - CPS525
Plant Assoc. of Wallowa-Snake Province (R6 E 255-86)
Ponderosa pine/bitterbrush-bluebunch wheatgrass - CPS231
Ponderosa pine/bluebunch wheatgrass - CPG132
Ponderosa pine/Idaho fescue - CPG131
USDA Forest Service Ecological Sub-region
M332 “Blue Mountains”
LANDFIRE BpS model 0710531
Northern Rocky Mountain Ponderosa Pine Woodland and Savanna – Mesic
Natureserve Terrestrial Ecological System (2020)
Northern Rocky Mountain Ponderosa Pine Woodland and Savanna, CES306.030e
Ecological site concept
This site represents a commonly occurring ponderosa pine (Pinus ponderosa) site in the foothills of the Blue, Ochoco and Wallowa mountains of Oregon. The overstory is composed of almost exclusively ponderosa pine and the understory is dominated by grasses such as Idaho fescue (Festuca idahoensis), and bluebunch wheatgrass (Pseudoregnaria spicata). Western juniper (Juniperus occidentalis) may be occasionally present as well as antelope bitterbrush (Purshia tridentata). This site exists toward the lower moisture threshold of forested communities in these mountains and as such often transitions into shrublands, woodlands and grasslands. These may be grasslands dominated by Idaho fescue and bluebunch wheatgrass shrublands dominated by big sagebrush (Artemesia tridentata) and antelope bitterbrush, woodlands dominated by western juniper (Juniperus occidentalis) and mixed woodlands dominated by juniper with occasional ponderosa pine. Forested sites on adjacent protected aspects and with ashier soils with few coarse fragments, experience higher soil moisture retention facilitating higher productivity of ponderosa pine, higher shrub cover and occasional components of Douglas-fir (Pseudotsuga menziesii). The soil moisture regime of this site is xeric and the soil temperature regime is frigid. Disturbance was historically influenced by a fire regime characterized by relatively frequent surface fires. These frequent fires, as well as bark beetles, were historically a critical element of the disturbance regime of this site, acting to thin crowded understories and allow fire resistant ponderosa stands to attain an open, savanna-like forest structure.
This is a provisional ecological site that groups characteristics at a broad scale 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
F043CY607OR |
Cool Moist Conifer Foothills and Mountains (PIPO-PSME/SYAL) Occupying adjacent soils with somewhat deeper depth to a restrictive layer and higher moisture retention |
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F043CY609OR |
Warm Dry Conifer Foothills and Mountains (PIPO-PSME/SYAL/CAGE) Downslope positions with warmer soil climates |
R043CY808OR |
Claypan (ARAR8/FEID-PSSPS) Adjacent scablands with very shallow soils |
Similar sites
F043CY607OR |
Cool Moist Conifer Foothills and Mountains (PIPO-PSME/SYAL) Higher available water content, somewhat deeper soils, lower coarse fragment content, andic soil properties more common |
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F043CY609OR |
Warm Dry Conifer Foothills and Mountains (PIPO-PSME/SYAL/CAGE) Downslope positions with warmer soil climates, mesic soil temperature regime |
Table 1. Dominant plant species
Tree |
(1) Pinus ponderosa |
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Shrub |
Not specified |
Herbaceous |
(1) Festuca idahoensis |
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Ecosystem states
States 1 and 5 (additional transitions)
T1a | - | Long term fire exclusion (50-100+) years |
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T1b | - | Widespread catastrophic stand replacing fire event |
T1c | - | Invasion of introduced cool season grasses or exotic annual grass |
T1d | - | Site converted to annual cropland or pasture/hayland |
R2a | - | Restoration practices that reduce excessive fuel loads and reduce overstory crown bulk density |
T2a | - | Widespread catastrophic fire occurs |
R3a | - | Conifer planting |
R4a | - | Practices that promote the reestablishment of native understory species |
R4a | - | Practices are applied which reduce or eliminate unwanted weeds and invasive species |
R5a | - | Practices that promote the reestablishment of native understory species |
T5a | - | Poor management or abandonment leads to weed invasion |