Natural Resources
Conservation Service
Ecological site R043AY506WA
Cool-Mesic Dry-Xeric Loamy Hills and Mountains
(PSSP/FECA/FEID)
Last updated: 10/15/2020
Accessed: 08/15/2026
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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): 043A–Northern Rocky Mountains
Major Land Resource Area (MLRA): 043A–Northern Rocky Mountains
Description of MLRAs can be found in: United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.LRU notes
Major land resource area (MLRA): 043A-Northern Rocky Mountains
Modal LRU – 43A01 - Okanogan Plateau
This LRU is composed predominantly of glaciated mountains and foothills. The soils tend to be loamy to sandy andisols, inceptisols, and mollisols with mixed or distinct ash surfaces. Recent alluvium, till, outwash and residuum from granitic or metamorphic rock are the dominant parent materials. Soil climate is a frigid or cryic temperature regime and xeric moisture regime with average annual precipitation around 450 mm (18 inches).
Others where occurring: 43A03 Columbia-Colville Valleys
44A01 Spokane-Rathdrum Outwash PlainsClassification relationships
This ES group fits into the National Vegetation Standard’s Central Rocky Mountain Foothill Grassland Group and is most closely related to Washington State’s Natural Heritage Program’s Northern Rocky Mountain Lower Montane, Foothill, and Valley Grassland. (Compare to previous Washington range sites: R043AY102WA, LOAMY 16-24 PZ and R043AY103WA, COOL LOAMY 16-24 PZ)
Ecological site concept
Ecological Site Concept:
This ES is found on well drained, loamy sites with mesic temperatures and a plant community dominated by grass species such as bluebunch wheatgrass, rough fescue and Idaho fescue.Table 1. Dominant plant species
Tree Not specified
Shrub (1) Symphoricarpos albus
(2) Amelanchier alnifoliaHerbaceous (1) Pseudoroegneria spicata
(2) Festuca idahoensisPhysiographic features
Physiographic Features
This ecological site occurs mainly on hillslopes, lower mountain slopes, outwash terraces and stream terraces. Parent materials are primarily till, outwash or colluvium and residuum from metamorphic rock with a mantle of volcanic ash and loess.
Landscapes: Mountains, Foothills, Valleys and Scablands
Landforms: hillslopes, mountain slopes, outwash terraces
Elevation:
Total range = 350 to 1510 m
(1,150 to 4,955 feet)
Central tendency = 730 to 1045 m
(2,400 to 3,425 feet)
Slope (percent):
Total range = 0 to 75 percent
Central tendency = 10 to 40 percent
Water Table Depth:
>200cm
(>80 in)
Flooding:
Frequency: None
Duration: None
Ponding:
Frequency: None
Duration: None
Aspect: 65-210-340
Central tendency: 150-210-305Table 2. Representative physiographic features
Landforms (1) Mountains > Mountain slope
(2) Foothills > Hillslope
(3) Valley > Outwash terrace
Elevation 2400 – 3425 ft Slope 10 – 40 % Water table depth 0 in Aspect W, NW, SE, S, SW Table 3. Representative physiographic features (actual ranges)
Elevation 1150 – 4955 ft Slope 0 – 75 % Water table depth 0 in Climatic features
Climatic Features
During the spring and summer, a circulation of air around a high-pressure center brings a prevailing westerly and northwesterly flow of comparatively dry, cool and stable air into the region. As the air moves inland, it becomes warmer and drier which results in a dry season beginning in the late spring and reaching a peak in mid-summer. In the fall and winter, a circulation of air around two pressure centers over the ocean brings a prevailing southwesterly and westerly flow of air into the Pacific Northwest. This air from over the ocean is moist and near the temperature of the water. Condensation occurs as the air moves inland over the cooler land and rises along the windward slopes of the mountains or highlands. This results in a wet season beginning in October, reaching a peak in winter, then gradually decreasing in the spring.
The elevation within the LRU varies from approximately 1,000 feet in the lower river valleys to about 7,200 feet in the higher mountains. The annual precipitation increases from 9 inches in the valleys to over 48 inches in the highest mountains. Winter season snowfall averages about 43 inches. Both rainfall and snowfall increase with elevation. Snow can be expected after the first of November and to remain on the ground from the first of December until March or April.
In January, the average maximum temperature is near 29° F and the minimum temperature is 14° F. Minimum temperatures from -5° to -20°F are recorded almost every winter and temperatures ranging to -25° F have been recorded. In July, the average maximum temperature is 81° and the minimum temperature 47° F. Maximum temperatures reach 100° F on a few afternoons each summer and temperatures as high as 108° F have been recorded. The average date of the last freezing temperatures can be expected by early-June and after early-September in the warmer areas.
(Compiled from WRCC: Climate of Washington and available station data)
Frost-free period (days):
Total range = 85 to 145 days
Central tendency = 95 to 115 days
Mean annual precipitation (cm):
Total range = 265 to 700 mm
(10 to 28 inches)
Central tendency = 410 to 525 mm
(16 to 21 inches)
MAAT (C)
Total range = 3.6 to 10.1
(38 to 50 F)
Central tendency = 5.9 to 7.6
(43 to 46 F)
Climate stations: REPUBLIC, REPUBLIC RSTable 4 Representative climatic features
Frost-free period (characteristic range) 70 days Freeze-free period (characteristic range) 130 days Precipitation total (characteristic range) 20 in Frost-free period (actual range) 70 days Freeze-free period (actual range) 130 days Precipitation total (actual range) 20 in Frost-free period (average) 70 days Freeze-free period (average) 130 days Precipitation total (average) 20 in Characteristic rangeActual rangeBarLineFigure 1. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 2. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 3. Monthly maximum temperature range
BarLineFigure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6 Annual average temperature pattern
Climate stations used
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(1) REPUBLIC [USC00456974], Republic, WA
">Influencing water features
Water Table Depth:<br />
>200cm<br />
(>80 in)<br />
<br />
Flooding:<br />
Frequency: None <br />
Duration: None <br />
<br />
Ponding:<br />
Frequency: None <br />
Duration: NoneSoil features
Representative Soil Features
This ecological site is associated with the Borgeau, Cheney, Conconully, Cubhill, Foggydew, Haploxerolls, Hum, Mires, Mires variant, Molcal, Molson, Narcisse, Thuso, Wagberg, and Wenner series. The soils are Alfic Humic Vitrixerands, Calcic Haploxerolls, Cumulic Haploxerolls, Humic Vitrixerands, Vitrandic Argixerolls, Vitrandic Calcixerolls, and Vitrandic Haploxerolls. These soils have developed in a variety of materials. These include till, outwash, glaciolacustrine deposits as well as colluvium and residuum from granite, metamorphic and volcanic rocks. Most sites have a surface influenced by volcanic ash and loess. Volcanic ash layers are mixed at lower elevations and form distinct, thicker layers at higher elevations.
Parent Materials:
Kind: volcanic ash, loess, till, outwash, glaciolacustrine
Origin: mixed
Kind: colluvium, residuum
Origin: granite, metamorphics, metasediments, volcanic rock, calcareous shale
Surface Texture: (<2mm fraction)
(1) Ashy-Loam
(2) Ashy-Sandy Loam
(3) Ashy-Silt Loam
Surface FragmentsTable 5. Representative soil features
Parent material (1) Volcanic ash
(2) Loess
(3) Till
(4) Outwash
(5) Lacustrine deposits
(6) Colluvium – igneous and metamorphic rock
Surface texture (1) Ashy loam
(2) Ashy sandy loam
(3) Ashy silt loam
Drainage class Well drained Permeability class Moderate Depth to restrictive layer Not specified Surface fragment cover <=3" Not specified Surface fragment cover >3" Not specified Available water capacity
(0-40in)4.7 in Calcium carbonate equivalent
(0-60in)Not specified Electrical conductivity
(0-60in)Not specified Sodium adsorption ratio
(0-60in)Not specified Soil reaction (1:1 water)
(0-60in)7 Table 6. Representative soil features (actual values)
Drainage class Well drained Permeability class Very slow to moderately rapid Depth to restrictive layer 0 in Surface fragment cover <=3" 0 % Surface fragment cover >3" 0 % Available water capacity
(0-40in)3.2 – 8.1 in Calcium carbonate equivalent
(0-60in)0 – 30 % Electrical conductivity
(0-60in)0 – 8 mmhos/cm Sodium adsorption ratio
(0-60in)0 Soil reaction (1:1 water)
(0-60in)6.1 – 8.4 Ecological dynamics
State and transition model
Custom diagramStandard diagram
Figure 7. Narritive
Figure 8. STM
More interactive model formats are also available. View Interactive Models
Additional community tables
Interpretations
Supporting information
References
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1980. USNVC [United States National Vegetation Classification]. 2019. United States National Vegetation Classification Database, V2.03. Federal Geographic Data Committee, Vegetation Subcommittee, Washington DC.. USNVC: http://usnvc.org/.
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Gerald, R. 2004. NRCS - Washington; Interim Ecological Site Descriptions for Rangeland.
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Rocchio, J.F. and R.C. Crawford. 2015. Ecological systems of Washington State. A guide to identification. Washington Department of Natural Resources.. Natural Heritage Report.. Washington Department of Natural Resources, Natural Heritage Program, Olympia, WA. 1–397.
Contributors
Stephanie Shoemaker
Brian GardnerApproval
Curtis Talbot, 10/15/2020
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 08/15/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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