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Ecological site R043AY504ID

Mesic Dry-Xeric Loamy Hills and Canyons (FEID/PSSP/ELGL)

Last updated: 10/15/2020
Accessed: 11/13/2024

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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): 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.

Available electronically at: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_053624#handbook

LRU notes

Major land resource area (MLRA): 043A-Northern Rocky Mountains
Modal LRU – 43A08 Clearwater Canyons

This LRU is composed predominantly of low to mid elevation foothills, structural benches, valleys, flats, mountain slopes and ridges. The soils tend to be loamy argixerolls. Volcanics are the dominant parent materials, along with occasional granite and other intrusives. Soil climate is a mesic temperature regime and xeric moisture regime with average annual precipitation around 675 mm (27 inches).

Classification relationships

This ES group fits into the National Vegetation Standard’s Central Rocky Mountain Foothill Grassland Group (Compare to previous Idaho range site: R009XY016ID, LOAMY 22+ FEID-PSSPS)

Ecological site concept

This ES is found on well drained, loamy sites with mesic temperatures and moister microclimates. Soils tend to be very deep with adequate available water holding capacity and a plant community dominated by grass species such as bluebunch wheatgrass, Idaho fescue, and blue wildrye.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Symphoricarpos albus (2) Rosa woodsii var. glabrata
Herbaceous	(1) Festuca idahoensis (2) Pseudoroegneria spicata

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Physiographic features

This ecological site occurs mainly on range backslopes of hills, canyons, structural benches, ridges, and terraces. Parent materials are colluvium and residuum from basalt, metavolcanics, and loess.

Landscapes: Canyonlands, plateaus
Landforms: Hillslopes, canyons, structural benches, ridges, terraces,

Elevation:
Total range = 360 to 1100 m
(1,180 to 3,610 feet)
Central tendency = 570 to 850 m
(1,870 to 2,790 feet)

Slope (percent):
Total range = 0 to 90 percent
Central tendency = 15 to 45 percent

Water Table Depth:
>200 cm
(>80 inches)

Flooding:
Frequency: None
Duration: None

Ponding:
Frequency: None
Duration: None

Aspect: 20-95-340
Central tendency: 75-95-230

Table 2. Representative physiographic features

Landforms	(1) Canyonlands > Structural bench (2) Plateau > Hillslope (3) Plateau > Ridge (4) Canyonlands > Canyon wall
Elevation	1,870 – 2,790 ft
Slope	15 – 45%
Water table depth	Not specified
Aspect	NE, E, SE, S, SW

Table 3. Representative physiographic features (actual ranges)

Elevation	1,180 – 3,610 ft
Slope	90%
Water table depth	Not specified

Climatic features

The climate of this portion of the MLRA is controlled by a combination of large-scale and small-scale factors. The large-scale factors here include latitude, relative position on the North American continent, prevailing hemispheric wind patterns, and extensive mountain barriers. Small-scale or local factors include the topographic setting and position (valley, slope, or ridge location), as well as orientation or aspect, and vegetative cover. Elevation may cover various scales. Broadly, the climate is transitional between a northern Pacific coastal type and a continental type. The Pacific influence is noted particularly by the late autumn and winter maximum in cloudiness and precipitation; also in the relatively moderate average winter temperatures, compared with areas east of the Rocky Mountains. Summer is characteristically sunny and dry, though July and August are the only distinct summer months. July and August are thus also the peak fire-danger months. Annual precipitation (rain and melted snow) averages as little as 10 inches at the lowest canyon floors; over 100 inches at the highest elevations. Wettest months are normally November, December, and January. Close to 60 percent of the annual total occurs during the period November through March. A slight, secondary peak in precipitation normally appears in May and June, followed by a sharp decrease in July. Snowfall accounts for more than 50 percent of the total precipitation at elevations above 4,800 ft. Snow cover usually persists in the mid elevation valleys from early December through the end of March. High-elevation snowpack reaches a depth of 5 ft (1.5 m) or more in March and April and may linger into June. The main season of lightning (or thunderstorm) activity extends from late May through August. Storms occur on an average of 3 or 4 days each in June, July, and August. Monthly mean temperatures in populated valley locations range from 24 F (-4 C) in January to 65 F (18 C) in July; these are midpoint values between the average daily maximum and minimum temperatures. The annual mean is 43 F (6 C). A large diurnal range occurs in summer. Extreme temperatures have been as high as 103" to 105" F (about 40" C) and as low as -36" F (-38" C). Temperature inversions are commonplace, particularly on the clear summer and early autumn nights. The frost-free season, defined as the period with minimum temperatures staying above 32" F (0" C), varies widely with elevation and topographic position. The season is generally longer at lower elevation locations and on slope positions in the "thermal belt" around 3,500 ft. The season is shorter in positions affected by cold air drainage and slopes above the “thermal belt” at elevations >5,500 ft. Relative humidity is usually high throughout the day in late autumn and winter, averaging 70 to 80 percent or higher in midafternoon. In July and August, afternoon values average near 35 percent in the mid elevation valleys and 45 percent at 5,500 ft. Summer nighttime humidity in these valleys typically recovers to over 90 or 95 percent by dawn. On the slopes above the temperature inversion, at the same time, humidity may average only 50 to 60 percent. Winds have a prevailing (most frequent) direction from the southwest during all or most of the year. Local terrain effects modify the larger-scale wind that occurs in the adjacent free atmosphere. A nighttime drainage effect is common. Sunshine duration is at a minimum in December, when it may average only 20 percent of the maximum possible. July has close to 80 percent of the maximum possible.

(from Finklin, A. 1983. Climate of Priest River Experimental Forest, Northern Idaho.GTR-INT-159)

Frost-free period (days):
Total range = 95 to 156 days
Central tendency = 121 to 142 days

Mean annual precipitation (cm):
Total range = 505 to 680 mm
(20 to 27 inches)
Central tendency = 580 to 630 mm
(23 to 25 inches)
MAAT (C)
Total range = 7.3 to 11.1
(45 to 52 F)
Central tendency = 8.7 to 10.1
(48 to 50 F)

Climate stations: none

Soil features

This ecological site is associated with several soil components (Uhlorn, Lawyer, Jacket, Ferdinand, Hooverton). These components can be grouped into the soil subgroups: Typic Argixerolls, Pachic Ultic Argixerolls, Pachic Ultic Haploxerolls, Calcic Argixerolls. These soils are typically made up of loess over other parent materials. These parent materials are dominantly basalt or metavolcanics.

Parent Materials:
Kind: loess
Origin: mixed
Kind: colluvium and residuum
Origin: basalt, metavolcanics

Surface Texture:
(1) Silt Loam
(2) Gravelly-Loam

Table 4. Representative soil features

Parent material	(1) Loess (2) Colluvium – basalt (3) Residuum – basalt (4) Colluvium – metavolcanics (5) Residuum – metavolcanics
Surface texture	(1) Silt loam (2) Gravelly silt loam
Drainage class	Well drained
Permeability class	Moderate
Depth to restrictive layer	Not specified
Available water capacity (0-40in)	7.1 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)	6.7
Subsurface fragment volume <=3" (10-60in)	7%
Subsurface fragment volume >3" (10-60in)	2%

Table 5. Representative soil features (actual values)

Drainage class	Well drained
Permeability class	Slow to moderate
Depth to restrictive layer	24 in
Available water capacity (0-40in)	3.2 – 7.9 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)	6.1 – 7.3
Subsurface fragment volume <=3" (10-60in)	29%
Subsurface fragment volume >3" (10-60in)	27%

Ecological dynamics

Idaho fescue is the dominant grass. The site has a variety of forbs. The bluebunch wheatgrass on the site is usually rhizomatous. Composition is approximately 65-75 percent grass, 15-25 percent forbs, and 5-15 percent shrubs. Fire has historically occurred on the site at intervals of 20-40 years. In the absence of normal fire frequency Woods’ rose, snowberry, and willow, when present, will increase slightly. When fires become more frequent than historic levels (20-40 years), vigor of the bunchgrasses will generally be reduced. Root sprouting shrubs such as Woods’ rose and snowberry will increase. With continued short fire frequency, fine leaved grasses such as Idaho fescue, will have their vigor reduced significantly and death may result. These species may be replaced by cheatgrass, Kentucky bluegrass, Sandberg bluegrass, ventenata, and bulbous bluegrass along with a variety of annual and perennial forbs including noxious and invasive plants. Season-long grazing and/or excessive leads to reduced vigor of the bunchgrasses. As they decline, the plant community becomes susceptible to invasion by noxious and invasive plants.

State and transition model

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Supporting information

References

. 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/.
Finklin, A.I. 1983. Climate of Priest River Experimental Forest, northern Idaho. Gen. Tech. Rep. INT-159. U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. 53.
Jim Cornwell. 2009. NRCS Idaho Draft Range Site Descriptions.

Contributors

Stephanies Shoemaker
Brian Gardner

Approval

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	09/10/2022
Approved by	Curtis Talbot
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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:
Perennial plant reproductive capability:

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