Physiographic features

Physiographic Features
This ecological site occurs mainly on foot slopes and drainageways of mountains and hills. Parent materials are alluvium or residuum and colluvium derived from igneous (granitic) and metamorphic rock mantled by volcanic ash and loess.

Landscapes: Mountains, Foothills, River Valleys
Landforms: Mountain slopes, Hillslope, Stream Terraces, Floodplains, Drainageways, Valley Floors

Elevation:
Total range = 488 to 1530 m
(1,600 to 5,020 feet)
Central tendency = 735 to 1060 m
(2,4105 to 3,470 feet)

Slope (percent):
Total range = 0 to 75 percent
Central tendency = 10 to 35 percent

Aspect: none dominant

Table 2. Representative physiographic features

Table 3. Representative physiographic features (actual ranges)

Climatic features

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 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. 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 and 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 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 = 60 to 135 days
Central tendency = 90 to 110 days

Mean annual precipitation (cm):
Total range = 530 to 1405 mm
(21 to 55 inches)
Central tendency = 770 to 1035 mm
(30 to 41 inches)
MAAT (C)
Total range = 4.9 to 9.9
(41 to 50 F)
Central tendency = 6.7 to 8.0
(44 to 46 F)

Climate stations: Enaville, Mullan

Influencing water features

Water Table Depth: 54% of components have no observed water table (> 80 inches)
Where water table occurs (46% of components): range is 0 to 30 inches (median = 18 inches) during Dec-May


Flooding:
Frequency: None to Frequent
Duration: None to Very Long

Ponding:
Frequency: None
Duration: None

Soil features

Representative Soil Features
This ecological site is associated with several soil components (e.g. Floodwood, Odonnell, Chatcolet, Aquic Udifluvents, Dorb, Grandad, Hubub, Bouldercreek, Ramsdell, Seelovers, and Porrett). The soil components can be grouped into Endoaquepts, Endoaquolls, Epiaqualfs, Hapludalfs, Udifluvents, and Udivitrands. These soils have developed in various thicknesses of Mazama tephra deposits (often highly mixed with loess) over a number of other parent materials. These parent materials are dominantly: alluvium and material weathered from granite, gneiss or schist. The soils have adequate available water holding capacity within 40 inches. About half of the components have either a perched or apparent water table within 30 inches of the soil surface. They are very poorly to well drained and are in positions of moisture accumulation.

Table 4. Representative soil features

Table 5. Representative soil features (actual values)

Table 6. Representative site productivity

References

• . Idaho Department of Lands H.T. Groupings based on Forest HTs of Northern Idaho.

• Cooper, S.V., K.E. Neiman, R. Steele, and D.W. Roberts. 1991. Forest Habitat types of Northern Idaho, A Second Approximation.

• 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.

• McDonald, G.L., A.E. Harvey, and J.R. Tonn. 2000. Fire, Competition, and Forest Pests: Landscape Treatment to Sustain Ecosystem Functions, The Joint Fire Science Conference and Workshop.. Pages 195–211 in Proceedings from the Joint Fire Science Conference and Workshop: crossing the millennium: integrating spatial technologies and ecological principles for a new age in fire management.

• Miller and Gravelle. October, 2005. Species Selection Guidelines for Planting, Natural Regeneration and Crop Tree Selection on Potlatch Land in Northern Idaho, Forestry Technical Paper TP -2003-1.

• Smith and Fischer. 1997. Fire Ecology of the Forest Habitat Types of Northern Idaho.

• Zack, A. 1997. Biophysical Classification- Habitat Groups and Description of Northern Idaho and Northwestern Montana, Lower Clarkfork and Adjacent Areas..

Approval

Curtis Talbot, 10/23/2020