LOCATION AHPAH                   CA

Established Series
Rev: JHP/JPS/ET
07/2016

AHPAH SERIES

The Ahpah series consists of moderately deep, well drained soils formed in residuum and colluvium derived from schist and sandstone. Ahpah soils are on mountains and have slopes of 15 to 75 percent. The mean annual precipitation is about 2160 millimeters (85 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, mixed, active, isomesic Typic Dystrudepts

TYPICAL PEDON: Ahpah gravelly clay loam - on a northeast-facing convex slope of 32 percent under second-growth Douglas-fir, redwood, tanoak, western hemlock, red alder, huckleberry, salal, and rhododendron at 475 meters (1560 feet). (Colors are for moist soil unless otherwise noted. When described February 22, 1984, the soil was moist throughout.)

Oi--0 to 5 centimeters (0 to 2 inches); fresh and slightly decomposed tanoak leaves, conifer needles and twigs; very strongly acid (pH 4.5). (0 to 8 centimeters thick)

A--5 to 22 centimeters (2 to 9 inches); brown (7.5YR 4/4) gravelly clay loam, brownish yellow (10YR 6/6) dry; weak fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine, fine and medium roots throughout; few very fine irregular, and common very fine and fine tubular pores; 18 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (5 to 33 centimeters thick)

Bw1--22 to 53 centimeters (9 to 21 inches); yellowish brown (10YR 5/6) gravelly silty clay loam, yellow (10YR 7/6) dry; weak fine and medium subangular blocky structure; soft, friable, moderately sticky and slightly plastic; common very fine, fine and medium, and few coarse roots throughout; common very fine and fine, and few medium tubular pores; 19 percent gravel; strongly acid (pH 5.5); gradual wavy boundary.

Bw2--53 to 70 centimeters (21 to 28 inches); yellowish brown (10YR 5/6) gravelly clay loam, yellow (10YR 7/6) dry; weak medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; few very fine, fine and coarse, and common medium roots throughout; few very fine and fine tubular pores; krotovina, 15 cm by 30 cm, filled with reddish yellow (5YR 6/6) clay loam, yellowish red (5YR 5/6) moist; 21 percent gravel; strongly acid (pH 5.5); clear irregular boundary. (combined thickness of Bw horizons is 15 to 75 centimeters)

C--70 to 87 centimeters (28 to 34 inches); variegated olive gray (5Y 5/2) and yellowish brown (10YR 5/6) very gravelly loam, light gray (2.5Y 7/2) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine, fine and medium roots throughout; few very fine and fine tubular pores; 42 percent gravel; strongly acid (pH 5.5); clear wavy boundary. (0 to 33 centimeters thick)

Cr--87 to 115 centimeters (34 to 45 inches);weathered schist easily cut with knife, schist foliation and rock macrostructure still evident; contains pockets of hard (lithic) rock, amounting to approximately 5 percent of the area exposed.

TYPE LOCATION: Redwood National Park, Humboldt County, California; located approximately 19 kilometers northeast of the town of Orick; 0.6 kilometers east on G-Line Road from intersection of G-Line and C-Line Roads, then 53 meters south, uphill to bank cut on abandoned secondary logging haul road; southeast quarter, southwest quarter, Section 10, T. 9 N., R. 1 E. 41 degrees, 10 minutes, 34 seconds north latitude and 124 degrees, 3 minutes, 12 seconds west longitude; HBLM; WGS84 Decimal degrees 41.1762250N and -124.0534444 W; USGS Rodger's Peak Quadrangle; UTM Zone 10 411639mE 4558856mN; NAD83.

RANGE IN CHARACTERISTICS:

Soil moisture: The soil is usually moist in all parts of the soil moisture control section in most years and becomes nearly dry in the upper part from about September 15 to October 15 in most years. The soils have a udic soil moisture regime.

Soil temperature: 10 to 13 degrees C.(50 to 55 degrees F). The difference between mean summer and mean winter temperature is 2 to 4 degrees C. The soils have an isomesic soil temperature regime.

Depth to a paralithic contact: 50 to 100 centimeters.



Organic matter: There are 12 to 20 Kg per square meter of organic carbon above the paralithic contact.

Reaction: moderately or strongly acid, and the base saturation, by ammonium acetate, is less than 50 percent throughout.

Particle-Size Control Section (weighted average):

Rock fragments: 15 to 30 percent gravel and 0 to 5 percent cobbles.
Clay content: 20 to 32 percent.

O horizon

Hue: 10YR.
Value: 2 through 6 dry and moist.
Chroma: 1 through 4 dry and moist.

Texture: slightly decomposed organic material.
Wood fragments: 0 to 35 percent.
Reaction: moderately to slightly acid.

A horizon

Hue: 7.5YR or 10YR.
Value: 5 or 6 dry, 3 through 5 moist.
Chroma: 2 through 5 dry, 2 through 6 moist.

Texture of fine earth: loam or clay loam.
Rock fragments: 15 to 25 percent gravel and 0 to 10 percent cobbles.
Clay content: 20 to 30 percent.

Bw horizon

Hue: 7.5YR, 10YR, or 2.5Y
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 4 or 6 dry, 4 or 6 moist.

Texture of fine earth: sandy clay loam, loam, clay loam, or silty clay loam
Rock fragments: 15 to 30 percent gravel and 0 to 5 percent cobbles.
Clay content: 20 to 32 percent.

C horizon

Hue: 7.5YR, 10YR, 2.5Y, or 5Y.
Value: 5 through 7 dry, 3 through 6 moist.
Chroma: 2 through 6 dry, 2 through 6 moist.

Texture of fine earth: loam, clay loam, silty clay loam, or sandy clay loam.
Rock fragments: 35 to 50 percent gravel and 0 to 5 percent cobbles.
Clay content: 20 to 27 percent.

COMPETING SERIES: This is the Watches soil. Watches soils are over 150 centimeters deep to bedrock.

GEOGRAPHIC SETTING: Ahpah soils occur on rounded main and spur ridges and convex slopes on mountains. Slopes are 15 to 75 percent. Elevations are 19 to 926 meters (60 to 3035 feet). The soils formed in residuum and colluvium derived from schist and sandstone. The climate is humid with cool, foggy summers and cool, moist winters. Coastal influence limits the annual and diurnal range in temperature. Mean annual precipitation ranges from 1780 to 2550 millimeters (70 to 100 inches). Mean January temperature is about 9 degrees C; mean July temperature is about 14 degrees C; and the mean annual temperature is 10 to 13 degrees C 50 to 55 degrees F). Frost-free season is 220 to 290 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coppercreek, Lackscreek and Tectah soils. All have argillic horizons. Coppercreek soils are more than 150 centimeters deep to a lithic contact. Lackscreek soils are skeletal and 50 to 100 centimeters deep to a lithic contact. Tectah soils have an argillic horizon, fine particle-size class, and are more than 150 centimeters deep to a paralithic contact. Coppercreek soils occur on straight slopes below the Ahpah soils on sloping spur ridges. Tectah soils occur on ridge shoulders below the Ahpah soils on ridge crests. The Lackscreek soils are on narrow ridges and on locally steeper, or more strongly convex slopes.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high to very high runoff; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: This soil has been used for commercial timber, wildlife, and watershed. Natural vegetation consists of redwood, Douglas-fir, western hemlock, tanoak, madrone, rhododendron, and huckleberry.

DISTRIBUTION AND EXTENT: California Coastal Redwood Belt; MLRA 4B. The series is not extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Humboldt County, California, 2007. Source of name is from Ahpah Creek, located 29 kilometers northeast of the town of Orick.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

1. Ochric epipedon - the zone from 0 to 22 centimeters (Oi & A horizons)
2. Cambic horizon - the zone from 22 to 70 centimeters (Bw1 & Bw2 horizons)
3. Paralithic contact - the bedrock interface at 87 centimeters
4. Dystrudepts feature - base saturation of less than 60 percent, by ammonium acetate, in the zone from 25 to 75 centimeters
5. Particle-size control section - the zone from 30 to 87 centimeters, averages 25 percent clay, by weight, and 26 percent gravel, by volume. CEC/clay ratio averages 0.53.

The assignment of the active activity class is inferred from lab data from the Lackscreek soils. Soil profile samples 82-RNP-10 and 83-RNP-14.

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

NASIS User Pedon ID 84CA605REDW0003.

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National Cooperative Soil Survey
U.S.A.