LOCATION BIGTREE CA

Established Series
Rev: ACF/JPS/ET/RLM
07/2016

BIGTREE SERIES

The Bigtree series consists of very deep, well-drained soils formed in alluvium derived from mixed sources. Bigtree soils are on gently sloping alluvial fans and low terraces and have slopes 2 to 9 percent. Surface runoff is at a negligible to low rate. The mean annual precipitation is 1780 millimeters (70 inches) and the mean annual temperature is about 11 degrees C (52 degrees F).

TAXONOMIC CLASS: Fine-loamy, isotic, isomesic Andic Humudepts

TYPICAL PEDON: Bigtree loam - on a northeast facing, linear slope of 2 percent under redwoods, hemlock, evergreen huckleberry, Oregon grape, trillium, and swordfern at 85 meters (280 feet) elevation. (Colors are for moist soil unless otherwise stated. When described June 8, 2004, the soil was moist throughout).

A1--0 to 15 centimeters (0 to 6 inches); very dark brown (10YR 2/2) loam, dark grayish brown (10YR 4/2) dry; moderate very fine and fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots and common medium, coarse, and very coarse roots; many very fine and fine interstitial pores and common fine and medium tubular pores; 3 percent gravel; slightly acid (pH 6.2); abrupt smooth boundary.

A2--15 to 26 centimeters (6 to 10 inches); dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; moderate very fine subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; many medium and coarse roots and common very fine, fine, and very coarse roots; many very fine and fine interstitial pores and common fine and medium tubular pores; 3 percent gravel; moderately acid (pH 6.0); abrupt wavy boundary. (Combined thickness of the A horizons is 25 to 55 centimeters)

Bw1--26 to 56 centimeters (10 to 22 inches); strong brown (7.5YR 4/6) loam, yellowish brown (10YR 5/6) dry; weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots and common coarse and very coarse roots; common very fine and fine interstitial pores and common fine tubular pores; 2 percent gravel; strongly acid (pH 5.4); abrupt smooth boundary.

Bw2--56 to 105 centimeters (22 to 41 inches); dark yellowish brown (10YR 3/4) loam, light yellowish brown (2.5Y 6/4) dry; weak fine subangular blocky structure; moderately hard, firm; slightly sticky and slightly plastic; common fine, medium, and very coarse roots; common very fine and fine interstitial pores and common fine tubular pores; 1 percent gravel; moderately acid (pH 5.6); abrupt smooth boundary.

Bw3--105 to 120 centimeters (41 to 47 inches); olive brown (2.5Y 4/4) loam, light yellowish brown (2.5Y 6/4) dry; weak fine subangular blocky structure; moderately hard, firm, slightly sticky and slightly plastic; common fine, medium, and coarse roots; common very fine interstitial pores; 1 percent gravel; strongly acid (pH 5.2); abrupt smooth boundary. (Combined thickness of the Bw horizons is 50 to 100 centimeters)

2C1--120 to 145 centimeters (47 to 57 inches); very dark grayish brown (2.5Y 3/2) sandy loam, grayish brown (2.5Y 5/2) dry; single grain; loose, loose, slightly sticky and slightly plastic; moderately few very fine roots; common very fine interstitial pores; 7 percent gravel; strongly acid (pH 5.2); clear smooth boundary.

2C2--145 to 160 centimeters (57 to 63 inches); olive brown (2.5Y 4/3) silt loam, light yellowish brown (2.5Y 6/3) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; moderately few very fine roots; common very fine interstitial pores; 1 percent gravel; very strongly acid (pH 5.0). (Combined thickness of the C horizons is 40 to 70 centimeters)

TYPE LOCATION: Prairie Creek Redwoods State Park, Humboldt County, California; located 0.2 km (0.1 miles) east on South Fork trail from Newton Drury Parkway, approximately 10 meters south of trail; northwest quarter, northwest quarter, Section 36, T.12N. R.1E., WGS84 Decimal Degrees 41.3880278 latitude and -124.0159722 longitude; HBLM, USGS Fern Canyon Quadrangle; UTM Zone 10 415058mE 4582332mN; NAD83.

RANGE IN CHARACTERISTICS:

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

Soil temperature: The mean annual soil temperature is 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 temperature regime.

The umbric epipedon is 25 to 55 centimeters thick.

Particle-Size Control Section (weighted average):

Rock fragments: 0 to 15 percent gravel and 0 to 5 percent cobbles.
Clay content: 18 to 25 percent clay.

Some pedons have an Oi horizon. (0 to 5 centimeters thick)

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 very strongly acid.

A horizon

Hue: 10YR or 2.5Y.
Value: 3 through 5 dry, 2 through 4 moist.
Chroma: 2 through 4 dry, 2 or 3 moist.

Texture of fine earth: loam.
Rock fragments: 0 to 10 percent gravel.
Clay content: 15 to 25 percent.
Reaction: moderately to strongly acid

Bw horizon

Hue: 7.5YR, 10YR, 2.5Y.
Value: 5 through 7 dry, 3 through 5 moist.
Chroma: 2 through 4 dry, and 3 through 6 moist.

Texture of fine earth: loam and silt loam.
Rock fragments: 0 to 15 percent gravel; 0 to 5 percent cobbles.
Clay content: 18 to 25 percent.
Reaction: strongly acid or moderately acid

C horizon

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

Texture of fine earth: sandy loam or silt loam.
Rock fragments: 0 to 35 percent gravel, 0 to 5 percent cobbles, 0 to 5 percent paragravels.
Clay content: 5 to 18 percent.
Reaction: strongly acid

COMPETING SERIES: At this time there are no other series in this family.

GEOGRAPHIC SETTING: These soils are on gently sloping alluvial fans, low terraces, and fan remnants, and have slopes of 2 to 9 percent. Elevations are 2 to 205 meters (5 to 670 feet). These soils form in alluvium derived from mixed sources. The climate is humid with cool, foggy summers and cool, rainy winters. Mean annual precipitation is 1520 to 1900 millimeters (60 to 75 inches). Mean January temperature is about 8 degrees C; mean July temperature is about 13 degree C; and the mean annual temperature is 10 to 13 degrees C (50 to 55 degrees F). Frost free season is about 300 to 320 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arlynda, Bigriver, Mystery and Russ soils. Arlynda soils are very poorly drained and have redoximorphic features near the surface. Bigriver, Mystery and Russ soils are coarse-loamy; they have less than 18 percent clay in the particle control section. Arlynda soils are in swampy depressions. Bigriver, Mystery and Russ are in locations on alluvial flats where the velocity of floodwaters is relatively high, such as natural levee margins close to channels.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: well drained; low runoff; moderately high saturated hydraulic conductivity, rarely flooded.

USE AND VEGETATION: This soil has been used for commercial timber and is used for wildlife recreation, and watershed. Natural vegetation consists of redwood, Sitka spruce, red alder, Douglas-fir, western hemlock, tanoak, cascara, western thimbleberry, evergreen huckleberry, salmonberry, salal, and swordfern.

DISTRIBUTION AND EXTENT: MLRA 4B. The series is not extensive.

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

SERIES ESTABLISHED: Humboldt County, California, 2004. The source of the name is from Big Tree Wayside Scenic Area, Prairie Creek Redwoods State Park, Humboldt, California.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Umbric epipedon - the zone from 0 to 26 centimeters.
2. Cambic horizon - the zone from 26 to 120 centimeters.
3. Particle-size control section - the zone from 25 to 100 centimeters, averages 20 percent clay and 30 percent fine sand or coarser, by weight, and 1 percent rock fragments by volume.
4. Andic Humudepts features - horizon greater than 18 centimeters thick within the upper 75 centimeters with bulk density of .77 and Al plus Fe percentages (by ammonium oxalate) totaling 2.8 percent of less than 2 millimeters.
5. Isotic feature: Sodium fluoride pH (NAF pH) is 9.4 to 10.6 and ratio of 1500 kPa waater to measured clay is .6 throughout the mineralogy class control section.

ADDITIONAL DATA:

NSSL, Lincoln Lab sample number: 04N1046.

NASIS User Pedon ID: 04CA605REDW041

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.
10th Edition classification was Fine-loamy, isotic, isomesic Andic Dystrudepts.

National Cooperative Soil Survey
U.S.A.