Major Land Resource Area 018X
Sierra Nevada Foothills
Accessed: 12/21/2024
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-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime thermic
- Site not as above, primarily bedrock controlled soils
- Site not as above
- Not as above
- Soils occur in concave landscape position on hills, or undulating plateaus with deep to very deep soils F018XA201
-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime mesic
- Site not as above
- Soils are moderately deep to deep - support closed oak woodland with scattered pine.
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP < 30 inches
- Site ocurs on all aspects, generally on moderately deep to very deep soils. Vegetation consists of blue oak woodland and savannas - F018XC201CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP ≥ 30
- Site occurs in deep to very deep soils on concave positions
- Site occurs on broadly concave mountain slopes, generally in granite PM, closed canopy (interior/canyon live oak) and buckeye, often with California bay. - F018XC203CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
- Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
- Site is an upland
- Soil temperature regime is borderline mesic and landform is hills or mountains (buckeye, foothill pine, and interior live oak indicator species) -F018XE201
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP ≤ 25 inches
- Site on upland, bedrock controlled
- Shallow to moderately deep soils, parent material derived from metavolcanic, slate, or granitic lithologies.
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- Site not as above
- Site not as above
- Site not as above
- Site occurs on moderately deep soils on slopes generally < 30%- blue oak, foothill pine, annual grasses, moderate density of shrubs.
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- Site not as above
- Site not as above
- Site not as above
- Soils are generally deeper, live oak dominated and dense overstory - F018XI202CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in a mesic STR
- Site on sideslopes and often steeper and/or north-facing (California black oak dominant tree and high density of shrubs and a few conifers)
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- PM intrusive igneous, excluding footslope and toeslope positions (depositional areas)
- Cooler aspect. Blue oak/interior live oak woodland
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- Site not as above
- Trees and vegetation stunted due to high Ca content (PM ~ marble)
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occuring on lava plateaus or erosion remnants, and skirting the adjacent hillslopes
- Soils moderately to very deep (oak/shrub savannahs)
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- Site not as above
- Site not as above
- Site dominated by volcanic bedrock
- Soil depth deep to deeper, oak woodland or savannah, AWC 3-7 - F018XI207CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- Mean Annual Precipitation (MAP) is generally well below 18 inches
- Sites consist of ridges and or terraces or alluvial fan remnants
- Sites occur on deeper soils located on backslopes to footslopes
-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime thermic
- Site not as above, primarily bedrock controlled soils
- Occur on plateau formations. Soils within a swale/mound microtopgraphy complex
-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime thermic
- Site not as above, primarily bedrock controlled soils
- Site not as above
- Landform a lower foothill position or strath terrace, generally water shedding positions
-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime thermic
- Site not as above, primarily bedrock controlled soils
- Site not as above
- Not as above
- Soils on volcanic ridges or rocky, undulating foothills
- Soils very shallow to shallow (AWC < 3)
-
i
Key Characteristics
- Not as above,
- Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
- Soil temperature regime mesic
- Site not as above
- Soils are very shallow to shallow - support open blue oak with annual herbaceous communities
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- Mean Annual Precipitation (MAP) < 23 "
- Soils have shrink-swell properties and clayey PSC
- Slope percent < 25, on terraces and low hills
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- Mean Annual Precipitation (MAP) < 23 "
- Soils have shrink-swell properties and clayey PSC
- Slope percent ≥ 25, on upper foothills and mountains
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- Mean Annual Precipitation (MAP) < 23 "
- Site not as above
- Soils shallow depth class
- Soils occuring on lower foothill position, slope < 25%
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- Mean Annual Precipitation (MAP) < 23 "
- Site not as above
- Soils shallow depth class
- Soils occuring on steep slopes (≥ 25%), with rock outcrop area > 25%
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- Mean Annual Precipitation (MAP) < 23 "
- Site not as above
- Soils moderately deep to deeper
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a key factor in defining site- ultramafic soils with reduced productivity
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP ≥ 30
- Site occurs in shallow to moderately deep soils
- Soils on granite and support dense chaparral - R018XC107CA
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP < 30 inches
- Soils occur on south to southwest aspects, shallow to moderately deep soils- chaparral
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP ≥ 30
- Site occurs in shallow to moderately deep soils
- Soils on other parent materials
- Soils are on marble, often on canyon walls, yucca-chamise associations are common - R018XC109CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
- Soil chemistry a lesser contributing factor
- MAP ≥ 23
- MAP ≥ 30
- Site occurs in deep to very deep soils on concave positions
- Site occurs in steep narrow drainages , often metamorphic PM, dominated by California buckeye and mesic chaparral shrubs (Mahogany, flannelbush) - R018XC110CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
- Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
- Site is an upland
- Soil temperature regime is solidly thermic and landform is hills or terraces
- Soils are calcareous and very deep, pH ranges into alkaline (> 8 pH) - R018XE101CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
- Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
- Site is an upland
- Soil temperature regime is solidly thermic and landform is hills or terraces
- Soils not as above
- Soils have heavy texture or exhibit cracks with seasonal wetting-drying cycles - R018XE102CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
- Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
- Site is an upland
- Soil temperature regime is solidly thermic and landform is hills or terraces
- Soils not as above
- Site not as above
- Soils are shallow (AWC 1-2 inches); vegetation is annual forbs/grasses with very few trees - R018XE103CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
- Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
- Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
- Site is an upland
- Soil temperature regime is solidly thermic and landform is hills or terraces
- Soils not as above
- Site not as above
- Soils are moderately deep to deep (AWC 3-5 inches), often with mollic epipedons; vegetation includes oak woodland with dense annuals. - R018XE104CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occuring on lava plateaus or erosion remnants, and skirting the adjacent hillslopes
- Soils very shallow to shallow (annual forbs & grasses)
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site occurs on ultramafic soils
- Site with very low Ca:Mg ratios ( 0.5) indicated by greater cover of barren soil/rock
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site occurs on ultramafic soils
- Site not as above
- Sites with Ca:Mg ratios greater than 0.5 (but rarely than 2.0) continuous vegetation with only minor breaks
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site occurs on ultramafic soils
- Site not as above
- Sites on north-facing slopes greater in shrub diversity
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Site is steep AND aspect dependent, generally occuring on north-facing slopes on lower elevations, and on reverse aspects (s-facing) as elevation increases
- Site approaching mesic STR but still thermic, generally annual ppt > 34
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in a mesic STR
- Site occurs along edges of MLRA 22A break, mesic STR more common
- Site not as above, slope gradient generally steep
- Soils shallow to moderately deep (rarely deep) on S-facing slopes. Vegetation consists of chaparral shrubs - R018XI105CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Site is steep AND aspect dependent, generally occuring on north-facing slopes on lower elevations, and on reverse aspects (s-facing) as elevation increases
- Site definitely thermic STR, ppt < 34
- Slopes less than 55 %, chamise and other chaparral shrubs dominate site, generally thick. Very low cover of forbs and grasses
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- PM intrusive igneous, excluding footslope and toeslope positions (depositional areas)
- South to west-facing aspects, usually chamise dominated - R018XI106CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP ≤ 25 inches
- Site on upland, bedrock controlled
- Soils towards shallow end and very low AWC (< 2)- volcanic PM
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Not as above
- Site in thermic soil temperature regime
- Site not as above
- Site not as above
- Site dominated by volcanic bedrock
- Soil depth shallow (Inks, Pentz, Amador soils) annuals dominate the site, AWC 1-4 - R018XI107CA
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP ≤ 25 inches
- Concave-Concave microsite positions - generally dominated by Juncus-Carex and annual forbs
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- MAP is at least 18 inches
- MAP > 25 inches
- Site is steep AND aspect dependent, generally occuring on north-facing slopes on lower elevations, and on reverse aspects (s-facing) as elevation increases
- Site definitely thermic STR, ppt < 34
- Slope exceed 55 %, often occuring on canyon walls, herbaceous plants are diverse and dominate the site
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- Mean Annual Precipitation (MAP) is generally well below 18 inches
- Sites consist of ridges and or terraces or alluvial fan remnants
- Sites occurring on shallow to moderately deep soils, sometimes rocky
- Soils are shallow (often over tuffaceous parent materials)
-
i
Key Characteristics
- Not as above,
- Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
- Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
- Site not as above
- Site occurs on a hill or hillslope (various geologies)
- Mean Annual Precipitation (MAP) is generally well below 18 inches
- Sites are low, rolling dissected erosional surfaces, concave and accumulation of fine particles
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Zoom in to display soil survey map units for an area of interest, and zoom out to display MLRAs. Select a map unit polygon to view ecological sites correlated to that map unit. View a brief description of an ecological site by clicking on its name in the map popup. Soil survey correlations may not be accurate, and ecological site classification of a location should always be verified in the field. Each selection may require the transfer of several hundred KB of data.
Ecological site keys
MLRA 18
I.
Azonal, ecological sites defined by hydrology rather than soil properties (ie riparian) (LRUX)
A.
Soils in a thermic temperature regime
1
Site receives surface water flow or has a water table associated with stream hydrology
i.
Site occurs along perennial streams and rivers
b.
Lower stream gradient, often higher order stream (4th or above)
... R018XX101CA – Mid Gradient Riparian Complex, 4Th Order Stream
ii.
Site associated with ephemeral streams or drainages - R018XX999CA
2
Site not as above
i.
Site occurs on concave landscape positions- dominated by Juncus, Carex and forbs - follow key for LRU I
ii.
Site not as above
a.
Site occurs in a meadow or near a stream riparian complex- but on soils which support upland plant species- Valley oak common in overstory - follow key for LRU I
b.
Site not as above, may be another type of wetland not associated with streams - R018XX999CA
B.
Soils in a mesic temperature regime
1
Site occurs in alluvial floodplains, but vegetation is more upland: oaks, Valley oak dominates the site - LRU 22AI
2
Site is clearly riparian. - LRU 22AX
II.
Not as above,
A.
Geology consists of young (Tertiary) volcanic flows originating in Southern Cascades (north & west of Lake Oroville) (LRU A)
1
Soil temperature regime thermic
i.
Riparian systems (lentic, lotic, floodplains, etc.) - R018XX999CA
ii.
Site not as above, primarily bedrock controlled soils
a.
Occur on plateau formations. Soils within a swale/mound microtopgraphy complex
... R018XA101CA – Basalt Flow Plateaus
b.
Site not as above
1)
Landform a lower foothill position or strath terrace, generally water shedding positions
... R018XA102CA – Clayey Thermic Terraces
2)
Not as above
a)
Soils on volcanic ridges or rocky, undulating foothills
(2)
Soils not as above
(a)
Soil occurs on volcanic cone, in a mesic pocket (otherwise thermic dominated area) and with infrequent plant communities of knobcone pine/incense cedar/ ponderosa pine
... CX018XA203 – Mesic Volcano Cones
b)
Soils occur in concave landscape position on hills, or undulating plateaus with deep to very deep soils F018XA201
... F018XA201CA – Deep Thermic Hillslopes
2
Soil temperature regime mesic
i.
Soil texture class medial or with an isotic mineralogy class (vegetation tends to be dominated by coniferous forest, including sugar pine, doulgas fir, knobcone pine) - F018XA203CA
... CX018XA203 – Mesic Volcano Cones
ii.
Site not as above
a.
Soils are very shallow to shallow - support open blue oak with annual herbaceous communities
... R018XA104CA – Shallow Mesic Volcanic Ridges
b.
Soils are moderately deep to deep - support closed oak woodland with scattered pine.
... F018XA202CA – Deep Mesic Mountain Slopes & Summits
B.
Geology older (generally Mesozoic Era) or mixed ages associated with Sierra Nevada (beginning around Lake Oroville)
1
Geology is dominated by granitoid almost exclusively. Break between Valley (MLRA 17) and the foothills abrupt, with steep slopes occuring from the lowest foothills to the MLRA 18/22A break.
i.
Subhumid climate. Soil moisture regime is xeric and only aridic at the lowest elevations (usually in conjunction with the valley). (LRU C)
a.
Soil chemistry a key factor in defining site- ultramafic soils with reduced productivity
... R018XC106CA – Thermic Ultramafic Foothills
b.
Soil chemistry a lesser contributing factor
1)
Mean Annual Precipitation (MAP) < 23 "
a)
Soils have shrink-swell properties and clayey PSC
(1)
Slope percent < 25, on terraces and low hills
... R018XC101CA – Thermic Clayey Terraces and Hills
(2)
Slope percent ≥ 25, on upper foothills and mountains
... R018XC102CA – Steep Thermic Clayey Shallow
b)
Site not as above
(1)
Soils shallow depth class
(a)
Soils occuring on lower foothill position, slope < 25%
... R018XC103CA – Lithic Thermic Foothills
(b)
Soils occuring on steep slopes (≥ 25%), with rock outcrop area > 25%
... R018XC104CA – Thermic Free Face Foothills
2)
MAP ≥ 23
a)
MAP ≥ 30
(1)
Site occurs in shallow to moderately deep soils
(a)
Soils on granite and support dense chaparral - R018XC107CA
... R018XC107CA – Thermic Granitic Foothills south-facing
(b)
Soils on other parent materials
(1)
Soils are on marble, often on canyon walls, yucca-chamise associations are common - R018XC109CA
... R018XC109CA – Steep Marble Canyon Walls
(2)
Site occurs in deep to very deep soils on concave positions
(a)
Site occurs in steep narrow drainages , often metamorphic PM, dominated by California buckeye and mesic chaparral shrubs (Mahogany, flannelbush) - R018XC110CA
... R018XC110CA – Cool Thermic Shallowly Dissected Slopes
(b)
Site occurs on broadly concave mountain slopes, generally in granite PM, closed canopy (interior/canyon live oak) and buckeye, often with California bay. - F018XC203CA
... F018XC203CA – Cool Thermic Slopes
b)
MAP < 30 inches
(1)
Soils occur on south to southwest aspects, shallow to moderately deep soils- chaparral
... R018XC107CA – Thermic Granitic Foothills south-facing
(2)
Site ocurs on all aspects, generally on moderately deep to very deep soils. Vegetation consists of blue oak woodland and savannas - F018XC201CA
... F018XC201CA – Thermic Granitic Foothills
ii.
Semi-arid climate with interchanging soil moisture regimes (xeric & aridic). Moderately to steep hills & mountains at southern end of Great Central Valley.
a.
Mean elevation > 3,200 ft (soil temperature regime thermic to mesic). This LRU occurs at the crossroads of several MLRA's. Vegetation patterns reflect the confluence of desert (MLRA 29), mountains (MLRA 22A), and foothills (MLRA 18) vegetation, to include juniper/ blue oak woodlands, yucca and other species from adjacent regions. (MLRA 22AO)
b.
Mean elevation < 3,200 ft (Vegetation patterns conform to vegetation classes and ecosystem dynamics of other LRU's in MLRA 18 with annual grasslands/ blue oak savannahs being most common plant community.) (LRU E)
1)
Riparian (driven by hydrological features) - R018XX999CA
2)
Site is an upland
a)
Soil temperature regime is solidly thermic and landform is hills or terraces
(1)
Soils are calcareous and very deep, pH ranges into alkaline (> 8 pH) - R018XE101CA
... R018XE101CA – Very Deep Alkaline Alluvium
(2)
Soils not as above
(a)
Soils have heavy texture or exhibit cracks with seasonal wetting-drying cycles - R018XE102CA
... R018XE102CA – Steep Clayey Shallow
(b)
Site not as above
(1)
Soils are shallow (AWC 1-2 inches); vegetation is annual forbs/grasses with very few trees - R018XE103CA
... R018XE103CA – Loamy Low Hills
(2)
Soils are moderately deep to deep (AWC 3-5 inches), often with mollic epipedons; vegetation includes oak woodland with dense annuals. - R018XE104CA
... R018XE104CA – Thermic Granitic Hills
b)
Soil temperature regime is borderline mesic and landform is hills or mountains (buckeye, foothill pine, and interior live oak indicator species) -F018XE201
... F018XE201CA – Granitic Hills and Mountains
2
Geology highly complex, interfingering of volcanic, sedimentary (metamorphozed), and some granitics. The break between MLRA 17 and MLRA 18 is more gradual than in the southern LRU's, lower foothill slopes gently to strongly sloping. (LRU I)
i.
Site occurs on ultramafic soils
a.
Site with very low Ca:Mg ratios ( 0.5) indicated by greater cover of barren soil/rock
... R018XI102CA – Thermic Ultramafic Foothills Extremely High Magnesium Content (Ca:Mg Ratio Less Than 0.5)
b.
Site not as above
1)
Sites with Ca:Mg ratios greater than 0.5 (but rarely than 2.0) continuous vegetation with only minor breaks
... R018XI103CA – Thermic Ultramafic Foothills Moderately High Magnesium Content (Ca:Mg Ratio 0.5 To 2)
2)
Sites on north-facing slopes greater in shrub diversity
... R018XI104CA – Thermic Ultramafic North-Facing Steep Slopes
ii.
Site not as above
a.
Site occuring on lava plateaus or erosion remnants, and skirting the adjacent hillslopes
1)
Soils very shallow to shallow (annual forbs & grasses)
... R018XI101CA – Shallow Latite Ridgetops
2)
Soils moderately to very deep (oak/shrub savannahs)
... F018XI207CA – Deep Volcanic Plateaus and Hills
b.
Site occurs on a hill or hillslope (various geologies)
1)
Mean Annual Precipitation (MAP) is generally well below 18 inches
a)
Sites consist of ridges and or terraces or alluvial fan remnants
(1)
Sites occurring on shallow to moderately deep soils, sometimes rocky
(a)
Soils are shallow (often over tuffaceous parent materials)
... R018XI163CA – Thermic Low Rolling Hills
(2)
Sites occur on deeper soils located on backslopes to footslopes
... F018XI208CA – Deep Low Rolling Hills and Terraces
b)
Sites are low, rolling dissected erosional surfaces, concave and accumulation of fine particles
... R018XI164CA – Clayey Dissected Swales
2)
MAP is at least 18 inches
a)
MAP ≤ 25 inches
(1)
Concave-Concave microsite positions - generally dominated by Juncus-Carex and annual forbs
... R018XI111CA – Low Gradient, Concave Depressions
(2)
Site on upland, bedrock controlled
(a)
Shallow to moderately deep soils, parent material derived from metavolcanic, slate, or granitic lithologies.
... F018XI200CA – Low Elevation Foothills
(b)
Soils towards shallow end and very low AWC (< 2)- volcanic PM
... R018XI107CA – Shallow, Undulating Volcanic Hills
b)
MAP > 25 inches
(1)
Site is steep AND aspect dependent, generally occuring on north-facing slopes on lower elevations, and on reverse aspects (s-facing) as elevation increases
(a)
Site approaching mesic STR but still thermic, generally annual ppt > 34
... R018XI105CA – Mesic Steep Convex Slopes bordering thermic
(b)
Site definitely thermic STR, ppt < 34
(1)
Slope exceed 55 %, often occuring on canyon walls, herbaceous plants are diverse and dominate the site
... R018XI125CA – Very Steep Skeletal Hillslopes
(2)
Slopes less than 55 %, chamise and other chaparral shrubs dominate site, generally thick. Very low cover of forbs and grasses
... R018XI106CA – Steep Thermic Hillslopes and Canyon Walls
(2)
Not as above
(a)
Site in thermic soil temperature regime
(1)
PM intrusive igneous, excluding footslope and toeslope positions (depositional areas)
(a)
South to west-facing aspects, usually chamise dominated - R018XI106CA
... R018XI106CA – Steep Thermic Hillslopes and Canyon Walls
(2)
Site not as above
(a)
Trees and vegetation stunted due to high Ca content (PM ~ marble)
... F018XI206CA – Clayey Thermic Marble Hills
(b)
Site not as above
(1)
Site dominated by volcanic bedrock
(a)
Soil depth shallow (Inks, Pentz, Amador soils) annuals dominate the site, AWC 1-4 - R018XI107CA
... R018XI107CA – Shallow, Undulating Volcanic Hills
(b)
Soil depth deep to deeper, oak woodland or savannah, AWC 3-7 - F018XI207CA
... F018XI207CA – Deep Volcanic Plateaus and Hills
(2)
Site not as above
(a)
Site occurs on moderately deep soils on slopes generally < 30%- blue oak, foothill pine, annual grasses, moderate density of shrubs.
... F018XI201CA – Moderately Deep Thermic Foothills
(b)
Soils are generally deeper, live oak dominated and dense overstory - F018XI202CA
... F018XI202CA – Deep Thermic Steep Hillslopes
(b)
Site in a mesic STR
(1)
Site on sideslopes and often steeper and/or north-facing (California black oak dominant tree and high density of shrubs and a few conifers)
... F018XI204CA – North-facing Steep Draws and Hillslopes
(2)
Site occurs along edges of MLRA 22A break, mesic STR more common
(a)
Site generally shallow occuring on narrow ridges or sideslopes below prominent ridges, vegetation consists of annuals forbs and grasses and scattered shrubs/foohtill pine - R022AI101CA
(b)
Site not as above, slope gradient generally steep
(1)
Soils shallow to moderately deep (rarely deep) on S-facing slopes. Vegetation consists of chaparral shrubs - R018XI105CA
... R018XI105CA – Mesic Steep Convex Slopes bordering thermic
(2)
Soils generally deeper and occur on all aspects, PIPO-oak-shrubland - F022AI201CA
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
