Natural Resources
Conservation Service
Ecological site F018XI208CA
Deep Low Rolling Hills and Terraces
Last updated: 4/24/2024
Accessed: 09/14/2026
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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): 018X–Sierra Nevada Foothills
Major Land Resource Area (MLRA) 18, Sierra Nevada Foothills is located entirely in California and runs north to south adjacent to and down-slope of the west side of the Sierra Nevada Mountains (MLRA 22A). MLRA 18 includes rolling to steep dissected hills and low mountains, with several very steep river valleys. Climate is distinctively Mediterranean (xeric soil moisture regime) with hot, dry summers, and relatively cool, wet winters. Most of the precipitation comes as rain; average annual precipitation ranges from 15 to 55 inches in most of the area (precipitation generally increases with elevation and from south to north). Soil temperature regime is thermic; mean annual air temperature generally ranges between 52 and 64 degrees F. Geology is rather complex in this region; there were several volcanic flow and ashfall events, as well as tectonic uplift, during the past 25 million years that contributed to the current landscape.
LRU notes
This LRU (designated XI) is located on moderate to steep hills in the Sierra Nevada Foothills east of Sacramento, Stockton, and Modesto, CA. Various geologies occur in this region: metavolcanics, granodiorite, slate, marble, argillite, schist and quartzite, as well as ultramafic bands to a limited and localized extent. It includes mesa formations from volcanic flows, where vernal pool habitats occur. Soil temperature regime is thermic and soil moisture regime is xeric. Elevation ranges between 300 and 3400 feet above sea level. Precipitation ranges from 14 to 42 inches annually. Most precipitation falls between the months of November and March in the form of rain. Dominant vegetation includes annual grasslands, blue oak (Quercus douglasii), interior live oak (Quercus wislizeni), chamise (Adenostoma fasciculatum), buckbrush (Ceanothus cuneatus), and foothill pine (Pinus sabiniana).
Classification relationships
CLASSIFICATION RELATIONSHIPS
This site is located within M261F, the Sierra Nevada Foothills Section, (McNab et al., 2007) of the National Hierarchical Framework of Ecological Units (Cleland et al., 1997), M261Fb, the Lower Foothills Metamorphic Belt Subsection.
Level III and Level IV ecoregions systems (Omernik, 1987, and EPA, 2011) are: Level III, Central California Foothills and Coastal Mountains and Level IV, Ecoregion 6b, Northern Sierran Foothills, Ecoregion 6c, Comanche Terraces.Ecological site concept
This site is characterized by shallow to deep alluvial soils occurring on toeslope and footslope positions on undulating to rolling hillslopes and on ancient stream terraces. Slopes typically range from 1 to 23% with elevation ranging from 200 to 1300 feet. Precipitation typically ranges from 17 to 22 inches per year.
Deep soils and high soil moisture content from the water receiving landscape positions allows for greater production, both woody and herbaceous than the landscape positions where water is more readily lost. Mokelumne and Hicksville soil components are often correlated with this ecological site. Mokelumne soils are moderately deep soils on dissected terraces, hills, sideslopes of terrace remnants and in swales. They are classified as fine, kaolinitic, thermic Typic Haploxerults. Hicksville soils are deep to very deep, moderately well drained soils occurring on low stream terraces and alluvial flats along the eastern edge of the San Joaquin Valley. They are fine-loamy, mixed superactive, thermic Mollic Haploxeralfs.
The vegetation community consists of open blue oak (Quercus douglasii) and interior live oak (Quercus wislizeni) and scattered shrubs such as manzanita (Arctostaphylos spp.), California buckeye (Aesculus californica) and poison oak (Toxicodendron diversilobum). The open structure allow for high production of bromes (Bromus spp.), fillaree (Erodium spp.) and other forbs and grasses. However, production data still needs to be collected on this ecological site.Table 1. Dominant plant species
Tree (1) Quercus douglasii
(2) Quercus wislizeniShrub (1) Toxicodendron diversilobum
(2) ArctostaphylosHerbaceous (1) Bromus
(2) AvenaPhysiographic features
This site occurs on toeslope and footslope positions with slopes typically ranging from 1 to 23%. Elevation generally ranges from 200 to 1300.
Table 2. Representative physiographic features
Hillslope profile (1) Footslope
(2) Toeslope
Geomorphic position, terraces (1) Tread
Landforms (1) Foothills > Hill
(2) Foothills > Stream terrace
Runoff class Medium Flooding duration Very brief (4 to 48 hours) Flooding frequency None to rare Ponding frequency None Elevation 200 – 1300 ft Slope 1 – 23 % Water table depth 10 – 60 in Aspect Aspect is not a significant factor Table 3. Representative physiographic features (actual ranges)
Runoff class Medium Flooding duration Brief (2 to 7 days) Flooding frequency None to rare Ponding frequency None Elevation 120 – 2500 ft Slope 0 – 30 % Water table depth 0 in Climatic features
This ecological site is characterized by hot, dry summers and cool, wet winters, a typical Mediterranean climate. Mean annual precipitation ranges from 18 to 28 inches and usually falls from October to May. Mean annual temperature is 60 to 63 degrees F with 212 to 306 frost free days.
Table 4 Representative climatic features
Frost-free period (characteristic range) 210-310 days Freeze-free period (characteristic range) 370 days Precipitation total (characteristic range) 20-30 in Frost-free period (actual range) 210-350 days Freeze-free period (actual range) 370 days Precipitation total (actual range) 20-30 in Frost-free period (average) 260 days Freeze-free period (average) 370 days Precipitation total (average) 20 in Characteristic rangeActual rangeBarLineFigure 1. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 2. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 3. Monthly maximum temperature range
BarLineFigure 4. Monthly average minimum and maximum temperature
Figure 5. Annual precipitation pattern
Figure 6 Annual average temperature pattern
Climate stations used
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(1) FRIANT GOVERNMENT CAMP [USC00043261], Friant, CA
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(2) CAMP PARDEE [USC00041428], Valley Springs, CA
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(3) OROVILLE [USC00046521], Oroville, CA
">Influencing water features
Due to the topographic position, this site does not have water features or wetlands.
Wetland description
N/A
Soil features
The soils in this ecological site occur on stream and alluvial terraces and fans, and toeslopes of hills. They vary in depth from moderately to very deep, and the particle size control section ranges from fine-loamy to fine with surface textures including sandy loam, gravelly sandy loam and loam. The restrictive feature (when it occurs) tends to be incoherent densic material that can occur within the profile between 19 and 52 inches. Gravels (< 3 inch diameter) occupy between 1 and 5% of the soil surface and larger fragments (= 3 inch diameter) cover between 0 and 1% of the surface. Within the profile gravels range from between 6 to 28% and larger fragments from between 1 to 8% by volume. The soils in this ecological site are moderately well to well drained and the permeability class ranges from very slow to moderately slow. Available Water Capacity (AWC) ranges from 3.1 to 6.4 inches. The soil pH in the top 10 inches of the profile ranges from 5 to 6.4, and throughout the rest of the profile ranges from 3.8 to 7.
Two soils that commonly occur on this ecological site are the Mokelumne and Hicksville series. Mokelumne soils are fine, kaolinitic, thermic Typic Haploxerults and found on dissected terraces, hills, sideslopes of terrace remnants and in swales. Hicksville soils are classified as fine-loamy, mixed, superactive, thermic Mollic Haploxeralfs and are found on low stream terraces and alluvial flats along drainageways of terraces and hills.Table 5. Representative soil features
Parent material (1) Alluvium – sedimentary rock
(2) Colluvium – fanglomerate
(3) Alluvium – igneous rock
Surface texture (1) Loam
(2) Gravelly loam
(3) Sandy loam
Drainage class Moderately well drained to well drained Permeability class Very slow to moderately slow Depth to restrictive layer 17 – 57 in Soil depth 17 – 57 in Surface fragment cover <=3" 1 – 5 % Surface fragment cover >3" 0 – 1 % Available water capacity
(0-40in)3.1 – 6.4 in Soil reaction (1:1 water)
(0-10in)5 – 6.4 Subsurface fragment volume <=3"
(0-60in)6 – 28 % Subsurface fragment volume >3"
(0-60in)1 – 8 % Table 6. Representative soil features (actual values)
Drainage class Moderately well drained to well drained Permeability class Very slow to moderate Depth to restrictive layer 10 – 61 in Soil depth 10 – 61 in Surface fragment cover <=3" 0 – 5 % Surface fragment cover >3" 0 – 15 % Available water capacity
(0-40in)1.1 – 8.5 in Soil reaction (1:1 water)
(0-10in)4.5 – 7.3 Subsurface fragment volume <=3"
(0-60in)0 – 46 % Subsurface fragment volume >3"
(0-60in)0 – 27 % Ecological dynamics
State and transition model
Custom diagramStandard diagramMore interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Representative State (Blue oak/ live oak woodland)Community 1.1
Representative plant community
Annual grassland with QUWI2/QUDO 15-45% canopy cover. Scattered PISA2 Shrubs (AECA, ARCTO3, RHAMN, TODI, etc.) 0 – 5 % CC.
Community 1.2
Post-fire plant community
QUDO cover is less than 5% with very little regeneration. Shrubs usually absent, but sometimes CECU or RHMAN 5-10%. Dense annual grasses and forbs in understory.
Community 1.3
Blue oak recruitment community
Dominated by younger cohort of smaller QUDO(10-20 feet tall), Early phases will be dominated by seedlings/saplings. Shrub layer may play key role in this phase.
Pathway 1.1a
Community 1.1 to 1.2
Representative plant community
Post-fire plant communityThis community pathway occurs when a high severity fire removes most of the woody vegetation. Some oaks remain on or near the site. Alternatively, brushing or tree clearing may cause this community pathway.
Pathway 1.1b
Community 1.1 to 1.3
Representative plant community
Blue oak recruitment communityThis uncommon community pathway occurs when favorable conditions such as abundant moisture and/or seeds (acorns) etc. cause oak regeneration. Low intensity fire or clearing can also result in a resprouting of oaks.
Pathway 1.2a
Community 1.2 to 1.3
Post-fire plant community
Blue oak recruitment communityThis community pathway occurs shortly after CP 1.1a, resulting in profuse sprouting of oak trees, some of which escape herbivory and establish into sapling stage.
Pathway 1.3a
Community 1.3 to 1.1
Blue oak recruitment community
Representative plant communityThis community pathway occurs with normal time and growth.
Pathway 1.3b
Community 1.3 to 1.2
Blue oak recruitment community
Post-fire plant communityThis community pathway occurs with intense brushing/tree clearing which results in significant decrease of woody vegetation.
State 2
Annual Grassland StateCommunity 2.1
Grass-dominated system
This community phase is dominated by annuals. AVFA, BROMU, HORDE, and VULPI make up > 50 % cover.
Community 2.2
Forb-dominated system (Erodium)
This community phase is dominated by annuals. ERODI > 50 % cover.
Pathway 2.1a
Community 2.1 to 2.2
Grass-dominated system
Forb-dominated system (Erodium)This community pathway occurs as forbs become more dominant, often following low winter precipitation and reduced litter layers.
Pathway 2.2a
Community 2.2 to 2.1
Forb-dominated system (Erodium)
Grass-dominated systemThis community pathway occurs as grasses become more dominant, often in response to higher litter levels.
State 3
Invasive Annuals StateCommunity 3.1
Grass-dominated
TACA8, AETR, etc. > 25 % cover.
Community 3.2
Forb-dominated
Star thistle (CESO3) or (CEME2) . > 25 % cover.
Pathway 3.1a
Community 3.1 to 3.2
Grass-dominated
Forb-dominatedThis community pathway occurs as invasive forb species become dominant.
Pathway 3.2a
Community 3.2 to 3.1
Forb-dominated
Grass-dominatedThis community pathway occurs as invasive grass species become dominant.
Transition T1.a
State 1 to 2This transition occurs after mechanical clearing that results in loss of oak and acorn source. Grazing management also can be used to create/maintain an annual dominated state.
Transition T1.b
State 1 to 3This transition occurs when invasive grasses or forbs become established.
Restoration pathway R2.a
State 2 to 1This restoration pathway occurs with tree planting, often requires shade screens, and seedling protection from browsers to be successful.
Transition T2.a
State 2 to 3This transition occurs after invasive plants posing extreme economic/environmental issues become established.
Restoration pathway R3.b
State 3 to 1This restoration pathway occurs with tree planting, often requires shade screens, and seedling protection from browsers to be successful. This also may require integrated weed management to reduce the seedling’s competition from annual invasive species
Restoration pathway R3.a
State 3 to 2This restoration pathway occurs with integrated weed management. May require mowing, herbicides, and/or biological control.
Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 1.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 11. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 13. Community 3.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Inventory data references
Inventory data to be collected using future projects based on priorities.
References
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Natural Resources Conservation Service. . National Ecological Site Handbook.
Other references
Other References
Abrams, M.D. 1990. Adaptations and responses to drought in Quercus species of North America. Tree Physiology 7(1-4): 227-238.
Bartolome, J. W. 1987. California annual grassland and oak savannah. Rangelands 9:122-125.
Bolsinger, C. L. 1988. The hardwoods of Califonia’s timberlands, woodlands, and savannas. Portland, OR: Pacific Northwest Forest and Range Experiment Station, Forest Service, USDA.
Callaway, R.M. 1992. Morphological and physiological responses of three California oak species to shade. International Journal of Plant Science. 153(3): 434-441.
Hickman, G.W., Perry, E.J. and R.M. Davis. 2011. Wood Decay Fungi in Landscape Trees. University of California. Integrated Pest Management Program. Agriculture and Natural Resources. Pest Notes 74109.
Howard, J.L. 1992. Pinus sabiniana. In: Fire Effects Information System. (Online) USDA, Forest Service Rocky Mountain Research Station, Fire Sciences Lab (Producer). Accessed: http://www.fs.fed.us/database/feis/[April 20, 2017]
Jackson, L. 1985. Ecological origins of California’s Mediterranean grasses. Journal of
Biogeography 12:349-361.
Keeley, J. E., Lubin, D. and Fotheringham, C. J. 2003. Fire and grazing impacts on plant diversity and alien plant invasions in the southern Sierra Nevada. Ecological Applications 13:1355-1374.
McDonald, P.M. 1990. Quercus douglasii Hook & Arn. Blue oak. In: Burns, Russell M; Honkala, Barbara H, tech. cords. Silvics of North America. Vol. 2: Hardwoods. Agricultural Handbook 654. Washington DC: USDA, Forest Service: 631-639.
Perakis, S.S. and C.H. Kellogg. 2007. Imprint of oaks on nitrogen availability and delta N-15 in California grassland-savanna: a case of enhanced N inputs? Plant Ecology 191: 209-220.
Stewart, O. C., H. T. Lewis (ed.) and M. K. Anderson (ed.) 2002. Forgotten fires: Native Americans and the transient wilderness. University of Oklahoma Press: Norman, OK.
USDA, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on fire regimes of California oak woodlands. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/fire_regimes/CA_oak_woodlands/all.html[2018, March 21].Contributors
Dallas Glass
Julie Baker
Nathan RoeApproval
Kendra Moseley, 4/24/2024
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 09/14/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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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:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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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:
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Perennial plant reproductive capability:
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