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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Classification relationships
Valley Oak Woodland (CWHR)
Non-Native GrasslandSimilar sites
R019XD043CA Loamy Hill 16-20" p.z.
This site has scattered Califonia live oak with California sagebrush and annual grasses.
Table 1. Dominant plant species
Tree (1) Quercus lobata
Shrub Not specified
Herbaceous (1) Avena
Physiographic features
This site occurs on alluvial fans in valley bottoms. Slopes range from 1 to 9 percent. Aspects are variable. Elevation ranges from 600 to 2100 feet.
Table 2. Representative physiographic features
Landforms (1) Alluvial fan
(2) Valley floor
Flooding frequency None Ponding frequency None Elevation 600 – 2100 ft Slope 1 – 9 % Ponding depth 0 in Water table depth 0 in Aspect Aspect is not a significant factor Climatic features
The climate is characterized by a predominance of winter season precipitation and marine influence throughout the year. Average annual rainfall is between 14 and 16 inches. Snowfall is uncommon but not unheard of, especially in the higher elevations. Average annual air temperatures range from a minimum of 51 degrees F to a maximum of 70 degrees F.
There are no reliable climate stations for this specific ecological site. The two stations listed (Oxnard and Los Angeles Civic Center) are on the extreme northwest and southwest of the area, and are generally drier.Table 3 Representative climatic features
Frost-free period (average) 350 days Freeze-free period (average) 370 days Precipitation total (average) 20 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
This site has no influencing wetland or riparian features for this ecological site.
Soil features
This ecological site is associated with the Botella soil series. The Botella soils are very deep and well drained. They formed in alluvial material from sedimentary rocks. Botella soils are in valley bottoms and on alluvial fans and have slopes of 0 to 15 percent. The mean annual precipitation is about 18 inches and the mean annual air temperature is about 58 degrees F.
The surface texture is a silty clay loam to a depth of 41 inches. From 41 to 59 inches is a heavy sandy clay loam, from 59 to 65 inches a light sandy clay loam, and from 65 to 79 inches a heavy sandy clay loam.
The Botella soils are classified as Fine-loamy, mixed, superactive, thermic Pachic Argixerolls.
This site is found on in the following soil survey areas and mapunits:
SSA MapUnit Component Percent
692 320 Botella 85
692 202 Botella 5
692 430 Botella 7
692 431 Botella 10
692 432 Botella 5
692 503 Botella 10
Table 4. Representative soil features
Surface texture (1) Loam
Family particle size (1) Clayey
Drainage class Well drained Permeability class Slow Soil depth 60 – 72 in Surface fragment cover <=3" Not specified Surface fragment cover >3" Not specified Available water capacity
(0-40in)7 – 8 in Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)5.6 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)Not specified Subsurface fragment volume >3"
(Depth not specified)Not specified Ecological dynamics
This ecological site is associated with valley oak (Quercus lobata) savanna. Historically perennial bunch grasses were dominant in the understory, but non-native annual grasses and forbs are present in most of this area now. Valley oak (Quercus lobata) is a threatened California endemic species, and valley oak savannas have declined dramatically in the last 100 years. Most of the habitat has been converted for pasture, croplands, or urbanization. Non-native species have invaded the savannas in the remaining areas. The native bunchgrasses are hard to find, and many native annuals have been extirpated. In addition the old oaks are dying and there is very little oak regeneration.
Valley oak (Quercus lobata) is a large deciduous broad leaf tree. It can grow 35 to 75 feet tall with crowns just about as wide or more. They can live for 400 to 500 years, and mature stands are at least 100 years old. They have deep taproots that can reach 80 feet or more and an abundance of lateral surface roots (Howard, 1992). Oaks are highly mycorrhizal with several fungi. They also produce inhibitory tannins that suppress growth under the tree canopy. Large valley oaks often survive the flashy grassland fires, and smaller ones that are top killed can resprout from the root crown. Valley oaks are generally found on alluvial flats, valley bottoms, and lower foothills, where they can reach the water table.
Valley oak is often infected with the honey mushroom (Armillaria mellea), which does not usually kill the oaks, but can infect and kill orchard trees. Valley oak can be infected by the introduced fungus (Phytophthora ramorum) that causes sudden oak death. This fungus is less of a threat in drier areas, such as inland foothills and southern California mountains.
The loss of the mature oaks has largely been from clearing practices, but lower water tables, saline runoff, and overwatering have also killed oaks. There are three main reasons for the lack of young oak seedlings. First, most of the acorns are eaten by insects, squirrels, birds, deer and/or cattle. Second, if any acorns germinate, the young seedlings have to survive being browsed by deer and cattle. Third, young seedlings have difficulty competing with the annual grasses and other non-native weeds for water.
The valley oaks in the southern California Coast Ranges, Transverse Ranges, and the Bay area were prioritized for conservation efforts due to the high genetic diversity in these areas. It was theorized that the oaks in these areas may have survived the Pleistocene era, and their genetic diversity may help this species survive the pressures of global warming. Climate charge is predicted to reduce the suitable habitat for valley oak by about 50%, and move the species upward in elevation and northward (Grivet et. Al., 2008).
State and transition model
Custom diagramStandard diagram
Figure 3. Loamy upland State and Transition Model
More interactive model formats are also available. View Interactive Models
More 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 4 submodel, plant communities
State 5 submodel, plant communities
State 1
Valley oak with non-native annual grasses 2.1Community 1.1
Valley oak with non-native annual grasses 2.1This plant community is the reference plant community for this ecological site. It has an occasional large valley oak (Quercus lobata) with non-native annual grassland in the understory. There may be a few patches of native grassland. Non-native annual grasses compose of up to 70 percent of the annual production. Specific species were not inventoried, but a mix of oats (Avena spp.) and Bromes (Bromus spp.) would be common.
This community has changed significantly from the historic state primarily because heavy grazing in the past reduced the cover of the native species, and the non-native grasses have since outcompeted the native species for water.
The annual grasses also compete with the young valley oak seedlings for water, and may cause mortality.
Fires are common and flashy in these annual grasslands. Fire frequency data is hard to find for this community. In the event of a fire pathway 2.1 is followed.Figure 4. Annual production by plant type (representative values) or group (midpoint values)
State 2
Valley oak and perennial bunchgrasses 1.1Community 2.1
Valley oak and perennial bunchgrasses 1.1This plant community represents the historic plant community. It is difficult to find species composition for the historic valley oak woodlands in the Southern California mountains. There was probably a more mixed age structure for the valley oaks than is present today. A notable difference would be presence of young seedlings and sapling valley oaks. Native perennial grasses that may have been present include purple needlegrass (Nassella pulchra), foothill needlegrass (Nassella lepida), giant wildrye (Leymus condensatus), and meadow barley (Horduem brachyantherum). Several other grasses were present along with a variety of native forbs. Some of these perennial grasses can live for 100 to 300 years.
Historically native Americans may have burned these grasslands on an annual basis, but the natural cause of fire is from lighting which is less frequent in this area.
When fire does occur it initiates pathway 2.1, to the regeneration community.
State 3
Valley oak and resprouting perennial grasses and trees 1.2Community 3.1
Valley oak and resprouting perennial grasses and trees 1.2This community develops after a flashy grassland fire. The large valley oaks would survive these fires. The smaller valley oaks may be top killed, but will resprout from the root crown. Many of the perennial bunchgrasses can resprout after low to moderate intensity fires. Historically there was probably a high diversity of fire following annuals.
State 4
Valley oak with non-native annual grasses 2.2Community 4.1
Valley oak with non-native annual grasses 2.2This is a post burn community, which is not much different from the pre-burn community. The annual grasses and forbs regenerate from seed that survived the fire, or seed from nearby sources. If the fire was severe or in early spring before seed was set, then recovery of the annual grasses may be slower. There may be native fire follower species present for a year or two.
State 5
Non-native annual grasses and forbs State 3Community 5.1
Non-native annual grasses and forbs State 3This plant community is dominated by non-native annual grasses and forbs. Valley oaks and native grasses are absent. The native species were unable to regenerate due to grazing or competition for water.
Non-native species listed by Dagit were the common non-native grasses (Avena fatua, Bromus sp., Cynodon dactylon, Festuca sp., Hordeum murinum, etc.) and mustard (Brassica nigra), followed by a variety of thistles (Centaurea melitensis, Salsola iberica, etc.).
Restoration of this community back to state 2 is possible, but would require a lot of management. Full restoration back to the historic state is desirable, but most likely unobtainable. Restoration should begin with reestablishing valley oak. Seeds or seedlings can be planted, but need to be protected from grazing, and weeds need to be pulled from the rooting zone. The reintroduction of native grasses is more difficult, and would require continual removal of annual grasses and weeds, until the perennial grasses become well established and dominate in cover.Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Non-native grasses 1300–4000 4 Native perennial grass 40–120 giant wildrye LECO12 Leymus condensatus 40–120 – Forb2 Annual fobs 300–960 Shrub/Vine3 Sub shrub 250–780 common deerweed LOSC2 Lotus scoparius 250–780 – Tree5 Tree 20–60 valley oak QULO Quercus lobata 20–60 – Table 6. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Valley oak is often hollow, or has other cavities suitable for nests and storage for wildlife. It is a fair to poor browse for deer, and poor browse for cattle. Acorns are eaten by California ground squirrels, pocket gophers, scrub jays, yellow-billed magpies, acorn woodpeckerss, black-tailed deers, feral pigs, and of cattle. Roots are consumed by feral pigs and pocket gophers (Howard, 1992).
Recreational uses
This area is suitable for hiking, biking, and horse riding trails. Picnic areas and campgrounds may be appropriate in some areas.
Wood products
The wood from valley oaks is not suitable for timber uses because it warps and cracks upon drying. It often has stains from fungi, that can be desirable for small hand worked crafts. Sometimes the wood is used to make cabinets and wine barrels or cut for firewood.
Other products
The acorns of valley oak can be eaten when processed.
Supporting information
Other references
Brown, Rodney W. and Davis, Frank W. (1991). Historical Mortality of Valley Oak (Quercus lobata, Nee) in the Santa Ynez Valley, Santa Barbara County, 1938-1989. USDA Forest Service Gen. Tech. Rep. PSW-126. 1991
Downer, Jim (2006). Some factors about soil that you need to know to understand the biology of the oak tree in California. Landscape Notes, University of California Cooperative Extension, Ventura County. Vol. 19 #2, March 2006.
Grivet, Delphine; Sork, Victoria; Westfall, Robert D.; and Davis, Frank W. (2008). Conserving the evolutionary potential of California valley oak (Quercus lobata Née): a multivariate genetic approach to conservation planning. Blackwell Publishing Ltd. Molecular Ecology (2008) 17, 139–156.
Howard, Janet L. 1992. Quercus lobata. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2008, January 4].
Contributors
Curtis Talbot, Marchel Munnecke
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 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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