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California Foothill Black Oak and Conifer Forest

EVT 7261Mediterranean California Lower Montane Black Oak-Conifer Forest and Woodland
CES206.923GNRTreeConifer-hardwood
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Summary
This ecological system is found throughout California's middle and inner North Coast Ranges, as well as the southern and eastern Klamath Mountains from 600-1600 m (1800-4850 feet) elevation, and the lower slopes of the western Sierra Nevada. It occurs in valleys and lower slopes on a variety of parent materials, including granitics, metamorphic and Franciscan metasedimentary parent material and deep, well-developed soils. It is characterized by woodlands or forests of Pinus ponderosa with one or more oaks, including Quercus kelloggii, Quercus garryana, Quercus wislizeni, or Quercus chrysolepis. Pseudotsuga menziesii may co-occur with Pinus ponderosa, particularly in the North Coast Ranges and Klamath Mountains. On most sites, the oaks are dominant, forming a dense subcanopy under a more open canopy of the conifers. On many sites, Quercus kelloggii is the dominant; in late-seral stands on more mesic sites, conifers such as Pinus ponderosa or Pseudotsuga menziesii will form a persistent emergent canopy over the oak. Stands may have shrubby understories (in the Klamath Mountains and Sierra Nevada) and, more rarely, grassy understories (in North Coast Ranges). Common shrubs include Arctostaphylos viscida, Arctostaphylos manzanita, Ceanothus integerrimus, and Toxicodendron diversilobum. Grasses can include Festuca californica, Festuca idahoensis, and Melica spp. Historical fire in this system was likely high frequency but of low intensity. Conifer species, such as Pseudotsuga menziesii, become more abundant with wildfire suppression.
Source: NatureServe Explorer
Vegetation
Vegetation is characterized by woodlands or forests of Pinus ponderosa with one or more oaks, including Quercus kelloggii, Quercus garryana, Quercus wislizeni, or Quercus chrysolepis. Pseudotsuga menziesii may co-occur with Pinus ponderosa, particularly in the North Coast Ranges and Klamath Mountains. On most sites, the oaks are dominant, forming a dense subcanopy under a more open canopy of the conifers. On many sites, Quercus kelloggii is the dominant; in late-seral stands on more mesic sites, conifers such as Pinus ponderosa or Pseudotsuga menziesii will form a persistent emergent canopy over the oak. Stands may have shrubby understories (in the Klamath Mountains and Sierra Nevada) and, more rarely, grassy understories (in North Coast Ranges). Common shrubs include Arctostaphylos viscida, Arctostaphylos manzanita, Ceanothus integerrimus, and Toxicodendron diversilobum. Grasses can include Festuca californica, Festuca idahoensis, and Melica spp. Historical fire in this system was likely high frequency but of low intensity. Conifer species, such as Pseudotsuga menziesii, become more abundant with wildfire suppression.
Source: NatureServe Explorer
Environment
Mediterranean climate where winter temperatures can be from near freezing to 10°C. Snow occurs in winter at higher elevations, but does not last all season. Annual precipitation is 100 cm (Barbour et al. 2007). Low-intensity fires are frequent (every 7-10 year). Elevation ranges between 520 and 1525 m (1700-5000 feet) in the Coast Ranges, Klamath Mountains and Sierra Nevada on deep often productive soils. North-facing aspects tend to have more conifers, with more oak dominating on south, east and west exposures.
Source: NatureServe Explorer
Dynamics
LANDFIRE model information: Historical fire frequency was 5 to 30 years in this type. Fire intensities were probably low in open stands but increased in severity as woodland vegetation transitioned to a denser, closed-canopy type along watercourses. Vegetation is fire-tolerant and therefore fire severity is low. The natural fire regime was a type I regime in the upland. With the more dense vegetation and the occurrence of fuel ladders, fire severity would become mixed. The fire regime may reflect a type III in this more mesic habitat.

Insects and disease may impact individual trees (ponderosa pine) locally. Armillaria root rot, western pine beetle, western oak looper, western tent caterpillar, and the pine engraver have the greatest potential for damage.
Source: NatureServe Explorer
Distribution
This system is found throughout California's middle and inner North Coast Ranges, as well as the Klamath Mountains from 600-1600 m (1800-4850 feet) elevation, and the lower slopes of the western Sierra Nevada.
Source: NatureServe Explorer
Ecologically Associated Plant Species

Plant species that characterize this ecosystem type, organized by vegetation stratum. These are species ecologically associated with the ecosystem, not confirmed present in any specific area.

Tree (canopy & subcanopy)

Pinus ponderosa, Pseudotsuga menziesii, Quercus chrysolepis, Quercus garryana, Quercus wislizeni

Tree canopy

Quercus kelloggii

Shrub/sapling (tall & short)

Arctostaphylos manzanita, Arctostaphylos viscida, Ceanothus integerrimus

Herb (field)

Festuca californica, Festuca idahoensis, Hastingsia bracteosa, Limnanthes alba ssp. gracilis, Plagiobothrys figuratus ssp. corallicarpus, Ranunculus austro-oreganus, Toxicodendron diversilobum

Nonvascular

Rhizopogon olivaceotinctus, Rubroboletus pulcherrimus
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (7)

Animal species ecologically associated with this ecosystem type based on NatureServe assessment. These are species whose habitat requirements overlap with this ecosystem, not confirmed present in any specific roadless area.

Mammals (1)

Common NameScientific NameG-Rank
Western Gray SquirrelSciurus griseusG5

Butterflies & Moths (2)

Common NameScientific NameG-Rank
Bramble Green HairstreakCallophrys dumetorumG4
Coastal Green HairstreakCallophrys viridisG1G3Q

Molluscs (4)

Common NameScientific NameG-Rank
Siskiyou ShoulderbandMonadenia chaceanaG2G3
Pacific SidebandMonadenia fidelis celeuthiaG4G5T2
Scaly ChaparralTrilobopsis loricataG2G3
Siskiyou HesperianVespericola sierranusG3
Source: NatureServe Ecological System assessment
At-Risk Species Associated with this Ecosystem (11)

Species with conservation concern that are ecologically associated with this ecosystem type. G-Rank indicates global conservation status: G1 (critically imperiled) through G5 (secure). ESA status indicates U.S. Endangered Species Act listing.

Common NameScientific NameG-RankESA Status
Coastal Green HairstreakCallophrys viridisG1G3Q--
Large-flower RushlilyHastingsia bracteosaG2--
Slender MeadowfoamLimnanthes alba ssp. gracilisG4T3--
Siskiyou ShoulderbandMonadenia chaceanaG2G3--
Pacific SidebandMonadenia fidelis celeuthiaG4G5T2--
Coral-seeded AllocaryaPlagiobothrys figuratus ssp. corallicarpusG4T1T2--
Southern Oregon ButtercupRanunculus austro-oreganusG3--
a fungusRhizopogon olivaceotinctusG2G3--
Red-pored BoleteRubroboletus pulcherrimusG3--
Scaly ChaparralTrilobopsis loricataG2G3--
Siskiyou HesperianVespericola sierranusG3--
Source: NatureServe Ecological System assessment
Component Associations (2)

Plant community associations that occur within this ecological system. Associations are the finest level of the U.S. National Vegetation Classification (USNVC) and describe specific, repeating assemblages of plant species. Each association represents a distinct community type that may be found where this ecosystem occurs.

NameG-Rank
Pinus ponderosa - Calocedrus decurrens - Quercus chrysolepis / Chamaebatia foliolosa ForestG4 NatureServe
Quercus kelloggii - Pinus ponderosa / Arctostaphylos viscida WoodlandG4 NatureServe
State Conservation Ranks (2)

Subnational conservation status ranks (S-ranks) assigned by Natural Heritage Programs in each state where this ecosystem occurs. S1 indicates critically imperiled at the state level, S2 imperiled, S3 vulnerable, S4 apparently secure, and S5 secure. An ecosystem may be globally secure but imperiled in specific states at the edge of its range.

StateS-Rank
CASNR
ORSNR
Roadless Areas (16)

Inventoried Roadless Areas where this ecosystem is present, identified from LANDFIRE 2024 Existing Vegetation Type spatial analysis. Coverage indicates the proportion of each area occupied by this ecosystem type.

California (15)

AreaForestCoverageHectares
BackboneShasta-Trinity National Forest5.7%262.62
Dog CreekShasta-Trinity National Forest2.8%56.97
Bear CanyonLos Padres National Forest2.2%127.44
Devils RockShasta-Trinity National Forest2.2%144
Chalk PeakLos Padres National Forest2.1%64.17
ThatcherMendocino National Forest1.7%117.9
Kettle Mtn.Shasta-Trinity National Forest1.6%30.42
Black ButteMendocino National Forest1.3%80.1
West GirardShasta-Trinity National Forest1.2%180.99
PortugueseKlamath National Forest1.0%78.12
East GirardShasta-Trinity National Forest1.0%110.61
Skeleton GladeMendocino National Forest0.8%31.68
Elk CreekMendocino National Forest0.8%72.27
Snow MountainMendocino National Forest0.7%41.67
Fox MountainLos Padres National Forest0.3%73.53

Oregon (1)

AreaForestCoverageHectares
North KalmiopsisSiskiyou National Forests0.4%133.47
Methodology and Data Sources

Ecosystem classification: Ecosystems are classified using the LANDFIRE 2024 Existing Vegetation Type (EVT) layer, mapped to NatureServe Terrestrial Ecological Systems via a curated crosswalk. Each EVT is linked to the USNVC (U.S. National Vegetation Classification) hierarchy through pixel-level co-occurrence analysis of LANDFIRE EVT and NatureServe IVC Group rasters across all roadless areas.

Vegetation coverage: Coverage percentages and hectares are derived from zonal statistics of the LANDFIRE 2024 EVT raster intersected with roadless area boundaries.

Ecosystem narratives and community species: Sourced from the NatureServe Explorer API, representing professional ecological assessments of vegetation composition, environmental setting, dynamics, threats, and characteristic species assemblages.

IVC hierarchy: The International Vegetation Classification hierarchy is sourced from the USNVC v3.0 Catalog, providing the full classification from Biome through Association levels.

Component associations: Plant community associations listed as components of each NatureServe Ecological System. Association data from the NatureServe Explorer API.

State ranks: Conservation status ranks assigned by NatureServe member programs in each state where the ecosystem occurs.