California Foothill Streamside Woodland

EVT 9629Mediterranean California Foothill and Lower Montane Riparian Shrubland
CES206.944GNRShrubRiparian
Summary
This system is found throughout Mediterranean California within a broad elevation range from near sea level up to 300 m (900 feet) in the Coast Ranges and inland to 1500 m (4545 feet). This system often occurs as a mosaic of multiple communities that are tree-dominated with a diverse shrub component and open shrublands. This system includes open channels and bare alluvial bars as well. The variety of plant associations connected to this system reflects elevation, stream gradient, floodplain width, and flooding events. Dominant trees and shrubs may include Alnus rhombifolia, Acer negundo, Alnus rubra (in Coast Ranges), Populus fremontii, Salix laevigata, Salix gooddingii, Pseudotsuga menziesii, Platanus racemosa, Quercus agrifolia, and Acer macrophyllum (in central and south coast). Dominant shrubs include Salix exigua and Salix lasiolepis. Exotic trees Ailanthus altissima, Eucalyptus spp., and herbs such as Arundo donax occur. These are disturbance-driven systems that require flooding, scour and deposition for germination and maintenance.
Source: NatureServe Explorer
Vegetation
Dominant trees and shrubs may include Alnus rhombifolia, Acer negundo, Alnus rubra (in Coast Ranges), Populus fremontii, Salix laevigata, Salix gooddingii, Pseudotsuga menziesii, Platanus racemosa, Quercus agrifolia, and Acer macrophyllum (in central and south coast). Dominant shrubs include Salix exigua and Salix lasiolepis. Exotic trees Ailanthus altissima, Eucalyptus spp., and herbs such as Arundo donax occur.
Source: NatureServe Explorer
Environment
This system occurs adjacent to perennial or intermittent streams, streams with at least seasonal channel flow, usually associated with a subsurface groundwater level that is shallower than surrounding uplands. Winter peak and summer discharges can be quite variable. The impact of seasonal high and low flows can be characterized as three regimes: (1) intense disturbances/minimal summer drought (close to channel, or narrow constricted floodplains); (2) moderate disturbances/summer drought (mid distance to channel, or moderate-sized floodplain); and (3) minimal disturbance/summer drought (greatest distance from channel, or wide floodplains). Type and extent of riparian vegetation are dependent upon the balance between the degree of summer drought as controlled by ground and surface water availability and the intensity of disturbance determined by discharge magnitudes and channel morphology (Ross and Swift 2001). This "distance from channel" can dictate the age and size of the riparian woody species.
Source: NatureServe Explorer
Dynamics
These are disturbance-driven systems that require flooding, scour and deposition for germination and maintenance.
Source: NatureServe Explorer
Distribution
This system is found throughout Mediterranean California within a broad elevation range from near sea level up to 300 m (900 feet) in the Coast Ranges and inland to 1500 m (4545 feet).
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)

Acer macrophyllum, Acer negundo, Ailanthus altissima, Alnus rhombifolia, Alnus rubra, Platanus racemosa, Populus fremontii, Pseudotsuga menziesii, Quercus agrifolia, Salix gooddingii

Shrub/sapling (tall & short)

Salix exigua, Salix lasiolepis

Tall shrub/sapling

Salix laevigata

Herb (field)

Arundo donax, Limnanthes alba ssp. gracilis, Perideridia erythrorhiza, Sidalcea malviflora ssp. patula, Sidalcea nelsoniana, Thelypodium howellii ssp. howellii

Nonvascular

Cortinarius pavelekii
Source: NatureServe Ecological System assessment
Ecologically Associated Animals (12)

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.

Reptiles (3)

Common NameScientific NameG-Rank
Northern Rubber BoaCharina bottaeG5
Ring-necked SnakeDiadophis punctatusG5
Southern Alligator LizardElgaria multicarinataG5

Amphibians (1)

Common NameScientific NameG-Rank
Oregon Spotted FrogRana pretiosaG2

Butterflies & Moths (1)

Common NameScientific NameG-Rank
Mardon SkipperPolites mardonG2

Insects (1)

Common NameScientific NameG-Rank
Siskiyou Slant-face GrasshopperChloealtis aspasmaG3

Molluscs (4)

Common NameScientific NameG-Rank
Siskiyou ShoulderbandMonadenia chaceanaG2G3
Pacific SidebandMonadenia fidelis flavaG4G5T1T2
Scarletback Taildropper SlugProphysaon vanattaeG4G5
Scaly ChaparralTrilobopsis loricataG2G3

Other (2)

Common NameScientific NameG-Rank
Umpqua SidebandMonadenia fidelis ssp. 2G4G5T1
Klamath taildropperProphysaon sp. 1G3
Source: NatureServe Ecological System assessment
At-Risk Species Associated with this Ecosystem (14)

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
Siskiyou Slant-face GrasshopperChloealtis aspasmaG3--
a fungusCortinarius pavelekiiG2--
Slender MeadowfoamLimnanthes alba ssp. gracilisG4T3--
Siskiyou ShoulderbandMonadenia chaceanaG2G3--
Pacific SidebandMonadenia fidelis flavaG4G5T1T2--
Umpqua SidebandMonadenia fidelis ssp. 2G4G5T1--
Red-root YampahPerideridia erythrorhizaG2--
Mardon SkipperPolites mardonG2--
Klamath taildropperProphysaon sp. 1G3--
Oregon Spotted FrogRana pretiosaG2Threatened
Spreading Checker-mallowSidalcea malviflora ssp. patulaG4G5T2--
Nelson's SidalceaSidalcea nelsonianaG2G3Delisted
Howell's ThelypodyThelypodium howellii ssp. howelliiG1T1--
Scaly ChaparralTrilobopsis loricataG2G3--
Source: NatureServe Ecological System assessment
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 (10)

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 (10)

AreaForestCoverageHectares
Pine CreekCleveland National Forest5.8%11.88
Cucamonga BSan Bernardino National Forest4.0%191.97
South SierraSequoia National Forest3.4%108.81
Hall Natural AreaInyo National Forest2.6%55.35
South SierraInyo National Forest2.1%363.6
Mokelumne - Hawkins PkHumboldt-Toiyabe National Forest0.9%61.29
Snow MountainMendocino National Forest0.7%40.14
Coyote SoutheastInyo National Forest0.6%119.25
GrindstoneMendocino National Forest0.5%52.74
Sespe - FrazierLos Padres National Forest0.4%172.44
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.