| EcoregionLevel3Code | EcoregionLevel3Name | EcoregionLevel3Descr | | 4 | Cascades | Mountainous, Cenozoic volcanics affected by alpine glaciations. West-steep ridges/river, East-high plateau, active/dormant volcanoes. Elev to 4,390m. Moist, temperate climate-extensive & productive coniferous forest. Subalpine meadows-high elevations |
| 13 | Central Basin and Range | Internally drained; characterized by xeric basins, scattered low/high mountains & salt flats. Hotter/drier climate, shrubland & mountain ranges. Sagebrush or saltbush-greasewood; cool season grasses less common. Not as hot, greater percent of grazing |
| 7 | Central California Valley | Intensive farming; long, hot dry summer & cool wet winter. Nearly half in cropland, ~75% irrigated. Environmental concerns: salinity due to evaporation of irrigation water, groundwater contamination from ag chemicals, wildlife habitat loss, & urban sprawl |
| 1 | Coast Range | Low mtns covered by highly productive, rain-soaked coniferous forests. Originally sitka spruce & redwood forests coastal; western red cedar, western hemlock, & seral Douglas-fir inland. Today Douglas-fir plantations on intensively logged/managed landscape |
| 9 | Eastern Cascades Slopes and Foothills | In rainshadow of Cascade Mtns. Climate exhibits greater temp extremes/less precipitation. Open forests ponderosa pine/some lodgepole pine. Vegetation adapted to dry continental climate & highly susceptible to wildfire. Volcanic cones & buttes common |
| 78 | Klamath Mountains | Physically/biologically diverse. Highly dissected/folded mountains, foothills, terraces & floodplains underlain by igneous, sedimentary & metamorphic rock. Mild, subhumid climate w/ summer drought. Vegetal mix-northern CA/Pacific Northwest conifers |
| 14 | Mojave Basin and Range | Scattered mountains. Creosote bush. Most federally owned; relatively little grazing activity because of the lack of water & forage for livestock. Heavy use of off-road vehicles & motorcycles in some areas has caused severe wind & water erosion problems |
| NA | NA | Not Applicable; used for stations that do not fall within an Ecoregion (e.g., sites in Pacific Ocean) |
| 80 | Northern Basin and Range | Arid tablelands/intermontane basins/lava plains/scattered mountains. Non-mtn areas-sagebrush/cool season grasses/Mollisols. Ranges-sagebrush/brush/fescue (lower/mid-elev); Douglas-fir/aspen (higher elev). Rangeland common; Dryland/irrigated ag (east) |
| NR | NR | Not Recorded |
| 5 | Sierra Nevada | Deep dissected block fault, arid basin/range(east), gentle slope to Central Valley. East glaciated. Central/southern parts granite underlay. Vegetation: ponderosa pine (lower elev; west)/lodgepole pine (east)/fir/spruce (higher elev)/alpine (highest elev) |
| 81 | Sonoran Basin and Range | Scattered low mountains, large tracts federal land (military training). Slightly hotter than the Mojave, contains large areas of palo verde-cactus shrub & giant saguaro cactus, whereas potential natural vegetation in the Mojave is largely creosote bush |
| 8 | Southern California Mountains | Mediterranean climate: hot dry summer/moist cool winter. Chaparral/oak woodlands predominate, elev higher, summers cooler, greater precipitation; ponderosa pine larger/ numerous. Severe erosion where veg cover destroyed by fire/overgrazing |
| 6 | Southern/Central California Chaparral/Oak Woodland | Mediterranean climate-hot dry summer/cool moist winter. Chaparral & oak woodlands; grasslands (lower elev); pine (higher elev). Open low mountains/foothills w/ areas of irregular plains (south) & near Central Valley. Livestock grazing; little cultivation |