This layer contains these three ecoregion sections:
- Great Valley (262A)
- Sierra Nevada Foothills (M261F)
- Northern California Interior Ranges (M261C)
These ecoregion sections were clipped within these counties:
- Solano
- Sacramento
- Yolo
- Colusa
- Napa
- Glenn
- Lake
- Sutter
- Tehama
- Shasta
- Placer
- Butte
- Yuba
This layer contains polygon features of Ecological Units for the state of California as described by ECOMAP (1993),.. "Ecological types are classified and ecological units are mapped based on associations of those biotic and environmental factors that directly affect or indirectly express energy, moisture, and nutrient gradients which regulate the structure and function of ecosystems. These factors include climate, physiography, water, soils, air, hydrology, and potential natural communities."