Range polygons may include areas not currently occupied by a species and, conversely, may omit areas potentially used by a species. The boundary delineations are primarily based on ecoregion subsections (USDA F.S., Ecomap Subsections 2007), watersheds (USGS HUC12) and 10 Kilometer occurrence buffers. The ecoregions subsections and hucs were combined and will heretofore be referred to as "ecohuc"s.

Criteria used to delineate range boundaries:

1. Select all occupied ecohucs.

2. Buffer species occurrences by 10 Kilometers (per maximum buffer distance suggested by scientific literature).

3. If occurrence buffer extends outside a selected subsection, expand subsection boundary to incorporate buffer or ecohuc after assessing vegetational characteristics with subject matter experts.

4. If non-selected subsection is surrounded by selected subsections, incorporate non-selected subsections into species range.

5. Clip species range by California State boundary.

6. Merge ecoregion subsections to create a seamless species range polygon.

EcomapSubsections 2007 - Metadata

The Ecomap Subsections feature class contains ecological subsection polygons attributed with subsection names and descriptions. The EcomapSubsections 2007 data set describes the ecological subsections within the conterminous United States. It contains regional geographic delineations for analysis of ecological relationships across ecological units. ECOMAP is the term used for a USDA Forest Service initiative to map ecological units and encourage their use in ecosystem-based approaches to forest land conservation and management. This is a collaborative effort with many partners. It is coordinated at the national and regional levels by USDA Forest Service staff and implemented in cooperation with State forestry agencies and others. ECOMAP mapping criteria are outlined in the National Hierarchical Framework of Ecological Units (https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5286434.pdf). The framework systematically divides the country into progressively smaller areas of land and water that have similar physical and biological characteristics and ecological processes.

Note: The "EcomapSubSections_2007" was downloaded from the USDA Forest Service Clearing House website on January 17, 2023.