Region 5 Forest Health Treatment Priority Mapping

BACKGROUND

The recent drought-induced tree mortality event as well as the increase in high severity wildfire in California have highlighted vulnerabilities to forest sustainability. Declining forest health conditions have reinforced the urgency for implementing preventive landscape-level tree density and fuels reduction treatments to restore and maintain forest resiliency to wildfires and drought (bark beetles).

Land managers must be able to prioritize areas of highest risk that are also conducive to project implementation. Projects need to address forest health issues issues across ownerships, be cost-effective, and use collaborative approaches where appropriate to treat larger landscapes. Forest Health Protection has used a variety of GIS data sets to identify areas that are considered the most at risk to high levels of bark beetle-caused tree mortality, have a high likelihood of experiencing stand replacing wildfire and are accessible and appropriate for thinning.

PRODUCT DEVELOPMENT

Priority locations for thinning were identified using existing GIS data including:

Region 5 Existing Vegetation
Stand density index
California Wildlife Habitat Relationships (CWHR) size class
Historic vegetation based on LANDFIRE
Vegetation burn severity
Stand-replacing disturbances from the Global Forest Watch project
FACTS data for areas thinned
Percent slope

Results were categorized to identify priority treatment areas based on vegetation type and stand density at risk of insects, disease and/or fire. The highest priority group consists of major pine types, pine dominated mixed conifer and white fir and fir dominated mixed conifer growing in areas that were historically pine dominated. The second priority group consists of white fir and fir dominated mixed conifer. Analysis only considered CWHR size classes 3, 4, 5, and 6. All mapped areas excluded (1) moderate and high severity wildfire areas since 1998, (2) areas thinned by USFS since 2005, and (3) areas that experienced stand-replacing disturbances since 2005.

Two versions of the priority treatment area layers were created: (1) for National Forest System lands only, with locations within wilderness areas, wild and scenic rivers, and inventoried roadless areas excluded,and (2) for all land ownerships, without wilderness areas, wild and scenic rivers, and inventoried roadless areas being excluded. In each version, separate layers were created for lands on slopes of <= 35% and for lands on slopes of > 35%.

For more information, please see the Forest Health Treatment Priority Mapping Briefing Paper: 2023 Update.

Click here to download the priority treatment geodatabases for all lands.

Click here to visit the priority treatment web map for all lands.