National Snag Hazard Map

Dead and dying trees, or snags, pose a major threat to wildland firefighter safety. Tree strikes are among the most frequent causes of severe injury and sometimes death. Across the western U.S., snag hazard to firefighters and others has grown as more forests suffer from damaging wildfires, insect infestations, and drought. 

Researchers at the Rocky Mountain Research Station and Oregon State University developed the National Snag Hazard Map, which shows where snag hazard is predicted to pose the greatest threat to wildland fire responders. The map illustrates where snag hazard is rated low, medium, high, or extreme on forests across the continental U.S. The more snags present, and the taller those snags are, the greater the risk of severe injury or death.

The underlying dataset that is used to produce the Snag Hazard map, called TreeMap, draws on USDA Forest Service Forest Inventory and Analysis (FIA) forest plot data, LANDFIRE maps of vegetation and recent disturbance, and modeled snag fall rates. Snag Hazard is mapped at a 30 x 30-meter spatial resolution. 

Purpose

To show where snag hazard poses the greatest threat of injury or death to wildland firefighters, field-going employees, recreators, researchers, and other forest users. Use of the Snag Hazard map can reduce risk to human safety.

Applicability and Overview

Incident management teams, Line officers, resource managers, and others can use the National Snag Hazard Map to inform strategic planning, public outreach, and incident decision making. Users can find it on the Risk Management Assistance Dashboard.

Inputs include LANDFIRE vegetation and disturbance layers, recent fire data, FIA forest plot data, and modeled snag fall rates.

Photo Credit

Dunn et al., (2019)