The Summer 2020 issue of FSEEE Forest News argues that the Forest Service improperly uses tree hazard assessments to justify closing public lands.
Based on the article, it appears that FS spokespeople have not always done a good job communicating the reason for post-fire closure areas. There are many reasons to close areas post-fire, but tree risk assessments by themselves would probably not justify backcountry trail closures.
The FS Field Guide for Hazard Tree Identification and Mitigation cited in the article applies a numerical probability assessment to hazards by scoring Failure Indicators and adding these with Damage Potential to obtain a numerical Hazard Rating. This methodology would be familiar to any arborist and follows standard arboriculture practices. If there are dead or damaged trees around developed FS facilities or campgrounds than clearly there would be a high Hazard Rating and it would make sense to close those areas until the hazard can be mitigated. But applying this same methodology to backcountry trails would result in scores that are relatively low because of the sparse or nonexistent targets for the hazard trees. So on this point the Forest News article is correct: hazard trees alone do not justify backcountry forest closures.
However, there are other hazards in recently burned areas besides dead trees, including active restoration/revegetation projects, burned-out root systems, unstable soils, potential debris flows, and obscured or impassable trails. It may make sense to close these areas to the public until trails can be repaired or ongoing restoration work is completed.
