From the latest USFS R&D newsletter — subscribe here.
“Most dead trees fall within 10 years after a wildfire. To keep firefighters and those involved in restoration efforts safe, Forest Service researchers and partners developed a new tool that maps where dead trees are likely to fall.”
A related study, “Spatial and temporal assessment of responder exposure to snag hazards in post-fire environments,” notes that:
“Snag hazard increased significantly immediately post-fire, with severe or extreme hazard conditions accounting for 47%, 83%, and 91% of areas burned at low, moderate and high-severity fire, respectively. Patch-size of severe or extreme hazard positively correlated with fire size, exceeding > 20,000 ha (60% of our largest fire) 10-years post-fire when reburn becomes more likely. After 10 years, snag hazard declined rapidly as snags fell or fragmented, but severe or extreme hazard persisted for 20, 30 and 35 years in portions of the low, moderate and high-severity fire areas.”
FWIW, I recently talked with loggers on a fire salvage timber sale, less that one year post-fire, on private land. They said it’s common to see or hear trees fall spontaneously, even with light winds.