Frequent wildfires can prevent black spruce forests from recovering between disturbances. Ecology has long treated Picea mariana as a tree species built to survive fire, but repeated burns can outpace its natural regrowth. When fires sweep through a stand before young trees grow tall enough to make seeds, the entire tree population fails to replace itself.
Fire burns living tree crowns and reduces standing trunks to ash. Surviving saplings must climb upward against gravity like runners on a track to rebuild their reproductive canopy. Slope direction and elevation alter how much sunlight and moisture reach the soil, changing how quickly each stem adds wood. On north-facing slopes, cold ground and low light slow tree growth, leaving young stands vulnerable to recurring fire.
Researchers combined airborne laser scans with light-spectrum species maps to track individual tree survival at the Caribou-Poker Creek Research Watershed from 2017 to 2023. The population models showed that black spruce need eleven to twenty-two years to reach reproductive height after accounting for terrain and competition. In the absence of fire, estimated tree life expectancy dropped to 581 years on north-facing slopes with recent burns.
These remote-sensing models allow scientists to quantify forest recovery and forecast tree population changes across large regions without field surveys. The maps identify vulnerable forest stands to target conservation where fire frequency threatens survival.