managed burns have their place in ecosystems where they're common.
most of these fires in Canada are because it needs to be -40C for about 2 weeks to kill off the pine beetle . if the beetle doesn't die then it, as the name suggests, infests pine trees and kills them.
after a couple seasons you have massive, absolutely immense swaths of dead pine trees, full of flammable pine tar and sap. eventually they burn, and the warm temps + beetles mean they don't come back. ecological change, biome collapse.