Based on the way aspen actually grow, it's more likely that the area was originally an aspen grove and was planted with spruce because spruce is a better lumber

Based on the way aspen actually grow, it's more likely that the area was originally an aspen grove and was planted with spruce because spruce is a better lumber product. I know in BC they actually spray (with Roundup) all the sites where there are forest fires so that the aspen can't come back, and then they replant with pine or spruce. Aspen is a natural fire break species. So it'll actually prevent more big forest fires in the future.