Tough economics to imagine attempting to effectively gather mulch from in between the trees when we're talking areas so remote they often aren't even harvested for actual lumber and are a huge distance from the nearest power plant (or grid connection of any significant capacity).

-------

However, this isn't addressing the other problem: Fire is an actual part of the ecosystem in those areas. Various plant/tree species are adapted around it. Some require fire for their seeds to germinate, others need the cleared ground that results (and their seeds can survive the fire), others rely on it to keep other species out with adaptations that make them much less likely to burn in a moderate intensity/natural fire (and so they survive while an invading species doesn't).

Fire also opens up areas and causes natural forest succession - which creates an environment for more than just the biggest trees to exist for a few decades. Etc, etc, etc.

You simply can't have the natural environment out there exist as it is evolved to function without fire in the long-term.