I forget which author I was reading made this argument, but he/they pointed out that very often, what is described as "low impact" or "no impact" camping is simply "displaced impact". Using a white gas campstove may reduce the impact where you are, but it takes advantage of the ecological damage inflicted elsewhere by the oil and gas industry.

Having said that:

Bear in mind that "dead trees" are not garbage - they are a vital part of the park's ecology. Many animals and plants rely on those dead trees for shelter and food; if campers routinely harvest all the dead wood for making campfires, those species may become locally extinct, with who knows what long-term results for the area.

Some trees are doomed by nature. I understand from Mors Kochanski that black spruce trees grow in clumps. Eventually, one of the trees wins out, and the others die off. Cutting one of them down, therefore, will have no long-term effect on the forest ecology.

So a deep understanding of the forest ecology is necessary to make informed decisions about what is ecologically friendly and what is destructive. Before I learned the above two facts, I would simply have assumed that cutting down live trees = bad, using dead trees = good. But in fact, it may be the other way around.

Not that you would necessarily get a Park Ranger to see it that way, of course :-(