So, I've heard that above around 35% O2 concentration in Earth-like atmospheres leads to wildfires that just never go out. I'm thinking of using this like California, with its regularly occuring fires that help clear the land for new growth, but on a global scale. Every couple of years, the O2 conc. is high enough for fires to never go out, so they spread and burn the world down but also use up a lot of that oxygen to the point that they may die again. Plants then regrow raising the O2 back up to the threshold starting the cycle anew.

If I set the oxygen concentration to or just below that threshold, will this be sustainable? If not, how could I get this to work?