Okay, stick with me here. Quite a gimmick, but this isn't an entirely serious setting.
Causes:
- Increased CO content in atmosphere increases plant growth speed and capacity
- Improper conservancy methods lead to tree species having to adapt to interference
- Lower oxygen in atmosphere means wildfires burn and spread more slowly
Effects:
- New species of Sequoia that's heavily adapted to growing in burned areas
- Its seeds adapt to spread by fire and withstand damage from heat
- Grows to nearly full size and dies quickly in order to reach critical mass of fuel biomass necessary to cause another uncontrolled burn
- Uncontrolled burn leads to less human interference and allows natural cycle of burning & growing to continue/accelerate
- Region has perpetual wildfires in forested regions, and non-forested regions are fields of ash soon to be populated with new Sequoias
Attached: Wildfire risk map - don't delete it hastily, it took a lot of searching to find an actual climate-oriented map rather than a seasonal projection.