Punch in cheap m-80 sized explosive devices onto trees 10 feet high with a custom pole nail gun.(3 seconds per tree at various intervals). Use a sound detector tower(above tree line) every 10 square miles with solar power charger.
When forest fire erupts, devices go boom, sound detector can track direction and approximate distance. Fire trucks pull up before flames get WAYYY out of hand. Or I just thought of this.. Why not just have a single sky balloon with solar power to use a camera to detect infrared and smoke rising above tree lines every 1000 square miles?
5 grams of ANY explosive will merely knock the bark off a large tree.
Selective critical areas with intermittent placement.