An idea partially from this old post:
Right now there is no way to stop fire from spreading on the savanna islands, which can prove to be a problem when the fire spawns near the ports and spreads to the point that you cant leave the island to escape it.
My idea is being able to destroy the ground or stir up the dirt and remove the grass to stop fire from spreading further.
Nichelings with digger paw can turn up the ground and it would look like it does when you dig up roots, just lighter in color since the dirt in the savanna is dryer and lighter in color. Digging 2-3 dirt spots will stop fire from spreading over from the lack of grass to burn.
After a couple of days (5-7 perhaps?) or after a rain the dirt tiles would turn back into grass tiles, and would be flammable again.
It would be nice to have a way to escape fire on the savanna islands other than leaving to another island. Animals in our world either fly to escape fire or reside in lakes and rivers, but for smaller animals like amphibians and lizards they hide under rocks, burrow underground or hide inside of logs. Maybe one of these if digging barriers doesn't work?