Trees

[jfw3661]

If an area is deforested, will any new trees respawn?

[zebratul]

No, you'll have to plant new trees.

[NeoBasilisk]

the dangers of climate change

[MagicManICT]

It will actually all turn to plain green grasslands over time. Used to be there was a whole terraforming process, but that is either bugged this version or isn't fully implemented. It's worth noting that if it turns to grassland instead of forest terrain, it makes trees take longer to grow. The trees will slowly change it back to a generic forest, though, as they mature.