The Lorax

Cut down the wrong tree, and the forest answers back.

How it works

Each surface has a Forest Unrest value. Destroying a tree that's still absorbing pollution, by any means, raises it. Left alone, it decays over time. When Unrest is high enough, destroying a qualifying tree can trigger a response: a unit, a worm turret, a spawner, an invasion?

Trees that were never absorbing pollution (dead ones) are safe to clear without consequence.

DeadWood, a companion mod that marks dead trees for you.