I did play the game, way too much actually. The biters don't actually destroy the biomass. Canonically, in the game, they've been there forever : https://wiki.

I did play the game, way too much actually. The biters don't actually destroy the biomass. Canonically, in the game, they've been there forever : https://wiki.factorio.com/Enemies https://wiki.factorio.com/Enemies , so their expansion is only triggered by the arrival of the engineer. They also consume pollution, making them symbiotic with the local biomass.