Originally posted by Tet:

Isn't there a balancing issue when going from forest to swamp ?
I feel that the difficulty increases really too high.

Whereas in the forest I can deal with 2 trolls and as many Greydwarfs that spawn, I can't deal with swamp creatures at all, with bronze equipment.

As soon as I go to the swamps, I die...

The short answer is "Yes."
The long answer is there is a massive difficulty spike whenever you go to a new biome. It can be mitigated somewhat by maxing out gear and stocking up on various meads, but it's still not the smoothest transition... Savanna is worse.