I'm currently toying with a post-nuclear apocalypse, with most, if not all, human survivors living in underground bunkers or vaults, and probably away from previous population centers—my test case is somewhere in rural Idaho. The details of the vaults, or of any humans that may have avoided the carnage by (for instance) fleeing into space, are not relevant here but may form another question or several later.
I am assuming/handwaving that the participants do not have enough tonnage to simply blanket their opponents in an attempt to zero population counts. Instead warheads are targeted at major population centers, seats of government, major military installations, et al. Due to its remoteness, I do not expect my characters to be living in the Hollywood ruin of Fallout or such, but I do expect that there was enough fallout from major targets to justify their bunker in the first place.
Naturally this will have major ecological impact, but I don't know what that might be, or how long (or how short) it might take the area to recover. On a timescale of up to, say, 400 years, what impacts will the effects of "standard" fallout have on the flora and fauna of the area? How long will it take the area to return to a state resembling its current one (2015), if it does at all? Will populations be decimated, will the food chain change, will evolutionary selection kick in?
In short, if my characters pop their heads out of their door at various points in the next couple centuries after a major nuclear war, and then go right back inside, what are they going to see?