[tshiggins]

I like what you've done, in this thread, rather a lot. Here's an interesting scenario, for you:

Assumptions
-TL 8 technology available at the time of the collapse
-Area is a temperate rainforest (two varieties -- most in the world are coastal, but it could also be one of the pockets in the Appalachians, or the Changai Mountains)
-Humanity is hunted by an enemy that has early TL9 assets.
--A rogue AI, perhaps.
--Possibly aliens who either arrived in an ark vessel, or got FTL early, or shifted over from another dimension.
-Alternatively, humanity is hunted by reasonably intelligent, winged, monsters or mutants.
-The enemies use two methods to target or hunt.
--Clusters of heat signatures significantly higher than ambient temperatures
--Interruptions (especially straight lines) in the physical geography

Thoughts
I'd think the situation would require a focus on foods that grow natively, planted in what I almost think of as "elvish agriculture." Rather than carve out areas in the forest to dedicate to foodstuffs, the existing biome is shaped to maximize useful plants while minimizing anything recognizable as "agriculture." Interruptions of the forest canopy are especially to be avoided.

At the same time, human beings need to work together for defense against actively hostile enemies, but must avoid clustering in large settlements.

So, what sorts of crops would work best (I'm betting grains aren't available, except for wild rice, possibly), what sorts of livestock could be supported (pigs would probably work best, and perhaps small cattle, but horses are right out), and what would be the population density?