There is a non-fiction book called something like TREE CROPS: Towards
a Sustainable Agriculture, ... sorry forget the authors name. Anyway
the author sings the praises (with photos, tables, figures, footnotes,
and lots of data) on trees as opposed to other agriculture. He
especially mentions how grain crops are in his opinion over-rated and
overdone ... given even a little drought or flooding they will go
under, while trees with deep roots go on and on ... and can be
productive going up steep hills, down ravines etc.

The amount of fruit, nuts, etc. that can be pulled out of trees given
reasonable care was surprising. When you add things like having pigs
forage on acorns you can theoretically get a surprisingly large
population supported out of what looks like non-stop forest.

Anyway, recommending a 50 year old book on agriculture as an Obvious
Gaming Accessory.