[Gregstrom]

It doesn't. I believe Haunted Forest turns battlefield dead into Manikins who disappear after the fight.

Carrion Woods turns province population into Carrion units of various sorts outside combat, and said units are yours to command like any other recruits. Some of the carrion units are really rather nice indeed - the carrion elephants and the Sagittarians are prime examples. I don't know if you can get Carrion Ettins this way, or whether that's some sort of hero event only.

Enchanted Forest generates free Vine Men in forest provinces you own.