Most large resources nodes (full size trees, copper ore nodes, silver ore nodes, scrap piles) are not supposed to respawn. This is according to several sources however players have been reporting that some of them occasionally do. It could be a bug, or it could be the will of Odin. Who knows?

Most single items like rocks, branches, flint, mushrooms, berries, and thistle will usually respawn but some players report bugs with berry bushes that are not regrowing the berries.