Several things that should be findable in forests but don’t currently exist.
Dead Wood: From entire downed trees to simple branches. I do some branches occasionally, but walking through the woods of New Hampshire I’d say dead wood is pretty common. You may simple wish to make it an action that you scavenge dead wood from an area instead of actually adding it.
Flowing Water: From little more than a trickle to a small stream, but still well short of a true river. Ponds and marshy low laying areas. Spring flooding is very much a thing. Summer lows are also.
Partially Logged Areas: Areas that are a mess and hard to get through because they are partially logged and there is a lot of dead wood left laying about.
Clearings with Lots of Brush: Areas that for whatever reason have few trees and of brush. Especially thorn bushes.
Free Standing Stone Walls: Old stone walls with no mortar. There are lots of these where I lived in New Hampshire. You go walking into the woods and find them in the middle of nowhere. Most of New England was clear cut during the early days of colonial settlement.
Maple Tree Taps: If the cataclysm happened at the right time of year, you could have maple tree taps with hose running between multiple trees and a bucket.
Some survival style suggestions for someone whose been stuck in the woods in their current game. Being able to find logs that are just dead wood sitting in the woods (especially now that stone axes are much harder to get)
Being able to “harvest”/break branches off of trees that you don’t harvest otherwise.
Being able to use tin cans and other such items to boil water in an emergency situation.
Being able to use/equip a log to float/swim across the water.
And a last suggestion… Dugout/birch bark canoes!