In one section of a trail I was on yesterday a large number of trees had markings like the following:
These are certainly not trail markings - the trail markers were entirely different (round plastic badges with writing).
The paint marks were varied (as shown) and were on trees somewhat deep into the woods from the trail.
Possibly unrelated, but I had read the area we were in is due to get some maintenance in the form of trail bridges / boardwalks being constructed. But I don't know if these tree markings specifically corresponded to that work.
This was located somewhat far off any road, within a NY State Forest.