Are hiking biking and horse trails that pass through private land useable for public access to cross the private looking at Colorado and noticed a lot of trails doing this
If they are it is likely posted as such. There are a few local trails here in Santa Fe that allow access to trails through private lands, but is clearly marked that way.
Best way to find out (other than boots on the ground) is to call the local FS office and ask them about the specific trails you were wondering about, they should be able to help you figure it out.