If you’ve bought a parcel of land with forest, there are plenty of things you can do to maintain it. You can sell trees or use them for firewood.
If you have dead trees on your property, you can tell that they’re dead now by observing that they have no leaves. Before Autumn rolls around, right about now, you can go through your forest and paint the dead ones, so that when all the leaves are gone you have a reminder of which ones are dead. This gives you time over the winter to fell, chop and season the wood. (Only paint them green if you’ve run out of white spray paint and need to get the job done today.)