In 1865 New Hampshire was 20% forested. We were a farming state. The White Mountain National forest had all been logged.
A hundred and twenty years later NH is 80% covered in forest.
All the smart farmers moved to Ohio, Indiana and Iowa. Too many rocks here. The forests of New England are Chris crossed with old stone walls that the farmers of the 1700s to 1800s piled up using horses and oxen. All three properties I have owned in southern NH had stone walls on at least one to three sides. Some rocks literally the size of a Vw bug.
I hike in former iron mining areas along the NY/NJ border; these places were stripped bare of trees to make charcoal for the forges. The few thick, old trees usually mark where a home had been (the tree was spared by the owner); everything else was cut. Much of that land is now state parks, and covered with trees; the only indications of what had happened 150 years ago are the lack of trees older than 150 years old and the many “coppiced?” trees (trees in which several seem to be sharing one trunk at the ground level - an indication that it had been cut and sprouted in a different direction afterwards).
NH's treeless acreage was called a "Rock Farm". I suspect the land was shovel-ready for success, but farming and erosion brought rocks to the surface.
The expression was “New Hampshire is 84% trees and the rest is under water.” That's changed, with the building of hundreds of storage warehouses that require treeless landscapes.