Trees are truly renewable, especially here in the northeast. Cut a tree and it is quickly replaced by many sprouts and seedlings. A forest is similar to a garden, with a long term outlook. In order to nurture your garden you must weed it and occasionally harvest the "ripe" ones. The same is true of a forest. To grow high quality, vigorous trees you should remove some "weeds," as well as harvest some mature trees. These periodic thinnings set the stage for the future forest.
Fact! New Hampshire is the second most heavily forested state in the country. Do you know which is first? In the mid-1800s New Hampshire was mostly cleared for sheep farming. It's amazing to me that we can grow these magnificent forests in only about 100 years. The most heavily forested state is Maine.