A diameter-based thinning-from-below reduces the stocking (to 60 percent) by removing all trees smaller that a calculated diameter. Because the decision about which individuals to remove are driven by diameter alone, there is no opportunity to deliberately allocate growing space to meet objectives. For instance, if all the trees on a site are approximately the same age, a common condition in Pennsylvania, the smaller ones are growing slowly and competing poorly with their larger neighbors. Removing them typically provides little additional growing space to the larger ones. Also, by removing all the trees of similar size, we may actually eliminate one or more tree species that happen to grow and develop naturally at a slower rate. Although the resulting forest can look almost park-like, which is pleasing to many, the treatment can have negative effects. Small trees and shrubs provide food, homes, and hiding places for wildlife, and their removal may significantly reduce wildlife use of the area. Also, a diameter-based cut from below will likely not be an economically viable option, in terms of both immediate cash flow and ultimate financial return.

Key Points

• Trees smaller then X diameter cut
• Creates an open, park-like appearance
• Remaining trees will not benefit much