Young woods don’t stay young. Old fields and shrublands gradually give way to older forest. You can maintain these important habitats with periodic mowing and brush hogging.
This fact sheet from University of Maryland Extension has a good section on maintaining old field areas and brush lots. Maintenance information starts on page 4.
This longer video describes how to use a bush hog, a tractor attachment for cutting larger brush up to 2 inches in diameter. Jump to 12:43 to see the attachment in action.
In the St Lawrence Valley of northern New York, landowners like Audubon New York and the New York Department of Environmental Conservation are using mowing and brush hogging to maintain old fields, shrublands, and forest edges for rare birds like the golden-winged warbler.