Over the past century, the landscapes of Pennsylvania and beyond have experienced deer populations that exceed both their historic numbers and the habitat’s ability to sustain them. Such prolonged overbrowsing has eroded biological diversity in ways that are sometimes apparent and other times surprising. Some of these changes occur so stealthily yet surely over time that the persons who recreate and work in these landscapes may not fully grasp the magnitude of the changes. "The Pennsylvania Forest Seminar: How to Recognize and Manage Eroded Ecological Memories in Over Browsed Landscapes" reviews the history of deer populations within the commonwealth, describes some of the changing ecological dynamics, and offers some management strategies at stand and landscape scales.