The state forests of Pennsylvania were formed as a direct result of the depletion of the forests of Pennsylvania that took place during the mid-to-late 19th century. Conservationists like Dr. Joseph Rothrock became concerned that the forests would not regrow if they were not managed properly. Lumber and Iron companies had harvested the old-growth forests for various reasons. They clear cut the forests and left behind nothing but dried tree tops and rotting stumps. The sparks of passing steam locomotives ignited wildfires that prevented the formation of second growth forests.