Before the land parcels were purchased to make the reservation, it was used for a variety of industrial needs by the surrounding communities. Not only was the waters of the Rahway River harnessed for local mills but trees were cut down to provide the wood and paper requirements of the area's ever growing population. Furthermore, the timber resources were used to provide tannins for Newark's leather factories. Logging practices lead to weakened tree stands and the forest was revitalized through the landscape forestry design and long-term planning of the Olmsted Brothers firm.
Thanks to the Olmsteds' vision, today South Mountain Reservation is home to a variety of native trees, including rhododendron, hemlock, and groves of oak, beech and white pine.