Residents in a historic community in Gloucester County are pushing back against a housing developer’s plans to build homes on what activists describe as an environmentally sensitive forest. The area developers are eyeing is more than 7 acres of old-growth forest between the Mantua Heights and Cold Springs Forest neighborhoods of Mantua Township. A petition, which has garnered nearly 300 signatures as of Wednesday, was started last month by Ashley Levinson, a 45-year resident of the township, to try to stop the development. “We started this movement to protect our communities and conserve natur…