nature reserve

Area set aside to protect a habitat and the wildlife that lives within it, with only restricted admission for the public. A nature reserve often provides a sanctuary for rare species and rare habitats, such as marshland. The world's largest is Etosha Reserve, Namibia; area 99,520 sq km/38,415 sq mi.

Many state and local preserves have been established in the USA since 1970. Some are called greenbelts and some are designated ‘forever wild,’ as well as those that are administered for limited or educational access.