The open space shall be used for wildlife habitat and conservation and one or more of the following additional purposes: historic preservation, education, outdoor education, recreation, park purposes, agriculture, horticulture, forestry, visual amenity, and shall be served by suitable access for such purposes. The Planning Board may permit up to 5% of the open space to be paved or built upon for structures accessory to the dedicated use or uses of such open space (i.e., pedestrian walks and bike paths).