Wiktionary
n. An area of land managed to conserve wildlife or plant habitat or other natural features.
Usage examples of "natural preserve".
Yellowstone Park, he explained, was the first wilderness to be set aside as a natural preserve anywhere in the world.
A few other visitors, thranx all, lounged among the striking surroundings, boldly taking their ease above ground, away from the immense city whose farthest reaches extended even beneath the wholly natural preserve.
Every single area of the giant natural preserve out there on the plain between the mountains had been documented here in the ministry.
Not only did the Hunt provide a real boost to the treasury of the colony, it attracted enough competent people to help the resident conservationists drive the snakes safely back to their natural preserve with a minimum of loss.
That means the place is shut off from the world, a natural preserve for prehistoric life forms.