What are the criteria should be available to declare an area as (natural protected area)?

Question

In conservation programs of biodiversity and geodiversity some international or local criteria should be available to declare the place as a protected area. What are these criteria?

Answer 1

the criteria can vary depending on the area and what is trying to be saved you could have a small pond it a urban area a few hundred sq yards to protect lets say a rare frog,or a large tract of land that is home to a wandering herd of caribou.Some of the criteria may also have to do with what is trying to be saved it usually seems the cuter the critter in distress the easier it is to save .Also if the animal is migratory then the  area may only get a reprieve when the animal is out of the territory when it leaves /migrates the work could resume until the critter returns the next year

Answer 2

It varies from place to place and politics is involved as often as not. Presence of an imperilled species of plant or animal is usually a good reason for protection. Interesting geological formations are worth saving too. Sometimes it is the whole ecosystem that is unusual enough to warrant preservation (pine barrens, serpentine barrens).