AP Photo/Leslie Mazoch
In honor of World Environment Day, held each year on June 5, we are taking another look at the most irreplaceable sites on earth, identified in a study published in Science last year.
In that report, scientists listed more than 100 irreplaceable environments or regions where many animal and plant species cannot be found anywhere else on our planet.
A total of 137 sites were selected from 173,000 protected areas, regions that cover 13% of the earth's landmass. These are some of the most biologically rich ecosystems in the world but face continued threats and are often poorly managed.
The top sites were the result of two combined rankings: irreplaceability for threatened species and irreplaceability for all - threatened and nonthreatened - species.
Each protected area was analyzed individually. But sometimes the regions overlap, effectively protecting the same species. For this reason, researchers combined adjacent or overlapping protected areas into 78 clusters around the world.
Here are some of the most irreplaceable areas from 10 different clusters. Bringing attention to these places is critical to preventing extinctions of the world's mammals, birds, and amphibians.