One-third of the world`s nature reserves are under threat from humans
(PHYSorg.com Biology)

In the 146 years since Yellowstone National Park in the northwestern United States became the world`s first protected area, nations around the world have created more than 200,000 terrestrial nature reserves. Together they cover more than 20 million km², or almost 15% of the planet`s land surface - an area bigger than South America.