The Arctic Plains of the world are made up of two distinct ecosystems: tundras and llanos. Tundras are treeless, marshy areas located in the far northern regions of the world, characterized by permafrost and low temperatures. Llanos are tropical grasslands found in South America, characterized by flat terrain and seasonal flooding. Both of these ecosystems are important habitats for a variety of wildlife, including caribou, polar bears, and many species of birds.