PLANET EARTH Great Plains

The East African savannas alone sustain nearly two million wildebeest. They trim the grass down to it’s roots leaving little in their wake but within days the plant will recover and continue to sustain the biggest herds on Earth. Grass is not confined to the tropics. It manages to grow even in the bitter conditions of the Arctic. Beyond the limits of the last tree the planet is barren and ice locked.



The frozen no man's land at the end of the Earth. But, for a short time each year, the long dark winter releases it’s grip. Temperatures rise, and grass that has lain dormant and frozen throughout the winter sprouts once more. Green returns to the Arctic. The receding ice reveals an immense flat plain, the size of Australia. This is the Arctic tundra. It's a desolate（荒芜的） silent wilderness but it's about to change.



Snow geese. They winter along the Gulf of Mexico and in spring they fly the entire length of North America to reach the Arctic tundra. Five million birds make this journey every year. Their marathon migration is almost three thousand miles long and has taken them three months. Exhausted and starving, they touch down inside the Arctic Circle back at their traditional breeding grounds, at last.