PLANET EARTH Seasonal Forests
Trees. Surely among the most magnificent of all living things. Some are the largest organisms on Earth dwarfing all others, and these are the tallest of them all. The deciduous（每年落叶的） and coniferous（针叶林的） woodlands that grow in the seasonal parts of our planet are the most extensive seasonal forests on Earth. Their sheer extent stuns the imagination.
The barren snows of the Arctic. A thousand miles from the North Pole, and heading south. This is the very first place that trees can grow. To begin with the conifers are sparse（稀疏的） but soon they dominate the land. This is the Taiga Forest. There are as many trees here, as in all the world's rainforests combined. The Taiga circles the globe and contains a third of all the trees on Earth. It produces so much oxygen, that it refreshes the atmosphere of the entire planet.
At the Taiga's northern extent the growing season can last for just one month a year. It can take fifty years for a tree to get bigger than a seedling. It's a silent world where little stirs, but there are occasional signs of life. Stories written in the snow. The prints of an Arctic fox and the hare it might've been stalking. A female polar bear and her two cubs. Some animals are so difficult to glimpse that they're like spirits.
