At the edge of the Arctic, the Taiga forest is a silent world of stunted conifers cloaked in snow and ice. The trees may be small but filming from helicopter and satellite reveal its true scale. Its a belt that circles the globe, broken only by ocean, and containing a third of all trees on Earth. During the short summer, it produces so much oxygen that it changes the atmosphere. The broadleaf forests of North America and Europe bustle with animal life. In the forest of Eastern Russia, the rare Amur leopard battles for survival in the freezing temperatures. There are fewer than 40 of these cats remaining in the wild. The baobab forests of Madagascar are the strangest trees of all. These bizarre upside-down trees store water in their swollen trunks and harbour equally curious wildlife, such as the tiny mouse lemur.