Эпизод 3

Seasonal forests, such as those that cover the UK and most of North America, are special. Their ecosystems have to cope with drastic change twice a year, in Spring and Autumn. Not only do the inhabitants have to deal with the change, but the entire ecosystem has to transform itself - and it has to do this in perfect synchronicity. In this episode, Chris spends all of his time in the vast seasonal forests of North America. Here, he sees why the whole forest depends on the Autumnal activities of a flying squirrel. And uncovers how the activities of an obscure moth caterpillar in Spring can mean the survival of the Canadian lynx in winter. Perhaps most amazing of all though, is how the great forests of British Columbia depend upon bears to catch salmon and take them into the forest, where their carcasses then fertilise its massive trees. Amazingly, up to 85% of the nutrients that feed these trees come from salmon. That's how much the tree needs the salmon.