Forests contain the overwhelming majority of life on Earth, including a staggering 80% of the planet’s terrestrial species. From the humid tropical rainforests of the Amazon to the temperate treetops of the Pacific Northwest, forests are incredibly dynamic and diverse environments; they provide warmth, shelter, water and food, and so are havens for a multitude of plants and animals.
But, while it can be easy to look at a forest and simply see ‘trees’, the incredible diversity of this plant group should not go unappreciated. There are over 60,000 different tree species in the world and natural forests can be made up of tens, hundreds or even thousands of different species.
Broadly speaking, there are three types of forest: tropical forests, which are confined to a broad geographical band that straddles the equator; temperate forests with highly variable seasons, which paint the northern hemisphere in rich tones of gold, ochre and red as deciduous species shed their leaves in autumn; and boreal forests, also known as taiga, which grow in northerly latitudes and are dominated by evergreen conifers that can tolerate freezing cold and a blanket of snow for months on end.
Many forests are so-called biodiversity hotspots – they are absolutely packed to the brim with life. Rainforests are the undisputed champions: a single square kilometre of Amazonian rainforest can harbour up to 100 different tree species, including 35-metre-tall giants encased in their own collection of vines, mosses and bromeliads. These towering titans and the fertile forest floor at their roots are a treasure trove of wildlife, from monkey-eating eagles and dazzling macaws to diminutive but deadly poison-dart frogs and a kaleidoscope of butterflies and other insects that fill the air like animated confetti.
Temperate forests, meanwhile, are alive with arguably less exotic but nevertheless iconic species. Oak, elm, beech, cedar and maple trees are just a few species typical of these forests, standing amid common herbs and shade-loving wild flowers. Squirrels, weasels, deer, wolves, wild cats and bears all favour these wooded habitats, while birds of prey wheel overhead during the day, and badgers, bats and owls emerge at night.
The boreal forest is a particularly challenging environment, and so biodiversity here is comparatively low but superbly adapted. The trees and other flora species tend to be particularly hardy (for example pine, fir, spruce, birch and aspen) and the fauna is equally so. Swarms of insects proliferate in the brief window of summer before vanishing abruptly. Migratory birds make themselves scarce after the short breeding season, while species that cannot relocate need to be adequately equipped to survive the extremes of winter. Some – like elk, wolves and the Eurasian lynx – grow a heavy winter coat. Others – such as boreal and great grey owls – rely on a thick quilt of feathers. Bears hibernate and beavers retreat to their lodge. Wood frogs have natural anti-freeze in their blood.