How much do you know about forests? You probably know them as mysterious green places where you can find lots of animals and plants. You might have even read about people living in or near forests, like in Laura Ingalls Wilder’s Little House in the Big Woods and J.K. Rowling’s Harry Potter and the Sorcerer’s Stone. But forests are much more than beautiful, tree-filled places where people (and sometimes wizards) have adventures – they also help people and animals everywhere have clean air to breathe and clean water to drink.
Forest biomes – natural clusters of different types of trees and plants – have thrived on the planet for approximately 420 million years. In the simplest terms, a forest is any tree grouping whose cover is bigger than 10 percent of 0.5 of a hectare (0.5 of a hectare is about one football field). There are approximately 3 trillion trees in the world’s forests, which make up around 30 percent of the planet’s land surface.
Forests are given different names based upon numerous features, but their distance from the equator is the most important consideration. While there are lots of groups and distinctions within every forest type, forests generally fall into three categories: Tropical, temperate, and boreal forests.
Tropical Forests
Tropical rainforests might make you think of jungles, with swinging vines, monkeys, and Tarzan. But jungles aren’t necessarily tropical rainforests, though they tend to exist on the perimeters of tropical rainforests and have thick plant life that can be extremely difficult to travel through. Basically, a jungle a common – non-scientific – term for any natural environment with thick, tangled vegetation, while rainforests have to meet certain environmental standards.
Tropical rainforests are home to the widest variety of plant and animal species on the planet. With dense tree coverings and broad leaves that prevent most sunlight from reaching the forest floor, most of the animal life – animals like monkeys, apes, lemurs, bats, birds, and insects – have adapted to life in trees. This is because the vegetation doesn’t grow as well on the forest floor in tropical forests, so animals have had to climb high in the trees to reach food. Rainforest temperatures range from 68° to 77°, as they are largely found close to the equator between the Tropics of Cancer and Capricorn (latitudes 23.5° North and 23.5° South). The average rainfall in tropical rainforests is100 inches of rain per year. A large amount of yearly rain makes rainforest soil poor in nutrients, in large part due to the fact that the rains wash most of them away.
There are two seasons in tropical rainforests – rainy seasons and dry seasons, but the length of the rainy and dry seasons can vary considerably. The following are common types of tropical forests:
- Evergreen rainforests. Evergreen rainforests do not have a dry season; rains occur year-round. Evergreen means that the trees stay green; leaves do not turn brown and fall away.
- Seasonal rainforests. Seasonal rainforests have a very short dry season with no changes to the characteristics of the plant life – vegetation remains evergreen.
- Semievergreen rainforests. These rainforests have a longer dry season than typical seasonal rainforests and feature deciduous trees (trees that flower and shed leaves on a seasonal basis).
- Montane rainforests. These are rainforests that exist on mountain slopes that typically have a thick cloud cover and persistent, heavy rainfall.
- Subtropical rainforests. Subtropical rainforests are rainforests that aren’t located within the equatorial regions of the majority of rainforests – they can be found as far north as North America, and as far south as Australia.
Temperate Forests
When you think of forests, you probably think of the thick, cool forests with lots of moss and wildflowers on the ground, tall and straight trees, and plenty of deer and squirrels (and maybe the occasional bear). These are temperate forests.
Temperate forests are the forests found in temperate zones in both the northern and southern hemispheres; deciduous temperate forests are mostly in western and central Europe, the northeastern portion of North America, and northeastern Asia. Coniferous temperate forests are found in South America, New Zealand, Southern Japan, and in the Pacific Northwest of the U.S. and Canada. Temperate forests have the following characteristics:
- Temperate forests temperatures vary widely; between -20° F to 85° F.
- Temperate forests’ precipitation from snow, hail, rain, and fog amounts to approximately 100 cm per year.
- Temperate forests have exceptionally fertile soil and minimal soil leaching.
- Vegetation in temperate forests consists largely of trees, moss, wildflowers, and ferns.
- Temperate forests have moderate canopies with a fair amount of light penetration; deciduous temperate forest trees shed their leaves seasonally, allowing sunlight to access the forest floor.
- Temperate forest wildlife includes bears, hawks, deer, rabbit, timber wolves, squirrels, boars, bobcats, and mountain lions.
- Temperate forests have approximately three species of tree per square kilometer.
Boreal Forests
When you see pictures of boreal forests, you might think that they look very similar to temperate forests. But boreal forests are much colder and have fewer animals and types of plant life.
Boreal forests are the largest found throughout the northern hemisphere, but 65 percent of all boreal forests are in Scandinavia. Other regions include Alaska, Canada, Northern Asia, and Siberia.
Also known as taiga forests, boreal forests are characterized by their long winters (up to eight months between October and May) and cold temperatures, which inhibit decomposition and result in thin and acidic soil layers. Most of the annual precipitation comes from snowfall, and temperatures during the long winter season range from -30° F and -65° F.
Boreal forests have the following characteristics:
- Boreal forests are largely evergreen coniferous forests – needles do not shed – though some of the southern boreal forests have a few deciduous trees.
- Light penetration is low, resulting in minimal undergrowth.
- Animal life in boreal forests consists of moose, woodpeckers, hawks, bears, wolves, deer, chipmunks, foxes, and bats.
- Vegetation is limited to mainly coniferous trees – spruce, pine, and fir – and shade-tolerant herbs and moss.
Boreal forests are in danger. Lots of boreal forests are disappearing due to logging and other deforestation practices (deforestation is the permanent removal of forest trees). Other reasons forests are vanishing include industrial impact, and environmental degradation – forest fires, climate change, and invasive plant and insect species.
Forest Founders is dedicated to supporting reforestation initiatives that not only plant trees with the hopes of creating thriving forest cover within a few decades but also protecting existing forests that are currently under threat. To learn more about Forest Founders’ mission, please visit Forest Founders information page.