Coniferous Forests
The coniferous forest is the world’s biggest biome. It covers nearly one-fifth of the Earth’s
land surface and stretches across northern Canada and northern Eurasia in an almost
unbroken belt for 7,000 miles. The main features of the coniferous forest are its evergreen
forests of needle-leafed trees, including pine, spruce, hemlock and fir. Although this
biome is not as harsh as the tundra, all its plants and animals have evolved to survive the
coniferous forest’s long, snowy winters.
Coniferous forest trees have many adaptations for surviving harsh winters, a short growing
season, and nutrient-poor soil. Their conical shapes allow snow to slip off easily, without
weighing down and breaking branches. Their needle-shaped leaves have waxy, protective
coatings to lock in moisture. Plus, the needles don’t all fall off in autumn. Keeping the
leaves through the winter means coniferous forest trees don’t need to use energy to
grow an entire set of new leaves each spring and they can capture energy from the sun
throughout the year.
The vast forests of the coniferous forests are being shrunk by massive logging operations.
The wood is used to make paper and build houses. When trees are clearcut, the forest
habitat is destroyed. Reducing the size of the world’s forests also contributes to global
warming. Forests are called “carbon sinks” because they absorb carbon dioxide and help
keep the world’s carbon cycle in balance. When too much carbon gas is released into the
atmosphere, the climate tends to warm—and that can have serious consequences for
humans and ecosystems.
Deciduous Forests
This biome is defined by its four distinct seasons and its forests of trees that drop their
leaves in autumn. (The word “deciduous” [dih-SID-yoo-uhss] comes from a Latin word
meaning “to fall.”) Located in the eastern United States, all over Europe, Japan, and parts of
Russia and China, temperate deciduous forests are home to deer, wolves, hawks and owls,
songbirds, and many other species.
Temperate deciduous forests change dramatically with the seasons. During spring, each
tree produces thousands of new leaves filled with green chlorophyll. The chlorophyll traps
sunlight and converts it into fuel for the tree’s growth. Unlike the trees of the coniferous
forests which are evergreens, these trees prepare for winter by breaking down the
chlorophyll in their leaves, storing some of the nutrients, and then dropping their leaves. A
by-product of the breakdown of the chlorophyll is the exposure of yellow, orange, and red
pigments that are normally masked. That means that in autumn, the trees in these forests
are alight with fiery colors.
Deciduous forests have at least three layers. The tallest trees make up the canopy. Saplings
and shrubs are found in the understory. Ferns, moss, and wildflowers grow on the forest
floor.
Savanna
Tropical savannas are vast grasslands dotted with trees that spread across Africa, northern
Australia, and parts of South America and India. With wide open spaces and so much grass
to graze on, savannas are home to large herds of plant-eating animals (herbivores). They are
also usually home to large predators that stalk the herds. In the African savanna, the planteaters include zebras, antelopes, wildebeest, giraffes, elephants, and rhinos. Predators
include lions, leopards, cheetahs, and hyenas. In the Australian savanna, kangaroos are the
primary plant-eaters.
Many of Africa’s savanna herbivores have long, powerful legs to help them travel long
distances and run away from predators. Some, like the ostrich and giraffe, have VERY long
legs—and they can even use them to kick predators. In the Australian savanna, kangaroos
have a slightly different strategy for getting around: They don’t run, but hop—as far as 30
feet in a single leap and can speed-hop at 35 mph.
The weather in the savanna is warm year-round, and there are basically two seasons—wet
and dry. To survive the dry season, many savanna animals must migrate in search of water.
Trees growing alone or in small clusters are also part of the savanna biome. In fact, without
the trees, the savanna biome would be considered a grassland. The variety of trees in a
particular savanna is dependent upon the geographic location of the savanna. The acacia
and baobab trees are common in African savannas.
The baobab tree has adapted to the savanna biome by only producing leaves during the
wet season. When leaves do grow, they are in tiny finger-like clusters. The small size of the
leaves helps limit water loss. Another adaptation that enables the baobab tree to survive
the long months of drought is its ability to store water in its large trunk.
Mediterranean
This is one of the world’s smallest biomes, occurring on the west coast of the United States,
along the coast of the Mediterranean Sea, and in coastal patches of South Africa, Australia,
and Chile. Winters are mild in this biome, and what little rain there is, falls in that season.
Summers are dry and hot. But it’s not a desert.
The plants of the Mediterranean biome are evergreen and shrubby, and they grow very
densely. Many have thick, leathery leaves that seal in moisture or leaves with small surface
areas to limit water loss. The plants also have adapted to survive occasional wildfires.
The Mediterranean biome is highly aromatic—with many plants emitting strong, spicy
smells. Many herbs used for cooking—including rosemary, thyme, sage, and oregano—all
grow wild in the coastal shrubbery surrounding the Mediterranean Sea.
Trees in Mediterranean climate must be able to survive long dry summers. Evergreens such
as Pine and Cypress trees are mixed with deciduous tress such as some Oaks. Fruit trees
and vines such as grapes, figs, olives, and citrus fruits grow well here.
Tropical Rainforest
Located in a belt around the equator, rain forests are a riot of life, with plants growing nonstop year-round. The hot, wet climate supports a jungle of plants and wildlife, from the
towering trees that make up the canopy down to the dark forest floor where sunlight barely
penetrates due to the thickness of the foliage above. Rain forests get drenched by as much
as 180 inches of rain annually.
The rain forest has more species than any other biome. Trees in the rain forest grow as high
as 200 feet, and each tree may be home to hundreds of species, from vines and bromeliads,
to butterflies, monkeys, birds, and frogs.
Rain forests once covered about 14 percent of the Earth’s land surface, but now account for
only about 6 percent. Rain forest habitats continue to be cut down for their wood products
and to create land for farming. Every year about 9,000 square miles of rain forest is cut
down – an area larger than Wales!
Most rainforest soil is very poor with all the nutrients available largely remaining at surface
level. Because of this rainforest trees have very shallow roots.
Some very tall trees have developed ways of obtaining much needed additional support
by forming buttressed roots, which grow out from the base of the trunk sometimes as high
as 4.5 meters above the ground. These extended roots also increase the area over which
nutrients can be absorbed from the soil.
Urban
Urban areas are dominated by human activities and human constructions. These include
towns, cities and associated landscapes, such as landfill sites. It can almost be described
as a patchwork of other habitats where buildings are artificial cliffs, sewers and drains are
waterways, and parks, gardens and brownfield sites provide forests and meadows.
Urban areas have a variety of animals that have adapted to live in a manmade habitat and
trees are no different.
The majority of trees that can be found in urban areas have been planted by humans, some
naturally growing trees can be found in gardens and in large parks. Trees in urban areas
are planted for the benefits of; improving the appearance of an areas, providing shade and
shelter, to encourage wildlife.
Many towns and cities are referred to as urban forests because of the trees that have been
planted. However urban trees can also cause major problems. If they are poorly planted, or
the wrong type of tree is planted this can lead to trees not being able to form deep enough
or healthy enough roots. This not only leads to unhealthy trees but can also damage
pavements and roads and lead to the possibility of trees falling on buildings or even people.
Did you know that on average 3 people a year are killed in towns and cities in the UK by
falling trees!