What Are Rainforests?

Pay Dirt

There are two types of rainforests -temperate andtropical. Tropical and temperate rainforests have some things in common. Both have very dense vegetation. Trees in temperate and tropical rainforests have trunks that flare out at the bottom and both types of rainforests are endangered biomes.

Round and Round

Tropical rainforests are warm and wet. The soil in the rainforest is nutrient-rich. The warm, wet conditions cause vegetation and animals to rot very quickly once they've died. Decaying plants and animals get recycled back into the soil.

Lots of Life

Rainforests also recycle their water! During the day, water in the rainforest evaporates and rises where it condenses and forms clouds above the trees. When enough water vapor collects in the clouds, it rains!

Temperate Rainforests

More than half of the world's species live in tropical rainforests. Some scientists think the number could be as high as 90 percent! The moisture and the warm temperatures in the tropical rainforest are perfect for sustaining lots of different species of plants and animals.

What's the Point?

Temperate rainforests are found near coastlines. The largest temperate rainforest stretches for over 1,000 miles along the coast of the Pacific Northwest from Oregon to Alaska. Smaller temperate rainforests can be found in Chile, Australia, New Zealand, Norway, Japan and Great Britain. Because temperate rainforests are near oceans, they are wet and cool and can receive up to 100 inches of rain a year. The moist, cool air of the temperate rainforest helps support many different types of plants and animals.

Tropical Rainforests

Trees in the tropical rainforest can grow very tall. Leaves are usually thick and have pointed "drip tips" to help rain roll off them. Tree trunks are wide and flared and tree bark is thin and smooth. Some trees have roots that are above the ground.

Ecosystem in a Plant

Tropical rainforests are found near the equator. It rains every day and tropical rainforests can get as much as 400 inches of rain each year. The seasons don't change and the average temperature is about 80 degrees Fahrenheit. About half of the world's tropical rainforests are in Latin America. Other tropical rainforests can be found in Asia, Africa and the Pacific islands.

The tropical rainforest is also home tobromeliads. These are plants that collect water in their centers. The water forms pools that can support miniature ecosystems! Many of these pools support bacteria, insects, crustaceans, tadpoles, frogs and even birds!

Growing in the Air

The rainforest is also home toepiphytes. Epiphytes like orchids and some bromeliads don't grow in the soil. They hang from trees and get their nutrients from the moisture and dust in the air. The tropical rainforest is also home to nepenthesor pitcher plants. These are plants that grow in the soil. They have leaves that form a cup where moisture gathers. Pitcher plants capture insects in these cups!

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What Are Grasslands?

The Prairie

Grasslands cover one fourth of the Earth's land and can be found on every continent, except for Antarctica. Grasslands occur where it is too wet for deserts but too dry for forests. Grasslands get about 10 to 24 inches of precipitation per year, although some tropical grasslands can get over 40 inches of rain a year.

Tropical Grasslands

The soil in prairies is excellent for growing crops and much of the grassland in North America has been turned into farms and ranches. The combination of high summer temperatures, strong winds and little rain makes prairies vulnerable to fire. Fire keeps trees from growing on the prairie, but grasses and other prairie plants can survive fire and even thrive! There are three types of prairies: tall grass, mixed grass and short grass.

Tall Grass Prairies

Tropical grasslands are close to the equator and are hot all year long. The African grasslands are called savannasor veldts and are home to animals like zebras, lions and ostriches.

Temperate Grasslands

Tall grass prairies get the most rain, about 30 inches a year. They have tall grasses, sunflowers and other plants. Grasses in this type of prairie can grow as high as five feet. Tall grass prairies are found in the eastern part of the Midwest.

Mixed Grass Prairies

Mixed grass prairies are found in the middle of the Midwest. They get less rain than tall grass prairies, between 15 and 20 inches a year, and the vegetation grows to about three feet tall.

Short Grass Prairies

Temperate grasslands are hot in the summer and cold in the winter. In Europe and Asia, temperate grasslands are called steppes. In South America grasslands are called pampas. In North America temperate grasslands are calledprairies.

Short grass prairies get the least amount of rain, less than 10 inches a year. They are found in the western part of the Midwest. Grass in short grass prairies is usually under two feet tall.

Living in the Prairie

Some animals that live in the prairie like the American bison are grazers. Others like theblack-tailed prairie dog and theAmerican badgerare burrowers and spend a lot of time underground. Other animals like the coyote prey on smaller prairie animals. The prairie has lots of insects like crickets, caterpillars and grasshoppers and is home to insect-eating birds like the western meadowlark and the killdeer.

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The Temperate Deciduous Forest

Plant Life

Temperate deciduous forests can be found in the eastern part of the United States and Canada, most of Europe and parts of China and Japan.

Temperate deciduous forests have a great variety of plant species. Most have three levels of plants. Lichen, moss, ferns, wildflowers and other small plants can be found on the forest floor. Shrubs fill in the middle level and hardwood trees like maple, oak, birch, magnolia, sweet gum and beech make up the third level. Conifers like spruce, fir and pine trees can also be found mixed in with the hardwood trees in this biome. Sometimes the taiga and the temperate deciduous forest overlap.

Animal Life

The temperate deciduous forest is a biome that is always changing. It has four distinct seasons: winter, spring, summer and fall. Winters are cold and summers are warm. Temperate deciduous forests get between 30 and 60 inches of precipitation a year. Precipitation in this biome happens year round. Because the soil is very fertile and hardwood trees are good for building, this biome has some of the world's largest population centers in it.

Changes

There is great diversity of life in this biome. Insects, spiders, slugs, frogs, turtles and salamanders are common. Birds like broad-winged hawks, cardinals, snowy owls, andpileated woodpeckers are also found in this biome. Mammals include white-tailed deer, raccoons,opossums, porcupines and red foxes.

Animals that live in the temperate deciduous forest must be able to adapt to the changing seasons. Some animals in this biome migrate or hibernate in the winter.

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The leaves of deciduous trees change color and fall off in the autumn and grow back in the spring. The broad, flat leaves of deciduous trees lose water quickly. In the winter when the ground is frozen, it is difficult for them to to absorb water, so they drop their leaves! Deciduous trees stay dormant in the winter and bloom again in the spring!

What Is the Taiga?

Living in the Taiga

The taiga (ty-ga) is the largest land biome. It stretches across a large part of Canada, Asia and Europe and can be found between the tundra and deciduous forests.

There are many animals that make the taiga their home. Many birds breed in the taiga in the spring and summer. As the snow melts in the spring, insects lay their eggs in the water. The insects attract a wide variety of species of birds to the taiga like the spruce grouse and mammals like pine marten, moose, wolf, fisher, Canada lynx, and grizzly bear can be found in the taiga. These mammals all have thick coats that protect them from the cold.

Adapted for the Taiga

Winters in the taiga are cold and the summers are warm. The taiga gets between 15 and 30 inches of precipitation a year. In the summer, temperatures can reach the 70s. In the winter, temperatures can be as cold as 65 degrees below zero! The taiga is sometimes called the coniferous or borealforest.

Ready for Snow!

Some animals have structural adaptations that help them survive in the taiga. The Canada lynx's wide paws work like snowshoes. They distribute the lynx's weight, and help it move in the snow. Grizzly bears avoid the coldest weather by going into their dens in the fall and staying there until the early spring. They have a protective layer of fat that allows them to stay in their dens while the weather is cold. They don't hibernate but just sleep lightly and stay out of the cold!

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Coniferous trees like spruce, hemlock, pine and fir are commonly found in the taiga. Most coniferous trees areevergreen and are specially adapted to survive in this biome. Evergreen trees are cone-shaped to help snow slide off them so the branches won't break. The leaves or needles of evergreen trees lose less water than other kinds of leaves. This also helps them survive. Some broad-leaved trees like birch and aspen have adapted to the taiga, too. Both trees are very flexible and don't break easily when covered with ice and snow!

What Is the Tundra?

Plants in the Tundra

The tundra is one of the harshest biomes and it is definitely the coldest! Temperatures in the tundra can reach as low as minus 25 degrees Fahrenheit! Beneath the tundra is permafrost. Permafrost is a permanently frozen sublayer of soil. There is very little rain or snow in the tundra, usually less than 15 inches a year.

There are thousands of species of plants in the Arctic tundra. The plants tend to be small and close to the ground. This protects them from strong winds and cold temperatures. Some plants that grow in the tundra include lichen, short shrubs, sedges, grasses, flowers, birch trees and willow trees. Cushion plants, which, also grow in the tundra, are types of plants that grow low to the ground in tight places. They are called cushion plants because they are soft and cushiony.

Living in the Tundra

There are two types of tundra, the arctic and thealpine tundra. The arctic tundra is the land around the North Pole. The alpine tundra can be found above the tree line of tall, cold mountains. Tundra covers one fifth of the Earth's surface. Tundra comes from the Finnish word tunturia and means barren or treeless land.

Defrosting the Tundra

Animals that live on the tundra must be able to adapt to very cold temperatures. They must also be able to raise their young during the very short summer months.

The growing season in the tundra is very short, usually only 6 to 10 weeks. In the summer, the top layer of soil may thaw out. When the ice melts, it can't drain into the soil because of the permafrost, so water collects inbogs and ponds. This makes up for the low rain and snowfall! As the top layer of soil thaws out, plants and microorganisms have a chance to grow. The sun is then out for most of the the day and night, so the plants have extra sunlight and can grow faster.

Animals found in the tundra include the musk ox, theArctic hare, thepolar bear, theArctic fox, thecaribou and the snowy owl. Many animals that live in the tundra, like the caribou and the semipalmated plover, migrate to warmer climates during the winter. Others, like the arctic ground squirrel, hibernate during the winter months. There are very few reptiles and amphibians found in the tundra because the temperatures are so cold.