The land areas of the Earth can be divided into several major biomes. (Here are some that are found on the North American continent:)
tundra
It’s so cold that the ground is frozen most of the year, and a deep layer of soil below the surface—called the permafrost—never melts at all. However, for two months during the summer, the temperature rises above freezing. The snow and surface soil melt, creating vast pools of water and bogs.
The tundra is a rocky landscape. Lichen—a combination of fungi and algae—grow on the rocks. Lichens are a favorite food of reindeer that migrate across the tundra in vast herds. During winter, these lichens are one of the only foods available and reindeer will dig through snow to find them.
It’s so cold that the ground is frozen most of the year, and a deep layer of soil below the surface—called the permafrost—never melts at all. However, for two months during the summer, the temperature rises above freezing. The snow and surface soil melt, creating vast pools of water and bogs.
The tundra is a rocky landscape. Lichen—a combination of fungi and algae—grow on the rocks. Lichens are a favorite food of reindeer that migrate across the tundra in vast herds. During winter, these lichens are one of the only foods available and reindeer will dig through snow to find them.
taiga or boreal (coniferous forest)
It’s so cold that the ground is frozen most of the year, and a deep layer of soil below the surface—called the permafrost—never melts at all. However, for two months during the summer, the temperature rises above freezing. The snow and surface soil melt, creating vast pools of water and bogs.
Taiga 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 taiga 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.
It’s so cold that the ground is frozen most of the year, and a deep layer of soil below the surface—called the permafrost—never melts at all. However, for two months during the summer, the temperature rises above freezing. The snow and surface soil melt, creating vast pools of water and bogs.
Taiga 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 taiga 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.
temperate deciduous forest
This biome is defined by its four distinct seasons and its forests of trees that drop their leaves in autumn. 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.
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 taiga 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 fall, the trees in these forests are alight with fiery colors.
This biome is defined by its four distinct seasons and its forests of trees that drop their leaves in autumn. 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.
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 taiga 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 fall, the trees in these forests are alight with fiery colors.
temperate grassland (plains/prairie) Temperate grasslands include the prairie in North America and the steppes of Europe and Asia. They are characterized by vast stretches of high grasses and wildflowers. Summers are very hot and winters are very cold. These regions are subject to droughts—periods without rain—as well as regular wildfires.
Before 1800, some 25 million bison roamed America’s grasslands. But the bison were so heavily hunted that by 1900, there were only a few hundred left. With the help of conservationists, bison populations have bounced back a little. Today, a few thousand wild bison live in national parks like Yellowstone.
Before 1800, some 25 million bison roamed America’s grasslands. But the bison were so heavily hunted that by 1900, there were only a few hundred left. With the help of conservationists, bison populations have bounced back a little. Today, a few thousand wild bison live in national parks like Yellowstone.
desert
The desert is the driest biome. Some deserts, such as the Sahara, get less than an inch of rainfall in an entire year. The flora and fauna that survive there have to be tough. Desert plants have evolved strategies to save water. In wet biomes, plants can have very large leaves—and they use them to catch as many rays as possible—but large leaves also lead to water loss. To conserve water, desert plants have very tiny leaves, or no leaves at all, transferring the work of photosynthesis to their trunks or stems. That’s why cacti have green “trunks.”
Desert animals also have to deal with high temperatures and minimal water supplies. Typically, they are nocturnal, hiding out in burrows during the day to beat the heat. Some animals, such as the desert tortoise, go into “estivation” in their burrows during the hottest part of the year. Estivation is the desert version of hibernation—the animal’s pulse and breathing slow down dramatically—so that they don’t need to use much water or energy.
The saguaro [suh-WAHR-oh] cactus grows in the deserts of the southwestern United States. When it rains, the trunk of the saguaro can expand to hold water. Sharp spines defend it from animals who might try to break open the saguaro and take a drink.
The desert is the driest biome. Some deserts, such as the Sahara, get less than an inch of rainfall in an entire year. The flora and fauna that survive there have to be tough. Desert plants have evolved strategies to save water. In wet biomes, plants can have very large leaves—and they use them to catch as many rays as possible—but large leaves also lead to water loss. To conserve water, desert plants have very tiny leaves, or no leaves at all, transferring the work of photosynthesis to their trunks or stems. That’s why cacti have green “trunks.”
Desert animals also have to deal with high temperatures and minimal water supplies. Typically, they are nocturnal, hiding out in burrows during the day to beat the heat. Some animals, such as the desert tortoise, go into “estivation” in their burrows during the hottest part of the year. Estivation is the desert version of hibernation—the animal’s pulse and breathing slow down dramatically—so that they don’t need to use much water or energy.
The saguaro [suh-WAHR-oh] cactus grows in the deserts of the southwestern United States. When it rains, the trunk of the saguaro can expand to hold water. Sharp spines defend it from animals who might try to break open the saguaro and take a drink.
But there are no firm rules about the exact number of biomes. In fact, scientists divide the world’s biomes into anywhere from six to seventeen categories. (No one way is better than another—it’s just that some classification systems are more general and others are more specific.)
- from Biomes for Kids
- from Biomes for Kids