11-8: Tundra

How is alpine tundra different from Arctic and Antarctic tundra?

Alpine tundra areas are found only at high elevations.

What challenges must be overcome by animals living on the tundra?

Animals must be able to keep warm, and they must be able to get the food and water they need to survive.

Biodiversity

Tundra biodiversity is very low. This seems to be obvious. What kinds of organisms would want to live in such an extreme environment? But biodiversity is not about what organisms want; it is about what can live there. For example, consider the plant life in the tundra biome. Recall that plants take carbon from the atmosphere and change it into a usable chemical form (sugar) through photosynthesis to create energy. Plant life faces an uphill battle in the tundra: The permafrost prohibits plants from growing very deep roots because the upper layers of soil are frozen most of the year. Summer, and the growing season that coincides with it, are very short--usually a month or two. Indirect sunlight is not as useful for photosynthesis as direct sunlight, so plants aren't able to make as much sugar as plants that are in other biomes. The tundra biome also experiences high winds, keeping plants (like the moss in this picture) from growing tall, as well as prohibiting them from creating broad leaves to catch the sun's rays. Q: How does the number and kinds of plants in a biome affect the number and kinds of animals in a biome and why? A: Animals depend on the ability to consume energy that plants make through photosynthesis. Decreased photosynthesis means a decreased amount of energy available to animals in an ecosystem. Therefore, that ecosystem will be able to support less types of animals, and biodiversity will be low.

Which of these describes the tundra biome?

coldest and least biodiverse

A biome is a geographical area that is characterized by two things. What are those two things?

Biomes are characterized by climate and plant life.

Types and Locations (summary)

The tundra biome is broken into three areas: Arctic and Antarctic tundra are near Earth's North and South Poles in the Arctic Circle and on the continent of Antarctica. Alpine tundra is found at high elevations.

Which behavioral adaptation do tundra animals use to conserve energy?

the ability to hibernate

What adaptations do tundra plants have that help them retain water?

Most plants grow very small leaves to minimize water loss, and some have leathery leaves or waxy coatings to help them retain moisture.

What adaptation is used by plants to either obtain or retain enough water in the tundra biome?

leathery or waxy leaves

How do you think climate change affects the alpine tundra biome? (Think about the fact that scientists believe the global average temperature is increasing.)

Climate change is likely to shrink the amount of area covered by the alpine tundra biome. Warmer temperatures will allow different types of plants, as well as more plants, to grow there. Some areas currently covered by tundra are likely to become coniferous forests.

Animal Adaptations

Cold Arctic and Antarctic temperatures and dry conditions prevent many animals from making the tundra their permanent home. In fact, very few animals live in Antarctica. Its animal population consists primarily of seals, penguins, and other forms of marine life. The Arctic tundra does have a few permanent residents, however. These include wolves, polar bears, foxes, and small rodents, such as hares and lemmings. Keeping warm is a big challenge for these animals, so they have physical adaptations, like thick coats and extra body fat, to help them stay warm. Other animals have specific adaptations that help them get food and water. Wolves and polar bears have stiff hairs on their paws to prevent them from slipping on the icy ground, while the musk-ox (shown here) has hard, sharp hooves that help it break through the ice to get water. For some animals, a behavioral adaptation, like migration, is part of their yearly cycle. Migration means the animals move to another area to live or reproduce during harsh weather. These animals live on the tundra during summer and for a short time after summer ends. They feast on the plants growing there during this time. Then they migrate south to more hospitable coniferous forests to reproduce and wait out the cold months of winter. Like animals in other biomes with cold winters, some animals hibernate (enter into a state of reduced activity). By not moving around much during hibernation, these animals save the energy they need to keep warm.

What behavioral adaptations do animals living on the tundra use to survive?

Some animals migrate, which means they move to warmer areas during the winter; other animals hibernate, meaning they enter into a state of reduced physical activity.

A tundra is characterized by cold temperatures and a lack of trees. What do you think are the biggest challenges faced by organisms that live in the tundra biome? (Hint: Think about adaptations to a desert biome.)

The biggest challenges to organisms in a tundra biome are surviving the cold temperatures and obtaining and keeping enough water.

Climate

The extreme latitudes at which the Arctic and Antarctic tundra are found correspond with a lack of direct sunlight and bitterly cold temperatures. The temperatures are so cold that the soil is permanently frozen year-round just about a foot below the surface. This layer, called permafrost (notice the prefix perma-), is a hallmark of Arctic and Antarctic tundra. Winter temperatures in the tundra biome stay around -28 degrees C (-18 degrees F) and can drop to -50 degrees C (-58 degrees F.) Summer temperatures rarely rise above 12 degrees C (54 degrees F) and generally remain around freezing (0 degrees C and 32 degrees F.) The extreme latitudes at which the Arctic and Antarctic tundra are found correspond with a lack of direct sunlight and bitterly cold temperatures. The temperatures are so cold that the soil is permanently frozen year-round just about a foot below the surface. This layer, called permafrost (notice the prefix perma-), is a hallmark of Arctic and Antarctic tundra. Winter temperatures in the tundra biome stay around -28 degrees C (-18 degrees F) and can drop to -50 degrees C (-58 degrees F.) Summer temperatures rarely rise above 12 degrees C (54 degrees F) and generally remain around freezing (0 degrees C and 32 degrees F.)

Biodiversity (summary)

The tundra biome has the least biodiversity. Biodiversity is low because low sunlight and very cold temperatures mean that only highly adapted plants are able to live there. Less plant life means that less animals live on the tundra because animals rely on plants to get their energy.

Location

The tundra biome is broken into three areas: Arctic, Antarctic, and alpine. Arctic and Antarctic tundra are near Earth's North and South Poles--that is, they are in the Arctic Circle and on the continent of Antarctica. (These areas are shown in light blue on the map.) Alpine tundra is found at high elevations (the distance from Earth's surface) on mountaintops all over the world. Q: What is the relationship between the distance from the equator and the plant life that can grow in a biome? Why? A: Latitude specifies the distance away from the equator. The greater the latitude (the further from the equator), the shorter the growing season and the fewer the number of plants that can grow there. This is because the high latitudes receive less direct sunlight than do latitudes close to the equator.

Given that the tundra is very dry most of the year, why don't the plants living there have deep roots to search for water?

The tundra has a layer of permafrost year-round that prevents plant roots from growing too deeply.

What is the relationship between the latitude of Arctic and Antarctic tundra and the amount of sunlight the plants in these biomes receive for photosynthesis?

The tundra is found at high latitudes that receive indirect sunlight.

Climate (summary)

This biome is Earth's coldest. Even summer temperatures generally remain around freezing. Precipitation is very low, meaning that conditions are desert-like.

Plant Adaptations

Weak sunlight and frozen soil mean that the plants growing in the tundra biome need very special adaptations to help them survive and reproduce. Two important challenges for plants that grow there are getting and retaining water and withstanding cold temperatures. Some plants in the tundra have adaptations similar to plants that live in other biomes. Q: Can you think of any adaptations that help plants prevent water loss? A: Plants in the desert and coniferous forest biomes have reduced (needle-like) leaves. Plants in the desert biome and trees in the emergent layer of the rainforest have waxy leaves to withstand strong sunlight, high temperatures, and high winds.

What is permafrost?

a constantly frozen layer of soil