BIOMES

Chapter 6

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Biomes

Section 1

Objectives

• Describe how plants determine the name of a biome.
• Explain how temperature and precipitation determine which plants grow in an area.

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Biomes

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What is a Biome?

• Biomes are large regions characterized by a specific type of climate and certain types of plant and animal communities.
• Each biome is made up of many individual ecosystems.

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Biomes

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Biomes and Vegetation

• Biomes are described by their vegetation because plants that grow in an area determine the other organisms that can live there.
• Plants in a particular biome have characteristics, specialized structures, or adaptations that allow the plants to survive in that biome.
• These adaptations include size, shape, and color. For example, plants in the tundra tend to be short because they cannot obtain enough water to grow larger.

Biomes

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The World’s Major Terrestrial Biomes

Biomes

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Biomes and Climate

• Climate is the average weather conditions in an area over a long period of time.
• Climate is the main factor is determining which plants can grow in a certain area, which in turn defines the biome.
• Temperature and precipitation are the two most important factors that determine a region’s climate.

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Biomes

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Temperature and Precipitation

• Most organisms are adapted to live within a particular range of temperatures and will not survive at temperatures too far above or below their range.
• Precipitation also limits the organisms that can be found in a biome because all organisms need water, and the bigger the animal, the more water it needs.

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Biomes

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Temperature and Precipitation

• In biomes where rainfall is not frequent, the vegetation is mostly cactuses and desert shrubs.
• The higher the temperature and precipitation are, the taller and denser the vegetation is.

Biomes

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Latitude and Altitude

• Latitude is the distance north or south from the equator, and is expressed in degrees.
• Altitude is the height of an object above a reference point, such as sea level or the Earth’s surface.
• Climate varies with latitude and altitude.

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Biomes

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Temperature and Precipitation

Biomes

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Latitude and Altitude

Biomes

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Forest Biomes

• Of all the biomes in the world, forest biomes are the most widespread and the most diverse.
• The large trees of forests need a lot of water, so forests can be found where temperatures are mild to hot and where rainfall is plenty.
• There are three main forest biomes of the world: tropical, temperate, and coniferous.

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Biomes

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Tropical Rain Forests

• Tropical rain forests are forests or jungles near the equator. They are characterized by large amounts of rain and little variation in temperature and contain the greatest known diversity of organisms on Earth.
• They help regulate world climate an play vital roles in the nitrogen, oxygen, and carbon cycles.
• They are humid, warm, and get strong sunlight which allows them to maintain a fairly constant temperature that is ideal for a wide variety of plants and animals.

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Tropical Rain Forests

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Layers of the Rain Forest

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Temperate Forests

• Temperate rain forests are forests communities that are characterized by cool, humid weather and abundant rainfall, where tree branches are draped with mosses, tree trunks are covered with lichens, and the forest floor is covered with ferns.
• They occur in North America, Australia, and New Zealand, and are dominated by evergreen trees such as the Douglas fir and Sitka spruce.

Biomes

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Temperate Deciduous Forests

• Temperate deciduous forests are forests characterized by trees that shed their leaves in the fall, and located between 30º and 50º north latitude.
• They receive 75 to 125 cm of precipitation annually which helps to decompose dead organic matter contributing to the rich soils of the forest.

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Biomes

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Temperate Deciduous Forests

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Plants of Deciduous Forests

• Plants in the deciduous forests grow in layers with tall trees, such as birch, dominating the canopy while shrubs cover the understory. Also, more light reaches deciduous forest floors than rain forests floors allowing more plants to grow.

Biomes

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Animals of Deciduous Forests

• The animals of temperate deciduous forests are adapted to use the forest plants for both food and shelter.
• Birds cannot survive the harsh winter of the deciduous forests so each fall they fly south for warmer weather and better availability of food.
• Other animals, such as mammals and insects, reduce their activity so that they do not need as much food for energy, enabling them to survive the winter.

Biomes

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Taiga

• The taiga is the region of evergreen, coniferous forest below the arctic and subarctic tundra regions.
• The taiga has long winters and little vegetation.
• The growing season can be as short as 50 days with most plant growth occurring during the summer months because of nearly constant daylight and larger amounts of precipitation.

Biomes

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Taiga

Biomes

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Plants of the Taiga

• A conifer is a tree that has seeds that develop in cones. Their leaves’ arrow shape and waxy coating helps them to retain water in the winter. The conifer’s shape also helps the tree shed snow to the ground and not get weighed down.
• Conifer needles contains substances that make the soil acidic when they fall to the ground preventing plants from growing on the floor.

Biomes

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Animals of the Taiga

• The taiga has many lakes and swamps that in the summer attract birds that feed on insects.
• Other animals, such as snowshoe hares, have adapted to avoid predation by shedding their brown summer fur and growing white fur that camouflages them in the winter snow.

Biomes

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Savannas

• Savannas are plains full of grasses and scattered trees and shrubs that are found in tropical and subtropical habitats. Found mainly in regions with a dry climate, such as East Africa and western India.
• Although savannas receive little precipitation throughout the year, they do have a wet season and a dry season.
• Many animals are only active during the wet season. Grass fires help to restore nutrients to the soil during the dry season.

Biomes

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Savannas

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Plants of the Savanna

• Because most of the rain falls during the wet season, plants must be able to survive prolonged periods without water.
• Some plants have large horizontal root systems to help them survive the dry season. These roost also enable the plant to grow quickly after a fire.

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Biomes

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Animals of the Savanna

• Grazing herbivores, like the elephant, have adopted migratory ways of life, following the rains to areas of new grass and fresh watering holes. Predators often stalk these animals for food.
• Many savanna animals give birth only during the rainy season, when food is abundant and the young are more likely to survive.

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Biomes

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Temperate Grasslands

• Temperate grasslands are communities (or biomes) that are dominated by grasses, have few trees, and are characterized by hot summers and cold winters, with rainfall that is intermediate between that of a forest and a desert.
• Temperate grasslands have the most fertile soil of any biome. Few natural temperate grasslands remain because many have been replaced by grazing areas and farms growing crops such as corn, soybeans, and wheat.

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Biomes

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Temperate Grasslands

• Temperate grasslands are located on the interiors of continents where too little rain falls for trees to grow and include the prairies of North America.
• Heavy precipitation is rare in the grasslands, allowing the hot temperatures in the summer to make the grasslands susceptible to fires.

Biomes

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Temperate Grasslands

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Plants of Temperate Grasslands

• The roots system of prairie grasses form dense layers that survive drought and fire allowing the plants to come back from year to year.
• Few trees survive on the grasslands because of the lack of rainfall, fire, and the constant winds.
• The amount of rainfall in the area determines the types of plants that will grow in that area with varying root depth and grass height.

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Biomes

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Grassland Plants

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Animals of Temperate Grasslands

• Some grazing animals, such as the bison and pronghorn antelope, have large, flat teeth for chewing the coarse prairie grasses.
• Other grasslands animals, such as prairie dogs, owls, and badgers, live protected in underground burrows that protect them from predators on the open grasslands.

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Biomes

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Chaparral

• Chaparral is a type of temperate woodland biome with vegetation that includes broad leafed evergreen shrubs and is located in areas with hot, dry summers and mild, wet winters.
• Chaparrals are located in the middle latitudes, about 30° north and south of the equator.
• Chaparrals are located primarily in coastal areas that have Mediterranean climates.

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Chaparral

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Plants of the Chaparral

• Most chaparral plants are low-lying, evergreen shrubs and small trees that tend to grow in dense patches and include chamise, manzanita, scrub oak, and herbs like sage and bay.
• These plants have small, leathery leaves that contain oils that promote burning, allowing natural fires to destroy competing trees.
• Chaparral plants are well adapted to fire and can resprout from small bits of surviving plant tissue.

Biomes

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Animals of the Chaparral

• A common adaptation of chaparral animals Is camouflage, shape or coloring that allows an animal to blend into its environment.
• Animals such as quail, lizards, chipmunks, and mule deer have a brownish gray coloring that lets them move through the brush without being noticed.

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Biomes

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Deserts

• Deserts are regions that have little or no vegetation, long periods without rain, and extreme temperatures.
• Although there are hot and cold deserts, one characteristic they both share is the fact that they are the driest places on Earth.

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Deserts

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Plants of the Desert

• All desert plants have adaptations for obtaining and conserving water, which allows the plants to live in dry, desert conditions.
• Plants called succulents, such as cactuses, have thick, fleshy stems and leaves that conserve water. Their leaves also have a waxy coating to prevent water loss, while sharp spines on the plant keep animals away.
• Many plant roots spread out just under the surface to absorb as much rain as possible.

Biomes

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Plants of the Desert

• Some plants are adapted to survive for long periods of time without water.
• When conditions are too dry, these plants die and drop their seeds that stay dormant until the next rainfall. Then, new plants quickly germinate, grow, and bloom before the soil becomes dry again.

Biomes

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Animals of the Desert

• Animals of the desert have adapted many different ways to prevent water loss.
• Reptiles have thick, scaly skin that prevents water loss. Amphibians survive by estivating, or burying themselves in the ground and sleeping through the dry season. Insects are covered with body armor that helps them retain water.

Biomes

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Tundra

• The tundra is a treeless plain that is located in the Arctic or Antarctic and that is characterized by very low winter temperatures, short, cool summers, and vegetation that consists of grasses, lichens, and perennial herbs.
• Permafrost is the permanently frozen layer of soil or subsoil and can be found in the tundra regions.

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Biomes

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Tundra

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Vegetation of the Tundra

• Mosses and lichens, which can grow without soil, cover vast areas of rocks in the tundra.
• The soil is thin, so plants have wide shallow roots to help anchor them against the icy winds.

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Biomes

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Animals of the Tundra

• Millions of migratory birds fly to the tundra to breed in the summer when food is abundant.
• Caribou migrate throughout the tundra in search of food and water. Hunters such as wolves prey on migratory caribou, deer, and moose.

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Threats to the Tundra

• The tundra is one of the most fragile biomes on the planet. The food chains are relatively simple so they are easily disrupted.
• Until recently these areas have been undisturbed by humans. But oil was located in parts of the tundra, and oil exploration, extraction, and transport has disrupted many tundra habitats.
• Pollution caused by spills or leaks of oil and other toxic materials may also poison the food and water sources of organisms of the tundra.

Biomes

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