Grassland, Desert and Tundra Biomes Chapter 6, Section 3

Transcription

1 Grassland, Desert and Tundra Biomes Chapter 6, Section 3

2 Biomes and Precipitation In areas with lower precipitation, forest biomes are replaced by Savanna, Grassland and Chaparral If rainfall is even lower, biomes are: Desert Tundra Greater = Greater species precipitation diversity Areas with low precipitation may have fewer types of species, but the number of each species can be high

3 Grasslands: Savannas Grasslands located in tropical and subtropical areas near the equator, and between the tropical rain forest and desert. Africa, Western India, N. Australia and S. America Contain grasses, scattered trees, shrubs and so they contain a large variety of grazing animals and their predators. Little precipitation with wet and dry seasons. Many animals are active only during wet season. Grass fires sweep across savanna during dry season and help restore nutrients to the soil.

4 Plants of the Savanna Because of wet and dry seasons, plants need to survive prolonged periods without water. Trees and grasses have large horizontal root systems to obtain water during dry season. Roots enable plants to quickly re-grow after a fire. Plant leaves are vertical to avoid being exposed to the sun and conserve water. Some trees and shrubs lose leaves during dry season to conserve water. Trees and shrubs have thorns to keep herbivores away.

5 Animals of the Savanna Grazing herbivores reduce competition by feeding on vegetation at different heights. Examples? Many animals are migratory: they follow the rains to areas of newly sprouted grass and watering holes. Some predators follow these migratory animals for food. Many animals only give birth during the rainy season. Why?

6 Grasslands: Temperate Grasslands Located on the interiors of continents where too little rain falls to grow trees Prairies of North America, steppes of Russia, and pampas of South America Hot summers and cold winters. Susceptible to fires. Moderate rainfall compared to a forest. Rainfall affected by mountains. How? Although they seem harsh and dry they have the most fertile soil of any biome because of slow decomposition. Many grasslands have been replaced with crops.

7 Plants and Animals of the Temperate Grassland Plants Perennials: plants that survive from yr. to yr. Prairie grasses and wild flowers Roots systems form dense layers that survive drought and fire and hold soil in place. Types of plants depend on the amount of rainfall (Figure 20 on page 157) Animals Grazing animals (antelope and bison) have large, flat back teeth for chewing coarse prairie grasses. Other animals: badgers, prairie dogs, owls live in burrows that protect them from fire, weather and predators.

8 Threats to Temperate Grasslands Farming and overgrazing are changing grasslands. Grain crops do not hold soil as well as native grasses so what occurs? Erosion is also caused by overgrazing because grasses that are trampled and eaten cannot hold soil. Constant use for grazing and farming will turn the grassland into less productive, desert-like biomes.

9 Grasslands: Chaparral Chaparrals are temperate woodland biomes Dry climates, but receive enough rainfall to support more plants than the desert. Scattered coniferous tree communities. Dominated by broad leafed evergreen shrubs Located in the middle latitudes, about 30 o north and south of the equator Located primarily in coastal areas with Mediterranean climates (Santa Barbara, CA) Warm dry summers and mild wet winters

10 Plants of the Chaparral Low-lying evergreen shrubs and small trees that grow in dense patches. Chamise, manzanita, scrub oak, olive tree and herbs Plants have small leathery leaves that retain water Leaves contain oils that promote burning and give some plants a characteristic taste and smell (i.e. sage). This is an advantage because: Chaparral plants are adapted to fire and can resprout, while other plants that would compete for light and space are destroyed

11 The Chaparral Animals Common adaptation is camouflage, shape or coloring that allows animals to blend in with its environment. Quail, lizard, chipmunks, and mule deer have gray coloring to blend with the brush. Threats to Chaparral Human development is the greatest threat Mild weather conditions and proximity to the ocean make the land desirable for commercial and residential use.

12 Deserts Located throughout the world. Arizona, Utah, China, Egypt Driest places on earth receiving less than 25cm of precipitation/year Often located near mountain ranges that block rain Little or no vegetation. Extreme temperatures. There are both hot and cold deserts.

13 Plants of the Desert All plants have adaptations to help them obtain and conserve water. survive for long periods of time without water. Succulents like cactuses: Thick fleshy stems and leaves that store water. Leaves have waxy coating to prevent water loss. Sharp thorns keep thirsty animals from eating the leaves. Rainfall does not penetrate deeply into the soil, so the root system is shallow and spread out to absorb as much as possible. Plants that die drop seeds that remain dormant until the next rainfall when they quickly germinate, grow and bloom.

14 Animals of the Desert Reptiles like Gila monsters, rattlesnakes Have thick scaly skin to prevent water loss Amphibians like the spadefoot toad Estivate (bury themselves in the ground and sleep through the dry season) Some animals like the elf owl nest in cactuses to avoid predators. Desert insects and spiders are covered with body armor to help them retain water. Most desert animals are nocturnal which means they are active at night when it is cooler.

15 The Tundra Located primarily north of the Arctic Circle Ex: Reykjavik, Iceland Biome dominated by grasses,lichens,herbs. Soil supports mostly tough grasses and shrubs. Plants flower in the summer. Summers are short so only the top few cm of soil thaw and form bogs and swamps. These areas are breeding grounds for insects and the birds that feed on them. Underneath the topsoil is a layer of soil that is permanently frozen called permafrost.

16 Plants of the Tundra Mosses and lichens, which can grow without soil cover rocks in the tundra. Plants have wide, shallow roots to anchor themselves in the thin soil. Most flowering plants (angiosperms like campion and gentian) are short to protect them from the wind and help them absorb heat from the soil. Woody plants (gymnosperms) and perennials such as willow and juniper have evolved dwarf forms and grow flat or along the ground.

17 Animals of the Tundra Millions of migratory birds fly to the tundra to breed in the summer because food is abundant (plants, mollusks, worms and insects) Caribou migrate through the tundra in search of food and water. Wolves and other predators roam the tundra and prey on caribou, deer, moose and smaller animals. Smaller animals like lemmings, mice and rabbits burrow underground during winter but they are still active. Animals like arctic foxes live in the tundra year round. They are will insulated, and change fur color to camouflage themselves in snow.

18 Threats to the Tundra The tundra is a fragile biome. Food chains are simple, so they are easily disrupted. Weather is extreme so the land is easily damaged and slow to recover. Until recently this land has been undisturbed, but the presence of oil has changed this. Oil exploration in tundras (like Northern Alaska) has disrupted the habitats of plants and animals. Pollution, caused by spills and leaks of oil has poisoned the food and water sources of the organisms.