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Chapter 6
Section 2 & 3
Different Biomes
Environmental Science
Spring 2011
Forest Biomes
•
•
•
•
Exist where precipitation is plentiful
Tropical forests
Temperate forests
Taiga
Tropical Rain Forest
• Location and Climate:
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▫
▫
▫
▫
▫
Located in a belt around equator
Humid and warm
Precipitation: 200-450cm/year
Strong sunlight year round
Relative constant temperature year round
Warm, wet conditions
Tropical Rain Forest
• Nutrients:
▫ Nutrient poor soil
▫ Nutrients are within the plants
▫ Organic matter decays quickly in hot, wet
conditions
▫ Fungi that live on trees can transfer nutrients
from dead organic matter directly to the tree
▫ Butresses or Braces: roots that grow sideways
from trees and provide extra support in thin soil
Tropical Rain Forest
• Layers of the Rain Forest:
▫ Emergent layer: tallest trees which reach
heights of 60 to 70m, grow and emerge into the
direct sunlight
▫ Canopy (upper and lower): grow more than
30m tall, form a dense layer that absorbs 95% of
sunlight, lower canopy receives less sunlight than
upper canopy
 Ephiphytes: use entire surface of a tree to live,
grow on tall trees so can have sunlight
Tropical Rain Forest
• Layers of the Rain Forest:
▫ Understory: little light, plants here are adapted
to conditions, most do not grow more than 3.5m
tall, usually flat leaves
Tropical Rain Forest
• Species Diversity:
▫ Greatest amount of species diversity
▫ Most rain forest animals are specialists that use
adaptations to capture prey and escape predators
Tropical Rain Forest
• Threats:
▫ 100 acres are cleared every
minute of every day
▫ Habitat destruction:
when land inhabited by an
organism is destroyed or
altered
▫ People are losing their
habitat as well
▫ Trade of plants and
animals is a threat
Temperate Rain Forest
• Occurs in North America, Australia, and New
Zealand
• Precipitation: large amounts
• High humidity
• Moderate temperatures
• Temperate rain forest: pacific northwest
houses North America’s only one
▫ Maintain moderate temperature all year, rarely
freezes, large amount of rainfall
▫ http://dsc.discovery.com/videos/planet-earthforests-redwood-forest.html
Temperate Deciduous Forest
• Trees drop broad, flat leaves each fall
• Located between 30 and 50 degrees north
latitudes
• Range of temperatures can be extreme
▫ 35 degrees C in summer to below freezing in
winter
• Growing season lasts 4 to 6 months
• Vegetation changes seasonally
• Soil contains more nutrients than tropical rain
forests
Temperate Deciduous
Forest
• Plants:
▫ Grow in layers
▫ Tall trees (maple, oak, birch) dominate forest
canopy
▫ Small trees and shrubs cover understory
▫ Because the floor gets more light than a rain
forest, more plants (ferns, herbs, mosses) can
grow
▫ Adapted to survive seasonal changes (shed leaves)
Temperate Deciduous Forest
• Animals:
▫ Adapted to use the forest plants for food and
shelter
▫ Squirrels eat nuts, seeds, and fruits in treetops
▫ Bears feast on leaves and berries
▫ Birds nest in safety of canopy
 Most migratory
▫ Some mammals reduce activity during winter so
that they don’t need as much food for energy
Taiga
• Northern coniferous forest that stretches in a
broad band across the northern hemisphere just
below the arctic circle
• Winters are long (6-10 months)
• Average temperatures below freezing, can fall to
-20 degrees Celsius
• Plant growth most abundant during summer
because of nearly constant sunlight and larger
amounts of precipitation
Taiga
Taiga
• Plants:
▫ Conifer: tree with needle-like leaves and seeds that
develop in cones
 Shape of leaves and waxy coating prevents lose of water
 Cone like shape of trees prevents snow from building up
 Conifer needles contain substances that make soil acidic
when they fall, most plants cannot grow here, one reason
why taiga floor has few plants
▫ Soil forms slowly because of climate and acidity of
needles- slow decomposition
Taiga
• Animals:
▫ Many lakes and swamps that attract birds in
summer
▫ Most birds migrate south during winter
▫ Food is scarce- some species (jumping mice)
burrow underground to hibernate
▫ Some animals have adapted to avoid predation
(snowshoe hare)
▫ http://dsc.discovery.com/videos/planet-earthforests-taiga-forest.html
Grassland, Desert, and Tundra
• Little precipitation
• Large trees cannot survive here, biomes
dominated by smaller plants
• Desert: almost no rainfall, few plants
• Savannah, Desert: warm areas with little
precipitation
• Grassland, Chaparral, Desert: temperate
areas
• Tundra, Desert: cold areas
Savannas
• Parts of Africa, western India, northern
Australia, and some parts of South America
• Grassland
• Savanna: tropical biome dominated by grasses,
shrubs, and small trees
• Rain falls mainly during wet season, lasts only a
few months of the year
▫ Only time that plants can grow
Savannas
• Plants:
▫ Most of rain falls during the wet season, plants must be able
to survive prolonged periods of time without water
▫ Dry season: plants lose leaves or die down to the ground
▫ Wet season: start to grow again
▫ Many have large horizontal root systems so can draw
water from wide area
▫ Vertical leaves: expose less of their surface area to help
conserve water
▫ Some trees lose leaves during dry season to conserve water
▫ Often have thorns or sharp leaves to keep herbivores away
Savanna
Savannas
• Animals:
▫ Grazing herbivores
 Eat vegetation at different heights
▫ Migratory way of life
 Follow rains
▫ Predators follow their prey
▫ Many savanna animals give birth during wet
season
Temperate Grasslands
• Cover large areas of the interior of continents
• Moderate rainfall, not enough for trees
• Prairies of North America, steppes in Asia, veldt in
South Africa
• Mountains often play a critical role in maintaining
grasslands
▫ Ex. Rain clouds release most of moisture as pass over
Rocky Mountains, shortgrass prairie just east of
Rockies receives so little rain it resembles desert,
amount of rain increases as move east, permits taller
grasses and shrubs
Temperate Grasslands
• Plants:
▫ Grasses and wildfires
▫ Single layer of vegetation, many species may be
present
▫ Shrubs and trees grow where soil contains extra water
▫ Root systems form dense layers that survive drought
and fire
▫ Fertile soil
▫ Summer is hot, winter is cold
 Plants die back to roots in winter
▫ Rate at which dead plants decay is slower than the rate
at which new vegetation is added each year – organic
matter accumulates in soil
Temperate Grasslands
• Animals:
▫ Grazing animals with flat teeth for chewing coarse
grasses
▫ Badgers, prairie dogs, burrowing owls, live
protected in underground burrows
 Shield animals from fire and weather and protect
from predators on open grassland
Temperate Grasslands
• Threats:
▫ Farming and
overgrazing
▫ Soil erosion
▫ Changes
grasslands
into less
productive,
desert like
biomes
Chaparral
• Temperate woodland, fairly dry climate but receives
enough rain to support more plants than desert
• Scattered tree communities of coniferous trees
• Chaparral: temperate shrubland that is found in
all 5 parts of the world with a Mediterranean climate
• Areas have moderately dry, costal climates, little
rain in the summer
• Located in middle latitudes 30 degrees north and
south of equator
Chaparral
Chaparral
• Plants:
▫ Low-lying, evergreen shrubs and small trees that
grow in dense packages
▫ Ex. Chamise, manzanita, scrub oak, olive trees,
herbs
▫ Plants have small leathery leaves that retain water
 Contain oils that promote burning- advantage
because fires destroy trees that might compete
 Chaparral trees adapted to re-sprout from small bits
of surviving plant tissues
Chaparral
• Animals:
▫ Common adaptation is camouflage
▫ Ex. Quail, lizards, chipmunks, mule deer
Chaparral
• Threats:
▫ Greatest threat is human development
▫ Because chaparral gets a lot of sun, are near oceans,
and have mild climates year round humans tend to
develop land here
Desert
• Many kinds, all are the driest places on Earth
• Desert: areas that have widely scattered
vegetation receive very little rain
• Little moisture in the air cause temperature to
change rapidly during 24h period
▫ Ranges from 40 degrees C during he day to below
freezing during the night
• Often located near mountain ranges, which
block passage of rain clouds
Desert
• Plants:
▫ Adapted for obtaining and conserving water
▫ Succulents: cactuses, have thick, fleshy
stems and leaves that store water
 Leaves have waxy coating that prevents water
loss, sharp spines keep animals from
devouring juicy flesh
▫ Rainfall rarely penetrates deep into soil, so
many plants roots spread out just under
surface of soil
▫ Many drop leaves in dry conditions
▫ When too dry, die and drop seeds that stay
dormant
▫ Some adapted to survive even if water
content drops to as low as 30% of their mass
Desert
• Animals:
▫ Thick, scaly skin to prevent water loss
▫ Estivating: burying themselves in the ground
and sleep through dry season
 Amphibians: spadefoot toad
▫ Elf owl nests in cactus
▫ Desert insects covered with body armor that helps
retain water
▫ Most are nocturnal when air is cooler
Tundra
• Located in northern arctic regions
• Winter is too cold and dry to permit the growth
of trees
• Permafrost: deeper layer of soil
▫ Some permanently frozen throughout the year
• Topsoil is very thin
• In summer when topsoil thaws, land becomes
moist and spongy with bogs
Tundra
• Plants:
▫ Mosses and lichens
 Can grow without soil
▫ Soil is thin, plants have wide shallow roots
▫ Most plants are short to keep out of wind and
help absorb heat from the sunlit soil in summer
▫ Willow and birch have evolved dwarf forms and
grow flat or grow along ground
Tundra
• Animals:
▫ Migratory birds
 Food is abundant
▫ Caribou migrate throughout in search of food and
water
▫ Wolves roam
▫ Small animals burrow underground during winter
▫ Animals are well insulated
▫ http://dsc.discovery.com/videos/planet-earthpole-to-pole-caribou-migration.html
Tundra
• Threats:
▫ One of most fragile biomes
▫ Food chains are relatively simple, so are easily
disrupted
▫ Conditions are extreme, land is easily damaged
and slow to recover
▫ Oil and pollution has disrupted habitat