46 lecture ppt

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Biology

Sylvia S. Mader Michael Windelspecht

Chapter 46 Major Ecosystems

of the Biosphere

Lecture Outline

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Outline

• 46.1 Climate and the Biosphere

• 46.2 Terrestrial Ecosystems

• 46.3 Aquatic Ecosystems

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46.1 Climate and the Biosphere

• Climate

 Prevailing weather conditions in a region

 Determined primarily by temperature and precipitation

 Influenced by a multitude of factors including latitude,

tilt of the earth’s axis, and topography

• Solar radiation

 Direct at the equator

 Tilt of the earth causes one pole to be closer than the

other to the sun

• Rotation of the earth affects precipitation and

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Climate and the Biosphere

• Effect of Solar Radiation • Solar radiation

 Direct at the equator, but indirect at the poles

 Tilt of the earth causes one pole to be closer than the other to

the sun

• Accounts for the seasons that occur in all parts of the Earth except the equator

 At the equator, warm, moist air rises and loses its moisture as it

cools in the form of rain

 Rising air moves toward the poles, but at 30 degrees north and

south latitude it cools and sinks

• Creates areas of high pressure with little rainfall

– Great deserts of Africa, Australia, and the Americas

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Climate and the Biosphere

• Effect of Solar Radiation (continued)

 At 60 degrees north and south latitude, warm air rises

and cools, producing an area of low pressure with high rainfall

• Great forests of the temperate zone

 Rotation of the earth affects precipitation and winds

• In the Northern Hemisphere these winds move clockwise

• In the Southern Hemisphere these winds move counterclockwise • Doldrums occur at the equator

– Regions of calm winds

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Distribution of Solar Energy

6

b. Seasonal changes equator equator sun 23° North Pole Vernal equinox sun aims directly at equator, March

South Pole

a. Temperature differences

Summer solstice Northern Hemisphere tilts toward sun, June

Autumnal equinox sun aims directly at equator, September

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Global Wind Circulation

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0°

Ascending moist air cools and loses moisture.

Descending dry air warms and retains moisture.

30°N 60°N

30°S

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Climate and the Biosphere

• Topography

 The physical features of the land

 Consider a coastal mountain range

• Windward side of the mountain

– Winds rise

– Release moisture

• Leeward side

– Dry winds subside

– Evaporates existing water and rarely rains – Create a rain shadow

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Formation of a Rain Shadow

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condensation

moist air

dry air

rain shadow

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Climate and the Biosphere

• Topography



Monsoon climate

• Ocean winds blow onshore for almost half the year

• Land heats more rapidly than the water, which causes an enormous circulation of air

• Warm air rises over land and is replaced by cooler ocean air

– As the air rises it loses its moisture and the monsoon season begins

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46.2 Terrestrial Ecosystems

• Biome

 Major terrestrial ecosystem characterized by climate

and geography

 A particular mix of plants and animals adapted to

living under certain environmental conditions

 Tend to repeat wherever temperature and

precipitation are the same

 Supports characteristic types of animals, although

many migrate from one biome to another

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Biome Pattern of Temperature

and Precipitation

12 25 20 15 10 5 0 -5 -10 -15

50 100 150 200 300 350 400 450

M ea n A n n u al T emp er atu re (° C) 30 tropical taiga Arctic-alpine cold temperate temperate rain forest warm temperate tropical seasonal forest tropical rain forest

Mean Annual Precipitation (cm)

a. Biome pattern of temperature and precipitation tundra grassland temperate deciduous forest savanna 250

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Distribution of Biomes

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polar ice taiga

mountain zone

temperate deciduous forest temperate rain forest tropical deciduous forest tropical seasonal forest tropical rain forest shrubland

temperate grassland semidesert

savanna tundra

desert

b. Distribution of biomes

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Terrestrial Ecosystems

• Biome

(continued)



Climate and biomes change with increasing

latitude and altitude

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Climate and Biomes

15

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Terrestrial Ecosystems

• Tundra



Arctic Tundra

- Encircles Earth just south of

ice-covered polar seas in Northern

Hemisphere



Covers 20% of Earth’s land surface



Permafrost

layer never thaws



Trees are not found in the tundra

• Growing season is too short

• Roots cannot penetrate permafrost

• Roots cannot become anchored in shallow boggy soil

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The Tundra

tundra

a. Tundra vegetation b. Tundra wildlife

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Terrestrial Ecosystems

• Coniferous Forests

 Found in the taiga, near mountaintops, and along the

Pacific Coast of North America

 Taiga typifies coniferous forest with cone-bearing trees

• Trees well adapted to cold

• Leaves and bark have thick covering

• Needle-like leaves can withstand weight of heavy snowfall

 Temperate Rainforest (old-growth forest) of Pacific Northwest

• Evergreen forest

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The Taiga

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taiga

b. Bull moose, Alces americanus, a large mammal

a. Spruce trees in the taiga biome

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Terrestrial Ecosystems

• Temperate Deciduous Forests



Found south of taiga in eastern North

America, eastern Asia, and much of Europe



Moderate climate

• Relatively high rainfall

• Four well-defined seasons with long growing seasons



Tallest trees form a canopy



Ground-life is plentiful

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Temperate Deciduous Forest

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temperate deciduous forest

Marsh marigolds, Caltha howellii Eastern chipmunk, Tamias striatus

Bobcat, Felis rufus

b. Animal life of forest biome

a. Temperate deciduous vegetation

a: © E. R. Degginger/Animals Animals; b (chipmunk): © Carmela Lesczynski/Animals Animals; b (bobcat): © Tom McHugh/Photo Researchers, Inc.; b (marigolds): © Virginia Neefus/Animals Animals

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Terrestrial Ecosystems

• Tropical Forests

 Tropical rainforests are found in equatorial regions

• Warm weather and plentiful rainfall

• Complex structure with forest floor, understory, and canopy • Most animals live in trees

– Abundant insect life

• Epiphytes grow in many areas • Soils are nutrient-poor

– Rapid recycling of nutrients

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Levels of Life in a Tropical Rain

Forest

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fern

lianas

epiphyte

fore

s

t

flo

or

un

de

rsto

ry

c

a

no

py

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Representative Animals of the

Tropical Rain Forests of the World

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tropical rain forest

Poison arrow frog,

Dendrobates azureus Cone-headed katydid,_{Panacanthus cuspidatus} Panther,_{Panthera onca}

Arboreal lizard, Calotes calotes Black howler monkey,

Alouatta pigra Brush-footed butterfly,

Anartia amalthea linnaeus Scarlet macaw,

Ara macao

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Terrestrial Ecosystems

• Shrublands



Tend to occur along coasts that have dry

summers and wet winters

• Shrubs are adapted to withstand arid conditions • Dense shrubland in California is known as

chaparral

– Lacks an understory and ground litter – Highly flammable

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Shrubland

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a. Shrubland overview b. Wildlife of the chaparral

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Terrestrial Ecosystems

• Grasslands



Occur where annual rainfall is greater than 25

cm, but generally insufficient to support trees



Grasses are well adapted to changing

environment



Temperate grasslands

have cold winters

and hot, dry summers



Savannas

have a cool dry season and a hot

rainy season

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Temperate Grassland

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temperate grassland

a. Vegetation of the temperate grasslands

b. Wildlife of the temperate grasslands

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The Savanna

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savanna

a. Herbivores of the savanna biome

b. A carnivore of the savanna biome

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Terrestrial Ecosystems

• Deserts



Usually found at latitudes of about 30

°

in both

hemispheres

• Cover nearly 30% of the Earth’s land surface • Descending winds lack moisture

• Annual rainfall is less than 25 cm

• Large temperature differential between day and night

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The Desert

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desert

a. Desert vegetation

Bannertail kangaroo rat, Dipodomys spectabilis

Greater roadrunner, Geococcyx californianus

Kit fox, Vulpes velox b. Animal life of desert biome

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46.3 Aquatic Ecosystems

• Aquatic ecosystems are classified as



Freshwater (inland) or



Saltwater



Brackish water is a combination of both

• Wetlands

are areas that are wet for at

least part of the year

 Marshes – frequently or continually inundated by water

 Swamps – dominated by woody plants or shrubs

 Bogs – characterized by acidic waters, peat deposits,

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Freshwater and Saltwater

Ecosystems

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Blue crab, Callinectes sapidus stream

Mayfly larva, Ephemeroptera sp.

delta

salt marsh lake river

Rainbow trout, Salmo gairdneri

Carp, Cyprinus carpio

(mayfly): Courtesy Michael Windelspecht; (trout): © William H. Mullins/Photo Researchers, Inc. (carp): © Robert Maier/Animals Animals; (crab): © Gerlach Nature Photography/Animals Animals

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Aquatic Ecosystems

• Lakes



Bodies of water classified by nutrient status

• Oligotrophic - Nutrient-poor • Eutrophic - Nutrient-rich

• Oligotrophic lakes can become eutrophic lakes through the process of eutrophication

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Types of Lakes

35 a. Oligotrophic lake

b. Eutrophic lake

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Aquatic Ecosystems

• Lakes (continued)



In temperate zones, deep lakes are stratified

in the summer and winter and have distinct

vertical zones

• In summer, lakes have three layers that differ in temperature:

– Epilimnion – surface layer (warm water)

– Thermocline – middle layer (cooler than epilimnion) – Hypolimnion – bottom layer (cold)

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Aquatic Ecosystems

• Lakes (continued)



Fall overturn

• Epilimnion water becomes cooler than the water in the hypolimnion

– Causes the surface water to sink and deep water to rise – Process continues until temperature is uniform

throughout the lake



Spring overturn

• As ice melts, cooler water on top sinks below warmer water on the bottom

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Lake Stratification in a Temperate

Region

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Summer Stratification

Fall Overturn Spring Overturn

wind

epilimnion 24°–25°C thermocline 13°–18 °

wind

ice 2°–3°C hypolimnion

5°–8°

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Aquatic Ecosystems

• Life Zones



Plankton

• Important community in fresh water and salt water ecosystems

– Phytoplankton - Photosynthetic algae

– Zooplankton – Tiny animals that feed on the

phytoplankton



Life Zones

• Littoral zone - Closest to shore • Limnetic zone - Sunlit areas

• Profundal zone - Below light penetration • Benthic zone - Soil-Water interface

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Zones of a Lake

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surface organisms fishes

insect larvae

phytoplankton zooplankton

Northern pike, Esox lucius

Littoral Zone clinging organisms Profundal Zone Limnetic Zone

Benthic Zone

bottom-dwelling organisms

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Aquatic Ecosystems

• Coastal Ecosystems



Estuary

• Partially enclosed bodies of water where fresh water and seawater meet and mix

• Organisms must be able to adapt to changing salinity

• Nearly two thirds of all marine fishes and shellfish require development in estuaries

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Aquatic Ecosystems

• Coastal Ecosystems



Rocky and sandy shores

• Constantly bombarded by the sea

• Intertidal zone

– Lies between high and low tide – Many attached organisms

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Coastal Ecosystems

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a. Mudflat

b. Mangrove swamp

c. Rocky shore

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Aquatic Ecosystems

• Oceans



Euphotic Zone (shallow ocean waters)

• Contain a greater concentration of organisms than the rest of the sea



Coral reefs

• Located just below the surface in shallow, warm, tropical waters

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Ocean Ecosystems

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abyssal plain low tide

intertidal zone euphotic zone

high tide

continental shelf

continental slope deep-sea

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Aquatic Ecosystems

• Oceans (continued)

 Pelagic Zones

• Epipelagic Zone

– Lacks inorganic nutrients

– Does not have high concentration of phytoplankton

• Mesopelagic Zone

– High concentration of organisms due to sunlight penetration and supply of inorganic nutrients

• Bathypelagic Zone

– Complete darkness except for bioluminescent light – Carnivores and scavengers

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Ocean Inhabitants of Pelagic

Zones

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Aquatic Ecosystems

• Oceans

 Abyssal Plain

• High pressure and extreme cold

• Organisms are dependent on debris sinking down from above

• Interrupted by oceanic ridges

• Hydrothermal vents

– Seawater percolates through cracks in the ocean floor and is heated to about 350 degrees

» Causing sulfate to react with water forming hydrogen sulfide

» Provides source of energy for chemoautotrophic organisms

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Biomagnification of Mercury

• Mercury becomes a serious environmental risk when it undergoes bioaccumulation in an organism’s body

• Mercury enters ecosystems at the base of the food chain and increases in concentration as it moves up

 Top-level predators and organisms that are long-lived are the most susceptible to high levels of mercury accumulation

• Mercury exposure for humans primarily occurs by eating contaminated fish

 Can lead to sterility in males, damage to the central nervous system, and birth defect in humans

• Mercury travels through food webs to terrestrial ecosystems

 High levels of mercury have been found in terrestrial birds

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Aquatic Ecosystems

• Ocean Currents



Major ocean currents move heat from the

equator to cooler parts of the biosphere

• Gulf Stream warms the east coast of North America and parts of western Europe

• Another current in the Southern Hemisphere warms the eastern coast of South America

• The Humboldt Current in the Southern Hemisphere carries cold water northward along the western

coast of South America

– El Nino Southern Oscillation--Cold upwelling off west

coast of South America subsides

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Ocean Currents

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Asia

Australia

Africa Europe

equator equatorial countercurrent

warm currents cold currents

west wind drift east wind drift

Antarctica North America