chapter 34 the biosphere: an introduction to earth's diverse environments

BIOLOGYCONCEPTS & CONNECTIONS

Fourth Edition

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor

From PowerPoint® Lectures for Biology: Concepts & Connections

CHAPTER 34The Biosphere: An Introduction to

Earth's Diverse Environments

Modules 34.1 – 34.6


• Ecology is the scientific study of the interactions of organisms with their environment

• The ocean is Earth’s largest and least explored ecosystem

• Recent explorations of the deep sea have brought previously unknown species to light, such as this “mystery squid”

A Mysterious Giant of the Deep


• Deep-sea submersibles like Alvin allow the exploration of the deep sea

– It can accommodate a pilot and two other people

– It is equipped with instruments to view and sample the ocean at depths of up to 2,500m


• Scientists have found seafloor life whose ultimate energy source is not sunlight, but energy that comes from the interior of the planet – This energy is

emitted from hydrothermal vents near the edges of Earth’s crustal plates


• Many animals thrive in the extreme environment around hydrothermal vents

– Tube worms were unknown to science until hydrothermal vents were explored

– They live on energy extracted from chemicals by bacteria


• Ecologists study environmental interactions at the organism, population, community, and ecosystem levels

– These clams that live near an ocean vent constitute a population

34.1 Ecologists study how organisms interact with their environment at several levels

Figure 34.1


• Ecosystem interactions involve living (biotic) communities and nonliving (abiotic) components

– Abiotic components include energy, nutrients, gases, and water

• Organisms are affected by their environment

– But their presence and activities often change the environment they inhabit


• The global ecosystem is called the biosphere

– It is the sum of all the Earth's ecosystems

– The biosphere is the most complex level in ecology

34.2 The biosphere is the total of all of Earth's ecosystems

THE BIOSPHERE

Figure 34.2A


• The biosphere is self-contained

– except for energy obtained from the sun and heat lost to space

• Patchiness characterizes the biosphere

– Patchiness occurs in the distribution of deserts, grasslands, forests, and lakes

– Each habitat has a unique community of species

Figure 34.2B


• Human activities affect all parts of the biosphere

– One example is the widespread use of chemicals

34.3 Connection: Environmental problems reveal the limits of the biosphere


• Rachel Carson was one of the first to perceive the global dangers of pesticide abuse

Figure 34.3

– Carson documented her concerns in the 1962 book Silent Spring

– This book played a key role in the awakening of environmental awareness


• Chemical pesticides are concentrated in food chains by biological magnification

Figure 38.3B

DDT in water0.000003 ppm

DDT inzooplankton0.04 ppm

DDT insmall fish0.5 ppm

DDT inlarge fish2 ppm

DDT infish-eating birds25 ppm

DDT concentration:increase of10 million times


• The most important abiotic factors that determine the biosphere's structure and dynamics include

– solar energy

– water

– temperature

34.4 Physical and chemical factors influence life in the biosphere


• Disturbances such as fires, hurricanes, and volcanic eruptions are also abiotic factors

Figure 34.4


• The presence and success of a species in a particular place depends upon its ability to adapt

• Natural selection adapts organisms to abiotic and biotic factors

– Biotic factors include predation and competition

34.5 Organisms are adapted to abiotic and biotic factors by natural selection

Figure 34.5


• Climate often determines the distribution of communities

• Earth's global climate patterns are largely determined by the input of solar energy and the planet's movement in space

34.6 Regional climate influences the distribution of biological communities


• Most climatic variations are due to the uneven heating of Earth's surface

– This is a result of the variation in solar radiation at different latitudes

Figure 34.6A

Low angle ofincoming sunlight

Sunlight directlyoverhead

Low angle ofincoming sunlight

Atmosphere

North Pole

60º N

30º N

Tropic ofCancer

0º (equator)

30º S

60º S

South Pole

Tropic ofCapricorn


• The seasons of the year result from the permanent tilt of the plant on its axis as it orbits the sun

Figure 34.6B

JUNE SOLSTICE(Northern

Hemisphere tiltstoward sun)

MARCH EQUINOX(equator facessun directly)

DECEMBERSOLSTICE(Northern

Hemisphere tiltsaway from sun)

SEPTEMBEREQUINOX


• The tropics experience the greatest annual input and least seasonal variation in solar radiation

• The direct intense solar radiation near the equator has an impact on the global patterns of rainfall and winds


Figure 34.6C

Ascending

moist air

releases

moisture

Doldrums

TROPICS

30º23.5º 0º 23.5º

30º

Descendingdry airabsorbsmoisture

TEMPERATEZONE

Descendingdry airabsorbsmoisture

TEMPERATEZONE

Trade winds Trade winds


• Warm, moist air at the equator rises

• As the air rises, it cools and releases much of its water content

– This results in the abundant precipitation typical of most tropical regions

• After losing their moisture over equatorial zones, high altitude air masses spread away from the equator


• They cool and descend again at latitudes of about 30° north and south

– This explains the locations of the world's great deserts

• As the dry air descends, some of it spreads back toward the equator

– This creates the cooling trade winds that dominate the tropics


• Temperate zones are located between the tropics and the Arctic Circle in the north and the Antarctic Circle in the south – They have seasonal variations in

climate

– The temperatures are more moderate than in the tropic or polar regions


• Prevailing winds result from the combined effects of the rising and falling of air masses and Earth's rotation

– In the tropics, Earth's rapidly moving surface deflects vertically circulating air, making the winds blow from east to west

– In temperate zones, the slower-moving surface produces the westerlies, winds that blow from west to east

Figure 34.6D


• Ocean currents have a profound effect on regional climates by warming or cooling coastal areas

– They are created by winds, planet rotation, unequal heating of surface waters, and the locations and shapes of continents


• Local high temperatures for August 6, 2000, in Southern California

Figure 34.6E

Fresno100º

Pacific Ocean

Santa Barbara 73º

Los Angeles(Airport) 75º

Burbank90º

Bakersfield100º

Santa Ana84º

Riverside 96º

San Bernardino 100º

Palm Springs 106º

DeathValley119º

40 miles

San Diego 72º

Key

70s (ºF)

80s

90s

100s

110s


• Landforms, such as mountains, can affect local climate

Figure 34.6F

PacificOcean

CoastRange

Winddirection

CascadeRange

East


Fourth Edition






Modules 34.7 – 34.11


• Oceans cover about 75% of the Earth's surface

• Light and the availability of nutrients are the major factors that shape aquatic communities

34.7 Oceans occupy most of Earth's surface

AQUATIC BIOMES


• Estuaries are productive areas where rivers meet the ocean

– The saltiness of estuaries ranges from less than 1% to 3%

– They provide nursery areas for oysters, crabs, and many fishes

– They are often bordered by extensive coastal wetlands

Figure 34.7A


• The intertidal zone is the wetland at the edge of an estuary or ocean, where water meets land – Salt marshes, sand

and rocky beaches, and tide pools are part of the intertidal zone

– It is often flooded by high tides and then left dry during low tides

Figure 34.7B


• Abiotic conditions dictate the kinds of communities that ocean zones can support

Figure 34.7C

Intertidal zone

Continental zone

Benthiczone(seafloor)

Photiczone

Aphoticzone

Pelagiczone


• The pelagic zone is the open ocean

– It supports highly motile animals such as fishes, squids, and marine mammals

– Phytoplankton and zooplankton drift in the pelagic zone

• The benthic zone is the ocean bottom

– It supports a variety of organisms based upon water depth and light penetration


• The photic zone is the portion of the ocean into which light penetrates

– Photosynthesis occurs here

• The aphotic zone is a vast, dark region of the ocean

– It is the most extensive part of the biosphere

– Although there is no light, a diverse and dense population inhabits this zone


• Coral reefs are found in warm tropical waters above the continental shelf

– They support a huge diversity of invertebrates and fishes

• Coral reefs are easily degraded by

– pollution

– native and introduced predators

– human souvenir hunters

Figure 34.7D


• Lake and pond communities are shaped by

– light

– temperature

– the availability of nutrients and dissolved oxygen

34.8 Freshwater biomes include lakes, ponds, rivers, streams, and wetlands


• A river environment changes greatly between its source and its mouth

– Temperature, nutrients, currents, and water clarity vary at different points

Figure 34.8A


• Wetlands are among the richest biomes in terms of species diversity

Figure 34.8B


• Climatic differences, mainly temperature and rainfall, shape the major biomes that cover Earth's land surface

• Biomes tend to grade into each other

• Within each biome there is local variation

– This gives vegetation a patchy, rather than uniform, appearance

34.9 Terrestrial biomes reflect regional variations in climate

TERRESTRIAL BIOMES


• Major terrestrial biomes

Figure 34.9

30º N

Equator

30º S

Tropical forest

Savanna

Desert

Polar and high-mountain ice

Chaparral

Temperate grassland

Temperate deciduous forest

Coniferous forest

Tundra (arctic and alpine)


• Several types of tropical forests occur in the warm, moist belt along the equator

34.10 Tropical forests cluster near the equator

Figure 34.10


• The tropical rain forest is the most diverse ecosystem on Earth

• Large-scale human destruction of tropical rain forests continues to endanger many species

– It may also alter world climate


• The Luquillo Experimental Forest in Puerto Rico allows ecologists to study the effects of disruption on tropical forests

– It contains deforested as well as still-forested areas

34.11 Talking About Science: Ecologist Arial Lugo studies tropical forests in Puerto Rico

Figure 34.11B


• The forest ecologist Dr. Ariel Lugo has been one of the key scientists at the Luquillo Experimental Forest

– He and other scientists have offered valuable insight into the peril these forests face as well as the promise they hold

• Studies indicate that tropical forests recover from natural disasters much more readily than they do from human destruction

Figure 34.11A


Fourth Edition






Modules 34.12 – 34.18


• Drier, tropical areas and some nontropical areas are characterized by the savanna

34.12 Savannas are grasslands with scattered trees

Figure 34.12


• Deserts are the driest of all terrestrial biomes

– They are characterized by low and unpredictable rainfall

34.13 Deserts are defined by their dryness

Figure 34.13

– Desertification is a significant environmental problem


• The chaparral biome is a shrubland with cool, rainy winters and dry, hot summers

• Chaparral vegetation is adapted to periodic fires

34.14 Spiny shrubs dominate the chaparral

Figure 34.14


• Temperate grasslands are found in the interiors of the continents, where winters are cold

– Drought, fires, and grazing animals prevent trees from growing

– Farms have replaced most of North America's temperate grasslands

34.15 Temperate grasslands include the North American prairie

Figure 34.15


• Temperate deciduous forests grow where there is sufficient moisture to support the growth of large trees

– Nearly all of the original deciduous forests in North America have been drastically altered by agriculture and urban development

34.16 Deciduous trees dominate temperate forests

Figure 34.16


• The northern

coniferous forest, or taiga, is the largest terrestrial biome on Earth

34.17 Coniferous forests are often dominated by a few species of trees

Figure 34.17


• The taiga is characterized by long, cold winters and short, wet summers

• Coastal coniferous forests of the Pacific Northwest are actually temperate rain forests


• The arctic tundra lies between the taiga and the permanently frozen polar regions

– It is a treeless biome characterized by extreme cold, wind, and permafrost

– Permafrost is continuously frozen subsoil

34.18 Long, bitter-cold winters characterize the tundra

Figure 34.18

chapter 34 the biosphere: an introduction to earth's diverse environments

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