56 lecture conservation

8/12/2019 56 Lecture Conservation

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LECTURE PRESENTATIONS

For CAMPBELL BIOLOGY, NINTH EDITIONJane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson

2011 Pearson Education, Inc.

Lectures by

Erin Barley

Kathleen Fitzpatrick

Conservation Biology and Global

Change

Chapter 56


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Overview: Striking Gold

Scientists have named and described 1.8 millionspecies

Biologists estimate 10100 million species exist

on Earth

Tropical forests contain some of the greatest

concentrations of species and are being

destroyed at an alarming rate

Humans are rapidly pushing many speciestoward extinction



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Figure 56.1


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Figure 56.2


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Conservation biology, whichseeks to preservelife, integrates several fields

Ecology

Physiology Molecular biology

Genetics

Evolutionary biology



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Concept 56.1: Human activities threaten

Earths biodiversity

Rates of species extinction are difficult to

determine under natural conditions

The high rate of species extinction is largely aresult of ecosystem degradation by humans

Humans are threatening Earths biodiversity



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Three Levels of Biodiversity

Biodiversity has three main components Genetic diversity

Species diversity

Ecosystem diversity



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Figure 56.3

Genetic diversityin a vole population

Species diversityin a coastalredwood ecosystem

Community andecosystem diversityacross thelandscape of

an entire region


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Genetic Diversity Genetic diversity comprises genetic variation

within a population and between populations



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Species Diversity Species diversity is the variety of species in an

ecosystem or throughout the biosphere

According to the U.S. Endangered Species Act

An endangered species is

in danger ofbecoming extinct throughout all or a significant

portion of its range

A threatened species is likely to become

endangered in the foreseeable future



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Conservation biologists are concerned aboutspecies loss because of alarming statistics

regarding extinction and biodiversity

Globally, 12% of birds, 21% of mammals, and

32% of amphibians are threatened with

extinction

Extinction may be local or global



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Figure 56.4Philippine eagle

Javan

rhinoceros

Yangtze River

dolphin


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Figure 56.4a

Philippine eagle


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Figure 56.4b

Yangtze River dolphin


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Figure 56.4c

Javan rhinoceros


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Ecosystem Diversity Human activity is reducing ecosystem diversity,

the variety of ecosystems in the biosphere

More than 50% of wetlands in the contiguous

United States have been drained and converted

to other ecosystems



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The local extinction of one species can have anegative impact on other species in an

ecosystem

For example, flying foxes (bats) are important

pollinators and seed dispersers in the Pacific

Islands


Fi 56 5


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Figure 56.5


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Benefits of Species and Genetic Diversity Species related to agricultural crops can have

important genetic qualities

For example, plant breeders bred virus-resistantcommercial rice by crossing it with a wild

population In the United States, 25% of prescriptions

contain substances originally derived from plants

For example, the rosy periwinkle contains

alkaloids that inhibit cancer growth


Figure 56 6


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Figure 56.6


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The loss of species also means loss of genes andgenetic diversity

The enormous genetic diversity of organisms has

potential for great human benefit



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Ecosystem Services Ecosystem services encompass all the

processes through which natural ecosystems

and their species help sustain human life

Some examples of ecosystem services

Purification of air and water

Detoxification and decomposition of wastes

Cycling of nutrients

Moderation of weather extremes



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Threats to Biodiversity

Most species loss can be traced to four majorthreats

Habitat destruction

Introduced species

Overharvesting

Global change



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Habitat Loss Human alteration of habitat is the greatest threat

to biodiversity throughout the biosphere

In almost all cases, habitat fragmentation and

destruction lead to loss of biodiversity

For example

In Wisconsin, prairie occupies


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Figure 56.7


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I ntroduced Species Introduced species are those that humans

move from native locations to new geographic

regions

Without their native predators, parasites, and

pathogens, introduced species may spread

rapidly

Introduced species that gain a foothold in a new

habitat usually disrupt their adopted community



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Sometimes humans introduce species byaccident

For example, the brown tree snake arrived in

Guam as a cargo ship stowawayand led to

extinction of some local species


Figure 56.8


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Figure 56.8

(a) Brown tree snake

(b) Kudzu

Figure 56.8a


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gu e 56 8a

(a) Brown tree snake


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Humans have deliberately introduced somespecies with good intentions but disastrous

effects

For example, kudzu was intentionally introduced

to the southern United States


Figure 56.8b


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g

(b) Kudzu


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Overharvesting Overharvesting is human harvesting of wild

plants or animals at rates exceeding the ability of

populations of those species to rebound

Large organisms with low reproductive rates are

especially vulnerable to overharvesting

For example, elephant populations declined

because of harvesting for ivory



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DNA analysis can help conservation biologistsidentify the source of illegally obtained animal

products

For example, DNA from illegally harvested ivory

can be used to trace the original population ofelephants to within a few hundred kilometers


Figure 56.9


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Overfishing has decimated wild fish populations For example, the North Atlantic bluefin tuna

population decreased by 80% in ten years


Figure 56.10


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Global Change Global change includes alterations in climate,

atmospheric chemistry, and broad ecological

systems

Acid precipitation contains sulfuric acid and nitric

acid from the burning of wood and fossil fuels



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Air pollution from one region can result in acidprecipitation downwind

For example, industrial pollution in the midwesternUnited States caused acid rain in eastern Canada

in the 1960s Acid precipitation kills fish and other lake-dwelling

organisms

Environmental regulations have helped to

decrease acid precipitation For example, sulfur dioxide emissions in the

United States decreased 31% between 1993 and2002


Figure 56.11


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Year

pH

1960 65 75 8070 85 90 95 2000 05 10

4.7

4.6

4.5

4.4

4.3

4.2

4.1

4.0


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Concept 56.2: Population conservation

focuses on population size, genetic diversity,

and critical habitat

Biologists focusing on conservation at the

population and species levels follow two mainapproaches

The small-population approach

The declining-population approach



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Small-Population Approach

The small-population approach studiesprocesses that can make small populations

become extinct



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The Extinction Vortex: Evolutionary

Implications of Small Population Size A small population is prone to inbreeding and

genetic drift, which draw it down an extinction

vortex

The key factor driving the extinction vortex is

loss of the genetic variation necessary to enable

evolutionary responses to environmental change

Small populations and low genetic diversity donot always lead to extinction


Figure 56.12


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Smallpopulation

GeneticdriftInbreeding

Lowerreproduction

Reduction inindividual

fitness andpopulationadaptability

Highermortality

Loss ofgenetic

variability

Smallerpopulation


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Case Study:The Greater Prair ie Chicken

and the Extinction Vortex Populations of the greater prairie chicken were

fragmented by agriculture and later found to

exhibit decreased fertility

To test the extinction vortex hypothesis, scientists

imported genetic variation by transplanting birds

from larger populations

The declining population rebounded, confirmingthat low genetic variation had been causing an

extinction vortex


Figure 56.13RESULTS


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(a) Population dynamics

(b) Hatching rate

Translocation

Year

Year

1970 19951975 1980 1985 1990

197074 907579 8084 8589 9397

200

150

100

90

80

7060

50

40

30

50

0

100

Num

bero

fm

alebirds

Eggs

hatc

he

d(%)

Figure 56.13a


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Translocation

Year1970 19951975 1980 1985 1990

RESULTS

200

150

50

0

(a) Population dynamics

100

Num

bero

fma

lebirds

Figure 56.13b


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(b) Hatching rateYear

197074 907579 8084 8589 9397

10090

80

70

60

50

40

30

Eggs

hatche

d(%)

RESULTS

Figure 56.13c


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Minimum Viable Population Size

Minimum viable population (MVP)is theminimum population size at which a species can

survive

The MVP depends on factors that affect a

populations chances for survival over aparticular time



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Effective Population Size

A meaningful estimate of MVP requiresdetermining the effective population size,

which is based on the populations breeding

potential



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Effective population size (Ne) is estimated by

where Nfand Nmare the number of females and

the number of males, respectively, that breed

successfully

Viability analysis is used to predict a populations

chances for survival over a particular time

interval

4NfNm

Nf+ N

m

Ne=



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Case Study:Analysis of Grizzly Bear

Populations One of the first population viability analyses was

conducted as part of a long-term study of grizzly

bears in Yellowstone National Park

It is estimated that a population of 100 bears

would have a 95% chance of surviving about 200

years

This grizzly population is about 400, but the Neisabout 100


Figure 56.14


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The Yellowstone grizzly population has lowgenetic variability compared with other grizzly

populations

Introducing individuals from other populations

would increase the numbers and geneticvariation



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Declining-Population Approach

The declining-population approach Focuses on threatened and endangered

populations that show a downward trend,

regardless of population size

Emphasizes the environmental factors thatcaused a population to decline



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Steps for Analysis and I ntervention

The declining-population approach involvesseveral steps

1. Confirm that the population is in decline

2. Study the speciesnatural history

3. Develop hypotheses for all possible causes of

decline

4. Test the hypotheses in order of likeliness

5. Apply the results of the diagnosis to manage forrecovery



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Case Study:Decline of the Red-Cockaded

Woodpecker Red-cockaded woodpeckers require living trees

in mature pine forests

These woodpeckers require forests with little

undergrowth

Logging, agriculture, and fire suppression have

reduced suitable habitat


Figure 56.15


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Red-cockaded woodpecker

(a) Forests with low undergrowth (b) Forests with high, dense undergrowth

Figure 56.15a


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(a) Forests with low undergrowth


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They have a complex social structure where onebreeding pair has up to four helperindividuals

Individuals often have a better chance of

reproducing by helping and waiting for an

available cavity, instead of excavating newcavities


Figure 56.15b


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(b) Forests with high, dense undergrowth

Figure 56.15c


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Red-cockaded

woodpecker


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Weighing Conflicting Demands

Conserving species often requires resolvingconflicts between habitat needs of endangered

species and human demands

For example, in the U.S. Pacific Northwest,

habitat preservation for many species is at oddswith timber and mining industries

Managing habitat for one species might have

positive or negative effects on other species



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Concept 56.3: Landscape and regional

conservation help sustain biodiversity

Conservation biology has attempted to sustain the

biodiversity of entire communities, ecosystems,

and landscapes

Ecosystem management is part of landscape

ecology, which seeks to make biodiversity

conservation part of land-use planning



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Landscape Structure and Biodiversity

The structure of a landscape can stronglyinfluence biodiversity



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Fragmentation and Edges

The boundaries, or edges, between ecosystemsare defining features of landscapes

Some species take advantage of edge

communities to access resources from both

adjacent areas


Figure 56.16


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(a) Natural edges

(b) Edges created by human activity

Figure 56.16a


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(a) Natural edges

Figure 56.16b


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(b) Edges created by human activity


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The Biological Dynamics of Forest FragmentsProject in the Amazon examines the effects of

fragmentation on biodiversity

Landscapes dominated by fragmented habitats

support fewer species due to a loss of speciesadapted to habitat interiors


Figure 56.17


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Corr idors That Connect Habitat Fragments

A movement corridor is a narrow strip ofquality habitat connecting otherwise isolatedpatches

Movement corridors promote dispersal and help

sustain populations In areas of heavy human use, artificial corridors

are sometimes constructed


Figure 56.18


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Establishing Protected Areas

Conservation biologists apply understanding ofecological dynamics in establishing protected

areas to slow the loss of biodiversity



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Preserving Biodiversity Hot Spots

A biodiversity hot spot is a relatively smallarea with a great concentration of endemic

species and many endangered and threatened

species

Biodiversity hot spots are good choices fornature reserves, but identifying them is not

always easy



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Designation of hot spots is often biased towardsaving vertebrates and plants

Hot spots can change with climate change


Video: Coral Reef

Figure 56.19
http://localhost/var/www/apps/conversion/tmp/scratch_7/56_19CoralReef_SV.mpg


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Terrestrial biodiversity

hot spots

Marine biodiversity

hot spots

Equator

Phil h f N R


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Philosophy of Nature Reserves

Nature reserves are biodiversity islands in a seaof habitat degraded by human activity

Nature reserves must consider disturbances as

a functional component of all ecosystems



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An important question is whether to create fewerlarge reserves or more numerous small reserves

One argument for large reserves is that large,far-ranging animals with low-density populations

require extensive habitats Smaller reserves may be more realistic and may

slow the spread of disease throughout apopulation


1000 50Figure 56.20


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Kilometers

WYOMING

MONTANA

MONTANA

IDAHO

IDAHO

WYOMING

Sho

R.

R.

Yellowstone

National

Park

Grand TetonNational Park Biotic boundary for

short-term survival;MVP is 50 individuals.

Biotic boundary forlong-term survival;MVP is 500 individuals.

Z d R


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Zoned Reserves

The zoned reserve model recognizes thatconservation often involves working inlandscapes that are largely human dominated

A zoned reserve includes relatively undisturbed

areas and the modified areas that surroundthem and that serve as buffer zones

Zoned reserves are often established asconservation areas

Costa Rica has become a world leader inestablishing zoned reserves


Nicaragua

C t

CARIBBEAN SEAFigure 56.21


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CostaRica

PACIFIC OCEAN

National park land

Buffer zone

(a) Zoned reserves in Costa Rica

(b) Tourists in one of Costa Ricas zoned reserves

Nicaragua CARIBBEAN SEAFigure 56.21a


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CostaRica

PACIFIC OCEAN

National park land

Buffer zone

(a) Zoned reserves in Costa Rica

Figure 56.21b


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(b) Tourists in one of Costa Ricas zoned reserves


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Some zoned reserves in the Fiji islands areclosed to fishing, which actually improves fishing

success in nearby areas

The United States has adopted a similar zoned

reserve system with the Florida Keys NationalMarine Sanctuary


Figure 56.22


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FLORIDAGULF OF MEXICO

Florida Keys NationalMarine Sanctuary

50 km

Figure 56.22a


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Concept 56 4: Earth is changing rapidly as


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Concept 56.4: Earth is changing rapidly as

a result of human actions

The locations of preserves today may beunsuitable for their species in the future

Human-caused changes in the environment

include Nutrient enrichment

Accumulation of toxins

Climate change

Ozone depletion


Nutrient Enrichment


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Nutrient Enrichment

In addition to transporting nutrients from onelocation to another, humans have added newmaterials, some of them toxins, to ecosystems

Harvest of agricultural crops exports nutrients

from the agricultural ecosystem Agriculture leads to the depletion of nutrients in

the soil

Fertilizers add nitrogen and other nutrients to the

agricultural ecosystem


Figure 56.23


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Critical load is the amount of added nutrientthat can be absorbed by plants withoutdamaging ecosystem integrity

Nutrients that exceed the critical load leach into

groundwater or run off into aquatic ecosystems Agricultural runoff and sewage lead to

phytoplankton blooms in the Atlantic Ocean

Decomposition of phytoplankton blooms causes

dead zonesdue to low oxygen levels


Figure 56.24


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Winter Summer

Figure 56.24a


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Winter

Figure 56.24b


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Summer

Toxins in the Environment


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Toxins in the Environment

Humans release many toxic chemicals,including synthetics previously unknown tonature

In some cases, harmful substances persist for

long periods in an ecosystem One reason toxins are harmful is that they

become more concentrated in successivetrophic levels

Biological magnificationconcentrates toxinsat higher trophic levels, where biomass is lower



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PCBs and many pesticides such as DDT aresubject to biological magnification inecosystems

Herring gulls of the Great Lakes lay eggs with

PCB levels 5,000 times greater than inphytoplankton


Figure 56.25


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Herring

gull eggs124 ppm

Lake trout4.83 ppm

Smelt1.04 ppm

Phytoplankton0.025 ppm

Zooplankton0.123 ppm

Conce

ntrationofPCB

s


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In the 1960s Rachel Carson brought attention tothe biomagnification of DDT in birds in her bookSilent Spring

DDT was banned in the United States in 1971

Countries with malaria face a trade-off betweenkilling mosquitoes (malarial vectors) andprotecting other species


Figure 56.26


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Greenhouse Gases and Global Warming


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Greenhouse Gases and Global Warming

One pressing problem caused by humanactivities is the rising level of atmospheric CO2


Rising Atmospher ic CO Levels


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Rising Atmospher ic CO2Levels

Due to burning of fossil fuels and other humanactivities, the concentration of atmospheric CO2has been steadily increasing

Most plants grow faster when CO2concentrations

increase C3plants (for example, wheat and soybeans) are

more limited by CO2than C4plants (for example,corn)


390

14.9

14.8

Figure 56.27


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Year

CO2

Temperature

CO

2concen

tra

tion

(ppm

)

Averageg

lobal

tempera

ture

(C)

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

380

370

360

350

340

330

320

310

300

14.7

14.6

14.5

14.4

14.3

14.2

14.1

14.0

13.9

13.8

13.7

13.6

How Elevated CO2 Levels Affect Forest


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How Elevated CO2Levels Affect Forest

Ecology: The FACTS-I Experiment

The FACTS-I experiment is testing howelevated CO2influences tree growth, carbonconcentration in soils, insect populations, soil

moisture, and other factors The CO2-enriched plots produced more wood

than the control plots, though less thanexpected

The availability of nitrogen and other nutrientsappears to limit tree growth and uptake of CO2


Figure 56.28


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The Greenhouse Effect and Climate


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The Greenhouse Effect and Climate

CO2, water vapor, and other greenhouse gasesreflect infrared radiation back toward Earth; thisis the greenhouse effect

This effect is important for keeping Earths

surface at a habitable temperature Increasing concentration of atmospheric CO2is

linked to increasing global temperature



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Climatologists can make inferences about pastenvironments and their climates

Pollen and fossil plant records reveal pastvegetation

CO2levels are inferred from bubbles trapped inglacial ice

Chemical isotope analysis is used to infer pasttemperature



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Northern coniferous forests and tundra show thestrongest effects of global warming

For example, in 2007 the extent of Arctic sea icewas the smallest on record

A warming trend would also affect thegeographic distribution of precipitation



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Many organisms may not be able to surviverapid climate change

Some ecologists support assisted migration,the translocation of a species to a favorable

habitat beyond its native range



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Global warming can be slowed by reducingenergy needs and converting to renewablesources of energy

Stabilizing CO2emissions will require an

international effort Recent international negotiations have yet to

reach a consensus on a global strategy toreduce greenhouse gas emissions

Reduced deforestation would also decreasegreenhouse gas emissions


Depletion of Atmospheric Ozone


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ep et o o t osp e c O o e

Life on Earth is protected from damaging effectsof UV radiation by a protective layer of ozonemolecules in the atmosphere

Satellite studies suggest that the ozone layer

has been gradually thinning since the mid-1970s


350

s)

Figure 56.29


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300

250

200

150

100

0

Year

O

zonelayerthickness(Do

bsons

1955 60 65 70 75 80 85 90 95 2000 05 10


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Destruction of atmospheric ozone results mainlyfrom chlorofluorocarbons (CFCs) produced byhuman activity

CFCs contain chlorine, which reacts with ozone

to make O2 This decreases the amount of ozone in the

atmosphere


Chlorine atom

Figure 56.30


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Chlorine atom

Sunlight

Chlorine

O2

CI2O2

O2

CIO

CIO

O3


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The ozone layer is thinnest over Antarctica andsouthern Australia, New Zealand, and South

America

Ozone levels have decreased 210% at mid-

latitudes during the past 20 years


Figure 56.31


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September 1979 September 2009

Figure 56.31a


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September 1979

Figure 56.31b


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September 2009


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Ozone depletion causes DNA damage in plantsand poorer phytoplankton growth

An international agreement signed in 1987 hasresulted in a decrease in ozone depletion


Concept 56.5: Sustainable development can


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p p

improve human lives while conserving

biodiversity

The concept of sustainability helps ecologists

establish long-term conservation priorities


Sustainable Biosphere Initiative


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p

Sustainable development is development that

meets the needs of people today without limiting

the ability of future generations to meet their

needs

The goal of the Sustainable Biosphere Initiativeis to define and acquire basic ecological

information for responsible development,

management, and conservation of Earths

resources



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Sustainable development requires connections

between life sciences, social sciences,

economics, and humanities


Case Study: Sustainable Development in


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y

Costa Rica

Costa Ricas conservation of tropical biodiversity

involves partnerships between the government,

nongovernmental organizations (NGOs), and

private citizens Human living conditions (infant mortality, life

expectancy, literacy rate) in Costa Rica have

improved along with ecological conservation


Life expectancy

Infant mortality

200 80

rths)

Figure 56.32


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y

1925 1950 1975 2000

150

100

50

0

70

60

50

40

30

Year

Infantmorta

lity(p

er

1,0

00live

bir

Lifeexpec

tancy

(yea

rs)

The Future of the Biosphere


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Our lives differ greatly from those of earlyhumans, who hunted and gathered and paintedon cave walls


Figure 56.33


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(a) Detail of animals in a 36,000-year-old cave painting,Lascaux, France

(b) A 30,000-year-old ivorycarving of a water bird,found in Germany

(d) A young biologist holdinga songbird

(c) Nature lovers on a wildlife-watching expedition

Figure 56.33a


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(a) Detail of animals in a 36,000-year-old

cave painting, Lascaux, France

Figure 56.33b


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(b) A 30,000-year-old ivory carving of a water bird, found in Germany

Figure 56.33c


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(c) Nature lovers on a wildlife-watching expedition

Figure 56.33d


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(d) A young biologist holding a songbird


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Our behavior reflects remnants of our ancestral

attachment to nature and the diversity of lifethe

concept of biophilia

Our sense of connection to nature may motivate

realignment of our environmental priorities

2011 Pearson Education, Inc. 2011 Pearson Education, Inc.

Figure 56.UN01


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Genetic diversity: source of variations that enablepopulations to adapt to environmental changes

Species diversity: important in maintaining structure

of communities and food webs

Ecosystem diversity: provides life-sustaining services

such as nutrient cycling and waste decomposition

Figure 56.UN02-1


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Figure 56.UN02-2


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