chapter 30cf.linnbenton.edu/mathsci/bio/klockj/upload/ch.30 conserving... · dedicated to...

Chapter 30

Conserving Earth’s

Biodiversity

Chapter 30 At a Glance

What Is Conservation Biology?

Why Is Biodiversity Important?

Is Earth’s Biodiversity Diminishing?

What Are the Major Threats to Biodiversity?

How Can Conservation Biology Help Preserve

Biodiversity?

Why Is Sustainability the Key to Conservation?

30.1 What Is Conservation Biology?

Conservation biology is the branch of biology

dedicated to understanding and preserving

Earth’s biological diversity

Biodiversity is the amazing variety of living

organisms that inhabit Earth

Ecosystem Services

Fig. 30-1

Ecosystem services

Directly used substances

• food plants and animals • building materials • fiber and fabric materials • fuel • medicinal plants • oxygen replenishment

Indirect, beneficial services

• maintaining soil fertility • pollination • seed dispersal • waste decomposition • regulation of local climate • flood control • erosion control • pollution control • pest control • wildlife habitat • repository of genes

Ecosystem services: Practical uses for biodiversity – In 1997, an international team calculated that

ecosystem services provide $33 trillion in benefits to humanity yearly—twice the world’s gross national product

– The 2005 Millennium Ecosystem Assessment concluded that 60% of all Earth’s ecosystem services are being degraded and used in an unsustainable fashion

30.2 Why Is Biodiversity Important?

Erosion and flood control

– Plants block wind that blows away loose soil, and

their roots stabilize soil and enhance its capacity

to hold water, reducing soil erosion and flooding

–The consequences of destroying riverside

forest, marshes, and grasslands to farmland

can be seen in the massive flooding that

occurred along the Missouri River in 1993

Loss of Flood Control Services

Fig. 30-2


Climate regulation

– By providing shade, reducing temperature, and

serving as windbreaks, plant communities have

a major impact on local climates

30.2 Why Is Biodiversity Important?

Genetic resources

– Crop plants, such as corn, wheat, and apples, have wild

ancestors that humans have selectively bred to produce

modern domestic crops


Recreation

– In the United States, more than 450 million people visit national parks and protected refuges each year, and hundreds of millions more go to wildlife refuges and state parks

– Ecotourism, in which people travel to observe unique biological communities, is a rapidly growing industry and includes destinations such as:

– Tropical coral reefs

– Rain forests

– The Galapagos Islands

– The African savanna

– Antarctica

Ecotourism

Fig. 30-3


Biodiversity is crucial to the ability of ecosystems to provide many services, particularly when stressed

– Biodiversity might protect ecosystems by way of the “redundancy hypothesis,” which states that several species in a community may have functionally equivalent roles, but vary in their abilities to withstand different stresses


Biodiversity is crucial to the ability of ecosystems to provide many services, particularly when stressed

30.3 Is Earth’s Biodiversity Diminishing?

Extinction is a natural process, but rates have

risen dramatically

– The fossil record indicates that extinctions occur

naturally at a very slow rate, called the

background extinction rate

– However, the fossil record provides evidence

that five previous mass extinctions led to the

eradication of many species in a relatively short

time



risen dramatically (continued)

– Most biologists believe that human activities are

now causing a sixth mass extinction

– The current extinction rate is 100 to 1,000 times

the background rate predicted in the absence of

humans



risen dramatically (continued)

– As of 2008, there are 16,928 threatened species

–12% of all birds

–21% of all mammals

–31% of all amphibians

–5% of reptiles

IUCN Classification of Mammals

Fig. 30-5

30.4 What Are the Major Threats to Biodiversity?

Humanity is depleting the Earth’s ecological

capital

– Two major interrelated factors underlie the

worldwide decline in the Earth’s biodiversity

–The increasing use of resources to support

human beings

–The direct impact of human activities, such as

habitat destruction, overexploitation of wild

populations, invasive species, pollution, and

global warming


Humanity is depleting Earth’s ecological capital

(continued)

– The human ecological footprint estimates the

area of Earth’s surface required to produce the

resources we use and to absorb the wastes that

we generate, expressed in acres of average

productivity

–Biocapacity estimates the sustainable

resources and waste-absorbing capacity of

Earth


Humanity is depleting Earth’s ecological capital

(continued)

– In 2005, the biocapacity available for each of

Earth’s 6.5 billion people was 5.2 acres, but the

average human footprint was 6.7 acres

–Therefore, we exceeded biocapacity by almost

30%, meaning that we would need 1.3 Earths

to support humanity at 2005 consumption and

population levels

Human Demand Exceeds Earth’s Estimated

Biocapacity

Fig. 30-6

world biocapacity

human footprint


Humanity is depleting Earth’s ecological capital (continued)

– Countries vary enormously in the size of their ecological footprints, from 12 to 24 acres for the U.S., Europe, Canada, and Australia, to 1 to 2 acres for poor African countries


Human activities directly threaten biodiversity

– Humans threaten biodiversity in a number of

ways

–Habitat destruction

–Overexploitation

–Harmful interaction with invasive species

–Pollution

–Global warming

Habitat Destruction

Fig. 30-7

Habitat Fragmentation

Fig. 30-8


Habitat destruction is the most serious threat to biodiversity (continued)

– Preserves have been created to protect endangered species

– To be functional, a preserve much support a minimum viable population (MVP), the smallest isolated population that can persist in spite of natural events, including inbreeding, disease, fires, and floods


Invasive species displace native wildlife and disrupt

community interactions (continued)

– Islands are particularly vulnerable to invasive species

– The Hawaiian Islands have lost about 1,000 species

of plants and animals since their settlement by

humans, and has the highest number of threatened

species of any state, with 394


Invasive species displace native wildlife and

disrupt community interactions (continued)

– Lakes are also particularly vulnerable

–The Nile perch, introduced to Lake Victoria in

Africa for fishing, now threatens 200 other

species

Invasive Species Endanger Native Wildlife

Fig. 30-9


Global warming is an emerging threat to biodiversity

– The use of fossil fuels, coupled with deforestation, has substantially increased atmospheric CO2 levels

Global Warming Threatens Biodiversity

Fig. 30-10a


Global warming is associated with dramatic

changes for many species (continued)

– Insect pests previously killed by freezes may

spread and thrive, such as the pine bark beetle

that infests and kills lodgepole pines


Fig. 30-10b


Global warming is associated with dramatic

changes for many species (continued)

– Warming waters causes bleaching of coral reefs,

leading to their death


Fig. 30-10c

How Can Conservation Biology Help Preserve

Biodiversity?

Research in conservation biology can help to

devise strategies for conserving biodiversity

– The four goals of conservation biology are to:

–Understand the impact of human activities on

species, populations, communities, and

ecosystems

–Preserve and restore natural communities

–Reverse loss of biodiversity caused by human

activities

–Foster sustainable use of Earth’s resources

30.5 How Can Conservation Biology Help Preserve

Biodiversity?

Core reserves are protected natural areas that preserve all levels of biodiversity

– These areas exclude all but low-impact human activities

– Core reserves should be large enough to withstand storms, fires, and floods without losing species

30.5 How Can Conservation Biology Help Preserve

Biodiversity?

Corridors connect critical animal habitats

– An individual core reserve, however, is seldom

large enough to maintain biodiversity and

complex community interactions by itself

– Wildlife corridors, strips of protected land that

link core reserves, allow for the safe passage of

animals between habitats separated by human

activities, thereby increasing the effective size of

smaller reserves by connecting them

Corridors Connect Reserves

Fig. 30-11

core

reserve

core

reserve

small

reserve buffer zones

corridors

Wildlife Corridors Connect Habitats

Fig. 30-12

Allows development and

tourism, as well as sustainable

fishing, forestry, and agriculture

Allows research, education,

training, tourism, and

low-impact development

core

reserve

buffer

zone

transition

area

Protected; may allow

animal monitoring and

low-impact development

The Design of an Ideal Biosphere Reserve

Fig. 30-13

30.6 Why Is Sustainability the Key to

Conservation?

Biosphere Reserves provide models for conservation

and sustainable development (continued)

– Few sites adhere to the ideal Biosphere Reserve model,

but the Chihuahuan Desert Biosphere Reserve is an

innovative reserve, consisting of three separate reserves

– Big Bend National Park in Texas serves as the core

reserve

– The Jornada portion of the reserve, located in New

Mexico, is considered the buffer zone

– In Mexico, the Mapimi reserve serves as the transition

area

A Unique Biosphere Reserve

Fig. 30-14

Why Is Sustainability the Key to Conservation?

Sustainable agriculture preserves productivity with reduced impact on natural communities

– The greatest loss of natural habitat occurs when people convert natural ecosystems to farms

– Because farmers must produce large amounts of food at low cost, this can lead to unsustainable practices


Conservation?

– Two issues must be considered

– What should human lifestyles look like and what

technologies are appropriate to produce those

lifestyles in a sustainable way?

– How many people can Earth support, at what lifestyle?


Conservation?

Changes in lifestyle and use of appropriate

technologies are essential

– A minimal lifestyle must include:

–Adequate food and clothing

–Clean air and water

–Good health care and working conditions

–Educational and career opportunities

–Access to natural environments

Human Population Growth Threatens

Sustainability

Fig. 30-16

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