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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
Why Is Biodiversity Important?
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
Why Is Biodiversity Important?
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
Is Earth’s Biodiversity Diminishing?
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
Is Earth’s Biodiversity Diminishing?
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
30.3 Is Earth’s Biodiversity Diminishing?
Extinction is a natural process, but rates have
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
30.3 Is Earth’s Biodiversity Diminishing?
Extinction is a natural process, but rates have
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
30.4 What Are the Major Threats to Biodiversity?
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
Global Warming Threatens Biodiversity
Fig. 30-10b
30.4 What Are the Major Threats to Biodiversity?
Global warming is associated with dramatic
changes for many species (continued)
– Warming waters causes bleaching of coral reefs,
leading to their death
Global Warming Threatens Biodiversity
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
30.6 Why Is Sustainability the Key to
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?
30.6 Why Is Sustainability the Key to
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