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 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 Fig. 30-1
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 world biocapacity human footprint Fig. 30-6
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 CO 2 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 core reserve buffer zones small reserve corridors core reserve Fig. 30-11
Wildlife Corridors Connect Habitats Fig. 30-12
The Design of an Ideal Biosphere Reserve core reserve Protected; may allow animal monitoring and low-impact development Allows research, education, training, tourism, and low-impact development buffer zone transition area Allows development and tourism, as well as sustainable fishing, forestry, and agriculture 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