1. Sustainable Ecosystems
UNIT 1
Sustainable Ecosystems
Chapter 1: Nutrient Cycles and Energy Flow
Chapter 2: Populations and Sustainable Ecosystems
Chapter 3: Biodiversity

2. CHAPTER 3 Biodiversity In this chapter, you will:
discover that Earth’s biodiversity includes millions of species
explain the role of certain species within a community or ecosystem
describe how human activities can affect biodiversity
assess how invasive species affect an ecosystem
explain why biodiversity is important for the sustainability of ecosystems
Copyright © 2010 McGraw-Hill Ryerson Ltd.

3. Biodiversity in Canada
(Page 87)
How diverse are the types of organisms found across Canada?
How might you graphically represent the biodiversity that exists in Canada to others?
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4. 3.1 Measuring Biodiversity
(Page 89)
So far, scientists have identified about 2 million species of organisms on Earth. Estimates of the total number of species that exist range between 5 and 100 million. Biodiversity is the number and variety of organisms that are found within a specific region.
New species, such as the shark and the orchid pictured to the right, are constantly being discovered by scientists.
To maintain Earth’s biodiversity, species must be protected. Organisms listed as endangered or threatened must be legally guarded in order to ensure their survival.
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5. How Do Scientists Measure Biodiversity?
(Page 90)
Scientists use several methods to determine biodiversity.
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6. How Do Scientists Measure Biodiversity?
(Page 90)
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7. Documenting Biodiversity and Its Distribution
(Page 91)
Since most ecosystems are now influenced by human activities, it is helpful for land-use planners to know the locations of different species, especially rare or sensitive ones.
Biological collections housed in museums have helped ecologists catalogue Earth’s species. Computer databases can handle huge volumes of such records.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

8. Canada’s Biodiversity
(Page 91)
Canada, a large country with many aquatic and terrestrial ecosystems, is home to thousands of species. Plants, insects, fungi, and small invertebrates are far more diverse than larger animals. Canadians have a special responsibility to protect organisms such as the Peary caribou (shown below) that are found only in Canadian ecosystems.
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9. Hotspots of Biodiversity
(Page 92)
A biodiversity hotspot is a place where there is an exceptionally large number of species in a relatively small area.
Carolinian Canada and the Georgian Bay Biosphere Reserve are two biodiversity hotspots. These areas are 1% of Canada’s landmass, but they have the highest number of species of any Canadian ecosystems.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

10. Biodiversity in the Tropics
(Page 93)
Most of the biodiversity hotspots in the world are found in the tropics, which are areas near the equator in developing nations. Developing nations are less likely to have a workforce that has the specialists needed to fill the roles of environmental planners. Developed nations such as Canada are often involved in initiatives designed to help protect the key ecosystems in these regions.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

11. The Biodiversity Index
The biodiversity index for an area can be calculated by dividing the number of species in an area by the total number of organisms in the ecosystem. The closer the index is to 1, the higher the biodiversity of the ecosystem.
Click the “Start” button to review the calculation of a biodiversity index.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

12. Concepts to be reviewed:
Section 3.1 Review
(Page 94)
Concepts to be reviewed:
What does the biodiversity of an ecosystem represent?
What is the biodiversity of Earth?
What are the methods used to determine the biodiversity of an ecosystem?
What are areas of particularly high biodiversity called? Why must they be protected?
Copyright © 2010 McGraw-Hill Ryerson Ltd.

13. 3.2 Communities
(Page 95)
In addition to observing and recording data related to the biodiversity of ecosystems, ecologists also measure biodiversity at the more complex level of communities. A community is composed of all of the populations of different species that interact in a specific area or ecosystem.
Certain species have a greater impact on a community or ecosystem than others. These species can impact food chain interactions and/or change the physical nature of the environment.
Dominant and keystone species impact communities most.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

14. Dominant and Keystone Species
(Page 96)
Dominant species are species that are so abundant they have the biggest biomass of any community member. The removal of a dominant species can result in a decrease in biodiversity within an ecosystem. A species of plant is often the dominant species in an ecosystem.
A keystone species is a species that can greatly affect population numbers and the health of an ecosystem. Keystone species are generally not abundant, and they can be plants or animals.
The sea otter is a keystone species because it controls the sea urchin population, allowing the kelp to survive.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

15. Keystone Species and Captive Breeding
(Pages 96-7)
The prairie dog is an example of a keystone species. Prairie dogs are important to prairie ecosystems because they turn over tonnes of soil during their activities. This increases the nitrogen content of the soil, allowing deeper water penetration and thus increasing plant diversity.
When a keystone species such as the prairie dog has its numbers reduced, other species such as the black ferret, which rely on the burrows left by the prairie dogs, suffer.
Species that have disappeared or had their numbers reduced may be re-established through captive breeding programs. They are bred in controlled settings before release into the wild.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

16. Ecosystem Engineers and Succession
(Page 98)
Ecosystem engineers are species that cause such dramatic changes to landscapes that new ecosystems are created. For example, beavers create beaver-pond ecosystems that benefit many species of fish, birds, amphibians, and insects.
By building a dam, beavers can start a succession of different ecosystems. Succession is a series of ecosystem changes that occurs over time, following a disturbance.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

17. Concepts to be reviewed:
Section 3.2 Review
(Page 99)
Concepts to be reviewed:
What is a community? How do the species within them interact?
What roles are played by the dominant and keystone species within an ecosystem?
What are ecosystem engineers? What effect do they have on ecosystems, and how do these effects encourage succession?
Copyright © 2010 McGraw-Hill Ryerson Ltd.

18. 3.3 Threats to Biodiversity
(Page 100)
For most of modern history, humans went about their activities with little thought as to how they might affect biodiversity. As scientists learn more about the impacts of human activities on ecosystems, more attention is being paid to how the impacts can be minimized and to the restoration of ecosystems that were previously altered.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

19. Habitat Loss and Deforestation
(Page 101)
Habitat loss is the destruction of habitats, which usually results from human activities. Deforestation is one of the leading causes of habitat loss.
Deforestation results from the practice of clearing forests for logging or other human uses and never replanting them.
Natural sources of habitat destruction are events such as volcanic eruptions, wildfires, droughts, and severe storms such as hurricanes.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

20. Draining of Wetlands
(Page 102)
In Canada and around the world, the draining of wetlands is another major cause of habitat loss. Wetlands cover about 6% of Earth’s surface, and about 24% of the world’s wetlands are in Canada. Plants, turtles, snakes, minks, and thousands of other organisms live in wetlands. Wetlands are often drained for farming or for building homes and other buildings.
As scientists have learned more about the importance of wetland areas, more is being done to preserve and protect existing wetlands and restore ones that have been damaged by human activities.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

21. Alien and Invasive Species
(Pages 102-3)
Alien species are species that have either been accidentally or intentionally introduced into a new location. Most alien species are either harmless or beneficial to their new environments. Alien species can also be invasive.
Invasive species are species that can take over the habitats of native species or invade their bodies. In many cases, invasive species upset the equilibrium of an ecosystem, causing problems for native species.
The round goby competes with native fish for spawning areas and eats their eggs.
Zebra mussels have been linked to the decline of small crustaceans (the food of many fish).
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

22. Overexploitation
(Page 104)
Biodiversity is threatened when overexploitation occurs. Overexploitation is the use or extraction of a resource until it is depleted. The passenger pigeon disappeared in the early 1900s due to overhunting. The populations of Atlantic cod and yellowfin tuna have been reduced by 90% due to overfishing.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

23. Disrupting Connectivity Across Ecosystems
(Page 105)
Species in an ecosystem are interconnected in a variety of ways and often rely on each other for their survival. Reductions in the carrying capacity and biodiversity of an ecosystem can be linked to a decline in a single species.
Salmon populations in British Columbia are linked to the health of bear, wolf, eagle and crow populations. Up to 70% of the nitrogen in plants, trees, insects, birds, and bears in the temperate rainforest ecosystem comes from the Pacific Ocean via the salmon.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

24. Extinction Reduces Biodiversity
(Page 106)
Extinction occurs when all the individuals of a species have died. Species have existed and become extinct in both terrestrial and aquatic ecosystems for the entire history of life on Earth. For a species to avoid extinction and maintain a stable population, its birth and death rates must be equal over a long period of time.
Two patterns of natural extinction have been described in Earth’s history. Background extinction is apparent over long periods of time as ecosystems gradually change. Mass extinction results from a relatively sudden change to Earth’s ecosystems.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

25. Current Extinction Rates
(Page 108)
Fossil records indicate that throughout most of Earth’s history only background extinctions occurred. Some scientists estimate that the current rate of extinction is 100 to 1000 times higher than a normal background rate.
This current accelerated rate of extinction is considered to be a biodiversity crisis.
Scientists hypothesize that the current crisis resulted from the actions of humans. Activities such as deforestation, habitat destruction, and air and water pollution are changing the abiotic and biotic conditions in ecosystems.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

26. Concepts to be reviewed:
Section 3.3 Review
(Page 109)
Concepts to be reviewed:
What is biodiversity? What are the current threats to biodiversity?
How does deforestation and the draining of wetlands affect biodiversity?
What patterns of extinction have occurred throughout Earth’s history?
How can human activities accelerate the rate of extinction?
Copyright © 2010 McGraw-Hill Ryerson Ltd.

27. 3.4 Restoration Ecology
(Page 110)
Environmental stewardship is the active assumption of responsibility for the welfare of the environment. There are both ethical and practical reasons for practicing environmental stewardship.
The ethical reasons for environmental stewardship are moral, and the practical reasons deal with protecting and preserving Earth’s ecosystems for other human beings and for future generations.
If too much damage is done to Earth’s ecosystems, they will lose their ability to sustain the species that rely on them, including humans.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

28. Restoring Altered Ecosystems
(Page 111)
Restoration ecology relates to the renewal of degraded or destroyed ecosystems through human intervention. The goal of restoration ecology is to stimulate natural processes of regeneration to produce an ecosystem that is at least sustainable, if not identical, to the original non-damaged ecosystem.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

29. Restoration Methods
(Page 112)
Restoration ecologists use many techniques to restore sustainable ecosystems.
Reforestation is the regrowth of a forest, either through natural processes or through the planting of seeds or trees in an area where a forest was cut down.
Images A though B show the stages of reforestation from logging to re-planting to natural succession.
Wetland restoration involves returning areas to their previous wetland state from a soil, water, and plant standpoint. Water control structures are used by wetland conservationists to help restore and maintain water levels.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

30. Controlling Alien Species
(Pages 113-4)
Being able to control the spread of an alien species is an important part of maintaining sustainable ecosystems. Biocontrol and chemicals are two methods used by ecologists to achieve this.
Biocontrol involves the use of a species to control the population growth or spread of an undesirable species.
A European fly called a parasitoid was introduced to regulate the European gypsy moth population.
Chemical control involves using chemicals such as pesticides or poisons to control the population of an undesirable species. An example would be using poison to control a rat population that was harming local bird populations off the coast of British Columbia.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

31. Bioremediation and Bioaugmentation
(Page 115)
Bioremediation is the use of living organisms to clean up contaminated areas. It involves the use of plants that can clean the soils at toxic sites by collecting poisons in their tissues as they grow.
Restoration ecology has developed tremendously, but many challenges, such as restoration of the tar sands, remain.
Bioaugmentation involves the use of organisms to add essential nutrients to depleted soils. Clover is often planted to replenish nitrogen levels in soil.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.

32. Concepts to be reviewed:
Section 3.4 Review
(Page 116)
Concepts to be reviewed:
What are the various methods used by restoration ecologists? How do they work?
How can restoration techniques offset problems related to the flow of nutrients in ecosystems due to human activities?
What are alien species? Why is it difficult to eradicate them?
What challenges will be faced when attempting to restore damage done to ecosystems such as the Alberta tar sands?
Copyright © 2010 McGraw-Hill Ryerson Ltd.