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- Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- Chapter 5
- Lecture
- Outline
- Learning Outcomes
- After studying this chapter, you should be able to answer the following
- questions:
- • What are nine major terrestrial biomes, and what
- environmental conditions control their distribution?
- • How does vertical stratification differentiate life zones in
- oceans?
- • Why are coral reefs, mangroves, estuaries, and wetlands
- biologically important?
- • What do we mean by biodiversity? List several regions of
- high biodiversity.
- • What are four major benefits of biodiversity?
- • What are the major human-caused threats to biodiversity?
- • How can we reduce these threats to biodiversity?
- 5-2
- In the end, we conserve only what we love.
- We will love only what we understand.
- We will understand only what we are taught.
- –Baba Dioum
- 5-3
- 5.1 Terrestrial Biomes
- • Biodiversity-the number and variety of
- species.
- • Biomes-broad types of biological communities
- with characteristic types of environments that
- occur in different conditions of temperature
- and precipitation.
- 5-4
- Figure 5.3 Biomes most likely to occur in the absence of human disturbance or other
- disruptions, according to average annual temperature and precipitation. Note: This
- diagram does not consider soil type, topography, wind speed, or other important
- environmental factors. Still, it is a useful general guideline for biome location.
- Source: Whitaker, Robert, C., Communities & Ecosystems, 2e. © 1975. Adapted by permission
- of Pearson Education, Inc., Upper Saddle River, NJ.
- 5-5
- 5-6
- • Vertical zonation
- is a term applied
- to vegetation
- zones defined by
- altitude.
- 5-7
- Annual temperature and precipitation
- levels in terrestrial biomes
- 5-8
- Tropical rainforests
- • Tropical
- rainforests
- occur where
- rainfall is
- abundant—
- more than 200
- cm (80 in.) per
- year—and
- temperatures
- are warm to
- hot year-round
- 5-9
- Tropical savannas and grasslands
- are dry most of the year
- • Where there is
- too little rainfall
- to support
- forests, we find
- open grasslands
- or grasslands
- with sparse tree
- cover, which we
- call savannas.
- 5-10
- Deserts are hot or cold, but always dry
- • Deserts occur
- where
- precipitation
- is uncommon
- and slight,
- usually with
- less than
- 5-11
- Temperate grasslands have rich soils
- • As in tropical
- latitudes,
- temperate
- (midlatitude)
- grasslands occur
- where there is
- enough rain to
- support abundant
- grass but not
- enough for forests
- 5-12
- Temperate forests
- can be evergreen or
- deciduous
- • These forests by are
- grouped by tree
- type, broad-leaved
- deciduous (losing
- leaves seasonally) or
- evergreen
- coniferous (cone-
- bearing).
- 5-13
- Temperate
- rainforests
- • The coniferous forests
- of the Pacific coast
- grow in extremely wet
- conditions. The
- wettest coastal forests
- are known as
- temperate rainforest,
- a cool, rainy forest
- often enshrouded in
- fog.
- 5-14
- Boreal forests lie north
- of the temperate zone
- 5-15
- Tundra can freeze
- in any month
- • Compared to other
- biomes, tundra has
- relatively low
- diversity.
- 5-16
- 5.2 Marine Ecosystems
- • Most marine communities depend on
- photosynthetic organisms.
- • Phytoplankton: algae or tiny, free-floating
- photosynthetic plants that often support a
- marine food web.
- 5-17
- Open ocean communities vary
- from surface to hadal zone
- 5-18
- Tidal shores support rich,
- diverse communities
- Coral reefs are among the best-known marine systems, because
- of their extraordinary biological productivity and their diverse
- and beautiful organisms
- 5-19
- Tidal shores continued: Mangroves
- Mangroves are a diverse group of salt-tolerant trees that grow
- along warm, calm marine coasts around the world
- 5-20
- Tidal shores continued:
- Estuaries & Salt Marshes
- Estuaries are bays where rivers empty into the sea, mixing fresh
- water with salt water. Salt marshes, shallow wetlands
- flooded regularly or occasionally with seawater, occur on
- shallow coastlines, including estuaries
- 5-21
- Tidal shores continued: Tide pools
- Tide pools are depressions in a rocky shoreline that are flooded
- at high tide but retain some water at low tide.
- 5-22
- 5.3 Freshwater Ecosystems: Lakes
- 5-23
- Freshwater Ecosystems continued:
- Wetlands
- 5-24
- Wetlands (swamps, marshes, &
- bogs) are shallow ecosystems in
- which the land surface is
- saturated or submerged at least
- part of the year.
- Freshwater Ecosystems continued:
- Streams & Rivers
- • Streams form wherever precipitation exceeds
- evaporation and surplus water drains from the
- land.
- • As streams collect water and merge, they form
- rivers.
- 5-25
- 5.4 Biodiversity
- • Biodiversity, the variety of living things.
- • Three kinds of biodiversity are essential to preserve
- ecological systems and functions:
- – genetic diversity is a measure of the variety of
- versions of the same genes within individual species
- – species diversity describes the number of different
- kinds of organisms within a community or
- ecosystem
- – ecological diversity means the richness and
- complexity of a biological community
- 5-26
- Increasingly, we identify species
- by genetic similarity
- • Species are distinct organisms that persist
- because they can produce fertile offspring.
- • The phylogenetic species concept, which
- identifies genetic similarity, allows for asexual
- organisms and sexually reproducing ones that
- don’t normally encounter each other.
- 5-27
- Biodiversity hot spots are
- rich and threatened
- 5-28
- 5.5 Benefits of Biodiversity
- • All of our food comes from other organisms
- – Many wild plant species could make important
- contributions to human food supplies.
- • Rare species provide important medicines
- – More than half of all prescriptions contain some
- natural products.
- • Biodiversity can support ecosystem stability
- • Biodiversity has aesthetic and cultural benefits
- 5-29
- 5.6 What Threatens Biodiversity?
- • Extinction, the elimination of a species, is a normal
- process of the natural world.
- • Threats to biodiversity:
- – Habitat destruction is the main threat
- – Fragmentation reduces habitat to small, isolated patches
- – Invasive species are a growing threat
- – Pollution poses many different types of risk
- – Human population growth
- – Overharvesting & commercial collection
- – Predator and pest control
- 5-30
- 5.7 Endangered Species
- Management and Biodiversity
- Protection
- • Hunting and fishing laws protect reproductive
- populations
- • The endangered species act protects habitat
- and species
- 5-31
- Endangered species act terminology
- • Endangered species are those considered in
- imminent danger of extinction
- • Threatened species are likely to become
- endangered, at least locally within the
- forseeable future.
- • Vulnerable species are naturally rare or have
- been locally depleted by human activities to a
- level that puts them at risk.
- 5-32
- Species Terminology
- • Keystone species are those with major effects on
- ecological functions and whose elimination would
- affect many other members of the biological
- community.
- • Indicator species are those tied to specific biotic
- communities or successional stages or environmental
- conditions.
- 5-33
- Species Terminology continued…
- • Umbrella species
- require large blocks of
- relatively undisturbed
- habitat to maintain
- viable populations.
- • Flagship species are
- especially interesting or
- attractive organisms to
- which people react
- emotionally.
- 5-34
- Controversy persists in species protection:
- • In 1995 the Supreme
- Court ruled that critical
- habitat—habitat
- essential for a species’
- survival—must be
- protected, whether on
- public or private land.
- • An important test of the
- ESA occurred in 1978 in
- Tennessee, when
- construction of the
- Tellico Dam threatened
- a tiny fish called the
- snail darter.
- 5-35
- 5-36
- Many countries have laws
- for species protection
- • Canada’s Committee on the Status of Endangered
- Wildlife in Canada (COSEWIC) of 1977 establishes
- rules for listing and protecting endangered species.
- • The European Union’s Birds Directive (1979) and
- Habitat Directive (1991).
- • Australia’s Endangered Species Protection Act (1992).
- • The Convention on Biological Diversity (1992) is an
- International agreement.
- • The Convention on International Trade in
- Endangered Species (CITES) of 1975.
- 5-37
- Habitat protection may be
- better than species protection
- • By focusing on populations already reduced to
- only a few individuals, we spend most of our
- conservation funds on species that may be
- genetically doomed no matter what we do.
- • It is time to focus on a rational, continent-
- wide preservation of ecosystems that
- supports maximum biological diversity rather
- than a species-by-species battle for the rarest
- or most popular organisms.
- 5-38
- Practice Quiz
- 1. Why did ecologists want to reintroduce wolves to Yellowstone
- Park? What goals did they have, and have their goals
- been achieved?
- 2. Describe nine major types of terrestrial biomes.
- 3. Explain how climate graphs (as in fig. 5.6) should be read.
- 4. Describe conditions under which coral reefs, mangroves,
- estuaries, and tide pools occur.
- 5. Throughout the central portion of North America is a large
- biome once dominated by grasses. Describe how physical
- conditions and other factors control this biome.
- 5-39
- Practice Quiz continued…
- 6. Explain the difference between swamps, marshes, and bogs.
- 7. How do elevation (on mountains) and depth (in water) affect
- environmental conditions and life-forms?
- 8. Figure 5.15 shows chlorophyll (plant growth) in oceans and
- on land. Explain why green, photosynthesizing organisms
- occur in long bands at the equator and along the edges of
- continents. Explain the very dark green areas and yellow/
- orange areas on the continents.
- 9. Define biodiversity and give three types of biodiversity
- essential in preserving ecological systems and functions.
- 5-40
- Practice Quiz continued…
- 10. What is a biodiversity “hot spot”? List several of them (see
- fig. 5.22).
- 11. How do humans benefit from biodiversity?
- 12. What does the acronym HIPPO refer to?
- 13. Have extinctions occurred in the past? Is there anything
- unusual about current extinctions?
- 14. Why are exotic or invasive species a threat to biodiversity?
- Give several examples of exotic invasive species (see fig. 5.27).
- 15. What is the Endangered Species Act? Describe some of the
- main arguments of its proponents and opponents.
- 16. What is a flagship or umbrella species? Why are they often
- important, even though they are costly to maintain?
- 5-41
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