Biodiversity Issues - PowerPoint PPT Presentation

About This Presentation
Title:

Biodiversity Issues

Description:

Biodiversity Issues Chapter 12 * – PowerPoint PPT presentation

Number of Views:239
Avg rating:3.0/5.0
Slides: 80
Provided by: Darre104
Category:

less

Transcript and Presenter's Notes

Title: Biodiversity Issues


1
Biodiversity Issues
  • Chapter 12

2
Biodiversity Loss and Extinction
  • Biodiversity is a broad term used to describe the
    diversity of genes, species, and ecosystems in a
    region.
  • Extinction is the elimination of all the
    individuals of a particular species.
  • Natural and common event in the history of
    biological evolution.

3
Causes of Extinction
  • Local extinctions, although relatively common,
    indicate the future of a species is not
    encouraging.
  • As population is reduced in size, some of the
    genetic diversity is likely to be lost.
  • Species Likely to Go Extinct
  • Small, dispersed populations.
  • Successful breeding is difficult.

4
Table 12.1
5
Species Likely to Go Extinct
  • Organisms in small, restricted areas.
  • Environmental changes have large effect.
  • Specialized Organisms
  • Relying on constancy of few key factors.
  • Organisms at higher trophic Levels.
  • Low population sizes and reproductive rates.

6
Extinction as a Result of Human Activity
  • As human population grew, and tools became more
    advanced, the impact a single human could have on
    surroundings increased.
  • Environmental modifications allowed larger, dense
    human populations to arise.
  • At expense of previously existing ecosystems.
  • Nearly all earths surface has been affected in
    some way by human activity.

7
Describing Biodiversity
  • Genetic Diversity is a term used to describe the
    number of genes present in a population.
  • High genetic diversity indicates many different
    kinds of genes present in individuals of a
    population.
  • Low genetic diversity indicates nearly all
    individuals share the same genes.

8
Genetic Diversity
  • Influences on a Populations Genetic Diversity
  • Mutations
  • Introduce new genetic information into a
    population by modifying current genes.
  • Migration
  • Allows movement of genes from one population to
    another.
  • Sexual Reproduction
  • Generates new genetic combinations.

9
Influences on a Populations Genetic Diversity
  • Population Size
  • The smaller the population, the less genetic
    diversity it can contain.
  • Fewer variations for each characteristic.
  • Selective Breeding
  • Elimination of undesirable characteristics.
  • Domesticated Plants and Animals.

10
Species Diversity
  • Species diversity is a measure of the number of
    different species present in an area.
  • Species Richness - Number of different kinds of
    species.
  • Taxonomic Richness - Takes into account the
    number of different taxonomic categories of the
    species present.

11
Species Diversity
  • When humans exploit an area, they influence
    species diversity.
  • Convert natural ecosystems to human-managed
    ecosystems.
  • Harvest certain species for their use.
  • Specifically eliminate species that compete with
    desirable species.

12
Species Diversity
  • Estimates of actual number of species range from
    a few million to 100 million.
  • About 1.4 million species have been described.
  • Many species are naturally rare, and others live
    in areas difficult to reach.

13
Ecosystem Diversity
  • Ecosystem diversity is a measure of the number of
    kinds of ecosystems present in an area.
  • Many regions of the world appear to be quite
    uniform in terms of ecosystems.
  • Deserts
  • Each is different and has specific organisms
    typical to the region.
  • Local topographic conditions create unique
    patches of landscape.

14
The Value of Biodiversity
  • Value of Biological and Ecosystem Services
  • Humans rely on organic molecules produced by
    other organisms for food.
  • Vegetation holds soil together and protects
    watersheds.
  • Plants remove carbon dioxide from the atmosphere.
  • Decomposers recycle organic wastes.

15
The Value of Biodiversity
  • Choices between competing uses for ecosystems are
    often determined by economic values.
  • Value can be assigned to services provided by
    intact, functioning ecosystems.
  • Current estimate of 33 trillion per year.
  • Some resources are difficult to assign specific
    monetary value
  • Wildlife
  • Medicinal Plants

16
Ethical Values
  • A case can be made that all species have an
    intrinsic value and a fundamental right to exist.
  • Extinction is not necessarily bad, but
    human-initiated extinction is.
  • Experiencing natural landscapes and processes is
    an important human right.

17
Ethical Values
  • The values held by a person are typically shaped
    by experience.
  • As the shift from rural to urban continues, there
    is continual erosion of natural experiences that
    can shape the values of people.
  • Important in determining how society will
    approach threats to biodiversity.

18
Threats to Biodiversity
  • Four major human activities threaten to reduce
    biodiversity.
  • Habitat Loss
  • Overexploitation
  • Introduction of Exotic Species
  • Persecution of Pest Organisms

19
Causes of Extinction
20
Habitat Loss
  • World Conservation Union estimates that 80-90
    of threatened species are a result of habitat
    loss or fragmentation.
  • Habitat loss and fragmentation are thought to be
    a major cause of past extinctions.

21
Conversion to Agriculture
  • About 40 of worlds land surface converted to
    cropland and permanent pasture.
  • Most productive natural ecosystems are the first
    to be modified by humans.
  • Pressures to modify the environment are greatest
    in areas with high population density.

22
Forestry Practices
  • Originally, 1/2 of US, 3/4 of Canada, and almost
    all of Europe was originally forested.
  • Because of increasing human population growth,
    forested areas are under increasing pressure to
    provide wood products and agricultural land.
  • Deforestation

23
Changes in Forest Area
24
Managing Forest Ecosystems
  • Modern forest management involves a compromise
    that allows economic exploitation while
    maintaining some environmental values of the
    forest.
  • Forested areas effectively reduce erosion.
  • Loss of soil (nutrients) reduces soil fertility.
  • Road building in forests increases erosion.

25
Environmental Implications of Various Harvesting
Methods
  • Clear Cutting - Removal of all trees in an area.
    Economical but increases erosion, especially on
    steep slopes.
  • Patch-Work Clear Cutting - Clear cutting in
    small, unconnected patches preserves
    biodiversity.
  • Selective Harvesting - Single tree-harvesting.
    Not as economical, but reduces ecosystem damage.

26
Special Concerns About Tropical Deforestation
  • Tropical forests have greater species diversity
    than any other ecosystem.
  • Not easy to regenerate after logging due to poor
    soil characteristics.
  • Currently, few tropical forests are being managed
    for long-term productivity.

27
Special Concerns About Tropical Deforestation
  • Significantly reduces species diversity.
  • Impacts climate via lowered transpiration.
  • Deforested lands are easily eroded.
  • CO2 trap - Increased global warming.
  • Human population pressure is greatest in tropics,
    and still increasing.

28
Plantation Forestry
  • Many lumber companies maintain forest plantations
    as crops and manage them in the same way farmers
    manage crops.
  • Plant single species, even-aged forests of fast
    growing hybrid trees.
  • Competing species are controlled by fire and
    insects controlled by spraying.
  • Mature rate as low as 20 years (vs. 100).
  • Quality of lumber reduced.
  • Low species diversity and wildlife value.

29
Rangeland and Grazing Practices
  • Rangelands - Lands too dry to support crops, but
    receive enough precipitation to support grasses
    and drought-resistant shrubs.
  • Often used to raise low-density populations of
    domesticated, or semi-domesticated species.
  • Wildlife are usually introduced species.

30
Use of Rangelands
31
Rangeland and Grazing Practices
  • Conversion of rangelands by domesticated animals
    has major impacts on biodiversity.
  • Selective eating habits of livestock tend to
    reduce certain species of native plants and
    encourages others.
  • Important to regulate number of livestock on
    rangelands, especially in dry areas.
  • Desertification
  • Over-grazing
  • Firewood cutting

32
Desertification
33
Habitat Loss in Aquatic Ecosystems
  • In marine ecosystems, much of the harvest is
    restricted to shallow parts of the ocean where
    bottom-dwelling fish can be easily harvested.
  • Trawls and nets dragged along the bottom.
  • Habitat Damage
  • About 25 of catch is undesirable, and thus
    discarded.

34
Habitat Loss in Aquatic Ecosystems
  • Freshwater systems are often modified for
    navigation, irrigation, flood control, or power
    production.
  • May alter natural ecosystem and change numbers or
    kinds of aquatic organisms present.

35
Changes in World Marine Fish Harvests
36
Conversion to Urban and Industrial Uses
  • About 4.3 of U.S. land is developed as urban
    centers, industrial sites, and transportation
    infrastructure.
  • Large proportion covered with impermeable
    surfaces that prevent plant growth and divert
    rainfall.
  • Difficult to generalize impact of urban centers
    on a worldwide basis.
  • Trend is toward greater urbanization.

37
Overexploitation
  • According to World Conservation Union,
    overexploitation is responsible for over 30 of
    endangered animal species and 8 of endangered
    plant species.
  • World Wildlife Fund estimates illegal trade in
    wild animals globally produces 2 - 35 billion
    annually.
  • Already resulted in local extinctions.

38
Overfishing of Marine Fisheries
  • U.N. estimates 70 of worlds marine fisheries
    are over-exploited or are in danger of being
    fully exploited.
  • Amount of fish caught has remained relatively
    constant since 1989.
  • Commercial fishing industry has been attempting
    to market species previously regarded as
    unacceptable.

39
Aquaculture
  • Fish farming is becoming increasingly important
    as a source of fish production.
  • Currently, about 60 of all aquaculture
    production is from freshwater systems.
  • Problems
  • Nutrient overloads
  • Escape into natural waters
  • Land conversion

40
Unsustainable Harvest of Wildlife and Plants
  • Meat from wild animals is often referred to as
    bush meat.
  • Hunting of wildlife is a part of all subsistence
    cultures.
  • Wildlife Conservation Society estimates 70 of
    wildlife species in Asia and Africa and about 40
    of species in Latin America are being hunted
    unsustainably.
  • Endangered species such as chimpanzees and
    gorillas are often harvested.

41
Unsustainable Harvest of Wildlife and Plants
  • Harvest of living animals for the pet and
    aquarium trade is a significant problem.
  • Method of capture is often problematic.
  • Destruction of bird nests.
  • Toxins used to stun fish.
  • Wildlife are also hunted because parts of the
    animal may have particular value.
  • Ivory
  • Traditional Medicines

42
Introduction of Exotic Species
  • Some exotic introductions are purposeful, while
    others are accidental.
  • World Conservation union estimates about 30 of
    birds and 15 of plants are threatened because
    they are unable to successfully compete against
    invasive exotic species.

43
Introduction of Exotic Species
  • Introduction of disease has had considerable
    impact on American forests.
  • Chestnut Blight
  • Dutch Elm Disease
  • Various insects have had effect on ecosystem
    structure.
  • Asian Longhorned Beetle
  • Freshwater ecosystems greatly affected.
  • Zebra Mussel

44
Control of Pest Organisms
  • Systematic killing of certain organisms that
    interfere with human activities also results in
    reduced biodiversity.
  • Large Predators
  • Preyed on domestic animals.
  • Passenger Pigeons
  • Increased conversion of forested land.

45
Control of Pest Organisms
  • Predator and competitor control activities are
    still used in some special situations.
  • Generally not considered to be cost-effective in
    most cases.
  • Wolves in Northern areas are exception.
  • Control of cowbird populations have been used to
    enhance breeding success of Kirtlands Warblers.

46
What is Being Done to Preserve Biodiversity?
  • World Conservation Union (IUCN) estimates by the
    year 2000, at least 500,000 species of plants and
    animals have been exterminated.
  • IUCN classifies species in danger of extinction
    into four categories
  • Endangered
  • Vulnerable
  • Rare
  • Indeterminate

47
Legal Protection
  • Most interest in extinction prevention occurs in
    developed countries. Most vulnerable species
    already eliminated.
  • Less-developed and developing countries have both
    highest population growth and the majority of the
    worlds species.
  • More concerned with immediate needs of food and
    shelter than long-range issues such as species
    extinction.

48
Legal Protection
  • U.S. Endangered Species Act (ESA -1973)
  • Gave U.S. government jurisdiction over threatened
    and endangered species.
  • Directs that no activity by a government agency
    should lead to the extinction of an endangered
    species.
  • Directs government agencies to use whatever means
    necessary to preserve the species in question.

49
Legal Protection
  • Endangered Species - Very low populations, could
    become extinct in very near future.
  • Threatened Species - Could become extinct if a
    critical environmental factor is changed.
  • Preservation question ultimately becomes one of
    assigning value to the species.
  • Amendments to ESA have weakened ability of U.S.
    government to add new species to the list.

50
Legal Protection
  • Many areas in the world have had minimal human
    impact.
  • Some are remote and may have harsh environmental
    conditions.
  • Wilderness Act (1964) - Wilderness
  • An area where the earth and its community of
    life are un-trampled by man, where man himself is
    a visitor who does not remain.

51
Sustainable Management of Wildlife Populations
  • Habitat Analysis and Management
  • Animals have highly specific habitat requirements
    that change throughout the year.
  • Steps can be taken to alter habitat and improve
    species success.
  • Fire to eliminate poor habitats.
  • Kirtland Warblers - Jack Pine stands.

52
Population Assessment and Management
  • Game species are often managed so they do not
    exceed carrying capacity of their habitat.
  • Wildlife managers use population censuses to
    check if populations are within appropriate
    levels.
  • With suitable habitat most wild animals can
    maintain a sizeable population.
  • High reproductive capacities and heavy protection
    can cause very large populations.

53
Population Assessment and Management
  • Wildlife management often involves harvesting for
    sport and meat.
  • Hunting regulation is crucial.
  • Seasons usually occur in the fall to take
    advantage of surplus animals.
  • When populations get too small, artificial
    introductions can be implemented.
  • Native species for augmentation.
  • Non-native species for empty niches.

54
Managing a Wildlife Population
55
Special Issues with Migratory Animals
  • Migratory birds can travel thousands of
    kilometers.
  • North in Spring to reproduce.
  • South in Fall to escape cold temperatures.
  • International agreements necessary to maintain
    appropriate habitat.
  • Canada
  • United States
  • Mexico

56
Migration Routes for North American Waterfowl
57
Sustainable Management of Fish Populations
  • Coastal regions are most productive regions of
    the oceans.
  • Sunlight penetration - shallow - warm.
  • Nutrient deposition from land.
  • Wind/wave action stirs nutrients.
  • Fishing pressure is concentrated.
  • One of the major problems associated with the
    management of marine fisheries is achieving
    agreement on harvest limits.

58
Sustainable Management of Fish Populations
  • Humans have easy access to freshwater ecosystems.
  • Typically easier to regulate because of
    containment within a smaller political region.
  • Many N.A. freshwater fisheries are primarily
    managed for sport fishery.
  • Fisheries managers must balance
  • Sport fisheries
  • Commercial harvesters

59
Fig. 12.2
60
Fig. 12.3
61
Fig. 12.5
62
Fig. 12.7
63
Fig. 12.8
64
Fig. 12.9
65
Fig. 12.10
66
Fig. 12.11
67
Fig. 12.12
68
Fig. 12.14
69
Fig. 12.15a
70
Fig. 12.15b
71
Fig. 12.16
72
Fig. 12.17
73
Fig. 12.18
74
Fig. p.251
75
Fig. p.277
76
Table 12.2
77
Table 12.3
78
Table 12.4
79
Table 12.5
Write a Comment
User Comments (0)
About PowerShow.com