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Chapter Six (also chapter 3 and 4) Sustaining Biodiversity: the Ecosystem Approach


Chapter Six (also chapter 3 and 4) Sustaining Biodiversity: the Ecosystem Approach Geog415 Dr Ye Biological diversity (Biodiversity): earth s variety of genes ... – PowerPoint PPT presentation

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Title: Chapter Six (also chapter 3 and 4) Sustaining Biodiversity: the Ecosystem Approach

Chapter Six (also chapter 3 and 4)Sustaining
Biodiversity the Ecosystem Approach
  • Geog415
  • Dr Ye

  • Biological diversity (Biodiversity) earths
    variety of genes, species, ecosystems, and
    ecosystem processes
  • Genetic diversity the variety of genetic
    material within a species or a population
  • Species diversity the number of species present
    in a different habitat
  • Ecological diversity the variety of terrestrial
    and aquatic ecosystems found in an area or on the
  • Functional diversity the biological and chemical
    processes such as energy flow and matter cycling
    needed for the survival of species, communities,
    and ecosystems.

Earths major biomes
Climate and Biomes Latitude and elevation have a
similar impact on vegetation distribution
  • Ecological Succession the gradual change in
    species composition of a given area (during
    succession some species colonize an area and
    their population become more numerous, whereas
    population of other species decline and may even
  • 1. Primary succession gradual establishment of
    biotic communities on essentially lifeless ground
    where there is no soil in a terrestrial community
    or no bottom sediment in an aquatic community.

  • 2. Secondary succession a series of communities
    with different species can develop in places
    containing soil or bottom sediment.

Climax community dominated by a few long-lived
plant species and is in balance with its
Humans Impact on Biodiversity
  • We disturbed or degraded about half to 84 of the
    earths surface (excluding Antarctica and
    Greenland) by filling in wetlands, and converting
    grassland and forests to crop fields and urban
  • In U.S. at least 95 of virgin forests in the
    lower 48 states have logged for lumber and
    converted to agriculture, housing, industry, 98
    of tallgrass prairie in the Midwest and Great
    Plains have disappeared, and 99 of Californias
    native grassland and 85 of its original redwood
    forests are gone. More than half of countrys
    wetland have been destroyed.
  • Aquatic biodiversity has been degraded. 27 of
    the worlds diverse coral reefs have been
    severely damaged or eliminated. ¾ of the worlds
    200 commercially valuable marine fish species are
    either over-fished or fished to their estimated
    sustainable yield.

  • Why should we care about biodiversity?
  • Usefulness to us and other species
  • Values
  • Intrinsic value components of biodiversity,
    regardless of their usefulness to us
  • Instrumental value usefulness to us
  • Use value benefit u in the form of economical
    goods and services, ecological services,
    recreation, scientific information and preserving
    options for such use in the future
  • (2) nonuse values existence value (redwood
    forest, wilderness or endangered species, even if
    we will never see it or get direct use from it)
    Aesthetic value (people appreciate a tree, a
    forest, a wild species, a vista because of its
    beauty) bequest value (willingness of some
    people to pay to protect some forms of natural
    capital for use by future generations.

Public land in US
  • More than 1/3 of U.S. land consists of publicly
    owned national forests, resource lands, parks,
    wildlife refuges, and protected wilderness areas
    (no nation has set aside as much of its land for
    public use, resource extraction, enjoyment, and
    wildlife as has the U.S.)
  • Federal government manages roughly 35 of the
    countrys land that belongs to every American.
    About 93 of this federal public land is in
    Alaska, and another 22 is in western states.
  • Land Management systems
  • National Forest System 155 forests and 22
    grasslands managed by the U.S. Forest Service
    (USFS) and are used for logging, mining,
    livestock grazing, farming, oil and gas
    extraction, recreation, hunting, fishing, and
    conservation of wetland, soil, and wildlife
  • National Resource Lands managed by the Bureau of
    Land Management (BLM) and used primarily for
    mining, oil, and gas extraction, and livestock
  • National Wildlife Refuges 542 places, managed by
    U.S. Fish and Wildlife Service (USFWS). Protect
    habitats and breeding areas for waterfowls and
    big games to provide a harvestable supply for
    hunters, a few protected endangered species from
    extinction. Permitted activities in most
    refugees including hunting, trapping, fishing,
    oil and gas development, mining, logging,
    grazing, some military activities and farming.
  • National Park Systems managed by National Park
    Services (NPS) include 56 major parks and 331
    national recreation areas, monuments, memorials,
    battlefields, historic sites, parkways, trails,
    rivers, seashores, and lakeshores. Only camping,
    hiking, sport fishing, and boating can take place
    in the national parks, but sport hunting, mining
    and oil and gas drilling is allowed in National
    Recreation Areas.
  • National Wilderness Preservation system most
    restricted public lands of 630 road less areas.
    There areas lie within the national parks,
    national wildlife refugees, national forests, and
    national resource lands, and are managed by
    agencies in charge of these lands. Most of there
    areas a re open only for recreational activities
    such as hiking, sport fishing, camping, and no
    motorized boating.

  • Controversy of Public Land Management
  • Most conservation biologists, environmental
    economists, and many free market economists
    believe the 4 principles should govern the public
  • Protecting biodiversity, wildlife habitats, and
    the ecological functioning of public land
    ecosystems should be the primary goal
  • No one should receive subsidies or tax breaks for
    using or extracting resources in public lands (a
    user pay approach)
  • The American people deserve fair compensation for
    the use of their property
  • All users or extractors of resources on public
    lands should be fully responsible for any
    environmental damage they cause
  • Oppositions are from economists, developers, and
    resource extractors, they view public lands in
    terms of their usefulness in providing mineral,
    timber, and other resources and their ability to
    increase short-term economic growth. They have
    succeeded in blocking implementation of the 4
    principles (received 1 billion a year in
    subsides to privately owned mining, fossil fuel
    extraction, logging, and grazing interests using
    US public land).

Stresses on U.S. Public Parks
  • Biggest problem may be popularity
  • Noise
  • Congestion
  • Pollution
  • Damage or destruction to vegetation and wildlife
  • Repairs needed to trails and buildings

Managing and Sustaining Forests
  • Forests at least 10 tree covered land
  • It occupies about 30 of the earths land surface
    (excluding Greenland and Antarctica)
  • Types
  • old-growth forests uncut forests or regenerated
    forests that have not been seriously disturbed by
    human activities or natural disasters for at
    least several hundred years (Storehouses of
    biodiversity because they provide ecological
    niches for a multitude of wildlife species-22 of
    the worlds forests)
  • Second-growth forests a stand of trees resulting
    from secondary ecological succession after the
    trees in an area have been removed by human
    activities (clear-cutting or conversion to
    cropland) or by natural forces (fire, hurricanes,
    volcanic eruption about 76 worlds forests)
  • Tree plantation (tree farm) a managed tract with
    uniformly aged trees of one species that are
    harvested by clear-cutting as soon as they become
    commercially valuable (5 of the worlds forests
    and produce about 1/5 of the worlds commercial

  • Forest managements
  • Even-aged managements involves maintaining trees
    in a given stand at about the same age and size
    (industrial forestry), consists of one or two
    fast growing and economically desirable species
    that can be harvested every 6-10 years).
  • Uneven-aged management involved maintaining a
    variety of tree species in a stand with many ages
    and sizes, to foster natural regeneration
    (biologically diverse, long-tem sustainable
    production of high-quality timber selective
    cutting of individual mature or intermediate-aged
    trees, and multiple use of the forests for
    timber, wildlife, watershed protection, and
  • Study suggests that intensive but sustainable
    management of as little as 1/5 of the worlds
    forests (twice size of India) could meet the
    worlds current and future demand for commercial
    wood and fiber.
  • Deforestation temporary or permanent removal of
    large expanses of forests for agriculture or
    other uses.

  • Harmful effects of tree harvest (build roads for
    access and timber removal)
  • Increase erosion and sediment runoff into
    waterways, habitat fragmentation, and
    biodiversity loss, expose forests to invasion by
    nonnative pests, diseases and wildlife species
    opened access for farmers, miners, hunters, and
    off-road vehicle users, disqualify the land for
    protection as wilderness

Fig. 6-4, p. 116
Natural Capital Degradation Harmful
Environmental Effects of Deforestation
Fig. 6-5, p. 117
Fig. 6-6, p. 118
Animation Hubbard brook experiment
Video Forest fire
Status of the World Forests
  • Bad news
  • During past 800 years, human activities have
    reduced the earths original forest cover by
  • Worlds forests are being cleared and degraded at
    a rate of 0.3-0.8 a year, (mostly over tropical
  • Good news
  • Total area of many temperate forests in North
    America and Europe has increased slightly
    because of the reforestation from secondary
    ecological succession on cleared forest areas and
    abandoned croplands
  • Some of the cut areas of tropical forest have
    increased tree cover from re-growth and plating
    of tree plantations
  • Ecological restoration the process of repairing
    damage caused by humans to the biodiversity and
    dynamics of natural ecosystems. Examples
    replanting forests, restoring grasslands,
    restoring wetlands, reclaiming urban industrial
    areas (brown fields), reintroducing native
    species, removing invasive species, and freeing
    river flows by removing dams.

Solution Sustainable Forestry
Solutions Sustaining Tropical Forests
Solutions A Model Biosphere Reserve
Biodiversity hot spots areas rich in plant ant
animal species that are found nowhere else and
are in great danger of extinction or serious
ecological disruption.
Sustaining aquatic biodiversity
  1. Greatest marine biodiversity occurs in coral
    reefs, estuaries, and the deep-sea floor
  2. Biodiversity is higher near coasts than in the
    open sea because of the greater variety of
    producers, habitats, and nursery areas in coastal
  3. Biodiversity is higher in the bottom region of
    the ocean than in the surface region because of
    the greater variety of habitats and food sources
    on the ocean bottom

Human Activities Are Disrupting and Degrading
Aquatic Habitats
  • Major threats to marine systems
  • Coastal development
  • Overfishing
  • Runoff of nonpoint source pollution
  • Point source pollution
  • Habitat destruction (1/4 coral reefs damaged
    bottom habitats are degraded and destroyed by
    dredging operations and trawler boats)
  • Introduction of invasive species
  • Climate change from human activities
  • Pollution of coastal wetlands and estuaries

Solutions Managing Fisheries