Sustaining Biodiversity: The Ecosystem Approach

1
Sustaining Biodiversity The Ecosystem Approach

• Chapter 9

2
What are the major threats to forest ecosystems?

• Section 9-1

3
Forests vary in their age, make-up, and origins

• Natural and planted forests occupy about 30 of
  the earths land surface (excluding Greenland and
  Antarctica).
• Two major types based on their age and structure
• Old growth forest Uncut or regenerated primary
  forest that has not been seriously disturbed by
  human activities or natural disasters for several
  hundred years or more.
• Second-growth forest A stand of trees resulting
  from secondary ecological succession that
  develops after the trees in an area have been
  removed by human activities such as clear-cutting
  for timber or cropland or by natural forces such
  as fire, hurricanes, or volcanic eruption.

4
Forests vary in their age, make-up, and origins

• A tree plantation (tree farm, commercial forest),
  is a managed tract with uniformly aged trees of
  one or two genetically uniform species that
  usually are harvested by clear-cutting as soon as
  they become commercially valuable.
• Forests provide important economic and ecological
  services.
• Forests remove CO2 from the atmosphere and store
  it in organic compounds (biomass) through
  photosynthesis.
• Forests help to stabilize the earths temperature
  and slow projected climate change.

5
The short rotation cycle of cutting and regrowth
of a monoculture tree plantation
6
Weak trees removed
25 yrs
Clear cut
30 yrs
15 yrs
Years of growth
Seedlings planted
5 yrs
10 yrs
Fig. 9-3a, p. 176
7
Forests provide many important economic and
ecological services
8
Unsustainable logging is a major threat to forest
ecosystems

• The first step in harvesting trees is to build
  roads for access and timber removal, but they can
  cause the following problems
• Increased erosion and sediment runoff into
  waterways.
• Habitat fragmentation.
• Loss of biodiversity.
• Forest exposure to invasion by nonnative pests,
  diseases, and wildlife species.

9
Unsustainable logging is a major threat to forest
ecosystems

• Methods of harvesting trees
• Selective cutting.
• Clear-cut.
• Strip cutting.

10
Three major tree harvesting methods
11
(a) Selective cutting
Clear stream
Fig. 9-6a, p. 179
12
(b) Clear-cutting
Muddy stream
Fig. 9-6b, p. 179
13
(c) Strip cutting
Cut 1 year ago
Uncut
Dirt road
Cut 310 years ago
Uncut
Clear stream
Fig. 9-6c, p. 179
14
Aerial view showing clear-cut logging, Washington
state
15
Fire can threaten or benefit forest ecosystems

• Surface fires usually burn only undergrowth and
  leaf litter on the forest floor.
• Kills seedlings and small trees but spares most
  mature trees and allows most wild animals to
  escape.
• Burns away flammable ground material and may help
  to prevent more destructive fires.
• Frees valuable mineral nutrients tied up in
  slowly decomposing litter and undergrowth.

16
Fire can threaten or benefit forest ecosystems

• Releases seeds from the cones of lodgepole pines.
• Stimulates the germination of certain tree seeds
  (e.g. giant sequoia and jack pine).
• Helps to control tree diseases and insects.
• Crown fires are extremely hot fires that leap
  from treetops, burning whole trees.
• Can destroy most vegetation, kill wildlife,
  increase soil erosion, and burn or damage human
  structures in their paths.

17
Surface fires and crown fires
18
Almost half of the worlds forests have been cut
down

• Deforestation is the temporary or permanent
  removal of large expanses of forest for
  agriculture, settlements, or other uses.
• Human activities have reduced the earths
  original forest cover by about 46, with most of
  this loss occurring in the last 60 years.
• If current deforestation rates continue, about
  40 of the worlds remaining intact forests will
  have been logged or converted to other uses
  within two decades, if not sooner.

19
Almost half of the worlds forests have been cut
down

• Clearing large areas of forests, especially
  old-growth forests, has important short-term
  economic benefits, but it also has a number of
  harmful environmental effects.
• The net total forest cover in several countries
  changed very little or even increased between
  2000 and 2007. Some due to natural reforestation
  by secondary ecological succession on cleared
  forest areas and abandoned croplands, or the
  spread of tree plantations.
• Concern about the growing amount of land occupied
  by commercial tree plantations, because
  replacement of old-growth forests by these
  biologically simplified tree farms represents a
  loss of biodiversity, and possibly of stability,
  in some forest ecosystems.

20
Harmful effects of deforestation
21
CASE STUDY Many Cleared Forests in the United
States Have Grown Back

• Forests that cover about 30 of the U.S. land
  area provide habitats for more than 80 of the
  countrys wildlife species and supply about
  two-thirds of the nations surface water.
• Today, forests in the U.S. cover more area than
  they did in 1920, primarily due to secondary
  succession.
• Every year, more wood is grown in the U.S. than
  is cut and the total area planted with trees
  increases.
• Protected forests make up about 40.
• Since the mid-1960s, an increasing area of the
  nations remaining old-growth and fairly diverse
  second-growth forests has been cut down and
  replaced with biologically simplified tree
  plantations.

22
Forest cover in the U.S.
23
Tropical forests are disappearing rapidly

• Tropical forests cover about 6 of the earths
  land area.
• At least half of the worlds known species of
  terrestrial plants and animals live in tropical
  forests.
• Brazil has more than 30 of the worlds remaining
  tropical rain forest in its vast Amazon basin.
• At the current rate of global deforestation, 50
  of the worlds remaining old-growth tropical
  forests will be gone or severely degraded by the
  end of this century.

24
Causes of tropical deforestation are varied and
complex

• There are a number of interconnected underlying
  and direct causes.
• Pressures from population growth and poverty,
  push subsistence farmers and the landless poor
  into tropical forests, where they try to grow
  enough food to survive.
• Government subsidies can accelerate the direct
  causes such as logging and ranching by reducing
  the costs of timber harvesting, cattle grazing,
  and the creation of vast plantations of crops
  such as soybeans.

25
Causes of tropical deforestation are varied and
complex

• Tropical forests in the Amazon and other South
  American countries are cleared/burned for cattle
  grazing and large soybean plantations.
• In Southeast Asia, tropical forests are being
  replaced with vast plantations of oil palm, whose
  oil is used in cooking, cosmetics, and biodiesel
  fuel for motor vehicles.
• In Africa, people struggle to survive by clearing
  plots for small-scale farming and by harvesting
  wood for fuel, which is causing deforestation on
  that continent.

26
Major underlying and direct causes of the
destruction and degradation of tropical forests
27
How should we manage and sustain forests?

• Section 9-2

28
We can manage forests more sustainably

• Certification of sustainably grown timber and of
  sustainably produced forest products can help
  consumers.
• Removing government subsidies and tax breaks that
  encourage deforestation would also help.

29
Ways to grow and harvest trees more sustainably
30
We can improve the management of forest fires

• In the United States, the Smokey Bear educational
  campaign has
• prevented countless forest fires, saved many
  lives and prevented billions of dollars in loss
  of trees, wildlife, and human structures.
• convinced the public that all forest fires are
  bad and should be prevented or put out.
• Trying to prevent all forest fires can make
  matters worse by increasing the likelihood of
  destructive crown fires due to the accumulation
  of highly flammable underbrush and smaller trees
  in some forests.

31
We can improve the management of forest fires

• Strategies for reducing fire-related harm
• Prescribed burns are small, contained surface
  fires to remove flammable small trees and
  underbrush in the highest-risk forest areas.
• Allow some fires on public lands to burn, thereby
  removing flammable underbrush and smaller trees,
  as long as the fires do not threaten human
  structures and life. Protect houses/buildings in
  fire-prone areas by thinning a zone of about 60
  meters (200 feet) around them and eliminating the
  use of flammable building materials such as
  wooden shingles.
• Thin fire-prone areas by clearing small
  fire-prone trees and underbrush under careful
  environmental controls.

32
We can reduce the demand for harvested trees

• Reduce inefficient use of construction materials,
  excess packaging, overuse of junk mail,
  inadequate paper recycling, and failure to reuse
  or find substitutes for wooden shipping
  containers.
• Paper can be made from fiber that does not come
  from trees.

33
Ways to reduce tropical deforestation

• Debt-for-nature swap can make it financially
  attractive for countries to protect their
  tropical forests.
• Conservation concessions occur when governments
  or private conservation organizations pay nations
  for agreeing to preserve their natural resources.

34
Ways to reduce tropical deforestation

• Consumers can reduce the demand for products that
  are supplied through illegal and unsustainable
  logging in tropical forests.
• For building projects, use recycled waste lumber
  or wood alternatives, such as recycled plastic
  building materials and bamboo.
• Reduce the use of throwaway paper products and
  replace them with reusable plates, cups, and
  cloth napkins and handkerchiefs.
• Individuals can plant trees.

35
Ways to protect tropical forests and use them
more sustainably
36
How should we manage and sustain grasslands?

• Section 9-3

37
Some rangelands are overgrazed

• Grasslands provide many important ecological
  services, including soil formation, erosion
  control, nutrient cycling, storage of atmospheric
  carbon dioxide in biomass, and maintenance of
  biodiversity.
• Rangelands are unfenced grasslands in temperate
  and tropical climates that supply forage, or
  vegetation, for grazing (grass-eating) and
  browsing (shrub-eating) animals.

38
Some rangelands are overgrazed

• Livestock also graze in pastures, which are
  managed grasslands or enclosed meadows usually
  planted with domesticated grasses or other
  forage.
• Overgrazing occurs when too many animals graze
  for too long and exceed the carrying capacity of
  a rangeland area.
• Limited data from surveys in various countries
  indicate that overgrazing by livestock has caused
  a loss in productivity in as much as 20 of the
  worlds rangeland.

39
Left of fence overgrazed landRight lightly
grazed land
40
We can manage rangelands more sustainably

• Control the number of grazing animals and the
  duration of their grazing in a given area so the
  carrying capacity of the area is not exceeded.
• Rotational grazing confine cattle to one area
  via portable fencing for a short time (12 days)
  and then moved.
• Provide supplemental feed at selected sites and
  strategically locate water holes and tanks and
  salt blocks to reduce overgrazing.
• Suppress the growth of unwanted invader plants by
  use of herbicides, mechanical removal, or
  controlled burning or use controlled, short-term
  trampling by large numbers of livestock.

41
Restoration via secondary ecological succession
42
How should we manage and sustain parks and nature
reserves?

• Section 9-4

43
National parks face many environmental threats

• More than 1,100 major national parks are located
  in more than 120 countries.
• Most too small to sustain many large animal
  species.
• Many parks suffer from invasions by nonnative
  species that compete with and reduce the
  populations of native species.
• Some parks are so popular that large numbers of
  visitors are degrading the natural features that
  make them attractive.
• Parks in less-developed countries have the
  greatest biodiversity of all parks, but only
  about 1 of these parklands are protected.

44
CASE STUDY Stresses on U.S. Public Parks

• The U.S. national park system, established in
  1912, includes 58 major national parks, along
  with 335 monuments and historic sites. States,
  counties, and cities also operate public parks.
• Popularity is one of the biggest problems. Noisy
  and polluting vehicles degrade the aesthetic
  experience for many visitors, destroy or damage
  fragile vegetation, and disturb wildlife.
• Many suffer damage from the migration or
  deliberate introduction of nonnative species.
• Native speciessome of them threatened or
  endangeredare killed or removed illegally.

45
Nature reserves occupy only a small part of the
earths land

• As of 2010, less than 13 of the earths land
  area was strictly or partially protected in
  nature reserves, parks, wildlife refuges,
  wilderness, and other areas.
• No more than 5 of the earths land is strictly
  protected from potentially harmful human
  activities.
• Conservation biologists call for full protection
  of at least 20 of the earths land area in a
  global system of biodiversity.
• Developers and resource extractors oppose
  protection and contend that these areas might
  contain valuable resources that would add to
  current economic growth.

46
Nature reserves occupy only a small part of the
earths land

• Ecologists and conservation biologists view
  protected areas as islands of biodiversity and
  natural capital that help to sustain all life and
  economies and serve as centers of evolution.
• The buffer zone concept strictly protects an
  inner core of a reserve and establishes buffer
  zones in which local people can extract resources
  sustainably without harming the inner core.
• By 2010, the United Nations had used this
  principle to create a global network of 553
  biosphere reserves in 109 countries.

47
CASE STUDY Costa RicaA Global Conservation
Leader

• Tropical forests once completely covered Costa
  Rica, but between 1963 and 1983 much of the
  countrys forests were cleared to graze cattle.
• Costa Rica is a superpower of biodiversity, with
  an estimated 500,000 plant and animal species.
• Costa Rica now has a system of nature reserves
  and national parks that, by 2010, included about
  a quarter of its land.
• Costa Rica now devotes a larger proportion of its
  land to biodiversity conservation than does any
  other country

48
CASE STUDY Costa RicaA Global Conservation
Leader

• The countrys largest source of income is its
  1-billion-a-year tourism industry, almost
  two-thirds of which involves ecotourism.
• To reduce deforestation, the government has cut
  subsidies for converting forest to rangeland.
• The government pays landowners to maintain or
  restore tree cover.
• Between 2007 and 2008, the government planted
  nearly 14 million trees.
• Went from having one of the worlds highest
  deforestation rates to having one of the lowest.

49
Costa Ricas eight megareserves
50
Nicaragua
Caribbean Sea
Costa Rica
Panama
Pacific Ocean
National parkland
Buffer zone
Fig. 9-20, p. 191
51
Protecting wilderness is an important way to
preserve biodiversity

• One way to protect undeveloped lands is to set
  them aside as wilderness, land officially
  designated as an area where natural communities
  have not been seriously disturbed by humans and
  where human activities are limited by law.
• Some critics oppose protecting large areas for
  their scenic and recreational value for a
  relatively small number of people.
• Conservation biologists support protecting
  wilderness in order to preserve biodiversity and
  as centers for evolution.

52
CASE STUDY Controversy over Wilderness
Protection in the United States

• Conservationists have been trying to save wild
  areas from development since 1900.
• The Wilderness Act (1964) allowed the government
  to protect undeveloped tracts of public land from
  development as part of the National Wilderness
  Preservation System.
• Only about 2 of the land area of the lower 48
  states is protected, most of it in the West.

53
What is the ecosystem approach to sustaining
biodiversity?

• Section 9-5

54
Here are four ways to protect ecosystems

• Most biologists and wildlife conservationists
  believe that the best way to keep from hastening
  the extinction of wild species through human
  activities is the ecosystems approach, which
  protects threatened habitats and ecosystem
  services.

55
Here are four ways to protect ecosystems

• Four-point plan of the ecosystems approach
• Map the worlds terrestrial and aquatic
  ecosystems and create an inventory of the species
  contained in each of them and the ecosystem
  services they provide.
• Locate and protect the most endangered ecosystems
  and species, with emphasis on protecting plant
  biodiversity and ecosystem services.
• Seek to restore as many degraded ecosystems as
  possible.

56
Protecting global biodiversity hotspots is an
urgent priority

• Some biodiversity scientists urge adoption of an
  emergency action strategy to identify and quickly
  protect biodiversity hotspots, areas especially
  rich in plant species that are found nowhere else
  and are in great danger of extinction .
• These hotspots cover only a little more than 2
  of the earths land surface, they contain an
  estimated 50 of the worlds flowering plant
  species and 42 of all terrestrial species.
• These hotspots are home for a large majority of
  the worlds endangered or critically endangered
  species, and one-fifth of the worlds population.

57
Biodiversity hotspots
58
We can rehabilitate and restore ecosystems that
we have damaged

• Almost every natural place on the earth has been
  affected or degraded to some degree by human
  activities.
• We can at least partially reverse much of this
  harm through ecological restoration the process
  of repairing damage caused by humans to the
  biodiversity and dynamics of natural ecosystems.
• Examples of restoration include
• replanting forests

59
We can rehabilitate and restore ecosystems that
we have damaged

• restoring grasslands
• restoring coral reefs
• restoring wetlands and stream banks
• reintroducing native species
• removing invasive species
• freeing river flows by removing dams.

60
We can rehabilitate and restore ecosystems that
we have damaged

• Four steps to speed up repair operations include
  the following
• Restoration.
• Rehabilitation.
• Replacement.
• Creating artificial ecosystems.

61
We can rehabilitate and restore ecosystems that
we have damaged

• Researchers have suggested a science-based,
  four-step strategy for carrying out most forms of
  ecological restoration and rehabilitation
• Identify the causes of the degradation.
• Stop the abuse by eliminating or sharply reducing
  these factors.
• If necessary, reintroduce key species to help
  restore natural ecological processes.
• Protect the area from further degradation and
  allow secondary ecological succession to occur.

62
We can share areas we dominate with other species

• Reconciliation ecology is the science that
  focuses on inventing, establishing, and
  maintaining new habitats to conserve species
  diversity in places where people live, work, or
  play.
• Examples include
• Protecting local wildlife and ecosystems can
  provide economic resources for their communities
  by encouraging sustainable forms of ecotourism.

63
We can share areas we dominate with other species

• Protecting vital insect pollinators such as
  native butterflies and bees by reducing the use
  of pesticides, planting flowering plants as a
  source of food for pollinating insect species,
  and building structures which serve as hives for
  pollinating bees.
• Protecting bluebirds within human-dominated
  habitats where most of the bluebirds nesting
  trees have been cut down by using nesting boxes
  and keeping house cats away from nesting
  bluebirds.

64
Ways you can help sustain terrestrial biodiversity
65
How can we help to sustain aquatic biodiversity?

• Section 9-6

66
Human activities are destroying and degrading
aquatic biodiversity

• Human activities have destroyed or degraded a
  large portion of the worlds coastal wetlands,
  coral reefs, mangroves, and ocean bottom, and
  disrupted many of the worlds freshwater
  ecosystems.
• Rising sea levels are likely to destroy many
  coral reefs and flood some low-lying islands
  along with their protective coastal mangrove
  forests.
• Loss and degradation of many sea-bottom habitats
  caused by dredging operations and trawler fishing
  boats.

67
Human activities are destroying and degrading
aquatic biodiversity

• In freshwater aquatic zones, dam building and
  excessive water withdrawal from rivers for
  irrigation and urban water supplies destroy
  aquatic habitats, degrade water flows, and
  disrupt freshwater biodiversity.
• The deliberate or accidental introduction of
  hundreds of harmful invasive species threatens
  aquatic biodiversity.
• Thirty-four percent of the worlds known marine
  fish species and 71 of the worlds freshwater
  fish species face premature extinction.

68
Before and after a trawler net
69
Overfishing gone fishing fish gone

• A fishery is a concentration of a particular wild
  aquatic species suitable for commercial
  harvesting in a given ocean area or inland body
  of water.
• The fishprint is defined as the area of ocean
  needed to sustain the consumption of an average
  person, a nation, or the world.
• Fifty-two percent of the worlds fisheries are
  fully exploited, 20 are moderately
  overexploited, and 28 are overexploited or
  depleted.

70
Overfishing gone fishing fish gone

• Overharvesting has led to the collapse of some of
  the worlds major fisheries.
• When overharvesting causes larger predatory
  species to dwindle, rapidly reproducing invasive
  species can more easily take over and disrupt
  ocean food webs.

71
The collapse of Canadas 500-year-old Atlantic
cod fishery
72
900,000
800,000
700,000
600,000
500,000
Fish landings (tons)
400,000
1992
300,000
200,000
100,000
0
1920
1940
1960
1980
2000
1900
Year
Fig. 9-25, p. 197
73
CASE STUDY Industrial Fish Harvesting Methods

• Industrial fishing fleets dominate the worlds
  marine fishing industry, using global satellite
  positioning equipment, sonar fish-finding
  devices, huge nets and long fishing lines,
  spotter planes, and gigantic refrigerated factory
  ships that can process and freeze their catches.
• Trawler fishing is used to catch fish and
  shellfish by dragging a funnel-shaped net held
  open at the neck along the ocean bottom.
• Purse-seine fishing, is used to catch
  surface-dwelling fish by using a spotter plane to
  locate a school the fishing vessel then encloses
  it with a large net called a purse seine.

74
CASE STUDY Industrial Fish Harvesting Methods

• Longlining involves lines up to 130 kilometers
  (80 miles) long, hung with thousands of baited
  hooks to catch open-ocean fish species or bottom
  fishes.
• Drift-net fishing catches fish with huge drifting
  nets that can hang as deep as 15 meters (50 feet)
  below the surface and extend to 64 kilometers (40
  miles) long.
• Drift-nets can trap and kill large quantities of
  unwanted fish, called bycatch, along with marine
  mammals, sea turtles, and seabirds.
• Almost one-third of the worlds annual fish catch
  by weight consists of bycatch species, which are
  mostly thrown overboard dead or dying.

75
Major commercial fishing methods
76
Fish farming in cage
Trawler fishing
Spotter airplane
Purse-seine fishing
Sonar
Drift-net fishing
Long line fishing
Float
Buoy
lines with hooks
Deep sea aquaculture cage
Fish caught by gills
Fig. 9-26, p. 198
77
We can protect and sustain marine biodiversity

• Protecting marine biodiversity is difficult for
  several reasons.
• The human ecological footprint and fishprint are
  expanding so rapidly into aquatic areas that it
  is difficult to monitor the impacts.
• Much of the damage to the oceans and other bodies
  of water is not visible to most people.

78
We can protect and sustain marine biodiversity

• Many people incorrectly view the seas as an
  inexhaustible resource that can absorb an almost
  infinite amount of waste and pollution and still
  produce all the seafood we want.
• Most of the worlds ocean area lies outside the
  legal jurisdiction of any country and is thus an
  open-access resource and subject to
  overexploitation.

79
We can protect and sustain marine biodiversity

• Several ways to protect and sustain marine
  biodiversity
• Protect endangered and threatened aquatic
  species.
• Establish protected marine sanctuaries.
• Protect whole marine ecosystems within a global
  network of fully protected marine reserves.

80
Ways to manage fisheries more sustainably and
protect marine biodiversity
81
Taking an Ecosystem Approach to Sustaining
Aquatic Biodiversity

• Strategies for applying the ecosystem approach to
  aquatic biodiversity include
• Complete the mapping of the worlds aquatic
  biodiversity, identifying and locating as many
  plant and animal species as possible.
• Identify and preserve the worlds aquatic
  biodiversity hotspots and areas where
  deteriorating ecosystem services threaten people
  and other forms of life.

82
Taking an Ecosystem Approach to Sustaining
Aquatic Biodiversity

• Create large and fully protected marine reserves
  to allow damaged marine ecosystems to recover and
  to allow fish stocks to be replenished.
• Protect and restore the worlds lakes and river
  systems (the most threatened ecosystems of all).
• Initiate worldwide ecological restoration
  projects in systems such as coral reefs and
  inland and coastal wetlands.
• Find ways to raise the incomes of people who live
  in or near protected lands and waters so that
  they can become partners in the protection and
  sustainable use of ecosystems.

83
Taking an Ecosystem Approach to Sustaining
Aquatic Biodiversity

• The harmful effects of human activities on
  aquatic biodiversity and ecosystem services could
  be reversed over the next 2 decades if an
  ecosystem approach is implemented, at a cost one
  of penny per cup of coffee consumed in the world
  each year.

84
Three big ideas

• The economic values of the important ecological
  services provided by the worlds ecosystems are
  far greater than the value of raw materials
  obtained from those systems.
• We can sustain terrestrial biodiversity by
  protecting severely threatened areas, protecting
  remaining undisturbed areas, restoring damaged
  ecosystems, and sharing with other species much
  of the land we dominate.
• We can sustain aquatic biodiversity by
  establishing protected sanctuaries, managing
  coastal development, reducing water pollution,
  and preventing overfishing.