Sustaining Terrestrial Biodiversity: The Ecosystem Approach

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Sustaining Terrestrial Biodiversity The
Ecosystem Approach

• Chapter 10

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10-1 What Are the Major Threats to Forest
Ecosystems?

• Concept 10-1A Forest ecosystems provide
  ecological services far greater in value than the
  value of raw materials obtained from forests.
• Concept 10-1B Unsustainable cutting and burning
  of forests, along with diseases and insects, are
  the chief threats to forest ecosystems.
• Concept 10-1C Tropical deforestation is a
  potentially catastrophic problem because of the
  vital ecological services at risk, the high rate
  of tropical deforestation, and its growing
  contribution to global warming.

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Forests Vary in Their Make-up, Age, and Origins

• Old-growth forest Original forests that have not
  been disturbed for logging, road building, or
  development
• Sometimes called primary, ancient, virgin, or
  primeval forests
• 36 of worlds forest
• High biodiversity because of many specialized
  niches

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Forests Vary in Their Make-up, Age, and Origins
Remaining Old-Growth Forests in the U.S.
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Forests Vary in Their Make-up, Age, and Origins

• Second-growth forest
• Area which has re-grown after a major disturbance
  such as fire, insect, or timber harvest
• 60 of worlds forest
• The area is reclaimed by the natural process of
  secondary succession
• Small shrubs and trees followed by the larger
  trees

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Forests Vary in Their Make-up, Age, and Origins

• Tree plantation (tree farm)
• Planted stands of a particular tree species that
  are maintained, harvested, and replanted
• Typically used for paper or particle board

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Forests Provide Important Economic and
Ecological Services
Estimated annual value Economic
services 1.8 trillion Ecological services 4.7
trillion
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Unsustainable Logging is a Major Threat to
Forest Ecosystems

• Building roads into previously inaccessible
  forests paves the way for increased erosion,
  habitat fragmentation, loss of biodiversity, and
  invasion by non-native species.
• For this reason, many federal wilderness areas do
  not allow the construction of roads.

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Unsustainable Logging is a Major Threat to
Forest Ecosystems

• Three major tree harvesting methods
• Selective cutting
• Clear-cutting
• Strip cutting

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Unsustainable Logging is a Major Threat to
Forest Ecosystems

• Selective Cutting
• Mature trees are harvested individually from
  diverse forests
• Younger trees left to harvest later
• Reduces crowding
• Removes diseased trees
• Encourages growth of younger trees

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Unsustainable Logging is a Major Threat to
Forest Ecosystems

• Clear-cutting
• Removing all trees in a single pass.

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Unsustainable Logging is a Major Threat to
Forest Ecosystems
Clear-cutting
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Unsustainable Logging is a Major Threat to
Forest Ecosystems

• Strip-cutting
• A type of clear cutting that involves clear
  trees along the contours of the land.
• Less erosion

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Fire, Insects, and Climate Change Can Threaten
Forest Ecosystems

• Forest fires can either benefit or harm forests
• Burn away flammable ground material
• Prevent larger, more destructive fires
• Release valuable mineral nutrients
• Stimulate new forest growth

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Fire, Insects, and Climate Change Can Threaten
Forest Ecosystems

• Surface fires
• Usually burn leaf litter and undergrowth
• May provide food in the form of vegetation that
  sprouts after fire
• Crown fires
• Extremely hot, burns whole trees, jump from
  treetop to treetop
• Fierce and hard to control

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Fire, Insects, and Climate Change Can Threaten
Forest Ecosystems

• Accidental or deliberate introduction of foreign
  diseases and insects are also a major threat to
  forests.

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We Have Cut Down Almost Half of the Worlds
Forests

• Human activities have reduced the earths forest
  cover by as much as half.
• Deforestation temporary or permanent removal of
  large areas of forests
• Results from unsustainable cutting of trees
• Losses are concentrated in developing countries.
• Use it for fuel heating and/or cooking
• Tropical forests
• Especially in Latin America, Indonesia, and
  Africa
• Boreal forests
• Especially in Alaska, Canada, Scandinavia, and
  Russia

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We Have Cut Down Almost Half of the Worlds
Forests
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Tropical Forests Are Disappearing Rapidly

• Large areas of ecologically and economically
  important tropical forests are being cleared and
  degraded at a rapid rate.

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Tropical Forests Are Disappearing Rapidly
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Tropical Forests Are Disappearing Rapidly

• Large areas of tropical forest are burned to make
  way for cattle ranches and crops.
• Soil in the rainforest is very poor
• Farmers burn the trees down to provide nutrients
  for the soil
• Heavy rain leaches away the nutrients so they
  move to another area and burn again

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Tropical Forests Are Disappearing Rapidly

• At least half of the worlds terrestrial plants
  and animals live in tropical rain forests.
• About 2,100 of the 3,000 plants identified by the
  National Cancer Institute as sources of
  cancer-fighting chemicals come from tropical rain
  forests.

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Tropical Forests Are Disappearing Rapidly
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10-2 How Should We Manage and Sustain Forests?

• Concept 10-2 We can sustain forests by
  emphasizing the economic value of their
  ecological services, protecting old-growth
  forests, harvesting trees no faster than they are
  replenished, and using sustainable substitute
  resources.

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10-2 How Should We Manage and Sustain Forests?

• We can use forests more sustainably by
  emphasizing
• Economic value of ecological services
• Harvesting trees no faster than they are
  replenished
• Protecting old-growth and vulnerable areas

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We Can Improve the Management of Forest Fires

• Fire prevention programs have been very
  effectivetoo effective.
• Large amounts of highly flammable underbrush have
  accumulated
• Leads to larger, more destructive crown fires

• To reduce fire damage
• Set controlled surface fires (Prescribed Fires).
• Allow fires to burn on public lands if they dont
  threaten life and property.
• Clear small areas around property subject to fire.

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10-3 How Should We Manage and Sustain Grasslands?

• Concept 10-3 We can sustain the productivity of
  grasslands by controlling the number and
  distribution of grazing livestock and restoring
  degraded grasslands.

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10-3 How Should We Manage and Sustain Grasslands?

• Important ecological services of grasslands
• Soil formation
• Erosion control
• Nutrient cycling
• Storage of atmospheric carbon dioxide in biomass
• Maintenance of diversity

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10-3 How Should We Manage and Sustain Grasslands?

• Almost half of the worlds livestock graze on
  natural grasslands (Rangelands) and managed
  grasslands (Pastures).

• We can sustain rangeland productivity by
  controlling the number and distribution of
  livestock and by restoring degraded rangeland.

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Some Rangelands Are Overgrazed

• Overgrazing occurs when too many animals graze
  for too long and exceed carrying capacity of a
  grassland area.
• Grass/shrubs are damaged beyond repair
• Reduces grass cover
• Leads to erosion of soil by water and wind

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Some Rangelands Are Overgrazed

• Desertification - The degradation of land that
  results in a desert
• Caused by overgrazing, deforestation, or overuse
• The worlds deserts are getting bigger

• Prevention of overgrazing
• Rotational grazing
• Replant barren areas
• Apply fertilizer
• Reduce soil erosion

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?

• Concept 10-4 Sustaining biodiversity will
  require protecting much more of the earths
  remaining undisturbed land area as parks and
  nature reserves.

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?
Important Definitions

• Conservation
• Focuses on the proper use of nature
• Seeks to regulate the human use of wilderness and
  its resources
• Preservation
• Focuses on the protection of nature from use
• Seeks to eliminate the human use of wilderness
  and its resources

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?

• National park a reserve of land, usually, but
  not always declared and owned by a national
  government, protected from most human development
  and pollution.
• Countries have established more than 1,100
  national parks, but most are threatened by human
  activities.

• Local people invade park for wood, cropland, and
  other natural resources.
• Loggers, miners, and wildlife poachers also
  deplete natural resources.
• Many are too small to sustain large-animal
  species.
• Many suffer from invasive species.

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?

• 58 Major national parks in the U.S.
• Overused due to popularity litter, trampling,
  off road vehicles, etc.
• Many species are isolated and fragmented from
  the ecosystems around them
• Air pollution from areas outside of park

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?

• Nature Reserves (Nature Preserves)
• Protected areas of importance for wildlife,
  geological features, or other special interests,
  which are reserved and managed for conservation.
• Nature reserves may be designated by government
  institutions, by private landowners, or by
  charities and research institutions.
• Currently 12 of earths land area is protected.
• Only 5 is strictly protected from harmful human
  activities
• Conservation biologists call for full protection
  of at least 20 of earths land area

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10-4 How Should We Manage and Sustain Parks and
Natural Reserves?

• Wilderness is land legally set aside in a large
  enough area to prevent or minimize harm from
  human activities.
• Only a small percentage of the land area of the
  United States has been protected as wilderness.

• Wilderness Act of 1964
• Established 9.1 million acres of federally
  protected wilderness in national forests

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10-5 What is the Ecosystem Approach to
Sustaining Biodiversity?

• Concept 10-5A We can help sustain biodiversity
  by identifying severely threatened areas and
  protecting those with high plant diversity and
  those where ecosystem services are being
  impaired.
• Concept 10-5B Sustaining biodiversity will
  require a global effort to rehabilitate and
  restore damaged ecosystems.
• Concept 10-5C Humans dominate most of the
  earths land, and preserving biodiversity will
  require sharing as much of it as possible with
  other species.

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10-5 What is the Ecosystem Approach to
Sustaining Biodiversity?

• We can prevent or slow down losses of
  biodiversity by concentrating efforts on
  protecting global biodiversity hot spots where
  significant biodiversity is under immediate
  threat.

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10-5 What is the Ecosystem Approach to
Sustaining Biodiversity?
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10-5 What is the Ecosystem Approach to
Sustaining Biodiversity?