Transcript Understanding Our Environment

Introduction of
Exotic Species
Stress
zone
Species
absent
Optimal range
Abundant species
Stress
zone
Fewer
species
Fewer
species
Species
absent
OPTIMUM ENVIRONMENT
Most species do not survive when introduced into different
habitats because they have specialized habitat
requirements. Others do well and most of our invasive
species are very effective in competing for limited
resources with native species.
Classic example of an invasive species –
considered by some to be the biggest threat to
biodiversity conservation (this is a western world
view)
Protecting biodiversity conflicts with
indigenous community’s needs to survive and
obtain sufficient food for themselves
Pet parrots, Amazon Brazil,
TROPICAL FORESTS
Photo: K Vogt
Environmental Conservation: Forests,
Grasslands, Parks, and Nature Preserves
Chapter 6
Outline:
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Tropical Forests
Temperate Forests
 Harvest Methods and Fire Management
Rangelands
 Overgrazing and Land Degradation
Parks and Nature Preserves
 History - Problems - Size and Design
Wilderness Areas
Wildlife Refuges
FAO 1999,
WRI 1998-1999
GLOBE
Forests,
woodlands
= 33%
land area
~ 66% area in
RESOURCE
EXTRACTION
Ice, rock, desert
etc. = 32%
Range,
Pastures =
23%
Ag =
10%
Built
land
= 2%
WORLD FORESTS
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Forests play vital ecological roles:
 Regulating climate, controlling water
runoff, providing food and shelter for
wildlife, and purifying air.
Provide valuable materials.
 Wood, paper-pulp.
Scenic, cultural, and historic value.
World Forests
Forest Products
Forest Management
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Approximately 25% of world’s forests are
actively managed for wood production.
 Sustainable harvest is key to
regeneration.
- Many reforestation projects involve
Monoculture Forestry.
 Rapid growth and easier harvest.
 Disrupts ecological processes.
Tropical Forests
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Although they occupy less than 10% of
earth’s land surface, tropical rainforests are
thought to contain:
 More than two-thirds of all higher plant
biomass.
 At least one-half of all plant, animal, and
microbial species in the world.
Tropical Forest Losses
Causes of Deforestation
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Thin, nutrient-poor tropical soils are usually
worn out after a few years of cropping.
 Shifting cultivation often blamed for forest
destruction.
- Can be sustainable where population
densities are low and individual plots are
allowed to regenerate between
cultivation periods.
Debt-for-Nature Swaps
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Banks, governments, and lending institutions
hold nearly $1 trillion in loans to developing
countries.
 Conservation organizations buy debt
obligations on the secondary market at a
discount, and then offer to cancel the debt
if the debtor country will agree to protect or
restore an area of biological importance.
Temperate Forests
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Northern countries have a long history of
liquidating forest resources.
 For many years, “multiple use” was the
official policy of the U.S. Forest Service.
- Simultaneous uses.
 Incompatibility ?
Old-Growth Forests
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Today, less than 10% of the old-growth forest
in the United States remains intact.
 ??? 80% of what is left is scheduled to be
cut down in the near future (in text) ???
NO!!!
Environmentalists sued U.S. Forest Service
over logging rates in WA and OR in 1989.
 Protection of northern spotted owls.
 Timber industry claimed 40,000 jobs would
be lost.
Harvest Methods
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Clear-Cutting - Every tree in a given area is
cut regardless of size.
 Fast and efficient, but wastes small trees,
increases erosion, and eliminates wildlife
habitat.
Shelterwood - Remove mature trees in
series of cuts.
Harvest Methods
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Strip Cutting - Harvesting all trees in a
narrow corridor.
Selective Cutting - A small percentage of
mature trees are taken in 10-20 year rotation.
 Can retain many characteristics of mature,
old-growth forests.
Loggings and Roads in National Forests
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Increasing number of people in the U.S. are
calling for an end to all logging on federal
lands.
 $4 Billion annual harvest vs. estimated
$224 Billion from recreation and ecological
function.
USFS builds roads in order for timber
companies to extract trees.
 Hidden subsidy to timber industry.
Fire Management
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For more than 70 years, firefighting has been
a high priority for forest managers.
 Many communities are fire-adapted.
 Accumulation of woody debris.
Forest Service says 40% of all federal forest
lands are at risk of severe fires.
 68,230 fires burned 2.7 million ha in 2002.
- Firefighting costs of $1.6 Billion.
How to undo years of fuel build-up ?
Ecosystem Management
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1990’s saw USFS shift from timber
production to ecosystem management.
 Attempts to integrate sustainable
ecological, and social goals in a unified,
systems approach.
USFS is also using ‘Adaptative
Management’
(trying new science, etc)
RANGELANDS
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Pasture and Open range occupy about 25%
of the world’s land surface.
 More than 3 billion domestic livestock
producing meat and milk.
Attractive and frequently converted to
human-dominated landscapes.
Desertification?
New Approaches to Ranching
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Short-Duration Rotational Grazing
 Forces livestock to graze equally, trample
ground evenly, and fertilize with manure
before moving on.
Game Ranching
 Many wild species forage more efficiently,
resist harsh climates, and can fend off
predators and pests better than domestic
livestock.
PARKS AND NATURE PRESERVES
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Origins and History
 Historically, sacred groves were set aside
for religious purposes, and grounds
preserved for royalty.
- Only in the past 130 years have we
begun to preserve wild places for the
sake of wildlife and scenic beauty.
Park Problems
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Many parks have become islands of nature
surrounded and threatened by destructive land
uses stemming from growing human populations
crowding park boundaries.
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Park rangers often
spend more time
on crime prevention
and crowd control than natural history.
Mining and oil interests push to operate on
private inholdings.
Marine Preserves
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Shelter marine organisms from destructive
harvest methods.
 Coral reefs among most threatened marine
ecosystems.
- 90% face threats from sea temperature
change, destructive fishing methods,
coral mining, sediment runoff and other
human disturbance.
Size and Design of Nature Preserves
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Single Large or Several Small (SLOSS)
 Ideally, a reserve should be large enough
to support viable populations of
endangered species, keep ecosystems
intact, and isolate critical core areas from
external forces.
Conservation and Economic Development
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Tropics are suffering the greatest destruction
and species loss in the world.
 Ecotourism can be more beneficial to
many countries over the long-term than
extractive industries – BUT only if done
ecologically and not as money making
show only.
- Wildlife watching and outdoor recreation
can be a welcome source of income for
underdeveloped countries.
Indigenous Communities and Reserves
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Areas chosen for nature preservation are
often traditional lands of indigenous people.
 1986 UNESCO initiated its Man and
Biosphere Program (MAB).
- Encourages division of protected areas
into zones with different purposes.
WILDERNESS AREAS
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1964 - Wilderness Act defined wilderness:
 “An area of undeveloped land affected
primarily by the forces of nature, where
man is a visitor who does not remain…”
 Most areas meeting these standards are in
the Western US and Alaska.
WILDLIFE REFUGES
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1901 - President Teddy Roosevelt
established 51 national wildlife refuges.
 Now 511 refuges encompassing 40 million
ha representing every major biome in NA.
Wildlife Refuges
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Over the years, a number of other uses have
been allowed to operate within wildlife refuge
boundaries.
 Oil and Gas Drilling
 Cattle Grazing
 Motor-boating, Camping
Refuges also face threats from external
sources - expanding human populations.
 Water Pollution
Summary:
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Tropical Forests
Temperate Forests
 Harvest Methods and Fire Management
Rangelands
 Overgrazing and Land Degradation
Parks and Nature Preserves
 History - Problems - Size and Design
Wilderness Areas
Wildlife Refuges