Transcript Chapter 10

Chapter 10 Sustaining Terrestrial
Biodiversity: The Ecosystem Approach
Gray Wolf
• 1800-350,000 located lower 48 states especially west
• Preyed on bison, elk, caribou and mule deer
• 1850-1900 Most were shot, trapped, and poisoned by
ranchers, hunters, and government employees
• Keystone species entered ESA list in 1974
• Wolves provided uneaten meat for scavengers
• Wolves controlled populations of bison, elk, and caribou
• Reintroducing grey wolves has helped re-establish and
sustain biodiversity
Forests Vary
• Old growth forest – an uncut or regenerated
primary forest that has not been seriously
disturbed by human activities or natural disasters
for 200 years or more
• Reservoirs of biodiversity because of ecological
niches
• Second-growth forest – a strand of trees resulting
from secondary ecological succession develop
after trees have been removed by humans
Old Growth Forests in US state of
Washington’s Olympic National Forest
Old Growth Tropical Rainforest
in Australia
Forest Vary
• Tree plantation – managed track of uniformly
aged trees of one or two genetically uniform
species that usually are harvested by clear
cutting as soon as they become commercially
valuable
Price tags on Major Economical
Services
• Some conservation biologists urge establishing
tree plantations only on land that has already
been cleared or degraded instead of putting
them in place of existing old growth or
secondary forests
Major ecological services and
economical services
What’s the harm of building roads?
• Increases erosion and sediment runoff into
waterways
• Habitat fragmentation
• Loss of biodiversity
• Opens area to farmers, miners, ranchers,
hunters and off road vehicles to forest
degradation
Logging Roads
Forest Cutting
• Selective cutting – intermediate-aged or mature
trees in an uneven-aged forest are cut singly or in
small groups
• Strip cutting – involves clear-cutting a strip of
trees along the contour of land with in a corridor
narrow enough to allow natural regeneration
within a few years
• Clear cutting –removing all trees from an area,
most efficient way for a logging operation to
harvest trees
Selective, Clear and Strip Cutting
Clear Cutting Forests
Forest Fires
• Surface fires – burns only undergrowth and
leaf litter on the forest floor, kills seedlings
and small trees but spares most mature trees
and allow wild animals to escape
• Crown fires – extremely hot fires that leaps
from treetop to treetop, burning whole trees
occur in forests that have not experienced
surface fires in several decades
Surface fire and Crown Fire
Ecological benefits of Surface Fires
• Burn away flammable ground material help
prevent more destructive fires
• Free valuable mineral nutrients tied up in
slowly decaying material
• Release seeds from cones
• Stimulates germination of certain tree seeds
• Help control tree disease and insects
Ways to prevent Disease and Insects
• Accidental or deliberate introduction of foreign
diseases and insects are a major threat to forests
• Ban imported timber
• Remove or clear cut infested or infected trees
• Develop tree species genetically resistant to
common disease
• Apply conventional pesticides
• Biological control (bugs that eat harmful bugs)
Nonnative insect species and disease
organisms
Global Warming
• Climate change from global warming could harm
forests
• Sugar maples are heat sensitive, a change in
climate could kills these trees thus kill the maple
syrup industry
• Rising temperatures will cause insects
populations to rise
• Because of drier temperatures, forest will be
more susceptible to forest fires
• More CO2,will lead to more warming which will
lead to more forest loss
Where are forest losses the greatest?
• Developing countries are experiencing greatest
loss especially tropical areas Latin America,
Indonesia, and Africa
• 50,000 sq miles cleared each year
• Loss Boreal forest of Alaska, Canada,
Scandinavian, and Russia
• Makes up 1/4 of world’s forested area
• World’s greatest terrestrial storehouse of organic
carbon/ plays a major role in carbon cycle
Extreme tropical deforestation in Thailand, increases global warming
Deforestation
• The temporary or permanent removal of large
expanses of forest for agriculture, settlements,
or other uses
Harmful effects
of deforestation
US in Recovery
• Every year, more wood is grown in the US than
is cut and the total area planted with trees
increases
• Protected forests make up about 40% of the
country’s total forest area, mostly in the
National Forest System, which consists of 155
national forests managed by the US Forest
Services
Major causes of Deforestation
Manage Forests
Certifies timber
• Timber that is selectively cut and sold by a
nonprofit Forest Stewardship Council
Ways to reduce harms of Forest Fires
• Set small contained surface fires to remove
flammable small trees and underbrush
• Allow fires on public lands to burn and thereby
remove flammable underbrush and smaller trees
• Protecting houses and other buildings in fireprone areas by thinning a zone of about 60
meters
• Thin forest areas vulnerable to fire by clearing
away small fire-prone trees and underbrush
under careful environmental controls
Harvested Trees
• Up to 60% of the wood consumed in the
United States is wasted unnecessarily
• Inefficient use of construction material, excess
packaging, overuse of junk mail, in adequate
paper recycling, and failure to reuse wooden
shipping containers
Fuel wood Crisis
• Fuel wood is used by developing countries for
heating and cooking by more than 2 billion
people
• Reducing: establish small plantations of fast
growing fuel wood trees and shrubs
• Villagers can switch to burning the renewable
sun-dried roots of various gourds and squash
plants
• Scientists are also looking for ways to produce
charcoal for heating and cooking without cutting
down trees
Green Belt Movement
• Wangari Maathai began the Green Belt
Movement in 1977 in her backyard with a
small tree nursery
• Organize poor women in rural Kenya to plant
and protect millions of tees in order to combat
deforestation and provide fuel wood
• By 2004, 50,000 members in 6,000 villages
have planted and protected 30 million trees
Protecting Tropical Rainforests
Rangeland Overgrazed
• Rangelands – unfenced grasslands in temperate and
tropical climates that supply forage, or vegetation,
for grazing (grass-eating) and browsing (shrubeating) animals
• Cattle, sheep and goats graze on 42% of the world’s
grasslands
• Expected to be 70% by 2050
• Livestock graze on pastures – managed grassland or
enclosed meadows usually planted with
domesticated grasses or other forage
Overgrazing and Undergrazing
• Overgrazing –when too many animals graze for too long and
exceed the carrying capacity of a rangeland area
• Reduces grass cover, exposes soil to erosion, and compacts
the soil (which diminishes the capacity to hold water)
• Natural grassland ecosystems were maintained partially by
periodic wildfires sparked by lightning
• Some grasslands suffer from undergrazing, where the absence
of grazing for long periods (at least 5 years) can reduce the
net primary productivity of grassland vegetation and grass
cover
Sustaining Rangelands
• Widely used method is controlling the number of grazing
animals and the duration of their grazing in a given area (3 ways)
• Rotational grazing – cattle are confined by a portable fence for 12 days and then moved to another area
• Fencing off riparian zones (lush vegetation near water sources)
• Use of herbicides, mechanical removal or controlled burning
helps control invader species
• Replanting barren areas with native seeds and applying
fertilizers can increase growth of desirable vegetation and
reduce soil erosion
Cattle overgrazing of a stream
Ranchers and Urban Development
• Housing developments are slowly creeping
into rangelands of the southwester US
• Environmentalist have been working with
farmers to reduce overgrazing, now they have
to compete with developers for the natural
land
• One strategy is Conservation easements with
ranchers – deed restrictions that bar future
owners from developing the land
Threats to National Parks
• Too small to sustain a lot of large animal species
• Invasion of nonnative species that compete with
and reduce the populations of native species
• Parks of developing countries are not protected
• Illegal mining and logging, poaching occur in
these parks
US Public Parks
• Established in 1912, includes 58 major national
parks
• One of the biggest problems is popularity
• Noise and pollution from motor and recreational
vehicles degrade the parks
• Parks suffer damage from migrating or deliberate
induction of invasive species
• Polluted air and human activities are threatening
wildlife
Solutions to Parks
Nature Reserves
• Currently, only 12% of the earth’s land area is protected
strictly or partially in nature reserves, parks, wildlife refuges,
wilderness, and other areas
• 12% is misleading because no more than 5% of the earth’s
land is strictly protected from potentially harmful human
activities
• We have reserved 95% of the earth’s land surface for human
use
• Conservation biologists call for full protection of at least 20%
the earth’s land area in global system of biodiversity reserves
that would include multiple examples of all earth’s biomes
Buffer Zones for Nature Reserves
• Research indicates that in other locales, several well-placed,
medium sized reserves may better protect a wider variety of
habitats and preserve more biodiversity than would a single
large reserve of the same total area
• Buffer Zones – this means protecting an inner core of a
reserve by usually establishing two buffer zones in which local
people can extract resources sustainably without harming the
inner core
• This approach enlists local people as partners in protecting a
reserve from unsustainable uses such as illegal logging and
poaching
Buffer Zone Design (Biological
Reserve)
Costa Rica’s Nature Reserves
• Costa Rica has consolidated its parks and reserves into
eight zoned megareserves designed to sustain about 80%
of the country’s rich biodiversity
• Green areas are protected
Reserves and yellow areas are
Nearby buffer zones, which can
Be used for sustainable forms of
Forestry, agriculture, hydropower
hunting, and other human
activities
Wilderness
• Legally setting aside large areas undeveloped
land
• Preserving biodiversity as a vital part of the
earth’s natural capital
• Protect wilderness areas as centers for evolution
in response to mostly unpredictable changes in
environmental conditions
• Wilderness serves as a biodiversity bank and an
eco-insurance policy
Controversy over Wilderness
• Conservationists have been trying to save wild
areas from development since 1900
• 1964 Congress pass the Wilderness Act
• This act protect less than 2% of US wilderness
• Roadless rules have protected wilderness areas
20 years
• 2005, secretary of interior ended this protection
of roadless areas with in the national forest
systems
Biodiversity Hotspots
• Areas especially rich in plant species that are
found nowhere else and are in great danger of
extinction
• Suffer serious ecological disruptions mostly
because of rapid human population growth
and the resulting pressure on natural
resources
• Save biodiversity of the planet by protecting
these areas
Ecological Restoration
• The process of repairing damage caused by
humans to the biodiversity and dynamics of
natural ecosystems
• Restoration: returning a particular degraded
habitat or ecosystem to a condition as similar
as possible to it natural state
• Rehabilitation: turning a degraded ecosystem
into a functional or useful ecosystem without
trying to restore it to its original condition
Ecological Restoration
• Replacement: replacing a degraded ecosystem
with another type of ecosystem
• Creating artificial ecosystems
Strategies for Restoration
• Identify what caused the degradation
• Stop the abuse by eliminating or sharply reducing
these factors This would include removing toxic soil
pollutants, adding nutrients to depleted soil, adding
new topsoil, preventing fires, and controlling or
eliminating disruptive nonnative species
• Reintroduce species – especially pioneer, keystone,
and foundation species
• Protect the area from further degradation
Tropical Dry Forest of Costa Rica
• A small tropical dry forest was burned,
degraded, and fragmented by large-scale
conversion to cattle ranches and farms
• One of the world’s largest restoration project
• Goal is to eliminate damaging nonnative
grasses and reestablish a tropical dry forest
ecosystem over the next 100-300 years
Reconciliation or applied ecology
• This science focuses on inventing, establishing,
and maintaining new habitats to conserve
species diversity in places where people live,
work, or play
• We need to share with other species some of
the spaces we dominate
• Community –based conservation: scientists,
citizens, government work together to
preserve biodiversity