I.
Miller Review Chapter 10
Chapter 10: Sustainability Terrestrial Biodiversity: Saving Ecosystems and Ecosystem Services
a. 10-1: What Are the Major Threats to Forest Ecosystems?
i. Classify natural forests into two major types:
1. Old-Growth Forest (Primary Forest) – an uncut or regenerated forest that
has not been seriously disturbed by human activates or natural disasters for
200 years or more
a. Reservoirs of biodiversity because they provide ecological niches for a
multitude of wildlife species
2. Second-Growth Forest – a stand of trees resulting from secondary ecological
succession
a. Develop after the trees in an area have been removed by human
activities (clear-cutting for timber or conversion to cropland) or by
natural forces (forest fires, hurricanes, or volcanic eruptions)
ii. Tree Plantation (Tree Farm or Commercial Forest) – a managed forest containing
only one or two species of trees that are all of the same age
1. Downside – with only one or two tree species they are much less biologically
diverse and less sustainable than old-growth and second-growth forest
because they violate nature’s biodiversity principal of sustainability
a. Do NOT provide the wildlife habitats and ecosystem services such as
water storage and purification that diverse natural forest do
b. Can eventually deplete the topsoil of nutrients and hinder the
regrowth of any type of forest on such land
iii. Provide highly valuable economic and ecosystem services:
1. Forest remove CO2 from the atmosphere and store it in organic compounds
(biomass)
2. Help to stabilize average atmospheric temperatures and the earth’s climate
3. Provide habitats
4. Provide us with raw materials
a. Especially wood, biofuel (cooking and heating), industrial wood
(primarily used to make lumber and paper)
5. Important health benefits
6. Traditional medicines
iv. Harvesting of wood is one of the world’s major industries
1. 1st step: to build roads for access and timber removal
a. Harmful Effects: namely increased topsoil erosion and sediment
runoff into waterways, habitat fragmentation, and loss of biodiversity
nd
2. 2 step: Harvesting the trees
a. Variety of methods to harvest:
i. Selective Cutting – intermediate-aged or mature trees in a
forest are cut singly or in small groups
ii. Clear-Cutting – remove all trees from an area
1. Most efficient and often the least costly way to harvest
trees, but it can do considerable harm to an ecosystem
iii. Strip-Cutting – (a variation of clear cutting) – involves clearcutting a strip of trees along the contour of land within a
corridor narrow enough to allow natural forest regeneration
within a few years
v. One of the major threats to forests is the unsustainable harvesting of trees
vi. Two types of fires:
1. Surface Fires – usually burn only undergrowth and leaf litter on the forest
floor, they spare most mature trees and allow most wild animals to escape
a. Ecological Benefits:
i. Burn away flammable ground material
ii. Free valuable mineral nutrients
iii. Release seeds
iv. Stimulate the germination
v. Help to control destructive insects
2. Crown Fires – an extremely hot fire that leaps from treetop to treetop,
burning whole trees, can destroy most vegetation, kill wildlife, increase
topsoil erosion, and burn or damage human structures in their paths
a. Usually occur in forests that have not experienced surface fires for
several decades
vii. Another threat to forests is the accidental or deliberate introduction of diseasecausing organisms and destructive insects
viii. Projected climate change
1. The resulting combination of drier forests and more dead trees could also
increase the number and intensity of forest fire
2. The drier climate increases the risk of more and bigger natural forest fires,
which add more climate-changing CO2 to the atmosphere and further reduce
the number of trees that remove CO2 from the atmosphere
ix. Deforestation – the temporary or permanent removal of large expanses of forest for
agriculture, settlements, or other uses
1. These forest losses are concentrated in less-developed countries, especially
those in tropical areas of Latin America, Indonesia, and Africa
2. Has important short-term economic benefits, but it also has a number of
harmful environmental effects (severe erosion and loss of topsoil)
3. China now leads the world in new forest cover, due mostly to its plantations
of fast-growing trees
x. Ecological Tipping Point – an irreversible effect – beyond which a forest cannot
grown back in the area and is then often replaced by tropical grassland, or savanna
xi. Tropical Deforestation – results from a number of underlying and direct causes
1. Underlying Causes – pressures from population growth and poverty
a. Where they cut or burn trees for firewood or to try to grow enough
food to survive
2. Government subsidies can accelerate other direct causes such as large-scale
logging and ranching by reducing the cost of timber harvesting, cattle
grazing, and farming on vast plantations of crops such as soybeans, and oil
palms.
3. Tropical Forest in the:
a. Amazon and other South American countries - cleared or burned
primarily for cattle grazing and large soybean plantations.
b. Indonesia, Malaysia, and other areas of Southeast Asia – being
replaced with major plantations of oil palm (produces an oil used in
cooking, cosmetics, and biodiesel fuel for motor vehicles
c. Africa – people clearing plots for small-scale farming and harvesting
wood for fuel
d. In 2011 – China was by far the biggest consumer of tropical timber
4. The degradation of a tropical forest usually begins when a road is cut deep
into the forest interior for logging and settlement
5. Burning is widely used to clear forest areas for agriculture, settlement, and
other purposes
a. Healthy forests do not burn naturally, but roads, settlements, and
other developments fragment them. The resulting patches of forest
dry out and readily ignite
b. 10-2: How Should We Manage and Sustain Forests?
i. Loggers could use more sustainable practices in tropical forests
1. Sustainable selective cutting and strip cutting
2. Take care to cut canopy vines (lianas) before falling a tree and using the least
obstructed path to remove the logs
ii. Many economist are urging governments to begin making a shift to more
sustainable forest management
1. Phasing out government subsidies and tax breaks that encourage forest
degradation and deforestation and replacing them with forest-sustaining
economic rewards
2. Can also encourage tree planting programs to help restore degraded forests
iii. Smokey the Bear educational campaign:
1. Pros: Likely prevented many forest fires, saved many lives, and prevented
billions of dollars in losses of trees, wildlife, and human structures
2. Con: Has convinced much of the public that all forest fires are bad and should
be prevented or put out
iv. Ecologist and fire experts have:
1. Proposed several strategies for reducing fire-related harm to forests and to
people
a. Set small, contained surface fires to remove flammable small tress and
underbrush in the highest-risk forest areas (prescribed burns)
i. Experts contend that expensive prescribed burns and thinning
should not be used to prevent large fires in most western
forest except to protect human structures
b. 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
c. Protect houses and other buildings in a fire-prone areas by thinning
trees and other vegetation in a zone of about 60 meters (200ft)
around them
d. To thin forest areas that are vulnerable to fire by clearing away small
fire-prone trees and underbrush under careful environmental
controls
i. Thinning operations should not remove economically valuable
medium-size and large-trees for two reasons:
1. These are usually the most fire-resistant trees
2. Their removal encourages dense growth of more
flammable young trees and underbrush and leaves
behind highly flammable slash (the debris left behind by
logging operations)
v. Worldwide Institute and forestry analysts – up to 60% of the wood consumed in the
U.S. is wasted unnecessarily
1. Results from inefficient use of construction materials, excessive packaging,
overuse of junk mail, inadequate paper recycling, and failure to reuse or find
substitutes for wooden shipping containers.
vi. While timber companies successfully lobby for government subsides to grow and
harvest trees to make paper, there are no major lobbying efforts or subsidies for
producing paper from kenaf and other alternatives to trees
1. Sharply reduce the use of throwaway paper products made from trees
2. But now the demand for wood as fuel is becoming unsustainable in many
areas
vii. Example: Haiti
1. This unsustainable use of natural capital and failure to follow the principals
of sustainability have led to a downward spiral of environmental
degradation, poverty, disease, social injustice, crime, and violence
viii. International Level:
1. Debt-for-nature swaps – can make it financially attractive for countries to
protect their tropical forests
a. Swaps, participating countries act as custodians of protected forested
reserves in return for foreign aid or debt relief
2. Conservation Concessions – governments or private conservation
organizations pay nations for agreeing to preserve their natural resources
ix. Reforestation Programs - Governments can also end subsidies that fund the
construction of logging roads and instead subsidize more sustainable forestry and
the planting of trees
1. Wangari Maathai – a Nobel Peace Prize winner, promoted and inspired tree
planting in her native country of Kenya and throughout the world in what
became the Green Belt Movement
c. 10-3: How Should We Manage and Sustain Grasslands?
i. Grasslands provide many important ecosystem services:
1. Soil formation
2. Erosion Control
3. Chemical Cycling
4. Storage of atmospheric carbon dioxide in biomass
5. Maintenance of biodiversity
ii. Rangelands – unfenced grasslands in temperate and tropical climates that supply
forage, or vegetation for grazing (grass-eating) and browsing (shrub-eating) animals
1. Blades of rangeland grass grow from the base, not at the tip as broadleaf
plants do – therefore – as long as only the upper half of the blade is eaten
and its lower half remains, rangeland grass is a renewable resource that can
be grazed again and again
iii. Pastures – livestock also graze, which are managed grasslands or fenced meadows
often planted with domesticated grasses or other forage crops such as alfalfa and
clover
iv. Overgrazing – occurs when too many animals graze for too long, damaging the
grasses and their roots, and exceeding the carrying capacity of a rangeland area
1. Reduces grass cover, exposes the topsoil to erosion by water and wind, and
compacts the soil, which diminishes its capacity to hold water
v. Most widely used way to manage rangelands more sustainably is to 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
1. Rotational Grazing – which cattle are confined by portable fencing to one
area for a short time (often only 1-2 days) and then moved to a new location
2. Riparian Zone - Aggregate around natural water sources, especially along
streams or rivers lined by thin strips of lush vegetation – and around ponds
created to provide water for livestock
vi. Case Study: Cows vs. Condos
1. One preservation strategy involves land trust groups which pay ranchers for
conservation easements – deed restrictions that bar future owners from
developing the land
d. 10-4: How Should We Manage and Sustain Parks and Nature Reserves?
i. There are now more than 6,600 major national parks located in more than 120
countries
1. Most of these parks are to small to sustain many large animal species
2. Many parks suffer from invasions by harmful nonnative species that compete
with and reduce the populations of native species.
3. Large number of visitors are degrading the natural features that make them
attractive
ii. U.S. National Park System – established in 1912 – includes 59 major national parks,
sometimes called the country’s crown jewels, along with 339 monuments and
historic sites
1. States, counties, and cities also operate public parks
a. Popularity is one of the biggest problems for many parks
2. Many US national parks have become threatened islands of biodiversity
surrounded by seas of commercial development
a. Nearby human activities that threaten wildlife and recreational values
in many national parks include mining, logging, livestock grazing,
coal-fired power plants, water diversion, and urban development
iii. Most ecologist and conservation biologist believe the best way to preserve
biodiversity is to create a worldwide network of protected areas
1. Less than 13% of the earth’s land area (not including Antarctica) was
protected either strictly or partially in about 150,000 wildlife refuges, nature
reserves, parks, and wilderness areas
2. AKA: We have reserved 94% of the earth’s land for human use
iv. In establishing nature reserves, the size of the reserve is important as is the design
1. Buffer zone concept – to design and manage nature reserves, this means
strictly protecting an inner core of a reserve, usually by establishing two
buffer zones in which local people can extract resources sustainably without
harming the inner core
v. Habitat Corridor – a strip of protected land connecting two reserves that allows
animals to migrate from one area to another as needed.
vi. Case Study: Protecting Biodiversity in Costa Rica
1. Consolidated the country’s parks and reserves into several large
conservation areas (megareserves), distributed throughout the country
vii. Wilderness – land officially designated as an area where natural communities have
not been seriously disturbed by humans and where harmful human activities are
limited by law
1. “Leave is as it is. You cannot improve it”
2. Preserve Biodiversity – a vital part of the earth’s natural capital and to
protect wilderness areas as centers for evolution
viii. 1964 – Congress passed the Wilderness Act – it allowed the government to protect
underdeveloped tracts of public land from development as part of the National
Wilderness Preservation System
1. Most wilderness areas in the lower 48 states are also threatened habitat
islands in a sea of development
2. Wilderness protection is being eroded because since the 1980s, fewer people
are taking part in outdoor activities such as hiking, camping, fishing, and
hunting. Instead, people are more often opting for indoor activities involving
video games, the Internet, social networking, and viewing rented movies
a. Activities in the natural world become less popular, there could be
less citizen pressure for protecting wilderness and for setting aside
nature reserves
e. 10-5: What is the Ecosystem Approach to Sustaining Biodiversity and Ecosystem Services?
i. To protect threatened habitats and ecosystem services.
ii. This ecosystem approach would generally employ the following five point plan:
1. Map the world’s terrestrial ecosystems, inventory the species, and the
ecosystem services
2. ID terrestrial ecosystems that are resilient and that can recover
3. Locate and protect the most endangered terrestrial ecosystems and species
4. Seek to restore as many degraded ecosystems as possible
5. Make development biodiversity-friendly by providing significant financial
incentives
iii. Biodiversity Hotspot – areas especially rich in plant species that are found nowhere
else and are in great danger of extinction
1. Suffered serious ecological disruption, mostly because of rapid human
population growth and the resulting pressure on natural resources and
ecosystem services
2. Relied primarily on diversity of plant species as a way to ID biodiversity
hotspots because data on plant diversity were the most readily available
a. Also viewed plant diversity as an indicator of animal diversity
b. Only about 5% of the hotspots is truly protected with government
funding and law enforcement
3. Publishing its Red List of Ecosystems that are vulnerable, endangered, or
critically endangered as a companion of its Red List of Threatened Species
iv. Case Study: Madagascar
1. Many of Madagascar’s plant and animal species are among the world’s most
endangered, primarily because of habitat loss
2. Madagascar is one of the world’s most threatened biodiversity hotspots
3. Mounted efforts to slow the country’s rapid loss of biodiversity - such efforts
are hampered by Madagascar’s rapid population growth
4. To reduce the rapid losses of biodiversity, the country will need to slow its
population growth drastically and teach many of its people how to make a
living from reforestation, ecotourism, and more sustainable uses of its
forests, wildlife, and soil resources
v. Another way to help sustain the earth’s biodiversity is to ID and protect areas where
vital ecosystem services are being impaired enough to reduce biodiversity and harm
local residents
vi. The ecosystem services approach recognizes that most of the world’s ecosystem are
already dominated or influenced by human activities and that such pressures are
increasing as the human population, urbanization, resource use, and the human
ecological footprint all expand
1. Such efforts of conservation by themselves will not significantly slow the
steady erosion of the earth’s biodiversity and ecosystem services, nor will
they help to reduce the poverty that plays a major role in ecosystem
degradation
vii. Liferaft Ecosystem – these would be areas where poverty levels are high and where
a large part of the economy depends on various ecosystem services that are being
viii.
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degraded severely enough to threaten the well-being of people and other forms of
life.
1. Help protect human communities along with natural biodiversity and the
ecosystem services that support all life and economics (WIN-WIN)
Ecological Restoration – the process of repairing damage caused by humans to the
biodiversity and ecosystem services provided by ecosystems
1. Almost every natural place on the earth has been affected or degraded to
some degree by human activities
2. Examples: replanting forests, reintroducing native species, removing
invasive species, freeing river flows by removing dams, and restoring
grasslands, coral reefs, wetlands, and stream banks
Through secondary succession many disturbed areas of land can return to forest or
to other natural ecosystems, but this can take hundreds of years
How to speed up ecological succession processes using a variety of approaches:
1. Restoration – returning a degraded habitat or ecosystem to a condition as
similar as possible to its natural state
2. Rehabilitation – Turning a degraded ecosystem into a functional or useful
ecosystem without trying to restore it to its original condition
3. Replacement – replacing a degraded ecosystem with another type of
ecosystem
4. Creating Artificial Ecosystems
A science based four step strategy for carrying out most forms of ecological
restoration and rehabilitation
1. ID the causes of the degradation
2. Stop the abuse by eliminating or sharply reducing these factors
3. If necessary, reintroduce key species to help restore natural ecological
processes
4. Protect the area from further degradation and allow secondary ecological
succession to occur
Reconciliation Ecology – a form of conservation biology – this science focuses on
inventing, establishing, and maintaining new habitats to conserve species diversity
in places where people live, work, or play
1. AKA – on learning how to share with other species some of the space we
dominate