Transcript 6.8.05 Conservation and Biodiversity

The Layout Of Life (from BIG to small)
Biosphere (planet earth: water, land and sky)
Biomes (Tundra, Taiga, Dessert, Ocean, Lake)
Ecosystem
(all of the plants and animals in a community
that live together in a particular biome)
Biomes of the World
• A biome is a large biogeographical unit of the
biosphere that has a particular mix of plants and
animals that are adapted to living under certain
environmental conditions.
• Terrestrial: Tundra, Taiga, Coniferous and
Deciduous Forests, Temperate Rain Forests,
Grasslands, Shrublands (Chaparrel), Desert,
• Aquatic: Freshwater (lakes), Saltwater (Ocean),
Estuaries (salt and fresh combined)
• Ecology is the study of these ecosystems!
• Ecology is not just about plants, animals and
their environmets……
………………..it’s also about the humans!
(our lives tend to affect all other lives
disproportionately!)
Population Growth and Density
(one is dependent on the other)
• When the population reaches carrying capacity,
the population stops growing because
environmental resistance opposes biotic potential
• If the population does not stop growing, it will
demolish its resources, thereby killing itself.
Human Population Growth
• The human population is expanding
exponentially – it is not known how much longer
the earth will be able to support our population
at the current rate of exhausting natural
resources --- but it doesn’t look good. 
Chapter 34: Ecosystems and
Human Interferences
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
The Nature of Ecosystems
• An ecosystem contains biotic (living)
components and abiotic (nonliving)
components.
• The biotic components of ecosystems are
the populations of organisms.
• The abiotic components include inorganic
nutrients, water, temperature, and
prevailing wind.
Biotic Components of an
Ecosystem
• Autotrophs are producers that produce
food for themselves and for consumers.
• Most are photosynthetic organisms but
some chemosynthetic bacteria are
autotrophs.
• Heterotrophs are consumers that take in
preformed food.
Biotic components
• Consumers may be:
• Herbivores – animals that eat plants,
• Carnivores – animals that eat other
animals,
• Omnivores, such as humans, that eat plants
and animals, or
• Decomposers, bacteria and fungi, that
break down dead organic waste.
• Detritus is partially decomposed organic
matter in the soil and water; beetles,
earthworms, and termites are detritus
feeders.
Consumers
Energy Flow and Chemical Cycling
•
Every ecosystem is characterized by two
phenomena:
1) Energy flows in one direction from the
sun to producers through several levels
of consumers, and
2) Chemicals cycle when inorganic
nutrients pass from producers through
consumers and returned to the
atmosphere or soil.
Nature of an ecosystem
• Only a small portion of energy and
nutrients made by autotrophs is passed on
to heterotrophs, and only a small amount
is passed to each succeeding consumer;
much energy is used at each level for
cellular respiration and much is lost as
heat.
• Ecosystems are dependent on a continual
supply of solar energy.
• The laws of thermodynamics support the
concept that energy flows through an
ecosystem.
Energy balances
Energy Flow
• The feeding relationships in an ecosystem
are interconnected in a food web.
• Generally, the upper portion of a food web
is a grazing food web, based on living
plants, and the lower portion is a detrital
food web, based on detritus and the
organisms of decay.
Forest food webs
Trophic Levels
• A trophic level is all the organisms that
feed at a particular link in a food chain.
• A diagram that link organisms together by
who eats whom is called a food chain.
• A grazing food chain:
• Leaves → caterpillars → tree birds → hawks
• A detrital food chain:
• Dead organic matter → soil microbes → worms
Food chain
Ecological Pyramids
• The shortness of food chains can be
attributed to the loss of energy between
trophic levels.
• Generally, only about 10% of the energy in
one trophic level is available to the next
trophic level.
• This relationship explains why so few
carnivores can be supported in a food
web.
• The flow of energy with large losses
between successive trophic levels can be
depicted as an ecological pyramid that
shows trophic levels stacked one on the
other like building blocks.
• Usually a pyramid shows that biomass and
energy content decrease from one trophic
level to the next, but an inverted pyramid
occurs where the algae grow rapidly and
are consumed by long-lived aquatic
animals.
Ecological pyramid
Global Biogeochemical Cycles
• All organisms require a variety of organic
and inorganic nutrients.
• Since pathways by which chemicals cycle
through ecosystems involve both biotic and
abiotic components, they are known as
biogeochemical cycles.
• Biogeochemical cycles often contain
reservoirs, such as fossil fuels, sediments,
and rocks that contain elements available on
a limited basis to living things.
• Exchange pools are components of
ecosystems like the atmosphere, soil, and
water—which are ready sources of
nutrients for the biotic community that
uses the chemicals.
• Nutrients cycle among the members of the
biotic component of an ecosystem and
may never enter an exchange pool.
• Nutrients flow between terrestrial and
aquatic ecosystems.
Model for chemical cycling
The Water Cycle
• In the water, or hydrologic cycle, the sun’s
rays cause fresh water to evaporate from
the oceans, leaving the salts behind.
• Vaporized fresh water rises into the
atmosphere, cools, and falls as rain over
oceans and land.
• Precipitation, as rain and snow, over land
results in bodies of fresh water plus
groundwater, including aquifers.
• Water is held in lakes, ponds, streams,
and groundwater.
• Evaporation from terrestrial ecosystems
includes transpiration from plants.
• Eventually all water returns to the oceans.
• Groundwater “mining” in the arid West and
southern Florida is removing water faster
than underground sources can be
recharged.
The water cycle
The Carbon Cycle
• In the carbon cycle, a gaseous cycle,
organisms exchange carbon dioxide with the
atmosphere.
• Shells in ocean sediments, organic
compounds in living and dead organisms,
and fossil fuels are all reservoirs for carbon.
• Fossil fuels were formed during the
Carboniferous period, 286 to 360 million
years ago.
The carbon cycle
Carbon Dioxide and Global
Warming
• The transfer rate , the amount of a nutrient
that moves from one compartment of the
environment to another, can be altered by
human activities, allowing more carbon
dioxide to be added to the atmosphere.
• Atmospheric carbon dioxide has risen from
280 ppm to 350 ppm due to burning of fossil
fuels and forests.
• Besides CO2, nitrous oxide and methane are
also greenhouse gases.
• Similar to the panes of a greenhouse, these
gases allow the sun’s rays to pass through
but hinder the escape of infrared (heat)
wavelengths.
• Buildup of more of these “greenhouse
gases” could lead to more global warming.
• The effects of global warming could include
a rise in sea level, affecting coastal cities,
and a change in global climate patterns with
disastrous effects.
Earth’s radiation balances
The Nitrogen Cycle
• Nitrogen makes up 78% of the atmosphere
but plants are unable to make use of this
nitrogen gas and need a supply of
ammonium or nitrate.
• The nitrogen cycle, a gaseous cycle, is
dependent upon a number of bacteria.
• During nitrogen fixation, nitrogen-fixing
bacteria living in nodules on the roots of
legumes convert atmospheric nitrogen to
nitrogen-containing organic compounds
available to a host plant.
• Cyanobacteria in aquatic ecosystems and
free-living bacteria in the soil also fix
nitrogen gas.
• Bacteria in soil carry out nitrification when
they convert ammonium to nitrate in a twostep process: first, nitrite-producing bacteria
convert ammonium to nitrite and then
nitrate-producing bacteria convert nitrite to
nitrate.
• During denitrification, denitrifying bacteria in
soil convert nitrate back to nitrogen gas but
this does not quite balance nitrogen fixation.
The nitrogen cycle
Nitrogen and Air Pollution
• Human activities convert atmospheric
nitrogen to fertilizer which when broken
down by soil bacteria adds nitrogen
oxides to the atmosphere at three times
the normal rate.
• Humans also burn fossil fuels which put
nitrogen oxides (NOx) and sulfur dioxide
(SO2) in the atmosphere.
• Nitrogen oxides and sulfur dioxide react
with water vapor to form acids that
contribute to acid deposition.
• Acid deposition is killing lakes and forests
and also corrodes marble, metal, and
stonework.
• Nitrogen oxides and hydrocarbons (HC)
react to form photochemical smog, which
contains ozone and PAN
(peroxyacetylnitrate), oxidants harmful to
animal and plant life.
Acid deposition
• A thermal inversion, where these
pollutants are trapped under warm,
stagnant air concentrates pollutants to
dangerous levels.
• Nitrous oxide is not only a greenhouse
gas, but contributes to the breakdown of
the ozone shield that protects surface life
from harmful levels of solar radiation.
Thermal inversion
The Phosphorus Cycle
• The phosphorus cycle is a sedimentary
cycle.
• Only limited quantities are made available to
plants by the weathering of sedimentary
rocks; phosphorus is a limiting inorganic
nutrient.
• The biotic community recycles phosphorus
back to the producers, temporarily
incorporating it into ATP, nucleotides, teeth,
bone and shells, and then returning it to the
ecosystem via decomposition.
The phosphorus cycle
Phosphorus and Water Pollution
• Phosphates are mined for fertilizer
production; when phosphates and nitrates
enter lakes and ponds, eutrophication
occurs.
• Many kinds of wastes enter rivers which
flow to the oceans; oceans are now
degraded from added pollutants.
• If pollutants are not decomposed, they may
increase in concentration as they pass up
the food chain, a process called biological
magnification.
Chapter Summary
• An ecosystem includes autotrophs that
make their own food and heterotrophs that
take in preformed food.
• Solar energy enters biotic communities via
photosynthesis, and as organic molecule
pass from one organism to another, heat is
returned to the atmosphere.
• Chemicals cycle within and between
ecosystems in global biogeochemical
cycles.
• Biogeochemical cycles are gaseous
(carbon cycle, nitrogen cycle) or
sedimentary (phosphorus cycle).
• The addition of carbon dioxide (and other
gases) to the atmosphere is associated
with global warming.
• The production of fertilizers from nitrogen
gas is associated with acid deposition,
photochemical smog, and temperature
inversions.
• Fertilizer also contains mined phosphate;
fertilizer runoff is associated with water
pollution.
• Certain pollutants undergo biological
magnification as they pass through the
food chain.
Chapter 36: Conservation of
Biodiversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Conservation Biology and
Biodiversity
• Conservation biology studies all aspects of
biodiversity with the goal of conserving natural
resources.
• A primary goal of conservation biology is the
management of biodiversity for sustainable use
by humans.
•
1.
2.
3.
4.
Conservation biology supports these ethical
principles:
Biodiversity is desirable for all living things.
Extinctions, due to human actions, are
undesirable.
Complex interactions in ecosystems support
biodiversity.
Biodiversity resulting from evolutionary
change has value in and of itself.
Biodiversity
• Biodiversity is the variety of life on earth.
• There are between 5 to 15 million species in
existence.
• Important aspects of biodiversity are:
• Genetic diversity
• Community diversity
• Landscape diversity
Number of described species
Distribution of Diversity
• Biodiversity is not evenly distributed across the
biosphere.
• Biodiversity hotspots contain large
concentrations of species but may cover only
small portions of the earth.
• Rain forest canopies and the deep-sea benthos
are so diverse they are considered biodiversity
frontiers.
Value of Biodiversity
• Biodiversity is a resource of immense value.
• Direct values include:
• Medicinal value
• Agricultural value
• Consumptive use value
Medicinal Value
• Most of the prescription drugs used in the U.S.
were derived from living things.
• For example, many lives have been saved from
cancer with medicine made from the tropical
plant, rosy periwinkle.
• It is likely that an additional 328 types of drugs
will be found in tropical rain forests, with a value
to society of $147 billion.
Agricultural Value
• Certain wild plants serve as a source of genetic
variation for related crop species.
• Biodiversity can also provide biological pest
controls that reduce the need for chemical
pesticides.
• Wild bees are resistant to mites that have wiped
out the honeybee population that pollinates
many important crops.
Consumptive Use Value
• Much of the freshwater and marine harvest of
organisms used for food depends on natural
ecosystems rather than aquaculture.
• Wild fruits and vegetables, fibers, beeswax, and
seaweed are important economically.
• Wood, rubber, and latex are tree products of great
economic importance.
• Sustained production, rather than ecosystem
destruction, will ensure that these products are
available indefinitely.
Indirect Value of Biodiversity
• Indirect value of biodiversity includes:
• Biogeochemical cycles (simply: LIFE!)
• Waste disposal
• Provision of fresh water
• Prevention of soil erosion
• Regulation of climate
• Ecotourism
Biodiversity and Natural Ecosystems
• Scientific studies have shown that ecosystem
performance improves with increasing species
richness.
• Rates of photosynthesis also increases as
diversity increases.
• It remains to be determined whether more
diverse ecosystems are better able to withstand
environmental change.
!!! WARNING !!!
• Between 10-20% of living species will go extinct
in 20 to 50 years unless immediate steps are
taken to protect them.
• It is important to understand the:
• Concept of biodiversity
• Value of biodiversity
• Causes of present-day extinctions
• How to prevent extinctions from occurring
Causes of Extinction
• Causes of extinction include:
• Habitat loss
• Alien species
• Pollution
• Overexploitation
• Most threatened and endangered species
are imperiled for more than one reason.
Habitat Loss
• Habitat loss has occurred in all
ecosystems.
• Habitat loss in tropical rain forests and
coral reefs is of great concern because of
the great diversity of species living in
these ecosystems.
• Loss of habitat also affects freshwater and
marine biodiversity.
Habitat loss
Road construction in Brazil
Alien Species
• Alien species (exotics) are nonnative species
that migrate into new ecosystems or are
introduced there by humans.
• Introduction of alien species by humans has
been due to:
• Human colonization of new areas
• Horticulture and agriculture
• Accidental transport
• Alien species disrupt food webs.
Exotics on Islands
• Because islands have unique
assemblages of native species that are
closely adapted to one another,
introduction of exotic species is especially
disruptive.
• Examples:
• Myrtle trees in Hawaii
• Brown tree snake in Guam
• Black rats in the Galapagos Islands
Alien species
Pollution
• Pollution is any environmental change that
adversely affects the lives and health of
living things.
• Categories include:
• Acid deposition
• Eutrophication
• Ozone depletion
• Organic chemicals
• Global warming
Global warming
Overexploitation
• Overexploitation occurs when too many
individuals are taken and population size
is severely reduced.
• Overexploitation occurs in:
• Decorative plants
• Exotic aquarium fish
• Colorful parakeets and macaws
• Oceanic fishing areas
Trawling
Conservation Techniques
• To preserve species, it is necessary to
preserve their habitat.
• Preserving biodiversity hotspots will help
save greater numbers of species.
• The preservation of a keystone species
can preserve biodiversity in a habitat.
• Saving metapopulations, including the
source population and sink population, is
important in species preservation.
Habitat preservation
Landscape Dynamics
• A landscape encompasses different types
of ecosystems.
• Landscape protection for one species
often benefits other wildlife sharing the
same space.
• When preserving landscapes, the edge
effect must be considered because it can
have a serious impact on population size.
Edge effect
Computer Analyses
• Gap analysis uses the computer to find
gaps in preservation, places where
biodiversity is high outside of preserved
areas.
• A population viability analysis helps
researchers determine the amount of
habitat a species requires to maintain
itself.
Habitat Restoration
• Restoration ecology is a subdiscipline of
conservation biology that seeks scientific
ways to return ecosystems to their former
state.
• A restoration plan has been developed for
the Everglades that will sustain the
Everglades ecosystem while maintaining
flood control.
Restoration of the Everglades
•
Three principles of restoration ecology
have emerged:
1. It is best to begin as soon as possible
before remaining fragments of habitat
are lost.
2. It is best to use biological techniques that
mimic natural processes to bring about
restoration.
3. The goal is sustainable development, the
ability of the ecosystem to maintain itself
while serving human beings.
Chapter Summary
• Conservation biology is the scientific study
of biodiversity and its management for
sustainability.
• Biodiversity must be preserved as
genetic, community, and landscape
diversity.
• Biodiversity has direct and indirect values.
• Researchers have identified the major
causes of extinction, including habitat loss,
alien species introduction, pollution, and
overexploitation.
• To preserve species, habitat must be
preserved.
• Sometimes habitat must be restored
before sustainable development is
possible.