Download Human Impact On the Earth

Levels of Ecological Organization
Organism: A living thing-smallest level
Population: all the individuals of the same species (ducks)
Community: all the different species in an area (ducks + maple trees + dragonflies)
Ecosystem: the community plus the physical factors in an area (ducks + maple trees +
dragonflies + temperature + soil + rainfall)
Biosphere: thin zone of life around the planet-all the earth’s ecosystems-largest ecological
level
Factors Affecting Ecosystems
Biotic Factors: living elements in an ecosystem (plants & animals)
Abiotic Factors: non living elements in an ecosystem (soil, sunlight, temp, water, noise, air,
water, rocks,
minerals, climate)
Habitat: the physical space where an organism lives (its home)
BIODIVERSITY: a measure of the number of different species in an ecosystem. Some
ecosystems are more
diverse than others.
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Succession: process where organisms arrive and inhabit a new ecosystem:
Pioneer species: the first to inhabit a new area
Climax community-final community-ends succession
*See text on page 463-464.
Primary Succession: formation of an ecosystem from scratch
Secondary Succession: new ecosystem develops after an existing one is disturbed
Practice quiz:
http://www.ekcsk12.org/science/regbio/ecologyqz2.html
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Energy Flow in Ecosystems
Productivity: the total amount of photosynthesis carried out by producers in an ecosystem.
Producers: autotrophs-(self-feeders)capture energy from the sun, convert to organic
material -- plants (make their own food)
Consumers: Heterotrophs (other feeders)organisms that gain their energy from eating
other things – animals
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herbivores-eat only plants
carnivores--eat only animals
omnivores-eat both plants & animals
decomposers-consume dead organisms-most common are bacteria & fungi
Food Chain
Pathway in which energy flows from organism to organism
A food chain is a series of organisms each feeding on the one preceding it.
There are two types of food chains:
Decomposer - chains are composed of waste and decomposing organisms such as
fungi and bacteria.
Grazer - food chains begin with algae and plants and end with a carnivore.
primary producer
primary consumer
secondary consumer
tertiary consumer
decomposer
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Food Web
Complex array of interconnected food chains
Herbivores
Carnivores
Omnivores
Producers
Primary Consumers
Secondary Consumers
Tertiary Consumers
Decomposers - cause decay
Detritivore - an organism that feeds on dead or waste (bacteria, fungi)
Saprophyte-plant decomposers, such as mushrooms
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How Ecosystems Work
The Flow of Energy
Ecosystem Function
1. Energy moves thought ecosystems in a one-way flow. It must constantly be replenished.
2. Nutrients cycle and recycle in a continuous flow
Autotrophs: "self feeders", producers, plants
Heterotrophs: "other feeders", consumers, animals
The amount of life an ecosystem can support is determined by the energy captured by the
producers
Net primary productivity -- measured in calories or biomass -The more sunlight & water,
the more plants, the more animals etc
Trophic level - the level at which an organism feeds
Primary consumers (herbivores)
Secondary consumers (carnivores)
Tertiary consumers (carnivores that eat other carnivores)
Quaternary consumers (eat tertiary consumers)
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Organisms can move from one trophic level to another, by eating different types of
things.
Food Chains and Food Webs illustrate feeding relationships in ecoysystems
Detritus feeders: decomposers, feed on refuse and return nutrients to the cycle
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Energy Pyramids - illustrate how energy is transferred between trophic levels.
Energy Transfer - as you go up trophic levels, organisms lose energy.
An ecosystem can support more primary consumers, than tertiary consumers
Biological Magnification - toxins build up to higher levels as you move up in the food chain.
(Example: DDT)
Biogeochemical Cycles (Nutrient Cycles)
Ecosystems Cycle Material
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water cycle
carbon cycle
nitrogen cycle
phosphorus cycle
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Water Cycle
ground water-
transpiration (from plants)-
evaporation (from bodies of water) condensation-
precipitation (from clouds)-
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Carbon Cycle
Respiration (breathing of animals)
Combustion (burning)
Photosynthesis (uses CO2 and converts to oxygen)
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Nitrogen Cycle
Nitrogen is a fertilizer for plants
79% of the air is made of nitrogen
Legumes-
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Phosphorus Cycle
Phosphorus is found in ATP-adenosine triphosphate-an important molecule found in cellsconverted to get energy
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Community Interactions
Community: All the interacting populations in an ecosystem
Competition
Predation
Symbiosis
Symbiosis: means "living together" --, a close interaction between organisms of
different species.
Parasitism: one is harmed (host), one benefits (ticks and deer)
Commensalism: one benefits, the other is unaffected (birds and trees)
Mutualism: both species benefit (termites & protozoa)
The Ecological Niche - A species way of life, each species in an ecosystem occupies its own
niche-its job
Fundamental niche - the set of resources a population is theoretically capable of using under
ideal circumstances
Realized niche - the set of resources the population actually uses (due to competition and
resource partitioning)
Compare the following fish eating birds that live near a lake
Heron- wades in water, spears fish on the shoreline
Kingfisher - perches and nests in trees, hunts by swooping and spearing prey
Loon - a duck-like bird that paddles and dives to catch fish
Each bird lives in the same ecosystem, eats the same food, but occupies a different NICHE
Competitive Exclusion Principle - no two species can occupy the same niche. If two species
with the same niches are places together, they will be forced to compete, one will survive.
Resource Partitioning - species with similar requirements coexist but occupy smaller niches
than they would if they lived alone.
Other examples of interspecific competition and resource partitioning
5 species of warblers hunt for food in different areas of a tree
2 species of barnacles occupy deeper and shallower areas of a shoreline
Predators and Prey Coevolution drives adaptations. Prey become better at evading,
Predators better at catching Some prey adaptations
Camouflage - coloration allows organisms to blend
Warning coloration - bright colors advertise danger
Startle Coloration - eyespots on caterpillers
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Mimicry
Aggressive Mimicry - enhances predation
Mullerian mimicry - all dangerous species resemble each other (bright colors)
Batesian mimicry - harmless species resemble dangerous ones
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Biomes of the Earth
Climate is the primary factor that determines what organisms can live in any given habitat.
Therefore, climate is wha
causes certain areas of the earth to become distinctive
A BIOME is a major ecosystem spread over a wide geographic area, and characterized by
certain types of flora and
fauna. (plants and animals)
Note the relative locations of the biomes, anything between the two tropics is considered to be
"Tropical", areas above those lines are called "Temperate" and then even farther north (or
south) you have polar. It is important to remember those
words because there are both temperate and tropical forests - each having different attributes
determined primarily
by the climate of the area.
Classification of biomes is by PRODUCTIVITY - how much biomass is gained over a period
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Aquatic Biomes
Marine - oceans
Freshwater - lakes, ponds, rivers,
streams
Varies in temperature, depending on
location
Some lakes freeze over (Winterkill)
Saltwater
Photic zone - receives light
Aphotic zone - not enough light for
photosynthesis
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Terrestrial Biomes
Polar
Very little plant growth (if
any)
Photosynthetic organisms are
marine
Bitterly cold temperatures
Supports some marine
mammals & birds (penguins,
whales)
Chaparral
Temperate Grassland - Prairie
Few trees, good soil supports
grasses
Used as farmland
Animals: deer, buffalo
Found in dry regions of the
mediterranian
Also called "scrubland"
Plants are mainly spiny shrubs
Animals: lizards, rodents,
coyotes, birds
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Taiga - Coniferous Forest
Found in Northern areas and
on mountain sides
Conifers have needles shaped
to shrug off snow (evergreens)
Logging of treese has reduced
some forests
Animals: deer, wolf, foxes,
birds
Desert
Temperate Deciduous Forest
Very hot in day, cold at night
Low amounts of rainfall
Plant species are cactus or
plants that store water
Animals: many lizards, some
birds and small mammals
Usually located east of
mountains
Trees lose their leaves in the
fall
Animals: fox, coyote,
squirrels, rabbits,
deer
Plants(trees): Oak, Maple,
Sweet Gum
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Tundra
Rainforest
Savanna
Very dry, followed by short
periods of heavy rain
Plants - grasses and drought
resistant trees
Animals: elephants, gazelle,
zebra, giraffe
Can be tropical (near equator)
or temperate
High levels of rain
Great diversity of plants and
animals
In mature forests, the floor
doesn't have much growth due
to tree canopy blocking out the
light
Cold and Dry
Permafrost - layer of soil that
remains
permanently frozen
Large trees cannot grow, but
grasses can in
the warmer season
Supports migratory animals:
caribou, wolves, bear
Lichens - major photosynthetic
food source
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Population Growth and Regulation
How Populations Grow
Factors the determine how much a population will change
1. births
2. deaths
3. migration
Stable populations occur when as many individuals join (birth or immigration) as leave
(death or emigration)
Population change = (birth - deaths) + (immigrants - emigrants)
Factors that influence biotic potential:
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2.
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age of reproduction
frequency of reproduction
number of offspring produced
reproductive life span
average death rate under ideal conditions
Environmental Resistance: Decreases the birth rate, or increases death rate, related to
environmental conditions, such as food & space.
Density Independent Factors: weather and other natural disasters
Density Dependent Factors: food, space, water, parasitism, competition
Growth rate (r) = birth
rate (b) - death rate (d)
Population growth = rN
(r = growth rate, N =
original population size)
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J-shaped curve showing
exponential growth of a
population
S-shaped curve shows how a population
This population has not yet
reached its carrying capacity.
Carrying Capacity: the maximum size of
becomes limitied by environmental factors
a population that an area can support
Boom and Bust Cycles
Rapid population growth followed by a massive die-off
Populations that are influenced by seasonal weather patterns, such as cold and drought
Predator-Prey Cycles
Most populations fluctuate in cycles. The prey population rises, causing the predator population to also ris
then overfeed on prey, causing the prey population to drop, Once the prey population drops, the predato
drops due to lack of food. The cycle repeats indefinitely.
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Competition
Resources limit the size of populations as individuals compete
Interspecific competition: occurs between members of different species
Intraspecific competition: occurs beweeen members of the same species
Scramble competition: free-for-all, plants disperse seeds and as they grow they choke out other seedlings
Contest competition: social interaction in animals that leads to the gaining of resources
Contest competition: social behaviors, territoriality
Dominance heirarchies: pecking orders within members of a species, dominant individuals get more resou
priveleges
Population Patterns in Space and Tim
Distributions
Clumped
Random
Uniform
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Survivorship curve
Early loss
Constant loss
Late Loss
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Human Impact On the Earth
Pollution
DDT (dichloro diphenyl trichloro ethane)
Starting in the 1940's, the chlorinated hydrocarbon
DDT was used in vast quantities all over the world for
killing insects. It was cheaper and much more
effective than other insecticides against nearly all
insects. It saved millions of lives by killing the
mosquitoes that spread malaria and saved millions
from starvation by killing crop pests..
But: in the 1950's and 1960's there was an alarming
decline in the populations of several predatory birds,
particularly fish-eaters such as bald eagles,
cormorants, ospreys and brown pelicans.
DDT is toxic at high levels; but at lower levels it interferes with calcium deposition in
eggshells, causing them to be thin, fragile, and often crushed by the parents in the
nest.
Although DDT was suspected, the levels to which the birds had been exposed were
nowhere near high enough to have killed them. But when the bird's bodies were
analyzed, they were found to have up to one million times the concentration that
was present in the sprayed water. This led to the discovery of bioaccumulation (also
known as biological magnification), which means the steady increase in
concentration of a contaminant with increasing level in the food chain. In the case of
DDT, it results from the following factors:
1. DDT is not metabolized, and does not break down in the body.
2. It is much more soluble in fat than in water. So it accumulates in body fat and is
not excreted.
3. The transfer of energy from lower trophic levels to higher ones is inefficient -so
herbivores eat large quantities of plant material, and carnivores eat many times
their body weight of prey during their lifetime. Since DDT is not excreted, the
carnivore accumulates most of the DDT that was present in all of the prey
organisms.
AIR POLLUTION AND ACID RAIN
Each year the U.S. discharges into the atmosphere:
15 million tons sulfur dioxide:
70% from power plants burning coal or oil.
30% from smelters and refineries.
20 million tons nitrogen oxides:
40% from cars, trucks, planes
30% from power plants
30% from other industrial sources.
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Sulfur dioxide and nitrogen oxides combine with water in the air to form
sulfuric acid and nitric acid, causing acid rain, Acid rain destroys plants and
animals in several different ways:
1. Acidification of lakes directly kills algae, invertebrates, amphibians, and
ultimately fish. The result is a crystal clear lake that is beautiful but dead
2. Removal of soil nutrients. Acid rain dissolves essential nutrients, including
calcium and potassium, out of the soil thus reducing their availability to plants. It
also kills microorganisms, preventing decomposition from returning nutrients to the
soil.
3. Dissolving toxic metals. Acid rain also dissolves toxic metals, such as aluminum
and mercury, which are otherwise insoluble and harmless.
CLIMATE CHANGE
The earth's climate may be warming as a result of the accumulation of "greenhouse
gases", notably carbon dioxide. The kinds of data supporting this conclusion are.
Record breaking daily temperatures
Heat waves
Rise in sea level
Retreat of glaciers
Icebergs breaking of Antarctica
Early thaws
Increased rain and snow falls
*Many scientists feel that this is not enough data (over too small of a time period)
to judge
LOSS OF BIODIVERSITY
(Extinctions)
Habitat Loss **
Pollution
Overexploitation
International Trade (Poaching)
Disease
Introduction of Exotic Species
THE U.S. ENVIRONMENTAL
PROTECTION AGENCY (EPA)
EPA's purpose is to ensure that:
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All Americans are protected
from significant risks to human health and the environment where they live,
learn and work.
National efforts to reduce environmental risk are based on the best available
scientific information.
Federal laws protecting human health and the environment are enforced
fairly and effectively.
All parts of society-communities, individuals, business, state and local
governments, tribal governments-have access to accurate information
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sufficient to effectively participate in managing human health and
environmental risks.
Environmental protection contributes to making our communities and
ecosystems diverse, sustainable and economically productive.
The United States plays a leadership role in working with other nations to
protect the global environment.
**Some people feel the EPA is not doing what it was intended to do. That, the EPA
often finds itself in conflict with landowners, towns, and individuals --> Remeber the
Stossel Report on the Lead in Aspen?
The EPA's Pesticide Program
Over 20,000 pesticide products have been registered for use in the United States.
EPA is responsible for regulating the sale and use of pesticides, and the allowable
levels in or on food.
EPA is responsible for registering, or licensing pesticide products - based on
assessment of the potential effects on human health and the environment, when
used according to label directions.
EPA's Strategy for Persistent, Bioaccumulative and Toxic pollutants (PBT) :
When a company or individual introduces a new chemical or a significant new use of
a chemical, they must obtain a permit from the EPA. Tests include:
biodegradability in a single-organism test
biodegradability in a laboratory microcosm
bioaccumulation potential
chronic toxicity to fish (rainbow trout) and daphnids
CITES
International trade puts enormous economic pressure on suppliers and threatens
the existence of many rare plants and animals. For this reason in 1975 the U.S.,
along with nine other countries, signed the Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES). The objective of CITES, which
now involves over 150 countries, is to ensure that trade will not cause the extinction
of plant or animal species.
CITES maintains lists of threatened species and regulates the import and export of
those species.
Examples of animals on CITES lists: Great apes, Great whales, African elephant, All
rhinoceros species, Giant Panda, sea turtles, crocodilians, Large cats, Several
orchids, cacti and cycads
The U.S. Endangered Species Act of 1973 (ESA)
Unlike previous legislation, the act was not designed to protect only those species
that were economically useful or potentially useful to man; it is based on the idea
that species are of "aesthetic, ecological, educational, historical, recreational and
scientific value to the nation and its people". The ultimate purpose of the
Endangered Species Act is to bring about the recovery of endangered and
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threatened species. The Supreme Court has interpreted the act to mean that the
value of species cannot be calculated, and that listed species should be protected
whatever the cost. The ESA requires the following:
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It requires the Secretary of the Interior (through the U.S. Fish and Wildlife
Service or, for marine species, the National Marine Fisheries Service) to
identify and publish lists of species that are endangered (in imminent danger
of going extinct) or threatened (likely to become endangered in the
foreseeable future).
A decision whether to list must be based solely on the biological evidence;
economic factors are not relevant at this stage. Anybody that can provide
adequate evidence can make a proposal for listing.
Endangered species are given full legal protection against exploitation: they
cannot be "taken ". "Take" means harass, harm, pursue, hunt, shoot, wound,
kill, trap, capture, or collect, or to attempt to engage in such conduct. Such
activities directed against animals are illegal even on private land.
The federal government is prohibited from engaging in activities that could
jeopardize the continued existence of listed species or adversely affect their
designated critical habitat.
A recovery plan must be developed and the recovery of the species must be
monitored.
The species or its products cannot be exported or imported.
Criticisms of the ESA
1. It doesn't help endangered species
2. It makes enemies of landowners
3. Species listing becomes political
4. It interferes with human (and homeowners) rights
5. It damages the economy
Animal Welfare Act
Requires that animals have:
proper and sufficient food and water
adequate shelter
the opportunity to display normal patterns of behavior
physical handling in a way which minimizes the likelihood of unreasonable or
unnecessary pain or distress
protection from, and rapid diagnosis of, any significant injury or disease.
Act covers: pet stores, research, hunting, pets, zoos, circuses
Clean Air Act
The 1990 Clean Air Act is a federal law covering the entire country; states do much
of the enforcement. For example, a state air pollution agency holds a hearing on a
permit application by a power or chemical plant or fines a company for violating air
pollution limits.
Under this law, EPA sets limits on how much of a pollutant can be in the air
anywhere in the United States. This ensures that all Americans have the same basic
health and environmental protections. The law allows individual states to have
stronger pollution controls, but states are not allowed to have weaker pollution
controls than those set for the whole country.
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Environmental Issues
Human Overpopulation
" How to share and renew resources
" Energy Conservation
" Managing waste
" Managing populations
" Loss of fertile lands (desertification, topsoil loss)
Loss of Biodiversity (Extinctions)
" Deforestation
" Urban Sprawl
" Endangered Species Act
" Illegal Animal Trade
" Exotic (Invasive) Species
" Overfishing
Global Warming
" Greenhouse Gases
" Is global warming happening?
" How will it affect life on the planet?
Air Pollution / Water Pollution
" Acid Rain
" Clean Air Act
" Nitrification of Lakes (Runoff)
" Sources of Clean Water
" Ozone hole (Chloroflourocarbons)
" Toxins in the environment (DDT) & biological magnification
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