Transcript Document

Chapter 5
Populations
5-1
How Populations Grow
KWL
What
are three things you want
to know about population
growth?
What do you know about
population growth?
How Populations Grow
 Characteristics
of Populations
–Three important characteristics
of a population
geographic distribution
Density
growth rate
Geographic Distribution
Geographic Distribution
Geographic
distribution, or range, is
a term that describes
the area inhabited by a
population.
Population Density
 Population
density is the number of
individuals per unit area.
 The population of saguaro cactus in the
desert plant community has a low
density, whereas other plants in that
community have a relatively high
density.
Populations Growth
 Population
Growth
 Three factors can affect population size:
number of births
the number of deaths
the number of individuals that enter or
leave the population.
* Simply put, a population will increase or
decrease in size depending on how many
individuals are added to it or removed from it
Immigration & Emmigration
 Immigration
the movement of individuals into an
area, is another factor that can cause a
population to grow.
 Emigration
the movement of individuals out of an
area, can cause a population to
decrease in size.
Word Origin
 Immigration
is formed from the Latin prefix
in-, meaning “in,” and migrare, meaning “to
move from one place to another.
 If the Latin prefix e- means “out,” then
which of the following means “migration
out”?
A.) emigration
B.) migration
C.) Immigration
Exponetial Growth
 Exponential
Growth
If a population has abundant
space and food, and is protected
from predators and disease, then
organisms in that population will
multiply and the population size
will increase.
Exponential Growth
Exponential growth occurs when
the individuals in a population
reproduce at a constant rate.
Under ideal conditions with
unlimited resources, a
population will grow
exponentially.
Checkpoint
Which of the following is NOT a
condition for a population to reach
exponential growth?
A.) presence of unlimited resources
B.) Absence of predation and
disease
C.) movement of individuals out of
the population
Logistic Growth
 Logistic
growth occurs when a
population's growth slows or stops
following a period of exponential growth.
 As
resources become less available,
the growth of a population slows or
stops. The general, S-shaped curve of
this growth pattern, called logistic growth
Carrying Capacity
Carrying
Capacity
The number or the largest
number of individuals that a
given environment can support.
List three characteristics that are used to
describe a population.
What factors can change a population's
size?
What is the difference between
exponential growth and logistic growth?
 Using
Graphic Organizers
 Draw a concept map that shows how
populations grow. Include the following
terms: exponential growth, logistic
growth, birthrate, death rate,
immigration, emigration. Add any other
terms that you think are useful to
complete the map
Chapter 6
Humans in the
Biosphere
VIII. Humans in the Biosphere
A. Earth as an Island-
1. all organisms that live on Earth share limited
resource base
2. Understanding how humans interact is crucial to
protecting
resources
The iiwi (Hawaiian honeycreeper), a
native species in Hawaii is becoming
scarce due to disease, habitat loss, and
predation by introduced species
B. Human Activities
1. Industry and Technology give humans advantage
in competing with other species for limited resources
such as food, energy, and space
2. Today, humans most important source for
environmental change
a. Hunting and Gathering-have changed
environment since pre-historic times
Human hunters arrived in North America about 12,000
years ago. They caused one of major mass extinctions of
large animals (woolly mammoths, giant ground sloths,
sabertooth cats, cheetahs, zebras, etc.)
b. Agriculture- humans began practicing
farming 11,000 years ago (after last ice age)
1). Domestication of Animals- sheep,
goats, cows, pigs, horses, dogs (led to
overgrazing, eroded soils, large
demands on water
2). Modern Agriculture- In 1800’s,
advancement in science led to
remarkable changes in agriculture and
increased yields (irrigation, new crop
varieties, invention of farm machines
3). Green Revolution- global effort to
increase food production for fastgrowing world population (new,
intensive farming practices that
increase yields)
C. Renewable and Nonrenewable Resources
1. Two types of environmental resources
a. Renewable- can regenerate (are
replaceable) not necessarily unlimited
b. nonrenewable- one that cannot be
replenished by natural processes (eg.
Fossil fuels, oil and natural gas
2. Sustainable use- using natural resources so
that you don’t deplete them (based on
principles
of ecology and economics)
This proud, tall tree is no match for
a huge chainsaw. Once cut, it will
be used to make many consumer
products
A tiny tree will be placed in its stead.
Varieties of trees that reach
harvesting size in fewer years have
been developed
3. Land Resources- provides space for
cities, materials for industry, soils in which crops
are grown.
desertification- in certain parts of the world
with dry climates, a combination of
farming, overgrazing, and drought have
turned once productive areas into deserts
4. Forest Resources- provides products,
habitats and food for organisms, moderates
climate, limits soil erosion, protects freshwater
supplies, “lungs” of the Earth”
deforestation- loss of forest. Can
lead to severe erosion.
Sustainable-use strategies include
selective harvesting and
replanting.
What are two ways in which reforestation
might affect the biosphere?
5. Ocean Resources- provides valuable
resources.
How do you explain graph #2 (fish catch per
person remains the same despite steady increase
in world fish catch)?
food
6. Air Resources- Air is common resource.
Preserving air quality remains a challenge for
modern society.
a. Smog- common pollutant in large
cities. (pollutant- harmful material that
can enter the biosphere through land, air,
or water)
b. Acid rain- acidic gasses released into
air and combine with water vapor
forming
drops of nitric and surfuric acid.
Can kill
plants, change chemistry of
soils and standing
water ecosystems
Photomicrograph of
drop of acid rain.
Serious threat to
environment
7. Water Resources- water is renewable
resource but must be protected because supply
is limited.
a. Water pollution- threatened by
chemicals, domestic sewage, wastes
discarded on land- all can seep into
underground water supplies.
City sewage must be treated in
sewage-treatment plants. Organic
wastes are broken down by bacteria
and then chemicals are added to kill
harmful microorganisms.
Where does all of your trash end up?
Why do we have to be careful about
what goes into our garbage landfills?
Trawlers clean up an oil spill
caused by a disaster at sea. A
system of floats called booms
helps keep the oil from
spreading during the cleanup
process.
b. Domestic sewage, which
is the wastewater from sinks
and toilets, contains
nitrogen and phosphorous
compounds that can
encourage the growth of
algae and bacteria in aquatic
habitats
Algae bloom
D. Biodiversity- sum total of the genetically based
variety of all organisms in the biosphere
1. Forms of diversity
a. Ecosystem diversity- includes variety of
habitats, communities, and ecological
processes in the living world
b. Species diversity- number of different
species in the biosphere
c. Genetic diversity- sum total of all the
different forms of genetic information carried
by all living organisms
2. Biodiversity is one of Earth’s greatest
natural resources. Species of many kinds
have provided us with foods, industrial
products, medicines, etc.
3. Threats to Biodiversityhuman activity can reduce
biodiversity by altering
habitats, hunting species to
extinction, introducing toxic
compounds into food webs, and
introducing foreign species into
new environments
a. Pollution- many forms of
pollution can affect biodiversity.
Biological magnificationconcentrations of harmful
substances increase in
organisms at higher trophic
levels. Affects all levels, but
top-level carnivore are at
highest risk
By what number is the
concentration of DDT multiplied
at each successive trophic level?
b. Introduced Species- one of most
important threats. Introduced either
intentionally or unintentionally they have
destroyed habitats of species native to those
ecosystems.
Fire ants were accidentally
imported from Brazil about
45 years ago. Now found in
San Clemente
Kudzu was introduced into the U.S. from Russia and Japas
as an ornamental and to reduce soil erosion. It grows and
reproduces rapidly, smothering areas of native plants
Zebra mussels were introduced into
Great Lakes from ballast of ships. Fastgrowing mussels filter food from the
water, blocking many food chains
Can you name any introduced species that
have created problems locally?
4. Conserving Biodiversity- many
conservation efforts focusing on entire
ecosystems as well as single species
D. Charting a Course for the Future- two major
concerns
1. Ozone depletion- naturally occurring ozone gas
(20-50 km above Earth’s surface) absorbs good
deal of harmful ultraviolet radiation from
sunlight before it reaches Earth’s surface.
a. Beginning in 1970’s scientists
found evidence showing ozone
“hole” over Antarctica
b. Problem caused by
compounds called
chlorofluorocarbons (CFCs)
(CFCs act as catalysts that enable
UV light to break apart ozone
2. Global Warming- an increase in average
temperature of the biosphere.
a. Hypothesize that human
activities have added carbon
dioxide and other greenhouse
gasses (methane, H20) into the
atmosphere
b. Scientific models suggest that
could cause polar ice caps to melt
and raise sea level. This could also
cause more severe weather
disturbances
D. The Value of a Healthy Biosphere
1. Human society depends on
healthy, diverse, and
productive ecosystems
because of the environmental
and economic benefits they
provide
2. People need to make wise
choices in use of resources
and disposal or recycling of
materials
Review
Chapter 6
Humans in the
Biosphere
In the very distant past, most people
a.
lived in small groups.
b.
lived in permanent settlements.
c.
did not gather plants.
d.
did not hunt animals.
In the very distant past, most people
a.
lived in small groups.
b.
lived in permanent settlements.
c.
did not gather plants.
d.
did not hunt animals.
The arrival of Europeans in the Hawaiian Islands changed
the islands by introducing
a.
ranching.
b.
predators.
c.
disease.
d.
all of the above
The arrival of Europeans in the Hawaiian Islands changed
the islands by introducing
a.
ranching.
b.
predators.
c.
disease.
d.
all of the above