Transcript Primary Succession - St. John`s High School

Changes Over Time
• Ecological Succession – natural changes and
species replacements in communities of an
ecosystem
• Occurs in stages as different species create
conditions suitable for some species and
unsuitable for others
• Often difficult to observe
– can take decades
In the beginning…
• New land can be created or exposed where
no life existed before
– Lava destroying all life in its path and forms new land
– An avalanche exposes new areas and ledges
– A city street has never before had life growing from it.
• New communities of organisms colonizing these areas
is called Primary Succession
• The first species in the area are called Pioneer Species
Dreamstime
– Example: Lichens (can grow without
soil on rocks and other surfaces)
And then…
• Pioneer organisms die and become
the first patches of soil
• The presence of soil allows weedy
plants to emerge, and over time
vines, shrubs, and trees appear
• When this primary succession
slows down and the community
becomes stable
• This mature community undergoing
little or no change is called the
Climax Community.
From Pioneer Species to Climax
Community
Tiffany Boyette and Marianne Valentine
Disaster Strikes…
• When natural disaster or human
actions disrupt or destroy a
community, the following community
changes are called Secondary
Succession
• Like Primary Succession, the
communities of organisms
gradually change
• Unlike Primary Succession, this
occurs where there was once life and
on land that contains soil
Secondary Succession
• Because there is soil
– Pioneer Species will be different from the Primary
Succession
• Example: Lichens were pioneers in Primary where
wildflowers may be pioneers in Secondary
– Secondary Succession will take less time to reach
Climax Community
• Though Pioneer Species may be different, the
Climax Community will most likely be similar if
the climate it the same.
Secondary Succession
Population Growth
• What is Population
Growth?
• Some things exhibit
Linear Growth
– As time goes by, growth
occurs at a steady rate
– when graphed, it is a
straight line
350
300
Money Earned in Dollars
– An increase in the
size of a population
over time
Earned Wages Per Hour
250
200
150
100
50
0
0
10
20
30
Time in Hours
40
50
How do Populations Grow?
• Populations show a J-shaped
curve
• Initial increases are slow, but
as the population gets larger,
it grows faster
– Why?
• There are more organisms
available to reproduce
• This pattern is called
Exponential Growth
Can it go on Forever?
• Eventually, population growth will be affected
by limiting factors
– Such as: availability of food and space
• The number of organisms an environment can
support is called the Carrying Capacity
• In time, the population
growth will level off making
an s-shaped curve
Environmental Limitations
• Two main types of Limitation Factors
– Density-Dependent
– Density-Independent
• Density-Dependent Factors have an increased effect
as population increases (more organisms, more risk)
–
–
–
–
Disease
Competition
Parasites
Predation
Environmental Limitations
• Density-Independent Factors affect all populations
regardless of their density
(more organisms, same risk)
– Temperature
– Storms
– Natural Disasters
• (floods, hurricanes, etc)
– Drought
– Habitat Destruction
– Pollution
• Most are abiotic factors
Organism Interactions: Predation
• The number of
predators affects the
prey population
– More predators, more
risk to prey
• The number of prey
affects the predator
population
– More prey, more
food for predators
Louis J. Gross
Organism Interactions: Competition
• Competition – a density-dependant factor
– Organisms within a population must compete for resources
– If population numbers are low, resources are plentiful
– When populations grow, resources are in higher demand
• If demand is greater than supply……population must
decrease
– Fight and kill each other
– Reproduce less
Human Activities vs. Earth’s Processes
• Human populations have a carrying capacity as well.
• To have a sustainable population, there needs to be a
balance between the Earth’s resources, the needs of
humans, and the needs of other species on Earth.
• Factors that affect human population sustainability are:
– Population growth
– Technology
• Agricultural
• Industrial
• Alternative Energy
– Resource Consumption
• Population growth world-wide has
grown exponentially and is expected to continue to do so.
• Population growth will naturally slow down as it nears its
carrying capacity due to an increase in the death rate and a
decrease in the birth rate as a result of:
– Food and water shortages
– Pollution of the environment
– Spread of diseases
• An increasing population can have an effect on:
– the amount of available clean water
– the amount of waste that is produced
– the amount of available fertile soil for agriculture (food resources).
• When these resources become scarce, many natural processes
(such as the water cycle, the carbon cycle, the nitrogen cycle,
and the physical process of soil regeneration) are affected.
Earth Orbit
Population
Technology
• Technology applies scientific knowledge to help meet the needs of
humans. These technological advances in agriculture, industry, and
energy can have a positive or negative impact on Earth.
Agricultural technology
+ Advances in agricultural methods, tools, and biotechnology have
improved the ability to grow crops to sustain a growing world
population.
+ Sustainable agricultural practices can help conserve
fertile soil and reduce soil erosion.
- Farm machinery (such as tractors and combines)
consumes nonrenewable resources and can contribute
to erosion and air pollution.
- The addition of substances (such as fertilizers, pesticides,
fungicides, livestock waste) to the environment can alter
the composition of soil and can have a positive or negative effect on
the water, carbon or nitrogen cycles.
Industrial Technology
• Advances in industrial technology have changed the
world and have lead to developments in
communication, transportation, and industry.
• The development of certain chemicals have contributed to the
depletion of the ozone layer, which results in increased
ultraviolet rays reaching Earth.
• Technological advances have revolutionized the
communication industry; however, the disposal of outdated or
damaged equipment is becoming an increasing concern.
• The burning of fossil fuels for industry and transportation
increases sustainability of the growing human population;
however, it also:
– increases the greenhouse gases released in the atmosphere (mainly
carbon dioxide), which increases global temperatures (global warming)
that affect sea levels, climate and atmospheric composition
– produces acid rain (pollutants in the air combining with water to cause
the normal water pH to be lowered)
Technology
Alternative energy technology
• Using natural renewable energy sources (such as wind,
water, geothermal, or solar energy) decreases the
burning of fossil fuels, which increases the quality of
the atmosphere and the cycles involved.
• Using nuclear energy technology provides an
alternative energy source that does not impact the
atmosphere. However, the waste produced from
nuclear energy use is becoming an increasing concern.
Resource Consumption
• As the population increases and
technology expands, the demand for
Earth’s limited supply of resources
also increases.
• Some resources (such as food, clean water, and timber)
are considered renewable resources, those that can be
produced at roughly the same rate that they are
consumed.
– Renewable resources have factors that limit their production,
for example the amount of grain that can be produced is
limited by the amount of land available for farming, fertility
of the land, productivity of the grain, or availability of clean
water.
Resource Consumption
• Other resources, such as fossil fuels, are nonrenewable
resources, those that cannot be produced at the same
rate that they are consumed. For example,
– The demand for minerals, metals, and ores increases because these
strategic materials are vital to industry but are decreasing in availability.
– Minerals are regarded as nonrenewable because mineral deposits that can
be extracted economically are formed so slowly by geological processes
that their formation as a means of replacing what we are using is of no
practical use to us.
• Sustainable use of resources can be accomplished by reducing
consumption, reusing products rather than disposing of them,
or recycling waste to protect the environment.
Bibliography
• "High School Core Areas Academic Standards
Support Documents". South Carolina
Department of Education. August 2010
<https://www.ed.sc.gov/apps/cso/standards/s
updocs_hs.cfm#area_B>.
• Textbook 1
• Textbook 2
Image Citations
•
Boyette , Tiffany and Marianne Valentine. "Communities and Succession". North
Georgia College and State University. August 2010
<http://wiki.ngscied.org/index.php/Communities_and_Succession>.
• "Dreamstime for Free Images and Stock Photos". Dreamstime. August 2010
<http://www.dreamstime.com/free-photos>.
• Gross, Louis J. . "Alternative Routes to Quantitative Literacy for the Life Sciences".
University of Tennessee, Knoxville. August 2010
<http://www.tiem.utk.edu/bioed/bealsmodules/predator-prey.html>.
• Raven, Peter H. and Linda R. Berg. Environment Study Guide, 3rd Edition . New
York: Harcourt College Publishers, 2001.
• "To Do: U.S. Energy Policy". Earth Orbit. August 2010
<http://savingtheearth.net/earthorbit/>.
All other images from Microsoft clip art.