Transcript natural population

Population Ecology
3 CHARACTERISTICS
OF A POPULATION:
1) Density- individuals per unit
area
“natural population”
2) Growth Rate- change in the
number of individuals of any
species
3) Geographic distribution- area
inhabited by a population
3 FACTORS THAT
AFFECT POPULATION:
# Of Births
# Of Deaths
# Of Individuals that
ENTER and LEAVE a
population
2 TYPES OF
POPULATION
GROWTH
1) EXPONENTIAL GROWTH
Population grows
EXTREMELY
RAPID and at a
CONSTANT
RATE
Unlimited
resources
Results:
J-Shaped curve
2) LOGISTIC GROWTH
• Period of Exponential
Growth, but will
STOP or SLOW
DOWN
• CARRYING
CAPACITY: total #
of individuals a
population can
support
• Limited Resources
Goes through a # of Phases
 RESULTS:
S-shaped curve
Human Population Growth
Predator – Prey Relationship
LIMITING FACTOR
FACTOR THAT CAUSES THE
POPULATION TO DECREASE
1)Density Dependent
1)Density Independent
Density-Dependent Limiting
Factors
 Factors that
depend on the
SIZE of a
population
EXAMPLES:
*Competition
*Predation
*Disease
*Parasitism
Density-Independent Limiting
Factors
Factors that affect
ALL population
regardless of
population size
EXAMPLES:
*Natural disasters
*Weather
*Human Activities
Changes in Ecosystems:
Ecological Succession
What is Ecological
Succession?
• Natural, gradual changes in the types
of species that live in an area
• Can be primary or secondary
Primary Succession
• Begins in a place without any soil:
»Sides of volcanoes
»Landslides
»Flooding
• First, lichens that do not need soil to
survive grow on rocks
• Next, mosses (nonvascular plant---does
not have xylem or phloem) grow to hold
newly made soil and are known as a
PIONEER SPECIES (1st to inhabit an area)
Pioneer Species
Lichens break down rock to
form soil.
Low, growing moss
plants trap moisture
and prevent soil
erosion
Primary Succession Steps
1. Simple plants (ex: mosses and ferns) grow in
the new soil
2. Simple plants die (adding more nutrients to
the soil) thickening the soil and other plants
begin to grow
3. Process repeats; shrubs and trees survive
4. Insects, small birds, mammals, etc move into
an area and now can support a variety of life
Secondary Succession
• Begins in a place that already
has soil and was once the home
of living organisms
• Occurs faster and has
different pioneer species than
primary succession
• Example: after forest fires
Ecological Succession Recap
2 types of ecological succession:
Primary Succession (no soil; ex: volcano
lava flow with a pioneer species; longer
process)
Secondary Succession (existing soil;
disturbance; faster process)
Ecological Succession
Exit Ticket
Only write the answer! You may use your notes. Place in basket
with name when finished. No talking!!!!
1. List 3 factors that affect population growth.
2. What are 3 characteristics of a population?
3. What type of growth goes through a period of rapid growth,
and slows down or stops?
4. What is the term for the largest # of individuals a
population can hold?
5. What type of growth grows at a constant rate?
6. List 2 density-dependent limiting factors.
7. List 2 density-independent limiting factors.
8. Which type of succession begins in a place with no soil?
9. Natural, gradual changes in the types of species that live in
an area is known as _____________.
10. Lichens, moss, and ferns are all example of which type of
species? (Hint: 1st species to inhabit and area)
Human Impact on the
Environment
Global Warming:
in Earth’s average temperature due to the buildup of greenhouse gases
which prevents heat from escaping
Ozone depletion
• Caused by aerosol chemicals called
chlorofluorocarbons (CFCs)
• CFC’s
– Escape into atmosphere, reacts breaking
down the ozone (O3, a protective
atmospheric layer)
– UV rays penetrate the atmosphere and
cause harm to many organisms
Human Population
Current: 7+ billion
Estimated: 9+ billion (2042)
Effect of Disease on a Population
• 1. AIDS---final stage of HIV disease which
causes severe immune deficiency
• 2. Influenza--- seasonal infectious disease
caused by an RNA virus
• 3. Tuberculosis (TB)--- contagious bacterial
infection that involves the lungs
Effect of Disease on a Population
• 4. Dutch Elm Disease--- an introduced
species caused by a fungus and spead by elm
bark beetle
• 5. Pfiesteria--- associated with harmful algal
blooms and fish kills in NC
Human Impact
•
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Positive
Reforestation
Crop Rotation
Recycling
Sustainable practice
(Reduce, reuse, and
recycle)
Organic
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Negative
Acid Rain
Deforestation
Habitat Destruction
Invasive/Non-native
Species (no natural
predators)
• Ozone depletion from
the release of CFCs
North Carolina Ecosystems
• Acid Rain: effects in
mountains
• Beach Erosion: beach is
moving further inland
• Urban Development in the
Piedmont: habitat destruction
and water runoff
• Waste Lagoons: hog farms
(1995 an 8 acre hog waste
lagoon in NC burst, spilling 25
million gallons of manure in
the New River. The spill killed
about 10 million fish and
closed 364,000 acres of
coastal wetlands to
shellfishing.
• Kudzu: as an invasive/nonnative plant
Impact of Humans on
Natural Resources
Natural resources:
Non-renewable
includes fossil fuels
(petroleum, coal)
Renewable
includes animals,
plants, water, wind,
etc.
even renewable
resources can run out
Pollution:
• Agricultural
–DDT
–Fertilizers
–Animal wastes (nitrogen)
• Homes
–Strong cleaning agents
• Industry
–Toxic gases and wastes
–Acid rain
Deforestation
• Destruction of forest
• Caused by demand for
wood products, need for
space, farmland,
housing, roads, etc
 Causes Climate Changes
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Increase in temperature
Decrease in moisture
Disrupts carbon cycle
Soil erosion
Loss of Biodiversity
Habitat fragmentation
Habitat Fragmentation
Habitat Fragmentation
Pesticide Use and Bioaccumulation
♥ Pesticides negatively
affects humans,
animals, & the
environment
♥ Pesticide use can lead to
resistance in pests
♥ Pesticide concentration
INCREASED/MAGNIFIE
D as you go up the food
chain (Bioaccumulation)
 RESULTS:
Ex: Toxicity in fish caused
near extinction of fish
eating birds
Sustainable Practices:
environmental safe practice that promotes
conservation
♥ Help preserve the standard
of living for future
generations
♥ Will provide clean air,
water, fuel sources and air
 Practices:
♥ Recycle
♥ Use energy efficient
appliances
♥ Use Solar Power
♥ Use Wind power
♥ Use Hydro power