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
RESULTS:S-shaped curveGoes through a # of Phases
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 TicketOnly 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 PopulationCurrent: 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 ImpactPositive
• Reforestation• Crop Rotation• Recycling• Sustainable practice
(Reduce, reuse, and recycle)
• Organic
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/non-native 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
♥ 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/MAGNIFIED 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