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