AP Environmental Science - Unit 3 Population Dynamics Review

Population Math

• Rule of 70:
  • Equation: Period of doubling = 70 / growth rate
  • Usage: Estimates the time it takes for a population to double given a constant growth rate.

Population Change Calculations

1. City Population Growth:

   • Given: Population = 50,000, growth rate = 2%
   • Doubling Time: $\frac{70}{2} = 35$ years
   • Time to reach 100,000: 35 years from 2012 = 2047
   • Time to reach 200,000: 70 years from 2012 = 2082

2. Country Population Growth:

   • Given: 12 million (1992) to 24 million (2012)
   • Constant growth rate:
     • Time span = 20 years, Growth = 12 million
     • Growth rate: $\frac{12}{12} imes \frac{1}{20} imes 100 = 6\%$ per year.

3. Population Growth Characteristics:

   • Given: Crude birth rate = 45; Crude death rate = 20; Immigration rate = 1%; Emigration rate = 0.5%
     • Rate of natural increase: $(45 - 20) + 1 - 0.5 = 25.5$
   • Percent Rate of Growth: $\frac{25.5}{1000} imes 100 = 2.55\%$

Factors Influencing Population Growth

• Four Factors:
  • Birth rate, Death rate, Immigration, Emigration
  • Equation: Population Change = (Births - Deaths) + (Immigration - Emigration)
• Adding organisms: Births and Immigration
• Removing organisms: Deaths and Emigration

Population Momentum

• The concept where a population continues to grow despite a reduction in fertility rates due to a large youth population.

R vs K Selected Species Characteristics

1. R-selected species:
   • High reproductive rate, little parental care
2. K-selected species:
   • Low reproductive rate, high parental care

Examples of Selected Species

1. Whooping Crane: K-selected; endangered due to habitat loss.
2. California Condor: K-selected; endangered mainly due to lead poisoning and habitat destruction.
3. Orangutan: K-selected; endangered due to deforestation.
4. Dodo: R-selected; extinct due to human activity and invasive species.

Growth Models

• Linear Growth: Constant addition over time.
• Exponential Growth: Rapid increase; represented by a J-shaped curve.
• Logistic Growth: Begins exponentially but slows as it reaches carrying capacity; represented by an S-shaped curve.

Density Factors

• Density Dependent:
  • Depends on population density (e.g., disease, competition)
• Density Independent:
  • Unaffected by population density (e.g., natural disasters, climate)

Survivorship Curves

• Early-loss: Majority die young (type III)
• Late-loss: Majority survive to old age (type I)
• Constant-loss: Death rate is constant (type II)

Global Population Overview

1. Most Populated Countries:
   • 1) China
   • 2) India
   • 3) United States
   • 4) Indonesia

Economic Development Characteristics

• MEDCs vs LEDCs Characteristic Comparison:
  • Per capita GDP: High (MEDC) vs Low (LEDC)
  • Industrialization: High vs Low
  • Infant Mortality Rate: Low vs High
  • Fossil fuel use: High vs Low
  • Ecological Footprint: High vs Low
  • Greenhouse Gas Emissions: High vs Low
  • Health Risks: Heart Disease (High in MEDCs) vs Infectious Diseases (High in LEDCs)

Population Policies

• China and India: Implemented policies like family planning to slow growth.
  • Advantages: Improved resource management, lower population pressure.
  • Disadvantages: Potential demographic imbalance, human rights concerns.

Age Structure Diagrams

• Slow Growth: Pyramid where base is narrower than the middle.
• Rapid Growth: Pyramid with a broad base and narrow top.
• Negative Growth: Inverted pyramid where older population is larger.
• Zero Population Growth: Stable pyramid, base similar to the top.

Demographic Transition

• Stages of Transition: Birth rates and death rates undergo changes leading to stabilization of population size.

Mortality and Fertility Rates

• Total Fertility Rate: Average number of children a woman will have.
• Replacement Level Fertility: The number of children needed to maintain a population.
• Infant Mortality Rate: Number of deaths under one year of age per 1,000 live births.
• Crude Birth/Death Rate: Number of births/deaths per 1,000 people in a year.

Urbanization and Environmental Impact

• Urban Sprawl: Unplanned, uncontrolled spreading of cities into rural areas.
• Environmental Effects: Habitat fragmentation, loss of biodiversity, increased pollution.
• Zoning: Planning regulations that govern land use.

Trends In Death Rates

• Reasons for Decreased Death Rates: Advances in healthcare, sanitation, and nutrition leading to longer life expectancy.