Overview
This lecture covers key concepts related to population patterns, density, growth, decline, and migration in AP Human Geography Unit 2, providing definitions, models, and examples for exam preparation.
Population Distribution & Factors
- Population distribution is the pattern of where people live on Earth's surface.
- Physical factors affecting distribution include climate (preference for temperate regions), landforms (lowlands vs. mountains), and proximity to water bodies.
- Human factors include culture (ties to land), economics (job availability), historical migration patterns, and political situations.
Types & Measurement of Population Density
- Population density measures how many people occupy a given area.
- Arithmetic density: total population divided by total land area.
- Physiological density: total population divided by arable (farmable) land.
- Agricultural density: number of farmers divided by arable land.
- Use all three measures for a complete understanding of land pressure.
Population Density: Significance
- Affects political processes (representation), economic development (infrastructure spending), social access (public services), and environmental impact (resource use).
- Carrying capacity is the maximum population an environment can support.
Population Composition
- Age structure organizes population by age groups and affects dependency ratio (non-working/working population).
- Sex ratio compares number of males to females.
- Population pyramids visualize age and sex composition, indicating population growth or decline.
Population Dynamics: Growth & Decline
- Fertility rate: measured by crude birth rate (births per 1,000 people) and total fertility rate (average children per woman).
- Mortality rate: measured by crude death rate and infant mortality rate.
- Rate of natural increase (RNI) = crude birth rate - crude death rate.
- Doubling time estimates how long for a population to double at current growth rates.
Factors Influencing Fertility, Mortality, Migration
- Social/cultural: gender roles and education influence fertility.
- Political: government policies can encourage or restrict births (e.g., China's one child policy).
- Economic: financial stability affects birth and migration rates.
Population Growth & Decline Theories/Models
- Demographic Transition Model: stages explaining birth/death rate shifts as societies industrialize (Stages 1–5).
- Epidemiological Transition Model: explains shifts in causes of death (disease, famine, aging, new infectious diseases).
- Malthusian Theory: predicts population will outgrow food supply unless checked (historically inaccurate due to technological advances).
Government Policies & Consequences
- Anti-natalist policies: discourage births (e.g., China).
- Pro-natalist policies: encourage births to offset aging populations.
- Immigration policies: regulate population growth through migration.
Role of Women in Population Trends
- Higher education, access to family planning, and employment lower fertility rates.
- Improved women's status reduces infant mortality and alters migration patterns.
Aging Population: Causes & Consequences
- Caused by low fertility rate, longer life expectancy.
- If high, leads to political shifts, need for elder care, and economic challenges due to fewer working-age people supporting retirees.
Migration: Reasons, Types, Effects
- Push factors (war, disaster) drive people out; pull factors (jobs, safety) attract migrants.
- Intervening obstacles and opportunities alter migration paths.
- Types: forced (e.g., slavery, refugees) and voluntary (transnational, transhumance, internal, chain, step, guest workers, rural-to-urban).
- Migration impacts political representation, economies (remittances, labor force), and culture (cultural diffusion, social changes).
Key Terms & Definitions
- Population distribution — pattern of where people live.
- Arithmetic density — total population ÷ land area.
- Physiological density — population ÷ arable land.
- Agricultural density — farmers ÷ arable land.
- Dependency ratio — ratio of non-working (under 15 & over 65) to working-age population.
- Population pyramid — graph showing age and sex distribution.
- Total fertility rate (TFR) — average children per woman (2.1 = replacement).
- Rate of Natural Increase (RNI) — CBR minus CDR.
- Demographic Transition Model — stages of population change linked to industrialization.
- Epidemiological Transition Model — stages of mortality tied to causes of death.
- Malthusian theory — idea that population grows faster than food supply.
- Anti-natalist policy — policy to reduce births.
- Pro-natalist policy — policy to increase births.
- Remittance — money sent back home by migrants.
- Push/pull factors — reasons for leaving/attracting migrants.
- Refugee — person forced to flee country due to conflict/persecution.
Action Items / Next Steps
- Review demographic models (DTM, ETM) and population pyramids.
- Learn calculation methods for population density and dependency ratios.
- Know examples of migration types and government population policies.
- Prepare for questions on consequences of aging populations and migration impacts.