Applying Population Ecology: The Human Population
Current Population Trends
•World population = 6.4 billion (6,400,000,000) in 2004
•Doubled since 1963 = 3.2 billion
•In 2050 could be 7.2 – 10.6 billion
•Amplifies all environmental problems
•Largest increase expected in developing countries
•Decreasing in some developed countries
•Is human population experiencing exponential growth?
Factors Affecting Human Population Size
Population change equation
Population change = (Births + Immigration) – (Deaths + Emigration)
Crude birth rate = births per 1000 people in population per year
Crude death rate = deaths per 1000 people in population per year
Sex Ratio - Age Distribution
•Sex Ratio- Relative number of males and females in a population
•Age Distribution - Number of individuals of each age in a population
•Together they tell how a population will grow
Population Age Structure
Human Population Issue
•Several factors determine the impact of a society on natural resources.
•Degree of technological development
•Demography - Study of populations and their characteristics.
•Total Fertility Rate (TFR) - Number of children a woman has during her lifetime, averaged for population.
•same as biotic potential (r)
•Replacement Level Fertility - Number of children needed to replace everyone in the population.
•Varies between regions
•2.1 with low infant mortality
•2.5 with high infant mortality
•Zero Population Growth - Birth rate equals death rate.
Factors Affecting Birth Rates and Total Fertility Rates
•Children in Labor Force
•Cost of raising and educating children
•Availability of pension systems
•Education and employment for women
•Infant mortality rate
•Average marrying age
•Availability of birth control
Major social factor determining family size is the role of women in society.
•Early marriages foster high fertility rates.
•Lack of education opportunities for women reduces their options.
•When level of education increases, fertility rates fall.
•The most important factor is the ability of women to control the size of their family.
•Access to birth control is key.
United States Population Picture
•US population has a post-war baby boom period, significantly affecting pop. trends.
•20 yr period following WWII
•By 2030, 20% of US pop will be over 65
U.S. Birth Rates: 1910-2004
US Immigration rates
Case Study: Slowing Population Growth in India
•Generally disappointing results
•Low status of women
•Lack of support
Case Study: Slowing Population Growth in China
•Free medical care
•Very intrusive and coercive
Cutting Global Population Growth
•Improve health care
•Elevate the status of women
•Involve men in parenting
Urban Poor in Developing Countries
•Poverty and unemployment
US metropolitan areas
Undesirable impacts of urban sprawl
Urban Land-Use Planning and Control
•Urban growth boundary
•Mass transit vs. automobile
•What makes one or the other feasible?
•Why is most of the US developed around cars? When did it happen?
•Where does mass transit work?
•What are the pros and cons to each?
Sustainable city solutions