Applying Population Ecology: The Human Population

Chapter 5

Applying the principles of population dynamics and sustainability to the growth of the human population

Current Population Trends

• World population = 6.4 billion (6,400,000) 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

(approximately 97%)• Decreasing in some developed countries• Rate actually decreased between 1963-2004, but the

population has still doubled from 3.2 –6.4 billion

Rate = 80 million new people/year+ New York City every month+ Germany every year+ United States every 3.7 years

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Washington State Population

Population projectionsFor the next 20 years

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

• 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.

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

Growth is determined by teenagers – the population wave of the future. 30% of pop’n <15 years = 1.9 billion more into reproductive years.

Developing Countries Developed Countries

Population Trend Comparisons

Developed Countries• Low infant mortality rate

• Life expectancy 77 years

• Total fertility rate = 2.0

• 21% population <15

• 12% population >65

• Per capita GDP = $36,110

Developing Countries• High infant mortality rate

• Life expectancy 52 years

• Total fertility rate = 5.7

• 44% population <15

• 3% population >65

• Per capita GDP = $800

Human Population Issue

• Several factors determine the impact of a society on natural resources.• Population size• Population density• Degree of technological development

• Demography - Study of populations and their characteristics.

• Larger ecological footprint in U.S. than in developing countries. Why?

Environmental Impact

The fertility rateshave significantlyfallen since 1950.

• Children in Labor Force• Cost of raising and educating children• Availability of pension systems• Urbanization• Education and employment for women• Infant mortality rate• Average marrying age• Abortion• Availability of birth control

Factors Affecting Birth Rates and Total Fertility Rates

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

Immigration accounts for 41% of pop’n growth in the U.S. Should we have tougher immigration laws to help preserve ournatural resources?

Demographic Transition

As countries become industrialized, death rates, then birth rates decline.

Case Study: Slowing Population Growth in India

• Generally disappointing results• 1952 – 400 million• 2004 – 1.2 billion

• Poor planning• Bureaucratic inefficiency • Low status of women• Extreme poverty• Lack of support• Culture – Indian women believe you need children to

work, care for when they are old.

Case Study: Slowing Population Growth in China

• Economic incentives (food, large pensions, better housing, salary bonuses, free schooling)

• Free medical care• Free sterilization• Locally administered • Very intrusive and coercive • Problem with parents selecting for males• Fertility rate decreased from 5.7 in 1972 to 1.7 in

2004.

Cutting Global Population Growth

• Family planning• Improve health care• Elevate the status of women• Increase education• Involve men in parenting• Reduce poverty• Sustainability

Global Megacities

Number of large cities growing. World’s urban population will increase from 3.1 billion to 5 billion from 2004-2030.

US metropolitan areas

Undesirable Impacts of Urban Sprawl

Loss of crop land, forestland, and wetlands

Fragmenting fish and wildlife habitats

Increased impervious surfaces means more flooding

And soil erosion

And a larger ecological footprint

Beneficial is all a matter of one’s perspective…..

Urban Land-Use Planning and Control

• Land-use planning• Property taxes• Zoning • Smart growth• Urban growth boundary• Greenbelts

Growth Management Act1990

• The GMA requires state and local governments to manage Washington’s growth by identifying and protecting critical areas and natural resource lands, designating urban growth areas, preparing comprehensive plans and implementing them through capital investments and development regulations.

• GMA is passed to help protect areas critical for natural resources by concentrating growth in urban areas

Public voices concerns at GMA hearing - Sounding off: Land division and road upgrades among issues addressed at four-hour hearing

Transportation• 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?