Chapter 3
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What strategy do humans use?
Humans use K strategy
Characteristics of K strategy
Long lifespan, late sexual maturity, few young, high parental care
4000 BCE to 1347
Stable population, limiting factors are significant, S shaped growth curve
1347 to 1350
Bubonic plague (black death)
1700
industrial revolution, advanced agriculture methods, domestication of animals, advanced medicines, led to exponential growth
Today
J shaped exponential growth curve Exponential population growth is a large concern on our planet
Two ways to examine population growth
• Percent population growth - Doubling time
Percent population growth
Rapid population growth Why? Birth rate remains the same but death rate has fallen
Doubling Time
The time it takes for a population to double in number. This has greatly decreased from 200 yrs, 80 yrs to 46 yrs
Death rate is ___ in developed countries
Slower
Death rate is ____ in developing countries
Faster
Demographic Transition
A. theory that describes the pattern if birth rates, death rates & growth rates of populations overtime
Stage 1: (pre transitions) early human societies
• high BR (no knowledge of birth control) • high DR (no modern medicine) • zero population growth
Stage 2: (early transition/demographic trap)
• high BR (no knowledge of birth control) • low DR (more medicine, better food production) • rapid population growth • many under developing countries • being trapped in stage 2 is called the demographic trap
Stage 3: (late transition/demographic transition)
• decreased BR (knowledge of birth control, better living standards) • death rate decreases • population growth slows • most developing countries
Stage 4: (post transition)
• low BR • low DR • population growth slows to zero • most developed counties
Stage 5: (constricting population growth)
• BR falls below DR - population growth is shrinking
Population Pyramids
a bar graph used by demographers which shows the age distribution in a population • can be used to predict the populations growth potential • % of males in a different age group (left) • % of females in different age group (right) • age on y axis
Age Distribution=
% of people in different age groups
Expansive Population
• triangular shape • rapid population growth, why? • many young people of reproductive age • fewer old people (not reproducing) • decreased average lifespan (standard of living low) • fertility rate: 4.7 children per female
Stable Population
• rectangular shape • zero population growth, why? • fewer young people of reproductive age • increased average lifespan (high standard of living) • fertility rate: 1.7 children per family
Constrictive Population
• inverted triangular shape • negative population growth, why? • fewer young people of reproductive age • large number of people past reproductive age
Ecological Footprint
The amount of land that is required to support each person for their needs (food, water, transportation, housing & waste management in a country)
6 major categories to human demands…
a) crop land (how much land we require to grow food) b) grazing land ( how many animals do we eat) c) fishing ground d) forest land (building & paper) e) carbon absorption (transportation - cars, trains) f) building area