AP Environmental Science

Population growth - chapter 9 and 10

I. Growth rates and carrying capacity

A. definition of a population

B. growth rate is determined several factors:

1. growth rate = (b + i) - (d + e). This rate is called the intrinsic rate of increase, and is designated “r” in equations

2. the carrying capacity (“K”) of a population is the maximum amount that can be sustained

3. factors that limit (environmental resistance) or enhance (biotic potential) growth – fig. 9-3

C. Exponential growth – fig. 9-4

D. Logistic growth – fig. 9-5

E. examples of growth curves – fig. 9-6 and 9-7 and 9-8

1. density-independent growth occurs when population size is determined by habitat disruptions. Populations growing in this manner are called “r-selected”

2. density-dependent growth occurs when ecological relationships determine population size. These populations are termed “K-selected”

3. comparison of r- and K- selected species – fig. 9-9 and 9-10

4. predators and prey sometimes cycle together – fig. 9-8 (lynx and hare) and wolves and moose on Isle Royale

5. survivorship curves show the percentage of a population surviving over time - fig. 9-11

F. sampling/recording population growth

1. census

2. estimating

3. capture/mark/recapture

4. counting evidence (scat, etc.) | check out some research on deer, dragonfly, and other animal populations

II. History of human population growth/demographics

A. Worldwide human growth patterns

1. growth rates have slowed since the 1950s (fig. 10-5)

2. current growth rates vary around the world (fig. 10-4)

3. current population and projections for 2025 in leading countries (fig. 10-4)

4. fertility rates differ from growth rates. Check out worldwide trends in fig. 10-7, and US history in 10-8

5. projection for world population in 2050 – fig. 10-6

            6. Population age structure diagrams - p. 184-187

B. what factors influence the drop in fertility and overall population growth seen in developed countries?

1. education, economics, access to birth control

2. infant mortality

3. age structure of populations influences growth rates – counties with a high percentage of younger people will continue to grow even when fertility levels drop (see previous section)

4. demographic transition - fig. 10-20

III. Problems related to population growth

A. resource limitations – food, water, raw materials, fuel

B. Overcrowding

C. uncontrolled development ("sprawl") leading to habitat loss and species extinction (the east coast problem!!) (more on sprawl)

D. Pollution problems increase if other factors remain constant

IV. Solutions to the problems of population growth

A. the demographic transition – developed countries have followed this progression through four stages (fig. 10-20)

B. should population growth be limited?

C. other solutions involve “empowering women”

1. economic opportunity

2. access to birth control

D. case studies – China and India – p. 191-192; Iran p. 190

E. sustainable development is the “key word” (more discussion on this later).  The idea of "Smart Growth" is related and has become more common recently