# L10 - Population Growth

## 30 terms

### Population

group of individuals of ONE SPECIES that live in A PARTICULAR AREA

characteristics:
-size
-density
-distribution
-sex ratios
-age structure

### What determines a population's growth?

The characteristics of the population and the environment they live in determine a population's growth

### age structure

number of individuals in different age classes

-pre reproductive age: 0-15
-reproductive age: 15-45
-post-reproductive age: 46+

...

### Growth Rate

Determines how fast the population will grow

(crude birth rate + immigration rate) - (crude death rate + emigration rate)

rates are expressed as individuals per 1000

to express as a percentage: growth rate x 100%
Example: 20/1000 x 100% = 2%

### Exponential Growth

A STABLE RATE OF GROWTH leads to Exponential Growth

As the population size increases, the same percentage increase becomes a larger total increase

### J-Curve in Population

Occurs when a population is small and environmental conditions are ideal

### Limiting Factors

Physical, chemical, and biological factors that limit the amount of growth that is possible. Ex: space, nutrients, predators

All limiting factors together make up the "environmental resistance"

### "Environmental Resistance"

made up by all limiting factors

determines Carrying Capacity

### Carrying Capacity

the maximum population size that an environment can sustain

Determines how big the population can become

determined by Environmental Resistance

Carrying Capacity can change when limiting factors change

### Increasing our Carrying Capacity

Technology has allowed us to raise Earth's carrying capacity for our species time and again

Tool-making, agriculture, and industrialization each enabled humans to sustain greater populations

### Total Fertility Rate

The average number of children born per female during her lifetime

### Life expectancy

The average number of years that a person can expect to live from birth

### Human Population Growth

Human population growth has been greater than exponential.

Growth rate has increased over time (mostly because of lower death rates)

Varies from place to place

### Where is the majority of new population growth occurring?

The majority of new population growth is occurring in DEVELOPING COUNTRIES

### The Demographic Transition

a model of economic and cultural change to explain declining death rates, declining birth rates, and rising life expectancies in Western Nations as they became industrialized

### Doing a Demographic Transition, what growth rates to become very high?

Growth rates can become very high because death rate declines before birth rate

### Because most developed nations have passed through the demographic transition, what has happened to the global growth rate?

Because most developed nations have passed through the demographic transition, the GROWTH RATE has DECREASED

### Pre-industrial stage

High death rates and high birth rates

### Transitional Stage

death rates fall due to rising food production and better medical care.

birth rates remain high causing population to surge

### Industrial Stage

birth rates fall - women are employed and as children become less economically useful in an urban setting

population growth rate declines

### Post-Industrial stage

birth and death rates remain low and stable

society enjoys fruits of industrialization without threat of runaway population growth

### Since the 1960's, what has happened to the annual growth rate of the world population?

The annual growth rate of the world population has DECLINED since the 1960s

(population size is still rising)

### Total Fertility Rate (TFR)

average number of children born per woman during her lifetime

### Replacement fertility

the TFR that keeps population size stable

for humans RF = 2.1
Africans have highest, Europe has lowest

Female literacy and school enrollment are correlated with TFR, more educated have fewer children

Family planning, health care, and reproductive education can lower TFRs

### Is poverty correlated with population growth?

YES, poverty is correlated with population growth.

### IPAT model

I = P x A x T x S

(P)opulation - individuals need space and resources
(A)ffluence - greater per capita resource use
(T)echnology - increased exploitation of resources
(S)ensitivity - how sensitive an area is to human pressure

Also: effects of education, laws, and ethics on the formula

### Overshoot

humans have surpassed the Earth's capacity to support us

we are using renewable resources 30% faster than they are being replenished

### Modeling population and it's consequences

some models show population growth leading to resource depletion, which can result in declining food production, industrial output, and population

### What is environmental impact dependent on?

Environmental impact is dependent on POPULATION SIZE as well as AFFLUENCE (abundance of wealth) and TECHNOLOGY