evr- concepts of population dynamics

Population Dynamics

A general study of population changes

Population

Group of individuals of the same species living in the same area

All individuals that are capable of interbreeding; made up of population

Species

Demography (Demographics)

The statistics of human populations

5 Key Properties of Population

 1. Abundance

2. Birth Rates

3. Death Rates

4. Growth Rates 

5. Age Structure

As people increase in age, increase in the inability to reproduce/repopulate

Why is Age Structure (in Population) even more important than the other properties?

crude

Human population is often reported as ____ rates

Crude Rates

per 1,000 people (ex. 2 births per 1000 people per year)

Exponential growth

A population increasing by a constant percentage per unit time

Human Population growth peaked at 2.1% from 1965-1970, and has since slowed down to 0.9% in the present, despite predictions of it continuing to climb through the years

How has human growth grown/decayed exponentially from the 20th century? What was predicted?

4

How many stages of Human Population Growth are there?

Stage 1 of Human Population Growth

Early period of hunter and gatherers; total population, a few million

Stage 2 of Human Population Growth

Rise of agriculture, production of food without having to be hunter-gatherers; Increase in population density and human population bc people focused on other things besides next food source

Stage 3 of Human Population Growth

Industrial Revolution; Improvement in health and food security by transportation of goods lowered death rates and led to double in population

Stage 4 of Human Population Growth

Current stage; allowed for increase in population density and human population to be over 8B

Saltaire (UK); The owner, Sir Titus Salt, removed his workers from slums and poor living conditions and provided better resources for workers bc he realized it improved worker productivity, which made him more money; this idea spread and lead to growth of life expectancy and worker value

What was the largest industrial building in the world? How is it relevant to human population growth?

Industrial Revolution

An era of vast improvements in medicine, technology, and sanitation; reduced diseased and extended life expectancy

Green Revolution

An era of advances in plant breeding techniques, fertilizer use, and irrigation and agricultural mechanization that helped avoid the huge population crisis coming out of WW2 by helping prevent mass starvation

The Bubonic Plague (Black Death) in Europe

What event in history was the only time global death rates exceeded growth rates?

Doubling Time

Time required for a population to double in size; calculated by Rule of 70

Rule of 70

used to calculate doubling time for exponential growth; found by dividing annual growth rate (%) into 70

Yes

Make sure you know how to do the calculations for Rule of 70

Logistic Growth

S-shaped curve that TEMPORARILY increases exponentially to the inflection point; reaches upper population limit at the logistic carrying capacity where growth rate=0

Exponential growth shows unrestrained, rapid population increase (J-curve) with unlimited resources, while logistic growth models realistic growth, starting exponentially but slowing as it nears the environment's carrying capacity (K), resulting in an S-shaped curve as resources become limited.

Logistic Growth vs Exponential Growth

No, they do not have a constant environment, constant carrying capacity, or a homogenous population; the death rate also wouldn’t be as low if such

Do animal populations actually follow the Logistic Growth Curve?

Total Fertility Rate

Number of children born to an average woman over her lifetime; strongly influenced by the opportunities women have in society

Total Fertility Rate; repopulation is necessary for population growth

What is statistic is most important in population growth? Why?

1. Social Factors: Cultural expectations, Economic issues

2. Technical Factors: Access to birth control, economic

resources

3. First Child Decisions- Lengthen time between generations; slow growth

What 3 factors control Total Fertility Rate?

These curves ignore characteristics of the environment that affect different age groups (food, water, shelter, disease); Age structure is used to rectify this

Why are exponential and logistic growth curves not always reliable to measure data? What is used to rectify this?

Age Structure

Express how population is divided among age groups; displays implication of current and future social, economic, and environmental conditions

1. Pyramid

2. Inverted Pyramid

3. Column

4. Column with buldge

4 Types of Age Structure

Pyramid Pyramid Age Structure

shows a population with many young and high death rate (short average lifetime)

Inverted Pyramid Age Structure

Population with large elderly population and small youth (declining growth); nverse of pyramid

Column Age Structure

birth rate AND death rate are low, little change in pop

Column with bulge

Event in the past caused a high birth or death rate for some age group

Demographic Transition

A 3-stage pattern of change in birth rates and death rates

1. Occurred during the process of industrial and economic development

2. Observed across all western and developed nations

3. Leads to decline in population growth rate

What are the 3 stages of Demographic Transition?

Population growth rate

Birth Rate + Death rate= ___________

True

T/F: The demographic transition is not always the same for all countries (diff economies, diff cultures/religion, etc.)

Maximum Lifetime

Max possible age to which an individual in a species can live

Life expectancy

Average number of years an individual in a species can expect to live

Acute and Chronic diseases

What is a common aspect of life that heavily impacts life expectancy rates?

1. Number of People

2. Impact of each person on the environment

How does human population affect the environment? (2 factors)

T= P (population size) x I (environmental impact per person)

Formula for the total impact of human population on the environment

Modern tech

_____ increases the use of resources and enables us to impact the environment in new ways

Human Carrying Capacity

The maximum population the planet can sustain indefinitely; depends on quality of life people desire, willing to accept

1. Extrapolation from past growth (problem-solving)

2. Packing problem approach (only allow certain amount in certain places)

3. Deep ecology (sustain the biosphere)

Estimation Methods for Human Carrying Capacity

1. Short-term

2. Intermediate Term

3. Long Term

Limiting Factors of Human Carrying Capacity

Short Term Limiting Factors of Human Carrying Capacity

Affect population immediately (e.g.food shortages)

Intermediate-term Limiting Factors of Human Carrying Capacity

Affect population for 1-10 years (e.g. desertification, dispersal of pollutants)

effects not apparent until after 10 years (e.g. soil erosion, decline in groundwater supply, climate change)

Long-term Limiting Factors of Human Carrying Capacity

• Delay age of first child bearing

• Birth control

• National programs to reduce birth rates

What are some approaches for achieving Zero Population Growth?