1 / 82

Population Dynamics

Population Dynamics . Unit 2 APES. Why study Human Population?. The World may or may be soon overpopulated. Environmental Problems of Overpopulation: Resource Depletion Environmental Degradation. Essential Questions.

zareh
Download Presentation

Population Dynamics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Population Dynamics Unit 2 APES

  2. Why study Human Population? • The World may or may be soon overpopulated. • Environmental Problems of Overpopulation: • Resource Depletion • Environmental Degradation

  3. Essential Questions • What is the history of human population growth, and how many people are likely to be here by 2050? • How is population size affected by birth, death, fertility, and migration rates? • How is population size affected by percentages of males and females at each level? • How can we slow population growth? • What success have India & China had in slowing population growth? • What are major impacts of human activities on the world’s natural ecosystems?

  4. Is the World Overpopulated? • World pop is projected to increase from 6.6 billion to 8.9 billion between 2006 & 2050. • The debate over interactions between population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science. • Much of the world’s population growth is occurring in developing countries like China & India.

  5. Is the World Overpopulated? • Some people argue that the planet has too many people. • Some feel that the world can support billions of more people due to technological advances. • There is a constant debate over the need to reduce population growth. • However, moral, religious, and personal freedoms must be considered.

  6. Brief History of Human Population Growth • Grew slowly at first but has grown rapidly recently because of the expansion of agriculture and industrial production (Industrial Revolution) AND lower death rates from improvements in hygiene and medicine. • In 2006, the population of developed countries grew exponentially at 0.1% per year, while, developing countries grew at 1.5% per year (15x faster)

  7. Where is the World Population Headed? • We do not know how long we can continue to increase the Earth’s capacity for human before the environment breaks down. • There are likely to be between 7.2-10.6 billion people of Earth by 2050. • 97% of the population growth will come from people in developing countries living in acute poverty (< $2 USD/day ~12 Yuan/day)

  8. UN Projections for Pop Growth • Projections based on high, medium, or low world average fertility rates (# of children/woman). • High 2.5 • Medium 2.0 • Low 1.5

  9. Opposite Views Of Population Growth & Issues • Poverty • Thomas Malthus Human Pops grow exponentially until disease or famine, or social conditions reduced fertility rates.

  10. Opposite Views Of Population Growth & Issues • Exploitation • Oppression • Poverty • Excess Population Growth Pop Growth results from poverty and social ills. Pop Growth would slow if all people were treated justly. • Karl Marx

  11. Population Dynamics ~ The Basics • Biotic Potential: reproductive rate of an organism if resources were unlimited & conditions were ideal. • For example the common housefly can lay 120 eggs in each generation (56 days). If nothing hurt the eggs or the flies, in 7 generations (1 year) there would be 5.6 trillion flies from 1 proud parent! • However, there are of course limiting factors. • Scarcity of resources, competition, predation, disease, accidents, etc.

  12. “J Curve”

  13. Environmental Resistance • Exponential growth can only with unlimited resources, but factors usually limit growth (environmental resistance). • Carrying Capacity (K): Number of organisms that an area can support without depleting resources

  14. Adapting to Environmental Resistance • Over time species may increase their carrying capacity by developing adaptations. • Some species maintain their carrying capacity by migrating to other areas. • So far, technological, social, and other cultural changes have extended the earth’s carrying capacity for humans.

  15. Growth Patterns: • EXPONENTIALGROWTH: pop growth increases at a constant rate per unit of time. • 2-4-8-16-32-64-…. • LOGISITIC GROWTH: pop growth is slowed as it approached carry capacity due to scarcity of resources, etc.

  16. Logistic Growth “S Curve”

  17. Population Density • Number of organisms in a defined space • Density Dependent: growth rate depends on the population density. • Disease, stress, predation, etc. • Logistic Growth is density dependent • Density Independent: population control factors not dependent on population density. • Drought, fire, habitat destruction, weather

  18. Responding to Limits: Reproductive Strategies r-selected & K-selected species

  19. Survivorship Curves Late loss Constant loss Percentage surviving (log scale) Early loss Age

  20. Factors that Affect Population Growth • r = (B+I) – (D+E) • rate of growth • B = births • I = immigration • D = deaths • E = emigration

  21. Demographics • Vital statics about people such as • Births, • Deaths, • Immigration • Emigration • Where they live • Population size, • Etc.

  22. The Young, Poor, & Growing Countries • Asia, Africa, & Latin America • 80% of the world population, 90% of projected growth • Highest growth “hot spots” • Sub-Saharan Africa, Middle East • Economics, politics, religion, civil unrest, • High birth rates, low contraceptive use) • Highest growth rates • United Arab Emirates @ 6.8%

  23. The Older, Rich, Relatively Stable Countries • N. America, W. Europe, Japan, Australia, & New Zealand • Italy, Germany, Hungary & Japan have declining growth rates. • Average age = 40, Life expectancy = 90, women are choosing to not have children • Japan is currently around 127 million and expected to decrease to 100 million in 2050

  24. 1) Fertility/Birth Rates • Crude Birth Rate (B): number of births in a year per 1000 people • Total Fertility Rate (TFR): number of children born to an average woman in her reproductive life. • Replacement Level Fertility (RLF): number of children needed to replace the parents. • About 2.1 children in developed countries • Higher in other countries with a high infant mortality rate

  25. 1) Fertility/Birth Rates Cont. • Rates have declined in every region except for Africa • Thailand reduced their TFR from 7.0 in 1979 to 1.64 in 2009 • China went from a TFR 6.0 in 1970 to 1.8 in 1990 to 1.6 in 2009 due to the one-child policy • Macao has lowest TFR in the world with 0.9 • World Average TFR = 2.6

  26. Factors Affecting Fertility & Birth Rates • Cost of raising & educating the children • Availability of pensions • Urbanization • Education & employment opportunities • Infant deaths • Marriage age • Availability of contraception & abortion • Women’s Rights within a culture • Cultural beliefs, traditions, & cultural norms

  27. 2) Mortality (Death) Rates • Crude Death Rate: number of deaths per 1000 people in year • Less Developed countries, such as Africa, see death rates of 20+/1000. • Wealthier countries see about 10/1000 • Infant Mortality Rate: Number of child/infant deaths. • Natural Increase = crude birth rate – crude death rate

  28. Factors Affecting Mortality Rates • Increased food supplies and distribution. • Better nutrition • Medical & public health technology (immunizations/antibiotics) • Improved sanitation & personal hygiene • Safety of water supplies

  29. 2006

  30. 3) Immigration & Emigration • Immigration (I): people migrating into a population • Emigration (E): people migrating out of a population • Net Migration (I-E): Total number of people moving in and out of a population

  31. r = (B+I) – (D+E) • Total Growth rate (r): calculate using crude rates (per 1000) and divide by 10 = percentage • Zero Population Growth (ZPG): when B+I = D+E • Doubling time: amount of time it takes for a population to double • Rule of 70s: Divide 70 by annual natural increase equal the approximate doubling time

  32. r = (B+I) – (D+E) If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate?

  33. Doubling Time • If a population of a country grows at a rate of 5% a year, the number of years required for the pop to double is what?

  34. The world’s 10 most populous countries in 2006 with projections in 2025.

  35. U.S. Trends • Nearly 2.9 million people added to the US in 2006. • 59% occurred because of births outnumbering deaths. • 41% came from illegal and legal immigration. • Sharp Rise in US birth rates during 1946-1964 called the Baby boom. • Economic success & Men returning home from war.

  36. US Trends • The baby bust that followed the baby boom was largely due to delayed marriage, contraception, and abortion.

  37. Case Study: Fertility and Birth Rates in the United States • In 2006, the total fertility rate in the United States was slightly > 2.0

  38. U.S. Trends Since 1820, the U.S. has admitted almost twice as many immigrants and refugees as all other countries combined.

  39. U.S. Trends • U.S. infant mortality is higher than it could be (ranked 46th world-wide) due to: • Inadequate pre- and post-natal care for poor. • Drug addiction. • High teenage birth rate.

  40. 4) Life Expectancy (LE) • Age that a newborn infant can be expected to live to (average age of death) • Most population growth is due to a decline in death rates b/c of longer life expectancy. • General Trends: • More developed countries have higher LE • Women tend to have higher LE than men • More money, longer life

  41. Implications of Longer Lives on Populations • Increased dependency ratio: • Number of non-working compared to working individuals in a population. • Countries, such as US & Japan, are seeing the number in the working force decline as the number of retiring individuals increases.

  42. Age Structure • Percentage of people in young, middle, and older age groups determines how fast populations grow or decline. • Generation time: time it takes for one generation to pass • The number of people younger than age 15 is the major factor determining a country’s population growth. • Changes in the distribution of a country’s age groups have long-lasting economic and social impacts.

  43. Histograms • Graphs that shows the different age classes of a population • Pre-reproductive age (14 and under) • Not mature enough to reproduce • Reproductive age (15-45) • Able to reproduce • Post-reproductive age (46 and older) • To old to reproduce • Broken down by age. You can see the birth rate, maturity rate and death rate of an entire population. Usually broken down by country

  44. Histograms • Populations with a large proportion of its people in the reproductive ages 1-14 have a large potential for rapid population growth.

  45. 32% of the people in developing countries were under 15 years old in 2006 versus only 17% in developed countries.

  46. Today, baby boomers make up nearly half of all adult Americans and dominate the populations demand for goods and services.

  47. Expansive/rapid growth • Birth rate exceeds the death rate. Population is getting larger. Pyramid shaped histogram. • Ex’s. Kenya, Nigeria and Saudi Arabia.

More Related