Presentation on theme: "Population Ecology Part II HUMAN POPULATION DYNAMICS"— Presentation transcript:
1Population Ecology Part II HUMAN POPULATION DYNAMICS
2Thomas Malthus “diminishing returns” He argues that rising wages and improved well-being would lead to excess reproduction among the working class.A labor surplus would then cause wages to fall below subsistence levels, resulting in starvation, disease and crime.In his view, land for food production was the limiting factor in both population growth and economic development.
15Reasons for World Hunger Issues Unequal distribution of available foodLoss of arable landIncreasing population growth rateIncreasing poverty in developing countries
16Arable Land Assume no arable land is being lost for the next 33 years. 2006, there was 1.15 acres of arable land per person, world-wide(i.e billion acres / 6.68 billion people).
17Arable Land2039, there may be only 0.59 acres of arable land per person, world-widei.e billion acres / 13 billion peoplearable land is being lost at the alarming rate of over24.7 million acres per year. 2039, there may be only 0.53 acres of arable land per person, world-wide
19Reasons for Loss of Arable Land DeforestationOver exploitation for fuel woodOvergrazingOver farming (deplete nutrients)IndustrializationNo rich sediment replacement due to flooding – controlled by dams
20How have we still managed to grow enough food to feed the world How have we still managed to grow enough food to feed the world? Who grows most of the food? What affect could global warming have on this scenario?
24Ways to Increase Crop Production Modern farm equipmentReturn nutrients to soil (fertilizers)IrrigationNew genetically modified cropsHydroponics
25Strategies for ensuring adequate nutrition for a growing population: Increase the number of new food crops from a diversity of plant speciesDistribute food more equitablyIncrease land are that is dedicated to grain production rather than meat productionAssist developing countries in efficient crop irrigation systems.
26How many people can the earth feed on our arable land How many people can the earth feed on our arable land? What about over-fishing our oceans? What is the earth’s carrying capacity?
28#1 – Birth vs. Death Rates Birth rate - # live births per 1,000 people Death rate - # of deaths per 1,000 peopleTop 5 most populated countries: China, India, U.S., Indonesia, Brazil
29Annual Rate of Natural Population Change (%)= Birth rate – Death rate1,000 people x 100
30#2 - Fertility Rate # children born to a woman in her lifetime Replacement-level fertility rate = # children a couple must have to replace themselves (2.1 to 2.5)Total fertility rate = average # children a woman has during reproductive years (global average is 2.7, developed countries 1.6)
31#3 – Factors Related to Children Importance of children to labor forceCost of raising and educating a child ($250,000 in U.S. to age 18 vs. minimal in developing countries)
32#4 – Religion and Culture View of the familyRights of womenBeliefs concerning birth controlAge at marriageSex preference for children
33#5 - Pension SystemIf retirement plans are available and adequate – less childrenNo retirement – more children, particularly males to support them in old age
34#6 - Urbanization Better access to family planning services More job opportunitiesHigher standard of livingAll generally promote smaller families
35#7 – Opportunities for Women EducationFamily Planning optionsJob opportunitiesBest way to reduce fertility rates
36#8 – Infant Mortality Rate Better medicine and health care = lower infant mortalityThe more likely infants are to survive, the more fertility rates drop
37#9 – Average Age at Marriage Developing countries = 14 or 15Developed countries = 25
38#10 – Life ExpectancyRapid rise in world population in last 100 years is due to increased life expectancyModern medicine means infants do not die and people live to much older ages67 years globally, 78 years in U.S.Poorest countries with HIV = 49 years
39What factors affect death rates? Increased food supplies and distributionBetter nutritionImprovements in medical & public health technology (ex. immunizations and antibiotics)Improvements in sanitation & personal hygieneSafer water supplies to stop spread of infectious disease
40#11– Net Migration Immigration vs. Emigration Countries like the U.S. continue to grow due to ImmigrationCountries like Russia are decreasing due to emigration
42Growth Rate- includes birth rate, death rate, immigration and emigration Gross National Product- The most commonly used measure of the economic growth of a country.
43Population Change Growth Rate Population change = (Crude birth rate + Immigration) – (Crude death rate + Emigration)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?
46Zero Population Growth- When the number of births, equals the number of deaths. No growth in the population. .
47Rule of 70’s – Doubling Time Doubling time - # years it takes a population to double70/ growth rate = doubling time (daily)72/ growth rate = doubling time (years)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?
49Developing Countries- China is the largest but has taken drastic population control methods.By 2050, India is predicted to pass it. Pakistan is projected to become 3rd with Iran and Ethiopia following.However, Russia is losing 600,000 people a year, after being the 4th largest country in This is because of environmental pollution, hyperinflation, crime, corruption, disease and despair.
50Developed countriesUsually don’t have such population problems. It can be linked to poverty level even in developed countries.
51Demographic Transition As countries becomes industrialized their birth rates decline.
52Pre-industrialHarsh living conditions lead to a high birth rate and high death rate. Thus, there is little population growth.
53TransitionalAs industrialization begins, food production rises and health care improves.Death rates drop and birth rates remain highThe population grows rapidly
54Industrial Industrialization is wide spread Birth rate drops and eventually approaches the death rate.This is because of:better access to birth controldecline in the infant mortality rateincreased job opportunities for womenthe high cost of raising children who don’t enter the work force until after high school or college.
55The Industrial Revolution Modern Medicine Reasons human population growth has been so dramatic in the last centuryThe Industrial RevolutionModern Medicine
56PostindustrialThe birth rate declines even further, equaling the death rate and thus reaching zero population growth.Then, the birth rate falls below the death rate and the total population size slowly decreases.(Cont….)
5737 countries have reached this stage. (mainly in W. Europe) To most population experts, the challenge is to help the remaining 88% of the world to get to this stage.
60U.S. StatisticsBecause of the ‘Baby Boom’ the US has a bulge in the pyramid with people in their 50’s-60’s.There are also more women than men in the older age group because of differences in longevity between the sexes.(Cont…)
61The US has a high % of retired people because of long life expectancy The US has a high % of retired people because of long life expectancy. This makes us realize the importance of social security, etc.The US is considered a slow growth population.
62Some countries, including China, penalize couples who have more than one or two children by: Raising their taxesCharging other feesEliminating income tax deductions for a couple’s third childLoss of health-care benefits, food allotments and job options
63In China couples who pledge to have no more than one child receive Extra foodLarger pensionsBetter housingFree medical careSalary bonusesFree school tuition for their one childPreferential treatment in employment when their child enters the job market.
64However, according to some studies, there is a strong preference for male children. Girls are aborted at a higher rate than boysSome infant girls are killedMale children sometimes are fed better than female children.
65Environmental Impact Equation (Paul Ehrlich Formula) Population X affluence X technology = Environmental impact
66Developed Countries High rates of resource use Result in high levels of pollution and environmental degradation per personThese are believed to be the key factors determining overall environmental impact.(Cont….)
67It is estimated that a US citizen consumes 35 X’s as much as the average citizen of India and 100 X’s as much as the average person in the world’s poorest countries.(Cont…)
68Thus, poor parents in a developing country would need kids to have the same lifetime environmental impact as 2 typical US kids.
69UrbanizationUrban areas must import food, water, energy, minerals, & other resources.They produce enormous quantities of wastes that can pollute the air, water & land.44% of the world’s people live in urban areas that occupy only 5% of the world’s land & they consume 75% of the world’s resources.
701994 Global Summit on Population & Development Cairo, EgyptEncouraged action to stabilized the world’s population at 7.8 billion by 2050, instead of the projected billion.
71The major goals are to:Provide universal access to family-planning services.Improve the health care of infants, children & pregnant womenEncourage development of national population policiesImproving the status of women by expanding education & job opportunities
72Major goals continued: Increase access to education for girlsIncrease men’s involvement in child-rearing responsibility & family planningTake steps to eradicate povertyReduce & eliminate unsustainable patterns of production & consumption.