The Human Population and its Ecological Footprint, Production and Distribution of Food. November 5, Deffi Ayu P.S., Ph.D

Transcription

1 The Human Population and its Ecological Footprint, Production and Distribution of Food November 5, 2016 Deffi Ayu P.S., Ph.D

2 SOURCE Ch. 4, 8 and 12

3 Constant growth Population number at the start + (A constant * Time) = Ending population Exponential growth r = the number of times you multiply e by itself Starting population * A constant (e) * itself a certain number of times = Ending population Logistic growth Carrying capacity (K): the maximum population of a species that a given habitat can support without being degraded Starting population + (Reproductive capacity (r) * Population * a number represents how far the population is from the carrying capacity = Ending population

4 Three models of population growth Constant growth! Population! Carrying capacity (K) J-curve! S-curve! Generations!

5 Real-life growth

6 Biotic potential vs. environmental resistance Biotic potential: the number of offspring (live births, eggs, or plant seeds and spores) produced under ideal situations Measured by r (the rate at which organisms reproduce) Varies tremendously from less than 1 birth/year (some mammals) to millions/year (plants, invertebrates) Recruitment: survival through early growth stages to become part of the breeding population Young must survive and reproduce to have any effect on population size

7 Environmental resistance Abiotic and biotic factors cause mortality (death) Prevents unlimited population growth Environmental resistance: the biotic and abiotic factors that may limit a population s increase Biotic: predators, parasites, competitors, lack of food Abiotic: unusual temperatures, moisture, light, salinity, ph, lack of nutrients, fire Environmental resistance can also lower reproduction Loss of suitable habitat, pollution Changed migratory habits of animals

8 Biotic potential and environmental resistance

9 Reproductive strategies: r-strategists The interplay of environmental resistance and biotic potential drives the success of two reproductive strategies r-strategists (r-selected species): produce lots of young, but leave their survival to nature Results in low recruitment Rapid reproduction, rapid movement, short life span Adapted to a rapidly changing environment Boom-and-bust populations Weedy or opportunistic species For example, housefly

10 Reproductive strategies: K-strategists K-strategists (K-selected species): lower biotic potential Care for and protect young Live in a stable environment already populated by the species Larger, longer lived, well-adapted to normal environmental fluctuations Their populations fluctuate around carrying capacity Also called equilibrial species For example, elephant, California condor

11 Life histories Life history: progression of changes in an organism s life Age at first reproduction, length of life, etc. Visualized in a survivorship graph Type I survivorship: low mortality in early life Most live the bulk of their life span (e.g., humans) Type III survivorship: many offspring that die young Few live to the end of their life (oysters, dandelions) Type II survivorship: intermediate survivorship pattern (squirrels, coral) K-strategists have a Type I pattern; r-strategists show Type III

12 Survivorship curves

13 Predictable pattern in species There is a predictable pattern to the way human activities affect species r-strategists become pests when humans change an area Houseflies, dandelions, cockroaches increase K-strategists become rarer or extinct with change Eagles, bears, and oaks decline An exception: rare opportunistic species (r-selected) are separated from new habitat They cannot succeed, despite high biotic potential

14 I. HUMANS AND POPULATION ECOLOGY Demography: collecting, compiling, and presenting information about human populations Demographers: people who study population processes Migration, fertility changes, mortality Includes economic, cultural, social, and biological factors Includes wealth and health care Humans are critically different from other species They show exponential growth (r-strategists) But they have high parental care (K-strategists)

15 World population over the centuries

16 Hunter-gatherer culture

17 Industrial revolution 17 th & 18 th centuries

18 The medical revolution Before the early 1800s, human populations grew slowly and fluctuated Diseases (smallpox, diphtheria, measles, scarlet fever) hit infants and children hardest Epidemics (e.g., the black plague) killed adults High reproductive rates were balanced with natural enemies (e.g., diseases), resulting in a low population growth rate

19 The green revolution Concerns over producing food for the larger population led to increased agricultural efficiency Pesticides, irrigation, and fertilizer increased yields Countries could feed their growing populations Industrialized agriculture came at significant costs Erosion, soil and water pollution, loss of native plants Resources (soil, water) were used faster than they were replaced Resistance: target organisms are no longer affected by pesticides

20 The newest revolution Technological breakthroughs Have produced the Internet, computers, nanotechnology, robotics, and solar and other technologies Environmental revolution: will come from Efficient technologies, urban and regional planning Policy and industrial changes Personal decisions Humans are part of the natural world although they can produce drastic changes Natural laws still apply to people

21 The four types of tenure Consumptive and productive uses of natural ecosystem resources are the consequences of the rights of tenure (property rights) over land and water Private ownership: restricts access to natural resources Commercial ownership: permits use of natural resources by members of the community State ownership: implies regulated use Open access: resources can be used by anyone Each has the potential for abuse or stewardship

22 Maximum sustainable yield (MSY): the highest possible rate of use the system can match with its own rate of replacement or maintenance MSY applies to harvesting biota, air/water quality, soils Used in timber cutting, fishing, park visitation, pollution Carrying capacity of an ecosystem: the maximum population the ecosystem can sustainably support

23 Maximum sustainable yield

24 Do humans have a carrying capacity? It is hard to determine a carrying capacity for people Some people (e.g., economist Julian Simon) say that human ingenuity is the ultimate resource There is no human carrying capacity In the past, people have overcome carrying capacity Ecologists and demographers say humans are subject to limits and natural laws of population growth Humans have increased their carrying capacity Technology, agriculture, trade, fossil fuels, and medicine

25 II. RICH, MIDDLE-INCOME, AND POOR NATIONS The World Bank puts countries into economic categories based on average per capita gross national income High-income, highly developed, industrialized countries 1 billion: U.S., Canada, western Europe, Taiwan, Israel Middle-income, moderately developed countries: $936-$11,455/yr 4.3 billion: parts of Africa, China, some Arab states Low-income, developing countries: < $936/yr 1.3 billion: parts of Africa, southern Asia, some former Soviet republics

26 Major economic divisions of the world

27 Developed and developing countries Developed countries: high-income nations Developing countries: middle and low-income nations Terms no longer used: more developed countries (MDCs), less developed countries (LDCs), third-world countries The UN Development Program (UNDP) uses the Human Development Index to measure general well-being Based on life expectancy, education, per capita income Human Poverty Index: uses literacy and living standards Directly measures poverty

28 Population growth in different world regions

29 Fertility rates Total fertility rate (TFR): average number of kids each woman has over her lifetime If TFR = 2.0: the population is stable If TFR > 2.0: the population grows If TFR < 2.0: the population shrinks Replacement-level fertility: fertility rate that replaces the parent s population 2.1 for developed countries A bit higher in developing countries (high child mortality)

30 Total fertility rates around the world

31 Different populations, different problems A formula accounting for human factors contributing to environmental deterioration and resource depletion is I = P * A * T Environmental impact (I) equals Population (P) * Affluence and consumption (A) * Technology of the society (T)

32 The impact of wealth Wealth can help solve environmental problems The rich can afford technologies to lower pollution, clean water, treat sewage, etc. Environmental laws improve the environment Technology helps people minimize degradation But the relationship between economic wealth and environmental health is not so clear-cut Some issues (disease) may improve, but others (waste) increase Environmental problems are pushed into other areas

33 The environmental footprint Arguments that overpopulation is not a problem fall flat High-density places (e.g., Hong Kong) can be so crowded because they use resources from all over Ecological (environmental) footprint: estimate of the amount of land and ocean required to provide resources and absorb wastes Pollution, climate change, toxic wastes, species loss, etc. result from high consumption associated with affluence Calculate, validate and compare your green credentials with your friends!

34 Subsistence agriculture Subsistence farming: developing world farmers use labor-intensive traditional agricultural methods Practiced on marginal land Described as the silent giant that feeds most of the world s poor Subsistence farmers live on small plots of land They raise food for their household They may sell a small cash crop They do not consider themselves poor Subsistence farming is practiced in regions with rapid population growth But is best suited for low population densities

35 Subsistence farming

36 Climate change Deforestation and other land use changes in the tropics release 1.6 billion tons/year of CO 2 Livestock belching and flatulence release 100 million tons of methane/year Methane is another greenhouse gas Anaerobic decomposition of manure releases 30 million tons of methane/year Methane released by livestock makes up 3% of all gases causing global warming

37 Biofuels and food production Burning fossil fuels causes climate change Releases CO 2 (a greenhouse gas) Biofuel: a renewable fuel made from ethanol and oil derived from crops Can mitigate climate change No new CO 2 is released With rising oil prices, biofuel prices are competitive Ethanol: made from corn (in the U.S.) and sugar (Brazil) One-third of U.S. corn is devoted to ethanol production Food prices have risen worldwide

38 Consequences Critics say ethanol diverts corn from food production The U.S. produces 40% of the world s corn and 55 60% of the corn on the market Price increases take food away from children Does ethanol production decrease food? Wheat, rice, and soy prices have risen more than corn Land previously planted in soybeans is planted in corn Field corn is used to produce ethanol Only cornstarch is used for ethanol, leaving proteins, vitamins, and fiber to produce food

39 Factors contributing to high food costs Increased costs of oil for farm machinery and fertilizer China and India are competing for oil Bad weather and poor harvests in Australia A major wheat exporter Rising demand for meat and animal products from emerging economies 30% of increased prices from 2000 to 2007 is due to biofuels Ethanol could be produced from grasses and timber instead of corn

40 Future prospects for reducing hunger Projections predict grain production to remain the same Will slightly outpace population growth Also predict increased meat consumption in developing countries Developing countries will not be able to meet rising grain demands Most suitable land is already farmed Increases in grain yields are slowing down Many countries can t afford to pay for grain imports Sub-Saharan Africa will continue to have hunger

41 Global picture There are only two ways to increase food production: Increase crop yields Grow food crops on land now being used for feedstock crops, biofuels, or cash crops Yields differ because of weather Soil, rainfall, and sunlight limit productivity It is impossible to predict how climate change will affect rainfall patterns Developing countries could lose 334 million acres of farmland due to tropical temperature increases

42 Environmental benefits of bioengineered crops Reduced pesticide use Crops are already resistant to pests Less erosion No-till cropping Herbicide-resistant crops Less land brought into production Existing agricultural land produces more food

43 Problems of genetic engineering: environmental concerns Pests may become resistant to the toxin in pestresistant transgenic crops The crop loses its advantage Resistance has been found in weeds that infest fields Resistant weeds can spread rapidly Pollen from transgenic crops can spread to natural areas Kills beneficial insects This occurred in monarch butterflies in the lab Genes can spread by pollen to ordinary plants Create super weeds

44 Problems of genetic engineering: safety issues Transgenic crops contain proteins from other organisms This could trigger an allergic reaction in people Brazil nut genes incorporated in soybeans induced an allergic reaction to people allergic to the nuts Antibiotic-resistant genes are put into organisms This could convey resistance to pathogens Antibiotics could become ineffective Plants could produce new substances in response to foreign genes None of these concerns has become evident in the field

45 Problems of genetic engineering: access in the developing world Large agricultural-industrial firms developed early genetically modified organisms Profit is their major motive Poor farmers can t afford to buy the seeds Some noncommercial and donor-funded labs are helping Research in other countries allows farmers access to crops Genetically modified seeds are spreading through piracy The UN FAO reports that benefits are still mostly theoretical But millions have benefited from higher yields, etc.

46 Fear vs. acceptance Concerns and fear have generated controversy over genetically modified food Protests are strongest in Europe Concerns are made worse by other scares (e.g., mad cow) Governments may use the controversy to prevent importing cheaper food The U.S. is far less concerned 60% of food contains genetically modified substances U.S. policy does not require mandatory labeling

47 The policies In the U.S., the EPA, USDA, and FDA (Food and Drug Administration) regulate genetically modified food crops Conclusions of the National Research Council s report Genetically Modified Pest-Protected Plants: Science and Regulation Transgenic crops have been adequately tested Agencies need to better coordinate and present information to the public No evidence that these foods are unsafe Need more research on environmental and safety issues

48 to be continue in other time opportunity and remember to keep your ecological footprint low any questions or further discussion?