slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
Lecture Outlines Chapter 10 Environment: The Science behind the Stories 4th Edition Withgott/Brennan PowerPoint Presentation
Download Presentation
Lecture Outlines Chapter 10 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

Lecture Outlines Chapter 10 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

842 Views Download Presentation
Download Presentation

Lecture Outlines Chapter 10 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Lecture Outlines Chapter 10 Environment:The Science behind the Stories 4th Edition Withgott/Brennan

  2. This lecture will help you understand: • Challenges of feeding a growing human population • The Green Revolution • Preserving crop diversity • Strategies of pest management • Pollination • Genetically modified food • Feedlot agriculture • Aquaculture • Sustainable agriculture

  3. Corn (maize) originated in Mexico 9,000 years ago In 2001, genes from genetically modified corn appeared in traditional maize These transgenes (genes from another species) came from U.S. corn Could contaminate native crops The agrobiotech industry questioned these findings Transgenic maize in Southern Mexico

  4. Food production exceeds population growth We produce food through technology Fossil fuels, irrigation, fertilizer, pesticides, cultivating more land, genetic engineering Today, soils are in decline and most arable land is already farmed Today, we are producing more food per person By 2050, we will have to feed 9 billion people

  5. Undernutrition and food security • 1 billion people do not have enough to eat • Undernutrition = people receive fewer calories than their minimum requirements • Due to economics, politics, conflict, and inefficiencies in distribution • Most undernourished live in developing nations • But 36 million Americans are “food insecure” • Food security = guarantee of an adequate, safe, nutritious, and reliable food supply

  6. Undernutrition decreased between 1970 and 1990 Higher food prices (2006–2008) and the economic slump (2008–2009) increased the number and percent of hungry Food security 15% of the world’s population is hungry

  7. Overnutrition and malnutrition • Overnutrition = receiving too many calories each day • Developed countries have abundant, cheap junk food, and people lead sedentary lives • In the U.S., 25% of adults are obese • Worldwide, over 400 million people are obese • Malnutrition = a shortage of nutrients the body needs • The diet lacks adequate vitamins and minerals • Can lead to diseases

  8. Kwashiorkor = diet lacks protein or essential amino acids Occurs when children stop breast-feeding Bloated stomach, mental and physical disabilities Marasmus = protein deficiency and insufficient calories Wasting or shriveling of the body Malnutrition can lead to diseases

  9. Spread to the developing world in the 1940s Wheat, rice, corn Depended on lots of: Synthetic fertilizers Chemical pesticides Irrigation Machinery The Green Revolution increased yields Norman Borlaug won the Nobel Peace Prize for his work

  10. Consequences of the Green Revolution • From 1900 to 2000, cultivated area increased 33% • While energy inputs increased 80 times • Positive effects on the environment • Prevented some deforestation and land conversion • Preserved biodiversity and ecosystems • Negative effects on natural resources • Pollution, erosion • Salinization, desertification

  11. The Green Revolution • Intensified agriculture saved millions from starvation • Turning India into a grain exporter • Rich farmers with lots of land benefited • Poor farmers were driven off the land into cities Today, yields are declining in some Green Revolution areas

  12. Monocultures increase output, but at a cost • Monoculture =large expanses of a single crop • More efficient, increases output • Devastates biodiversity • Susceptible to disease and pests • Human diet is narrowed: 90% of our food comes from 15 crop and 8 livestock species Armyworms easily destroy monocultures

  13. Biofuels affect food supplies • Biofuels = are derived from organic materials • Replace petroleum in engines • Ethanol = a biofuel derived from corn • 2007 subsidies doubled production • Food prices increased • Farmers sold corn for ethanol, not food • Farmers planted biofuels, not food crops • Riots erupted in many nations

  14. Preserving crop diversity: insurance against failure • Preserving native variants protects against crop failure • Monocultures are vulnerable • Wild relatives contain genes that can provide resistance to disease and pests • But Mexico has lifted its ban on transgenic corn • We have lost a great deal of genetic diversity in crops • U.S. crops have decreased 90% in diversity • Market forces discourage diversity in food’s appearance • Food producers prefer uniform, standardized food

  15. Seed banks are living museums • Seed banks = institutions that preserve seed types as living museums of genetic diversity • Seeds are collected, stored, and periodically planted The “doomsday seed vault” in Norway stores millions of seeds from around the world

  16. We have thousands of pesticides • Pest= any organism that damages valuable crops • Weed = any plant that competes with crops • Pesticides = poisons that target pest organisms • Insecticides = kill insects • Herbicides = kill plants • Fungicides = kill fungi • 400 million kg (900 million lb) of pesticides are applied in the U.S. each year • 75% of this is applied to agricultural land • $32 billion/year is spent on pesticides worldwide

  17. Pests evolve resistance to pesticides • Some individuals are genetically immune to a pesticide • They pass these genes to their offspring • Pesticides stop being effective • Pesticide treadmill = chemists increase chemical toxicity to compete with resistant pests • Pesticides also kill nontarget organisms • Including predators and parasites of pests • Pest populations become harder to control

  18. Pesticide resistance • Over 556 insect species are resistant to 300 pesticides • Weeds and plant diseases have evolved resistance to pesticides

  19. Biological control (biocontrol) Biological control = uses a pest’s predators to control the pest Reduces pest populations without chemicals Reduces chemical use Cactus moths control prickly pear Bacillus thuringiensis (Bt) = soil bacteria that kills many pests

  20. Biocontrol agents may become pests It is risky to introduce an organism from a foreign ecosystem into a new ecological context The effects of an introduced species are unpredictable The agent may have “nontarget” effects on the environment and surrounding economies Cactus moths are eating rare Florida cacti Removing a biocontrol agent is harder than halting pesticide use Biocontrol use must be carefully planned and regulated

  21. Integrated Pest Management (IPM) Techniques to suppress pests: Biocontrol Chemicals, if necessary Population monitoring Habitat alteration Crop rotation and transgenic crops Alternative tillage methods Mechanical pest removal IPM in Indonesia increased rice yields 13% and saved $179 million/yr in phased-out subsidies

  22. We depend on insects to pollinate crops Not all insects are pests; some are absolutely vital 800 crop species rely on insect pollinators Pollination = male plant sex cells fertilize female sex cells By wind or animals Pollinators include: Hummingbirds Bats Insects (bees, wasps, etc.) Flowers are evolutionary adaptations to attract pollinators

  23. Conservation of pollinators is vital Populations of pollinators (e.g., bees) have plummeted Colony collapse disorder = entire beehives have vanished Unknown causes—Insecticides? Parasites? Stress? Reducing or eliminating pesticide use and planting flowering plants will help preserve bees Bees pollinate over 100 crops and contribute $15 billion in services/year

  24. Genetically modified organisms • Genetic engineering =laboratory manipulation of genetic material • Add, delete, modify DNA • Genetically modified (GM) organisms = organisms that have been genetically engineered by … • Recombinant DNA = DNA created from multiple organisms

  25. Biotechnology is impacting our lives Biotechnology = the application of biological science to create products derived from organisms Transgenic organism = an organism that contains DNA from another species Transgenes =the genes that have moved between organisms Biotechnology has created medicines, cleaned up pollution, and dissolved blood clots

  26. Some genetically modified foods

  27. Genetic engineering versus agricultural breeding • Traditional breeding = changes organisms through selective breeding of the same or similar species • Works with organisms in the field • Genes come together on their own • Uses the process of selection • Genetic engineering = mixes genes of different species • Works with genetic material in the lab • Directly creates novel combinations of genes • Resembles the process of mutation

  28. GM foods are a big business Most GM crops are herbicide and pesticide resistant Large-scale farmers grow crops more efficiently Most U.S. corn, soybeans, cotton, and canola are genetically modified Biotechnology is changing our world Globally, 14 million farmers grew GM foods on 134 million ha

  29. What are the impacts of GM crops? • As GM crops expanded, scientists, citizens, and policymakers became concerned • Impacts on human health • Concerns over escaping transgenes • They could harm nontarget organisms • Pests could evolve resistance • They could ruin the integrity of native ancestral races and interbreed with closely related wild plants

  30. Genetic engineering has benefits and risks • Environmental benefits of genetic engineering: • Reduced use of chemical insecticides • Increased no-till farming • Decreased irrigation, deforestation, land conversion • Negatives of genetic engineering: • Increased herbicide use affects health and habitats • Some GM fields support less biodiversity • Precautionary principle = don’t undertake a new action until the effects of that action are understood

  31. The GM debate involves ethics • People don’t like “tinkering” with the food supply • With increasing use, people are forced to use GM products, or go to special effort to avoid them • Multinational corporations threaten the small farmer • Research is funded by corporations that profit if GM foods are approved for use • GM crops have not eradicated hunger • GM crops do not focus on increased nutrition, drought tolerance, etc. The GM industry is driven by market considerations driven by financial interests of corporations

  32. GMO producers are suing farmers Corporations go to great lengths to protect their GM investments • Monsanto has launched 112 lawsuits against 372 farmers, winning an average $385,000 per case • Monsanto sued Percy Schmeiser of Canada for using its GM seeds without paying for them • Schmeiser said the seeds blew onto his field from adjacent fields • The courts sided with Monsanto, saying that Schmeiser had violated Monsanto’s patent

  33. The future of GM foods • Europeans demand that GM foods are labeled • U.S. consumers have mostly accepted GM crops • They don’t realize most food contains GM products • The U.S. sued the European Union before the World Trade Organization for hindering free trade • The Cartagena Protocol on Biosafety lays out guidelines for open information about exported crops • The U.S. has not joined • Brazil, India, and China approve GM crops

  34. Consumption of animal products is growing • As wealth and commerce increase, so does meat, milk, and egg consumption • Since 1950, global meat production has increased fivefold and per capita meat consumption has doubled • Domestic animals raised for food increased from 7.2 billion in 1961 to 24.9 billion in 2008

  35. Our food choices are also energy choices • Eating meat is far less energy efficient than eating crops • 90% of energy is lost from one trophic level to the next • Eating lower on the food chain feeds more people • Some animals convert grain into meat more efficiently than others

  36. Environmental ramifications of eating meat • Land and water are needed to raise food for livestock • Producing eggs and chicken meat requires the least space and water • Producing beef requires the most

  37. Resources needed for livestock production When we choose what to eat, we choose how we use resources

  38. Feedlot agriculture • Feedlots (factory farms) = also called Concentrated Animal Feeding Operations (CAFOs) • Huge warehouses or pens deliver food to animals living at extremely high densities • Over half of the world’s pork and most of its poultry U.S. farms house hundreds of thousands of debeaked chickens in crowded cages

  39. High consumption leads to feedlot agriculture • Traditional agriculture keeps livestock on grasslands • Feedlot animals are fed grain grown on cropland • One-third of the world’s cropland is fed to livestock • Feedlot agriculture allows economic efficiency • Greater production of food • Unavoidable in countries with high meat consumption, like the U.S. • Reduced grazing impacts on the land • Manure can be applied to fields as fertilizer

  40. Livestock agriculture pollutes water and air • Feedlots produce huge amounts of manure and urine • Causing eutrophication • Waterborne pathogens sicken people • Crowded, dirty housing causes outbreaks in disease • Heavy use of antibiotics, hormones, heavy metals • Chemicals are transferred to people • Microbes evolve resistance to antibiotics • Air pollution: odors, ammonia (acid rain) • More greenhouse gases (CO2, methane, nitrous oxides) than automobile emissions

  41. We raise fish on “fish farms” • World fish populations are plummeting • Technology and increased demand • Aquaculture = raising aquatic organisms in a controlled environment • Species are raised in open-water pens or land-based ponds

  42. Aquaculture is growing rapidly • Over 220 freshwater and marine species are grown • The fastest-growing type of food production • Provides ¾ of the world’s fish, ½ of the shellfish • Most widespread in Asia

  43. Benefits: A reliable protein source Can be sustainable Reduces pressure on overharvested wild fish Energy efficient Drawbacks: Diseases require expensive antibiotics Lots of waste Uses grain Escaped GM fish introduce disease or outcompete wild fish The benefits and drawbacks of aquaculture

  44. Sustainable agriculture • Industrial agriculture may seem necessary • But less-intensive agricultural methods are better • Sustainable agriculture = does not deplete soil, pollute water, or decrease genetic diversity • Low-input agriculture = uses smaller amounts of pesticide, fertilizers, growth hormones, water, and fossil fuels than industrial agriculture • Organic agriculture = uses no synthetic fertilizers, insecticides, fungicides, or herbicides • Relies on biological approaches (e.g., composting and biocontrol)

  45. Organic approaches reduce inputs and pollution • Organic Food Production Act (1990) establishes national standards for organic products • The USDA issued criteria in 2000 by which food could be labeled organic • Some states pass even stricter guidelines for labeling • California, Washington, Texas • Nearly 500 organizations offer certification services

  46. The benefits of organic farming • Farmers have lower input costs, enhanced income, reduced chemical pollution, and soil degradation • They practice stewardship to the land • Obstacles include risks and costs of switching to new methods • Consumers are concerned about pesticide’s health risks • They want to improve environmental quality • Obstacles include the higher price of organics

  47. Organic agriculture is booming • Organic farmers can’t keep up with demand • U.S. consumers pay $22.9 billion/year • Production is increasing • 1.8 million ha in the U.S.

  48. Governments can support organic farming • In 1993, the European Union adopted a policy supporting farmers financially during conversion to organic farming • The U.S. offers no support so organic production lags • The 2008 Farm Bill gives $112 million over 5 years for organic agriculture • Many farmers can’t switch, because they can’t afford the temporary loss of income • In the long run, organic farming is more profitable than conventional farming

  49. Locally supported agriculture is growing • Sustainable agriculture reduces fossil fuel use from long-distance transport of products • Food is chemically treated for freshness and color • Farmers’ markets = provide fresh, locally grown food • Community-supported agriculture (CSA) • Consumers pay farmers in advance • Consumers get fresh food • Farmers get a guaranteed income

  50. Sustainable agriculture mimics natural ecosystems • Ecosystems operate in cycles • Stabilized by negative feedback loops • Small-scale Japanese farmers add ducks to rice fields • Ducks eat weeds, insects, snails • Their waste is fertilizer • Their paddling oxygenates the water • Fish and ferns provide food and habitat