1. Global Food Supplies & Natural Resources

2. What do humans use and consume from ecosystems?  __________________________________________  Human harvesting activities impact natural resources such as: air, water, & soil  As the human population increases, productivity of natural and cultivated ecosystems is threatened by our demand --- how can we feed, clothe, and shelter ourselves and provide energy for our activities without destroying the environment that provides it?  How can we manage ecosystems so that they are productive & sustainable?

3. Examples of Products Harvested from Natural Ecosystems Forest ProductsLumber, fuelwood, pulp for paper & fiberboard, food products (nuts, tropical fruits, maple syrup, etc.) Products of prairies, savannas, & deserts Furs and hides of animals, tusks, food (deer, kangaroo, ostrich eggs), pharmaceuticals Products from aquatic ecosystemsFish and shellfish, fishmeal (animal feed and fertilizer), whale oil

4. Examples of Products from Cultivated Ecosystems

5. Which products are harvested from both natural & cultivated systems?

6. Give advantages & disadvantages of harvesting products from a cultivated system

7. Ecologists & Productivity  Concerned with the flow of matter & energy through different parts of the ecosystem  Sun = energy source in almost all natural ecosystems; plants capture ~1% of solar energy through photosynthesis and fix the energy in organic compounds. Some compounds are used by plants to carry out their metabolism and some becomes part of the plant

8. Ecologists & Productivity  The rate at which organic matter is being fixed in an ecosystem through photosynthesis = gross primary productivity  Not all of the organic matter will become available to the rest of the food web, as some of it is used by plants. What remains = net primary productivity (similar to paycheck after taxes)

9. Estimated Net Primary Productivity BiomeAverage Net Primary Productivity (kg/square meter per year) Tropical Forest Temperate Forest Northern Coniferous Forest Shrub land Grassland Savanna Desert Tundra & Mountain zones Wetlands (marshes & swamps) 1.8 1.2 0.8 0.6 0.5 0.7 0.1 2.5 Agricultural land0.1 – 4.0 *depends on crop

10.  Which biomes appear to be the most productive?  Which biomes appear to be the least productive?  What reasons can you give for the high productivity of estuaries compared to that of the open ocean?  What kind of climate is found in the two most productive terrestrial biomes?  What kind of climate is found in the two least productive terrestrial biomes?  What conclusions can you draw, if any, about the relationship between climate & productivity?

11. Net Productivity & Biomass  The net productivity of the primary producers in an ecosystem is a major factor in determining the carrying capacities of other species in that system  Plant biomass is the total amount of organic matter in plants at any one moment  Net productivity is a measurement of how much biomass is being added over a period of time

12. Rate of Decomposition  Cycles of matter are also important when studying the productivity of an ecosystem  Ecologists are interested in the distribution of elements such as: oxygen, carbon, nitrogen, and phosphorous throughout the system.  At times, these elements may be present in inorganic substances such as salt; at other times they are parts of organic matter  The decomposers play an important role in how these elements are distributed

13. Rate of Decomposition  Decomposers are the organisms that break down dead plant & animal matter, eventually reducing them to compounds that are usable by living plants  Examples include: soil dwellers such as earthworms, certain beetles, insect larvae, and numerous fungi & bacteria  The rate of decay in an ecosystem is an important factor in productivity

14. Rate of Decomposition  Decomposition rates are affected by variables such as: -erosion of topsoil (carries away decomposers) -climate (decomposers inactive during cold)

15. Farmers & Productivity  Farmers view productivity in terms of yield; yield = the amount of salable crop that can be obtained from a field (this is closely related to biomass)  How do yield & biomass differ?  Ecologists are interested in what limits productivity in an ecosystem whereas farmers are likely to be more interested in overcoming limits  Farmers add energy to the ecosystem in order to obtain a higher crop yield

16. Farmers & Productivity  Energy inputs in agricultural systems are required during: -cultivation -irrigation -fertilization -insect & weed control What is the energy source for the inputs listed above?  Energy inputs increase yields but if the cost of inputs is greater than that of outputs, the farmer will not realize a profit and must go into debt

17. The Green Revolution  A planned international effort to eliminate hunger by improving crop performance  This period of increased productivity began in the 1950’s; the movement to increase yields used: -new crop cultivars such as more highly productive strains of wheat & rice -mechanization -pesticides -fertilizers -irrigation

18. Dr. Norman Borlaug  Considered the Father of the Green Revolution, a U.S. Plant pathologist/breeder  Worked in the international maize & wheat improvement center in Mexico & doubled the amount of wheat Mexico was producing; went on to work in India, Pakistan, Asia & Africa  Won a Nobel Peace Prize in 1970

19. The Green Revolution  Credited with feeding much of the world’s population in the last few decades – still considered by many to be the only hope of feeding the world’s growing population

20. The Green Revolution  There are problems: -the rapid increase in yields is diminishing -population is still on the rise -modern practices have caused many environmental problems and increased the cost of production  Controversy abounds - today, biotechnology is leading the 2 nd phase of the Green Revolution [we will address this later]

21. The Green Revolution http://www.livinghistoryfarm.org/farminginthe50s/crop s_13.html Clip from Dr. Borlaug re: organic farming & criticism of green revolution

22. Sustainability in Cultivated Ecosystems  Agricultural ecosystems differ from natural ecosystems  In the past, humans hunted & gathered food from natural ecosystems, this required a lot of time spent on getting food & a lot of land to supply enough food for one person  The shift to agriculture meant more work on less land but the increased productivity enabled a few to feed themselves & many others

23. Sustainability in Cultivated Ecosystems  Agricultural systems generally have a high productivity but a low sustainability – the high energy inputs required can be too expensive for farmers to maintain  Agricultural practices, over time can lead to erosion or exhaustion of the soil -plowing & tilling = vulnerability to soil erosion -exposure to wind & rain = erosion &/or leaching -annual crops do not have root systems capable of holding the soil

24. Sustainability in Cultivated Ecosystems  Many agricultural systems focus on a single crop (monoculture), which tends to be more profitable for the farmer but does limit sustainability -single crops tend to speed up depletion of soil nutrients -single crops are vulnerable to diseases & pests ex: Irish Potato Famine

25. How Can Agricultural Systems Be Managed so That They Are More Sustainable?

26. Integrated Pest Management (IPM)  A general philosophy of safe & effective pest control that uses several different methods of control to reduce the population of a particular pest  Involves identifying & understanding each pest, its life cycle, breeding sites, and density threshold (# of pests per area that can be tolerated without overall crop damage) & selecting remedies that address the specific pest problem

27. Diversity  Producing several crops (may be combined with livestock production)  Crop diversity can improve soil health & prevent devastation by a single pest or disease  When livestock & crops are both raised, they can provide inputs for one another ex: sow manure fertilizes sorghum & sorghum can be used to feed cattle

28. Alternative Tillage Methods  In no-tillage farming, the old crop is left in the field to form mulch (covering of organic matter) which reduces water loss, soil erosion, & weed growth

29. Reduced Use of Water  Drip irrigation lines are hoses at or under the ground which deliver water directly to crop roots = reduced water loss from evaporation  Rainwater recovery systems  Selection of drought-resistant crops

30. Composting  The use of animal manure, crop residues, tree clippings, & other organic material to make compost, which tends to be laden with beneficial microbes & plant nutrients

31. Sustainability in Natural Ecosystems  Natural Ecosystems tend to be stable due to: -biological communities that remain fairly constant in their makeup = stable populations -an abundance of perennial species -relatively high species diversity

32. Harvesting of Natural Resources  Renewable resources should last indefinitely because they can be replaced through natural processes Ex: trees, fish, wildlife, fresh water, clean air, fertile soil, etc.  Renewable resources may not last indefinitely due to depletion or degradation Ex: pollution, deforestation, removal of water faster than it is replaced by natural processes

33. Summary  The availability of food supplies & natural resources is a global matter  Past methods of farming have been very productive but do not appear to be sustainable over a long period of time; farmers may have to think more like ecologists and focus on the flow of matter and energy through the system  The harvesting of natural resources also requires attention to sustainability – the methods by and rate at which resources are harvested may need regulation

34.  Adapted from: CORD: Community of Life

36. December 15 Toward a Sustainable Agriculture 36 What is Sustainable Agriculture? “…a journey, not a destination” Iowa Farmer

37. December 15 Toward a Sustainable Agriculture 37 Sustainable Agriculture  “…an integrated system of plant and animal production practices…that will  satisfy human food and fiber needs  enhance environmental quality  make the most efficient use of nonrenewable resources  sustain economic viability  enhance quality of life.” 1990 Farm Bill

38. December 15 Toward a Sustainable Agriculture 38 The three-legged stool of sustainability

39. December 15 Toward a Sustainable Agriculture 39 Economically sustainable  Provides a secure living for farm families  Provides a secure living to other workers in the food system  Provides access to good food for all

40. December 15 Toward a Sustainable Agriculture 40 Environmentally Sound Preserves the quality of soil, water, and air

41. December 15 Toward a Sustainable Agriculture 41 Cooperates with and is modeled on natural systems Environmentally Sound

42. December 15 Toward a Sustainable Agriculture 42 Socially sustainable  Good for families  Supports communities  Fair to all involved

43. Where are we? What are the Strengths and Weaknesses of our current agricultural system?

44. Successes  abundant food supply in the developed world  fresh fruits and vegetables available year-round  cheap food  luxury foods such as coffee, tea, chocolate, and spices easily available around the world  effective food preservation technologies (refrigeration, freezing, canning, packaging)  convenience foods  mechanization produces high labor efficiency  improvements in soil conservation  availability of agricultural inputs for quick solutions to production problems

45. Problems  continuing soil loss  food safety concerns (mad cow disease, food poisoning outbreaks, antibiotic resistance, toxins and pesticides)  water pollution, air pollution (& odors), habitat loss, water depletion  continuing hunger – and rise of obesity  failing farms, economic uncertainty and stress  declining communities  farm accidents, chronic diseases linked to agricultural chemicals  reliance on fossil fuels, global warming  farmland loss to development, ugly countryside  difficulty of starting in farming

46. Conclusion  Agriculture has accomplished much  There are still many problems to solve, both old and new  Sustainable agriculture is about trying to solve these problems – without creating new ones.