1. Feeding Relationships

2. Ecosystem An association of organisms and their physical environment, interconnected by ongoing flow of energy and a cycling of materials energy input from sun PHOTOAUTOTROPHS (plants, other producers) nutrient cycling HETEROTROPHS (consumers, decomposers) energy output (mainly heat)

3. http://www.eduweb.com/portfolio/earthsystems /food/foodweb2.html

4. Important Terminology:

5. Modes of Nutrition Autotrophs –Capture sunlight or chemical energy –Producers Heterotrophs –Extract energy from other organisms or organic wastes –Consumers, decomposers, detritivores

6. Photosynthesis is the process by which plants convert energy from the sun to usable energy for humans Human survival depends on the stored energy in agricultural ecosystems

7. Consumers Herbivores Carnivores Parasites Omnivores Decomposers Detritivores SPRING rodents, rabbits fruits insects birds SUMMER rodents, rabbits fruits insects birds Seasonal variation in the diet of an omnivore (red fox)

8. Consumers Herbivores “plant eaters” Carnivores “meat eaters” Parasites“living eaters” Omnivores “all eaters” Decomposers“dead thing/waste eaters” Detritivores“eat materials from living things”

9. Herbivores Animals that get energy from eating plants Possess special digestive systems for digesting all kinds of plants Need a lot of energy to stay alive May eat all day long

10. Omnivores Animal that eats either other animals or plants Some will hunt and others will scavenge for dead matter or eggs of other animals Generally eat only the fruits and vegetation of fruit- bearing plants

11. Carnivores Generally eat herbivores, but will also eat omnivores Require large amounts of energy in order to hunt and kill The bigger the carnivore, the more it has to eat. Important to the ecosystem because they keep other species from becoming overpopulated.

12. Decomposers

14. Food Chain A straight line sequence of who eats whom Simple food chains are rare in nature MARSH HAWK UPLAND SANDPIPER GARTER SNAKE CUTWORM

15. Decomposer Food Chains Organisms that receive energy from dead plant and animal material Make up majority of food chains Scavengers eat the remaining energy in large dead organisms –Ex: Vultures eat the carcasses of dead animals

16. Food Web

17. http://www.vtaide.com/png/oceanchain.htm

19. Two Types of Food Webs Producers (photosynthesizers) herbivores carnivores decomposers detritivores ENERGY OUTPUT Grazing Food WebDetrital Food Web

20. Feeding Levels Important terms: –Trophic levels –Detrivores –Decomposers –Pyramid of Numbers –Pyramid of Biomass –Pyramid of Energy Flow

21. Trophic Levels

22. The source of energy (input) for all ecosystems is the sun All the organisms at a trophic level are the same number of steps away from the energy input into the system Producers are closest to the energy input and are the first trophic level

23. Feeding Levels First trophic level – always plants Second trophic level – primary consumers Third trophic level – secondary consumers

25. 1. Primary Producer = Autotrophs support all other trophic levels by synthesizing sugars and other organic molecules using light energy. 2. Primary Consumers = Herbivores consume primary producers. 3. Secondary Consumers = Carnivores eat herbivores. 4. Tertiary Consumers = Carnivores eat other carnivores. 5. Detritivores = Consumers derive energy from organic wastes and dead organisms Trophic Levels - Definitions

26. Energy Losses Energy transfers are never 100 percent efficient Some energy is lost at each step Limits the number of trophic levels in an ecosystem

27. Energy flows through the food chain but only about 10% of the energy is passed on from one trophic level to the next. –Ex: Plant has 100kJ, caterpillar uses 10% for life processes, 90% is lost as heat or waste

28. All Heat in the End At each trophic level, the bulk of the energy received from the previous level is used in metabolism This energy is released as heat energy and lost to the ecosystem Eventually, all energy is released as heat

29. Environmental Pyramids Food chains are useful for describing basic feeding relationships among organisms Pyramids illustrate different feeding relationships –visual comparisons among organisms at different trophic levels within the same pyramid and between pyramids Pyramid of Numbers Pyramid of Biomass Pyramid of Energy

30. Pyramid of Numbers Shows the numbers of organisms that are required to feed the next trophic level. The greatest number of organisms is in the first trophic level, least number on top of the trophic level

32. Pyramid of Biomass Shows the relative mass of the organisms at each trophic level Shows the energy available in each trophic level More useful than pyramid of numbers because it takes into account the size of the organism

34. Pyramid of Energy Flow Shows the amount of nutrient energy at each trophic level (difficult to measure Shows how the energy available at each trophic level is greatest at the bottom of the food chain and least at the top Pyramid of energy is always upright and cannot be inverted, the other pyramids can be

36. Pyramid of Energy

37. Pyramid of Energy Flow Primary producers trapped about 1.2 percent of the solar energy that entered the ecosystem 6-16% passed on to next level detritivores 21 383 3,368 20,810 kilocalories/square meter/year top carnivores carnivores herbivores producers decomposers

38. Food and Population Size The closer humans are to the producer, the more usable energy we consume The further we are down the food chain, the less energy we receive from the producers Fig 1.23 pg 28

39. Food and Competitors Monocultures – where humans mass produce a particular type of food This decreases biodiversity and increases pests –Ex: Population of aphids can become out of control when their food source is grown as a monoculture –Ex: Wheat Rust article

40. By selecting plants with desired characteristics, scientists have been able to produce also reduced the genetic variety of crops. Historically, humans relied on about 200 different species of plants. Today we rely heavily on about 20 different species – wheat rice, corn, and potatoes being the most common. Plants selected for rapid growth and desired aesthetic qualities may not be ideally suited to withstand disease an other negative environmental conditions

41. Poisons in Food Chains Pesticides are used to kill pests but are designed to not harm plants or humans Biological Magnification: –once pesticides enter a food chain, its concentration increases as it moves through the food chain –Ex: DDT in food chain (pg 30-31)

42. Biological Magnification A nondegradable or slowly degradable substance becomes more and more concentrated in the tissues of organisms at higher trophic levels of a food web

43. DDT in Food Webs Synthetic pesticide banned in the United States since the 1970s Birds that were top carnivores accumulated DDT in their tissues

44. Consuming the Planet Human population is increasing rapidly! –Due to decrease in death rate with medical and scientific advancements We are consuming the earth’s natural environment to feed ourselves We are also using up resources for convenience –Ex: cotton, tobacco, domestic pets (birds, fish, etc) We are destroying natural ecosystems –Burn forests, drain wetlands, pave highways, build golf courses

45. References/Resources http://faculty.southwest.tn.edu/rburkett/ ES%20- %20%20understanding_the_environm ent.htmhttp://faculty.southwest.tn.edu/rburkett/ ES%20- %20%20understanding_the_environm ent.htm http://www.globalchange.umich.edu/gc text/Inquiries/Inquiries_by_Unit/Unit_4. htmhttp://www.globalchange.umich.edu/gc text/Inquiries/Inquiries_by_Unit/Unit_4. htm