1. Energy in Ecosystems Lesson #5 November 23, 2010

2. What is the source of all energy for ecosystems? SUN

3. The Sun Lights and warms the surface of the earth Gives energy needed evaporate water from oceans and lakes to make rain and snow Provides energy used by green plants- which serve as food for all other organisms

4. The Sun Energy from the sun travels 150 million kilometers to reach Earth Only one billionth of the energy released by the sun reach Earth Much of that energy is then filtered out before it reaches Earth’s surface

5. The Sun Of that energy 30% is reflected by cloud’s or the Earth’s surface The leftover 70% warms the surface causing water to evaporate and generating the water cycle and weather Only 0.023% is used by green plants for photosynthesis Photosynthesis- process by which green plants use sunlight energy to produce carbohydrates Many gases on Earth actually trap energy rising from the surface and redirect it back to Earth

6. The Albedo Effect When sunlight strikes an object, some of the energy is absorbed and some is reflected Some materials reflect better than others Albedo is the measurement of the percentage of light that an object reflects.

7. The Albedo Effect Higher the albedo, the greater the object’s ability to reflect sunlight In terms of the Earth- the higher its albedo, the less energy will be absorbed and available for maintaining the global temperature

8. Snow Snow is extremely bright when sun is shining on it- snow has a high albedo. Snow contributes to low temperatures of winter by reflecting energy from the sun back into space Snow also delays warming in Spring Other high-albedo areas are sand, pale rocks and areas without forest

9. Cloud Cover Cloud cover also increases the albedo of the Earth If there is more water vapour there will be more cloud Higher temperatures cause more water to evaporate

10. Part 2 Energy Movement in Ecosystems

11. Trophic Levels Trophic level- a way of categorizing living things according to how they gain their energy Trophic comes from Greek word meaning feeder.

12. 1 st Trophic Level Organisms that can make their own food from basic nutrients and sunlight or some other non-living energy source Also referred to as producers or autotrophs i.e. plants, algae, and some types of bacteria

13. 2 nd Trophic Level Organisms that feed on the producers Primary consumers Rely directly on autotrophs for their source of energy

14. 3 rd Trophic Level Secondary consumers Rely on primary consumers for their source of energy Still dependent on autotrophs (indirectly)

15. 4 th Trophic Level Tertiary consumers Carnivore eats a secondary consumer (another carnivore)

16. Heterotrophs Consumers, no matter of their trophic level Heterotrophs cannot make their own food, so they must obtain their energy and food from autotrophs or other heterotrophs

17. Activity #1 At your table, develop a small skit that shows the trophic levels and the organism in each level Perform skits

18. Energy and Food Chains Every organism in an ecosystem provides energy for other organisms The final carnivore in any food chain is called a top carnivore Top carnivores are not eaten by other animals (at least not while alive)

19. Spruce Tree First Trophic Level Producer Deer Second Trophic Level Primary Consumer Wolf Third Trophic Level Secondary Consumer Top Carnivore

20. Food Webs What would happen if the spruce trees went extinct?

21. Dramatic cause and effect relationships are rare in natural ecosystems Deer do have other food sources such as buds, stems and bark of a variety of trees and shrubs and some grasses The wolf also eats rabbits, birds, beavers, etc.

22. Every organism in an ecosystem is involved in many food chains They all interlock with each other to form a feeding relationship called a food web

24. Ecosystems with greatest biodiversity are most stable as they have complex and well developed food webs The reduction of one organism or even the removal of one type of organism may have only a small effect on the overall food chain

25. However, where abiotic factors limit number of organisms, the webs look more like food chains i.e. in the Arctic where # of producers is small Less energy from sun and temperature are low and producers cannot photosynthesize as fast as in the South

26. Less energy is available so fewer organisms can live in that ecosystem Relationships are more direct Loss of one type of organism will have major effect on all the remaining organism

27. The higher the biodiversity, the more complex the food web and the less vulnerable the organisms are The lower the biodiversity, the simpler the food web and the more vulnerable the organisms are

28. Activity #2 Look at trophic levels from skits. Develop a food chain in ‘our ecosystem’

29. Limits on Energy Transfer Producers use sunlight to make molecules of sugar Sugar molecules contain the chemical energy that drives ecosystems Photsynthesis provides the energy required by the entire ecosystem

30. Not all energy that a plant creates reaches the animal that eats it The plant uses most of that energy to stay alive and grow Once an animal eats the plant, it does not store all the chemical energy it eats Most is used to function- move, pump blood, keep warm, etc.

31. The further up a food chain you travel, the less energy is available There is less energy available to secondary consumers than there is to primary consumers

32. Thermodynamics Thermodynamics- study of energy transformations 2 laws of thermodynamics 1- although energy can be transformed from one form to another, it cannot be created or destroyed 2- during any energy transformation some energy is converted into an unusable form, mostly heat that cannot be passed on. Each time energy is transformed some energy is lost from the system.

33. Limits on Energy Transfers and the Number of Trophic Levels Only about 10% of the energy of the plant that was transferred to the deer becomes available to the wolf Deer eats only the buds-not the whole tree Not all of the bud is digested by the deer Some is eliminated by the deer (waste) Some used to fuel the deer’s cells, maintains deer’s body heat Wolf does not eat all of deer-not the bones, hooves, fur, etc Wolf loses energy in digestion and body maintenance So only a portion of the energy stored in the total deer tissue is used by the wolf

34. The overall loss of energy at each step sets a limit on the number of trophic levels in a food chain at about five In most ecosystems there is not enough energy to support a higher-level consumer

35. Cultural Change: The Human Use of Energy in Ecosystems Humans have been part of ecosystems for about 60 000 to 90 000 years. Until 12 000 years ago, we had little influence on ecosystems The agricultural revolution and the industrial revolution have changed that They have placed demands on ecosystems and have reduced the amount of energy available to other organisms These revolutions increased food supply, improved health and increased lifespan leading to increase in human population Recently the increase has accelerated and threatens the ability of ecosystems to sustain themselves.

36. Hunting and Gathering We were hunters and gatherers for most of our history Survived by eating plants and animals Nomad lifestyles Moved when an area’s resources were depleted Energy demands on ecosystem were wood for fuel and food for energy Both were obtained from plants and animals Human populations grew dependent on food resources

37. Agriculture Change in climate allowed hunters and gatherers to farm life Planting of crops and domestication of animals allowed people to remain in one place Trees were cut to make permanent housing Wetlands were drained and forests cut so they could cultivate the land Farms produced more energy for humans allowing the population to grow, but made greater demands on local ecosystems The energy needed to sustain a farming community had to come from the ecosystem-humans took a larger share of the energy budget for the ecosystem they inhabited

38. Industry Invention of technological devices demanded more energy from the ecosystem Energy was used to power machines Products helped to increase food production and improve health of humans Each improvement allowed the ecosystem to support a greater population, but an increasing population placed greater demands on the ecosystem