How Ecosystems Work

1. How Ecosystems Work Chapter 5 Ms. Hubbuch The Howard School

2. Energy Flow in Ecosystems Energy comes to the Earth from the sun It enters an ecosystem when a plant captures the energy for a process called photosynthesis During photosynthesis, plants, algae and bacteria use solar energy to create sugar molecules or carbohydrates. 6CO2+ 6H2O + Solar Energy  C6H12O6 + 6O2

3. Energy Flow in Ecosystems Organisms can be divided into three groups- 1. Producers that make their own food. 2. Consumers gather energy from eating other organisms. 3. Decomposers gain energy by breaking down dead organisms.

4. Energy Flow in Ecosystems Consumers can be categorized into four groups: Herbivores eat plants. Carnivores eat flesh and meat. Omnivores eat everything. Detrivoresconsume dead organisms.

5. Energy Flow in Ecosystems All energy enters the ecosystem as sunlight and can be converted to sugar by plants. Organisms get energy by eating producers and consumers. Once ingested, organisms break down the food in a process called cellular respiration. C6H12O6+ 6O26CO2 + 6H2O + Energy *This is a very different process from breathing (respiring).

6. Energy Flow in Ecosystems Every time and organism consumes another organism, energy is transferred. A food chain is a sequence in which energy is transferred from one organism to the next as each organism eats another organism. A food web shows many feeding relationships that are possible in an ecosystem. Each step through which energy is transferred is called a trophic level.

7. Energy Flow in Ecosystems Food Web Food Chain

8. Energy Flow in Ecosystems About 90% of all energy is used within an organism for respiration, activity or is lost as heat. That leaves 10% stored within the body to be transferred to the next trophic level. As a result, ecosystems support large populations of producers and far smaller populations of secondary and tertiary consumers.

9. Cycling of Materials - Carbon Carbon is an essential component of proteins, fats and carbohydrates. It is continuously cycled between the atmosphere, land, water and organisms. Plants, algae, cyanobacteria and the ocean all take in carbon. All living things emit carbon dioxide. Humans burn fossil fuels that release large amounts of carbon dioxide into the atmosphere.

10. Cycling of Materials - Carbon

11. Cycling of Materials - Nitrogen Organisms use nitrogen to build proteins. Most of the atmosphere is nitrogen gas but most organisms can not use it in this form. Nitrogen must be “fixed” by a small number of bacteria. These bacteria are found in the soil and a group of plants called legumes. All organisms rely on the nitrogen fixing bacteria. In the nitrogen cycle, nitrogen cycles between the atmosphere, bacteria and other organisms. Nitrogen is released into the soil by death, organisms defecating and lightning.

12. Cycling of Materials - Nitrogen

13. Cycling of Materials - Phosphorous Phosphorous is an essential element and is used in bones and teeth of animals. Plants receive phosphorous from soil and water while animals receive theirs by eating plants and other animals. Phosphorous is cycled between the environment and organisms. It is a very slow cycle and does not include the atmosphere.

14. Cycling of Materials - Phosphorous

15. Cycling of Materials - Rock There are three main types of rock, Igneous, Sedimentary and Metamorphic Rock. There is continuous movement between all three forms. Use the link below to see the processes that form rocks. http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm

16. Cycling of Materials - Soil • Soil is formed by Organic Material + Sediment + Air + Water = Soil • It is influenced by five factors • Climate • Parent Material • Organisms • Topography • Time

17. Change in Ecosystems Ecosystems are constantly changing as the species that comprise them live and die. The gradual process of change and replacement of some or all of the species in a community is called ecological succession. Primary succession occurs on a surface where no ecosystem existed before. Secondary succession occurs on a surface where an ecosystem has previously existed. It usually occurs after a disturbance cause by humans or a natural process.

18. Change in Ecosystems Pioneer species are the first to colonize any newly available area. They make the area habitable for other species. A climax community is a final stable community. It continues to change in small ways but will remain generally the same unless it is disturbed. 

19. Change in Ecosystems Fire plays an important role in ecosystems. Many plants rely on fire to release seeds and cannot reproduce without it. Small fires remove brush and deadwood and can lessen the chances of a larger fire. New vegetation sprouts quickly and supports a variety of organisms. Our National Parks and Forests are burned on a schedule to prevent large, uncontrollable fires.

20. Change in Ecosystems Old – Field Succession occurs when farmland is abandoned.

21. Change in Ecosystems Primary succession occurs slowly on areas that have not previously been colonized. Bacteria and lichens are often the first to colonize because they do not need soil. Lichen are producers made up of an alga and fungus. They often grow on rocks and work to break it down and eventually form soil. Primary succession occurs in parking lots when plants sprout in cracks. If we did not maintain our cities, the plants would eventually take over.

22. At the end of this chapter you should…. Understand how the sun’s energy is transferred between organisms. Construct an aquatic and terrestrial food web for Tennessee. Be able to diagram carbon, nitrogen, phosphorous and rock cycling through the environment. Understand the formation of soil and nutrient cycling and primary succession are involved. Explain how ecosystems begin and react to disturbances. As always, be able to define and use the bold terms in discussions.