Ecosystems & Biological Communities

1. Ecosystems & Biological Communities

2. Interactions Ecology is the study of the interactions of living organisms with one another. What does the word really mean? house or place where one lives

3. The place where an organism lives is its habitat. A community is made up of manydifferent species that live together.

4. Interaction in an Ecosystem Define biotic factors: organisms in a habitat Fish in water Rabbit in a burrow Squirrel in a tree

5. Interaction in an Ecosystem • Define abiotic factors: physical aspects of a habitat Soil Sand Water

6. Energy Flow in Ecosystems Most life on earth depends on photosyntheticorganisms which capture some of the sun’s light energy and store it as chemicalenergy in organic molecules.

7. What is the equation for photosynthesis? 6 CO2 + 6 H2O + light  C6H12O6 + 6 O2

8. Organisms that are the first to capture energy are the producers which include plants, some kinds of bacteria, and algae. Consumers are those organisms that consume plants or other organisms to obtain the energy to build their molecules.

9. Trophic Levels

10. Food Chains What occupies the first or lowest trophic level of any ecosystem? Producers What occupies the 2nd trophic level? Herbivores (primary consumers) What occupies the 3rd trophic level? Secondary consumers

11. What is the difference between a carnivore and an omnivore? Carnivores eat meat only, Omnivores eat meat and plants Many ecosystems contain a 4th trophic level composed of carnivores that consume other carnivores.

12. Do ecosystems usually have more than 4 trophic levels? Rarely What role do bacteria and fungi play in an ecosystem? Decomposers (break down dead plant and animal matter)

13. Loss of Energy in Food Chain During every transfer of energy within an ecosystem, energy is lost as heat. The loss of useful energy limits the number of trophic levels an ecosystem can support. At each trophic level, the energy stored by the organisms in a level is about 1/10of that stored by the organisms in the level below. Ecologists often illustrate that flow of energy through ecosystems with an energy pyramid.

14. Energy Pyramid: a diagram in which each trophic level is represented by a block and the blocks are stacked on top of one another.

15. How many trophic levels are in Figure 9? Why is the top trophic level the smallest? 4 Least amount of energy

16. Practice If the first trophic level contained 10,000 kcal of energy, how much energy would the 2nd level have? 3rd? 4th? 1,000 kcal 100 kcal 10 kcal

17. Cycling of Materials in Ecosystems All materials that cycle through living organisms are important in maintaining the health of ecosystems, but 4 substances are particularly important: water, carbon, nitrogen and phosphorus.

18. Cycles The paths of water, carbon, nitrogen and phosphorous pass from the nonliving environment to living organisms, such as trees and then back to the nonliving environment.

19. The Water Cycle Water has the greatest influence on the ecosystem’s inhabitants. Water vapor in the atmosphere condenses and falls to the Earth’s surface as rain or snow. The water that seeps into the soil becomes part of the ground water.

20. Water Cycle Water is taken up by the roots of plants and then moves into the atmosphere by evaporating from the leaves through transpiration.

22. The Carbon Cycle Carbon dioxide in the air or dissolved in water is used by photosynthesizing plants, algae and bacteria as a raw material to build organic molecules. Carbon atoms may return to the pool of carbon dioxide in the air and water in 3 ways.

23. The Carbon Cycle 1. Respiration- all organisms use oxygen to oxidize organic molecules producing carbon dioxide.

24. The Carbon Cycle 2. Combustion- The burning of wood returns carbon to the atmosphere, as well as coal, oil, and natural gas. The carbon is released when the fossil fuel is burned. Smoke and pollution from Borneo fires, 1997.

25. The Carbon Cycle 3. Erosion-As limestone is exposed and erodes, the carbon becomes available to other organisms. Also includes decomposition

27. The Phosphorus and Nitrogen Cycles Organisms need nitrogen and phosphorus to build proteins and nucleic acids. Phosphorus is an essential part of both ATP and DNA.

28. Phosphorus and Nitrogen Cycles Phosphate is absorbed by the roots of plants and is eaten by animals. The atmosphere is 79% nitrogen gas, N2 but it is in an unusable form.

29. Phosphorus and Nitrogen Cycles Some bacteria can break the bond between the nitrogen molecules to form ammonia (NH3). This is called nitrogenfixation. These bacteria live in the soil and are also found in the nodules of roots of beans, alder trees and a few other kinds of plants.

30. The Phosphorus

31. 4 stages of the Nitrogen Cycle: 1. Assimilation- absorption and incorporation of nitrogen into plant and animal compounds 2. Ammonification- production of ammonia by bacteria during the decay of nitrogen- containing urea (found in urine).

32. 4 stages of the Nitrogen Cycle: 3. Nitrification- production of nitrate from ammonia 4. Denitrification- the conversion of nitrate to nitrogen gas.

34. Nitrogen Cycle Plant growth is limited by the availability of nitrate and ammonia in the soil. Most farmers add nitrates to the soil that has been made in a factory rather than by nitrogen fixation. Genetic engineers are trying to put the genes of the nitrogen-fixing bacteria into plants. This would eliminate the need for nitrogen-supplying fertilizers.

35. Biological Communities What is predation? The act of one organism killing another organism for food List 2 examples of predation. 1. bear and a fish 2. lions and gazelle

36. Symbiotic Species Define: symbiosis: two or more species live together in a close, long-term association Symbiotic relationships can be beneficial to both organisms or benefit one and leave the other harmed or unaffected.

37. Parasitism Parasitism is when one organism feedson and usually lives on or in another organism. Parasites do not usually kill their “host”. Example- fleas/ticks on dogs

38. Mutualism Mutualism is when both organisms benefit. Examples: plover and Rhino

39. Commensalism Commensalism is when one organism benefits and the other is neither harmed or helped. Examples: clown fish and sea anemone

40. Define: competition: two species use the same resource; they participate in a biological interaction What resources might species compete for? Water, food, nesting site, living space, light, mineral nutrients Do most interactions involve fighting? no

41. Define: niche: functional role of a particular species in an ecosystem In what ways can a niche be described? How an organism lives OR the “job” it performs within the ecosystem

42. Climate’s Effect on Where Species Live A. The 2 most important element of climate are temperature and moisture. B. A major biological community that occurs over a large area of land is called a biome.

43. 7 Most Widely Recognized Land Biomes Are: 1. Tropical Rainforest 2. Savanna 3. Taiga 4. Tundra 5. Desert 6. Temperate Grassland Temperate Forest Deciduous Evergreen

45. Many factors such as soiltype and wind play an important role in determining where biomes occur. Aransas National Wildlife Refuge Austwell, TX

46. Tropical Rainforest • 78-177 inches of rainfall annually • 68*F – 86*F = average 77*F • More species than other biomes, richest & most abundant, ½ of terrestrial species • Winter/Summer – little to no difference in temperature Dominica, West Indies

47. Savanna • 35-60 in. rainfall • 59*F – 86*F Temperature • Winter/Summer – more fluctuation than Rain Forest but still very little change • Widely spaced trees and grasses • Supports huge herds of grazing animals Africa

48. Taiga • Rainfall: 13 – 29 inches • Temperature: 50*F – 57*F • Cold, wet climate with long winters – Summers is when most precipitation falls • Coniferous trees (spruce & fir) • Home of elk, moose, deer, wolves, bears, lynxes, wolverines • Largest biome

49. Tundra • Found between taiga and permanent ice around North pole, Covers 1/5 of land surface • Permafrost- ground frozen within 3 ft. of surface • < 10 in. rainfall • Temperature: 35.6*F - 59*F • Winter – Long & cold 10 months • Summers – short and cool only last 2 months • Grasses and Mosses • Foxes, lemmings, owls, caribou

50. Desert • < 10 in. rainfall (varies greatly in specific locations) • Temperature 44.6*F – 100.4*F • Winters are cold & Summers are extremely hot • Sparse vegetation – cactus • Kit foxes, lizards, snakes • < 5% of North America • Usually in interior of continent Langtry, TX near Rio Grande River