Ch 3 What is Ecology?

1. Ch 3What is Ecology? • Ecology is the study of interactions among organisms and between organisms and their environment • The biosphere is the portion of the earth in which all life exists

2. Levels of Organization • Species- Group of organisms that are able to produce fertile offspring • Population- Group of individuals of the same species living in a particular space • Community- Group of interacting populations of different species. • Ecosystem- all the organisms living in one place with their nonliving environment.

5. Abiotic factors- non-living part of an ecosystem (sunlight, temperature, water, soil type, humidity) • Biotic factors- living parts of an ecosystem (animals, plants, & microorganisms) • Make a list of the biotic & abiotic parts of the salt marsh food web on p. 71

6. “Energy Flow In Ecosystems”Ch 3.2 • The source of energy for almost all organisms is the sun • Plants, algae, and some kinds of bacteria capture solar energy & produce food through photosynthesis

7. Leaves absorb sunlight, which drives a series of chemical reactions that require H2O and CO2 The result is the production of sugar (food) and water carbon dioxide + water + light energy → glucose + oxygen + water Photosynthesis

8. When an animal eats producers, it gets energy from the food the producer made during photosynthesis So, producers get their energy directly from the sun While consumers get their energy indirectly from the sun by eating producers or other organisms that eat producers

9. What Eats What

11. Respiration: Burning the Fuel • How do organisms get the energy from their food? • During cellular respiration, sugar & oxygen combine to produce CO2, H2O, & energy • Energy is used through daily activities, stored as fat or sugar, and/or to make more body tissue for growth

12. Energy Transfer: Food Chains, Food Webs, & Trophic Levels • A transfer of energy occurs each time an organism eats another organism • Food chains, food webs & trophic levels are used to trace the paths that energy flows through an ecosystem

13. Each time energy is transferred, less of it is available to organisms at the next level. • What accounts for the decreased amount of energy at each level? • Some energy is lost during the process of changing food to energy. • About 90% of the energy is used to carry out the functions of living- producing new cells, regulating body temp. etc. • The remaining 10% becomes part of the organism’s body, stored in its molecules. • This 10% is all that is available to the next trophic level when one organism eats another.

15. Another way to understand the reduced amount of energy at higher trophic levels is to think of how it could be similar to the flow of money. • Let’s say you pay $15 for a CD. How much of that $15 actually goes to the band members? Very little because your money passes through several intermediates, each of whom takes a cut, before it reaches the band

16. How does energy loss affect an ecosystem? • The energy loss results in fewer organisms at the higher trophic levels. For ex. Zebras & other herbivores outnumber lions by about 1,000 to 1

17. The loss of energy from trophic level to trophic level places a limit on the number of trophic levels in an ecosystem. • Ecosystems seldom have more than four or five levels.

18. The Cycling of Water • Water Cycle- the overall water on Earth stays about the same • Water moves between the Earth’s surface & the atmosphere • The sun provides the energy that drives the water cycle

19. Heat from the sun evaporates the water from the oceans, lakes & rivers, moist soil surfaces, from leaves of plants and from organisms’ bodies. • As water vapor cools in the atmosphere, it condenses & forms tiny droplets in clouds • When the clouds meet cold air, water returns to the Earth again as precipitation- rain, sleet, or snow. • Since oceans cover most of the planet, most precipitation falls on the oceans

20. The precipitation that falls on land may evaporate again into the atmosphere. • Or, it may collect in streams & rivers that flow into the oceans • Or, it may soak into the soil • Water that soaks into the soil may be used immediately by plants or it may seep down through the soil & rocks until it reaches a layer of rock or clay where it can go no further • This layer of underground water is called groundwater

21. How much of the Earth’s water is available for human consumption? • 97% of the Earth’s water is in the oceans • Leaving only 3% freshwater • However, 77% of that 3% is frozen in the icecaps and glaciers • 22% of the 77% is groundwater • 1% of freshwater is in lakes, rivers, soil and atmosphere • Thus, only a tiny fraction of the Earth’s water supply is available for our use. • The water we require for our everyday needs comes from two sources: surface water and groundwater

23. Underground Treasures • Some large cities, as well as many rural communities and individual farms, depend on aquifers for their water needs • The US has several huge aquifers that supply millions of gallons of water for homes and agriculture • This resource is tapped by drilling a well into the ground until the hole reaches the groundwater • Aquifers continuously receive water that percolates down from the surface, but this process is very slow • It may take millions of years for a large aquifer to form

24. The problem with aquifers is that people are pumping out the water faster than it can be replaced • The water levels of many aquifers are dropping rapidly • The largest aquifer in the US, the Ogallala Aquifer, is being depleted rapidly

25. Carbon Cycle • The sun is the source of energy that drives the Carbon Cycle • What form is carbon found in the atmosphere? • Where does it come from?

26. Cellulose, which makes up the walls of plant cells, contains Carbon. What is the source of this carbon? • How does carbon become • part of an animal’s body? • How is carbon released • from the body?

27. Human Impact on the Carbon Cycle • Humans are overloading the carbon cycle. • This carbon is not returned to the atmosphere until the leaves fall or the plant dies and decays. • Some plants, however, never completely decay. Instead, they are covered by sand and silt. • After millions of years underground, the plants become coal, oil, or natural gas. • When these fossil fuels are burned, they release the stored carbon as CO2

28. Tons of CO2 are poured into the atmosphere each year from power plants that burn coal or oil and from cars that burn gasoline. • The burning of living plants also releases CO2. This increases the CO2 in the air in 2 ways. • First, a burning plants gives off CO2. Second, when a living plant is burned, there is one less plant to remove CO2 from the air by photosynthesis.

29. Greenhouse Gases and the Earth’s Temperature • Greenhouse gases trap heat near the Earth’s surface • Major green house gases include: CO2, CFCs, methane, and nitrous oxide • Many scientists believe that as a result of increasing greenhouse gases, the Earth’s average temperature will increase by 4 degrees by 2050.

30. Weather Patterns • If the earth heats up significantly, the oceans will absorb more heat energy, which may make hurricanes and typhoons more common • It’s possible that global warming will also cause a change in ocean current patterns which could significantly affect the world’s weather • Some regions could receive more rain than normal, while others might have less • Severe flooding could occur in some regions at the same time that droughts devastate other regions

31. Sea Levels • As polar regions warm, more icebergs may break loose from glaciers and melt in the sea • Sea levels would then rise causing flooding in some coastal areas

32. Slowing the Temperature Change • Reduce the use of fossil fuels • Preserve forests • Plant trees

33. The Nitrogen Cycle • All organisms need nitrogen to build proteins • Nitrogen gas makes up 78%of the atmosphere

34. However, nitrogen-fixing bacteria are the only organisms that can use it • Nitrogen-fixing bacteria are an important part of the nitrogen cycle b/c they take the atmospheric nitrogen and “fix” it into a useable form for other organisms • These bacteria are found in the roots of beans, clover, & peas.

35. Mutualistic Relationship(nitrogen-fixing bacteria and plants) • The bacteria use sugars made by the plant and in exchange produce nitrogen for the plant • The excess nitrogen is released into the soil • Animals get nitrogen by eating plants or other animals

36. Bacterial and fungal decomposers break down wastes (urine, dung, leaves and other plant parts) and dead organisms, returning the nitrogen they contain to the soil • After it is returned to the soil, bacteria change a small amount of it into nitrogen gas

37. What source of energy ultimately drives the nitrogen cycle. 2. How do animals obtain nitrogen? 3. In what form does nitrogen appear in the air?

38. Niche & Habitat • Niche- Relationships with the environment, both living & non-living parts. • An organism’s niche is its way of life: when it reproduces, where it finds shelter, how many offspring,what time of day it is most active, etc).

39. Habitat is the actual place where an animal lives. Examples: savanna, desert, rain forest. • Choose an animal & describe the difference between that animal’s habitat & niche.

40. How Species Interact With Each Other 5 major types of species interactions: • Predation- one organism kills & eats another organism • Predator- one that does the eating • Prey- one that is eaten

41. 2. Competition occurs when 2 or more organisms of the same or different species attempt to use the same limited resource. • Plants also compete for the limited amount of sunlight that reaches the forest floor.

42. 3. Parasitism- organisms that live in or on another organism and feed on it without immediately killing it. • Parasites live on hosts. • Only the parasite benefits in this relationship.

43. 4. Mutualism- partnership between 2 species in which both species benefit. • Example of a mutualistic relationship: clownfish & sea anemones

44. 5. Commensalism- most rare of the 3 interactive relationships (parasitism, mutualism & commensalism). • Relationship in which 1 species benefits and the other is neither harmed nor helped. Shark & remoras

45. How Ecosystems Change • Succession is a regular pattern of changes over time in the types of species in a community.

46. Changes in Ecosystems • Ecosystems change over time • Changes result from natural events such as floods, forest fires, or volcanic eruptions • Some changes are due to human activities, like the clearing away of forests or filling in of wetlands to make land available for homes

47. Two Types of Ecological Succession Type 1: Primary Succession • Succession that occurs in an area where no communities exist is called primary succession • Primary succession may take place in an area that is devastated by a volcanic eruption or when a glacier retreats to expose bare rock • The main process that takes place during primary succession is the development of new soil

48. The first organisms to inhabit an ecosystem are called pioneer species • Lichens, fungi and mosses are pioneer species in primary succession b/c they help make new soil

49. PRIMARY SUCCESSION