APES Unit 3 Ecosystems

Transcription

1 APES Unit 3 Ecosystems Ecology From the Greek words oikos = house and logos = study of The study of how organisms interact with one another and with their environment. YOU SHOULD KNOW! The difference between eukaryotic and prokaryotic cells. The definition of species. The types of asexual and sexual reproduction. 1

2 THE NATURE OF ECOLOGY Ecology is a study of connections in nature. How organisms interact with one another and with their nonliving environment. Species Organism 2

3 Population A group of interacting individuals of the same species. Each individual will be different due to genetic diversity. Each population lives in a particular habitat spread over an area called a range. Population Community The total of all populations living and interacting in a given area. 3

4 Ecosystem A community and its nonliving environment. Animation: Levels of Organization YOU SHOULD KNOW! Lower part of atmosphere = troposphere. Next layer is the stratosphere. The lowest layers, the hydrosphere and lithosphere, make up the biosphere. Most life exists in the biosphere. 4

5 THE EARTH S LIFE SUPPORT SYSTEMS The biosphere consists of several physical layers that contain: Air Water Soil Minerals Life Figure 3-6 How is life sustained on Earth? Three interconnecting factors: 1. The one-way flow of energy from the sun through the biosphere back into space. 2. Matter cycling 3. Gravity 5

6 Energy Flow Earth is a closed system. Except for the negligible amount of cosmic matter entering the Earth s influence and the miniscule amount of matter that escapes the planet into space, the Earth is a closed system. We already have all of the matter we will every have. Energy Flow Energy, but not matter, is exchanged between the system and the environment. Energy Flow Open Systems Both matter and energy are exchanged. The human body is an open system matter (water, food, air) and energy is taken in; waste and energy is released into the environment. Individual organisms depend on both energy flow and matter flow. 6

7 Animation: Sun to Earth Solar radiation Energy in = Energy out UV radiation Absorbed by ozone Visible Light Absorbed by the earth Reflected by atmosphere (34% ) Lower Stratosphere (ozone layer) Troposphere Greenhouse effect Heat Radiated by atmosphere as heat (66%) Heat radiated by the earth Components of Ecosystems Two major parts of EVERY ecosystem Abiotic = the non-living parts Biotic = the living parts 7

8 Abiotic Factors Physical Factors for Land Ecosystems Sunlight intensity, duration Temperature variation, extremes Precipitation Frequency, duration, amount Wind Strength, direction, humidity Abiotic Factors Physical Factors for Land Ecosystems Latitude Altitude Fire frequency Nature of soil drainage rate, mineral content, ph Abiotic Factors Physical Factors for Water Ecosystems Water currents flow rate, temperature Dissolved nutrients Suspended solid material 8

9 Abiotic Factors Chemical Factors for Ecosystems Supply of water and air in soil Supply of plant nutrients Toxic substances dissolved in soil or water Salinity (aquatic ecosystems) Level of dissolved oxygen (aquatic ecosystems) Animation: Roles of Organisms in an Ecosystem 9

10 Animation: Diet of a Red Fox Abiotic and Biotic Factors Range of Tolerance Each population has a range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. Individuals of a population will differ due to small differences in genetic make-up, age, and health. 10

11 Law of Tolerance The existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species. These may change during an individuals lifetime. Range and Habitat 11

12 Law of Tolerance Threshold Affect The harmful or fatal effect of a small change in environmental conditions that exceeds the limit of tolerance of an organism or population of a species. 12

13 Threshold Affect Example: Swimmers ear is caused by a fungus. Changing the ph in the ear canal even a little bit can prevent or increase the infection. Limiting Factors Single factor that limits the growth, abundance, or distribution of the population of a species in an ecosystem. Example 1: The salinity of the soil in an estuary may limit plant growth as you get closer to the ocean. Example 2: A deserts limiting factor is the amount of precipitation. Organisms must adapt to preserve water or perish. Limiting Factors 13

14 Limiting Factors Example 3: Floods limit food, shelter, and may bring toxic materials into an environment. Example 4: Lack of shelter can limit the number of organisms/size of the population. Limiting Factors Limiting Factor Principle Too much or too little of any abiotic factor can limit or prevent growth of a population of a species in an ecosystem, even if all other factors are at or near the optimum range of tolerance for the species. Examples 14

15 Limiting Factor Principle Important limiting factors are: DO (dissolved oxygen) Temperature Sunlight Nutrient availability Salinity YOU SHOULD KNOW! Autotrophic organisms Heterotrophic organisms The role and process of photosynthesis Definition of herbivore, carnivore, and omnivore The difference between aerobic and anaerobic respiration Biotic Factors Three primary types of biotic factors: 1. Producers 2. Consumers 3. Decomposers 15

16 Producers Autotrophs (Plants) Most convert sunlight energy to chemical energy in the form of glucose. Photosynthesis Some do this by chemosynthesis Converting simple compounds from the environment into more complex nutrients. Very special bacteria Sun H 2 O Chlorophyll Light-dependent Reaction Energy storage and release (ATP/ADP) Chloroplast in leaf cell O 2 CO 2 Lightindependent reaction Glucose 6CO H 2 O Sunlight C 6 H 12 O O 2 Animation: Linked Processes 16

17 Producers Consumers Organism that cannot synthesize the organic nutrients it needs and gets its organic nutrients by feeding on the tissues of producers or of other consumers; generally divided into primary consumers (herbivores), secondary consumers (carnivores), tertiary (higher-level) consumers, omnivores, and detritivores (decomposers and detritus feeders). Primary Consumers Organism that feeds on all or part of plants (herbivore) or on other producers. 17

18 Secondary Consumer Organism that feeds only on primary consumers. Tertiary Consumers Also called higher-level consumers. Animals that feed on carnivores. They feed at high trophic levels in food chains and webs. Examples are hawks, lions, bass, and sharks. Do you agree? Detritivores Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. The two principal types are detritus feeders and decomposers. Detritus feeders do not break down their nutrients to a simple organic compound. 18

19 Decomposers Organism that digests parts of dead organisms and cast-off fragments and wastes of living organisms by breaking down the complex organic molecules in those materials into simpler inorganic compounds and then absorbing the soluble nutrients. Producers return most of these chemicals to the soil and water for reuse. Decomposers consist of various bacteria and fungi. Decomposers 19

20 Animation: Matter Recycling and Energy Flow Animation: Energy Flow 20

21 Food Web 10/12/2009 Animation: Prairie Trophic Levels Animation: Categories of Food Webs 21

22 Animation: Rainforest Food Web Animation: Prairie Food Web Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. 22

23 Animation: Energy Flow in Silver Springs Productivity of Producers: The Rate Is Crucial Gross primary production (GPP) Rate at which an ecosystem s producers convert solar energy into chemical energy as biomass. 23

24 Gross primary productivity (grams of carbon per square meter) What are nature s three most productive and three least productive systems? 24

25 Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest North. coniferous forest Savanna Agricultural land Woodland and shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean Average net primary productivity (kcal/m 2 /yr) SOIL: A RENEWABLE RESOURCE Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth and also helps purify water. Soil formation begins when bedrock is broken down by physical, chemical and biological processes called weathering. Mature soils, or soils that have developed over a long time are arranged in a series of horizontal layers called soil horizons. SOIL: A RENEWABLE RESOURCE 25

26 Layers in Mature Soils Infiltration: the downward movement of water through soil. Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower layers. The soil type determines the degree of infiltration and leaching. Soil Profiles of the Principal Terrestrial Soil Types 26

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28 Animation: Soil Profile MATTER CYCLING IN ECOSYSTEMS Nutrient Cycles: Global Recycling Global Cycles recycle nutrients through the earth s air, land, water, and living organisms. Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms. 28

29 The Water Cycle Animation: Hydrologic Cycle 29

30 Water Unique Properties There are strong forces of attraction between molecules of water. Water exists as a liquid over a wide temperature range. Liquid water changes temperature slowly. It takes a large amount of energy for water to evaporate. Liquid water can dissolve a variety of compounds. Water expands when it freezes. Effects of Human Activities on Water Cycle We alter the water cycle by: Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change. The Carbon Cycle: Part of Nature s Thermostat 30

31 Animation: Carbon Cycle Effects of Human Activities on Carbon Cycle We alter the carbon cycle by adding excess CO 2 to the atmosphere through: Burning fossil fuels. Clearing vegetation faster than it is replaced. The Nitrogen Cycle: Bacteria in Action 31

32 Animation: Nitrogen Cycle Effects of Human Activities on the Nitrogen Cycle We alter the nitrogen cycle by: Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation. 32

33 Effects of Human Activities on the Nitrogen Cycle Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30 The Phosphorous Cycle Animation: Phosphorous Cycle 33

34 Effects of Human Activities on the Phosphorous Cycle We remove large amounts of phosphate from the earth to make fertilizer. We reduce phosphorous in tropical soils by clearing forests. We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers. The Sulfur Cycle Animation: Sulfur Cycle 34

35 Effects of Human Activities on the Sulfur Cycle We add sulfur dioxide to the atmosphere by: Burning coal and oil Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment. The Gaia Hypothesis: Is the Earth Alive? Some have proposed that the earth s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes. The strong Gaia hypothesis: life controls the earth s life-sustaining processes. The weak Gaia hypothesis: life influences the earth s life-sustaining processes. Biodiversity Loss and Species Extinction: Remember HIPPO H for habitat destruction and degradation I for invasive species P for pollution P for human population growth O for overexploitation 35