Ecosystems: What Are They and How Do They Work?

Ecosystems: What Are They and How Do They Work?
Chapter 3

All things come from earth and to earth they all return
Menander ( B.C)

How environmentally true is the previous statement? Explain.

Main Questions of this chapter
What is ecology? What is an ecosystem and its main components? What happens to matter and energy in an ecosystem and how does that keep us alive?

Core Case Study: Tropical Rain Forests Are Disappearing
Cover about 2% of the earth’s land surface Contain about 50% of the world’s known plant and animal species Disruption of rain forest will have three major harmful effects Reduce biodiversity Accelerate global warming (burn, less absorption of greenhouse gases) Change regional weather patterns

Natural Capital Degradation: Satellite Image of the Loss of Tropical Rain Forest

3-1 What Is Ecology? Concept 3-1 Ecology is the study of how organisms interact with one another and with their physical environment of matter and energy. Ecology is the study of connections in nature

Cells Are the Basic Units of Life
Cell Theory (all living things are composed of cells , the smallest and most fundamental unit of life) Cell membrane (a) Eukaryotic Cell Nucleus (DNA) Protein construction Energy conversion Eukaryotic cells have: membranes, nucleus and organelles (internal specialized parts)

No specialized internal parts
Prokaryotic cell Has membrane No distinct nucleus No specialized internal parts All bacteria consist of a single prokaryotic cell Protein construction and energy conversion occur without specialized internal structures (b) Prokaryotic Cell DNA (no nucleus) Cell membrane Figure 3.2 Natural capital: (a) generalized structure of a eukaryotic cell and (b) prokaryotic cell. Note that a prokaryotic cell lacks a distinct nucleus and generalized structure of a eukaryotic cell. Stepped Art Fig. 3-2, p. 52

Animation: Prokaryotic and eukaryotic cells

Species Make Up the Encyclopedia of Life
1.75 Million species identified Insects make up most of the known species Perhaps 10–14 million species not yet identified

_________ of Glassfish in the Red Sea

__________ Diversity in a Caribbean Snail Population

Ecologists Study Connections in Nature
Levels of organization Population Group of individuals that live in same place Genetic diversity (variation in a population) Habitat: place where a population lives Community All populations that live in a particular place Ecosystem Describes the interaction of a community and their habitats Biosphere consists of parts of the earth where life is found, in effect the largest ecosystem

Biosphere Ecosystem Community Population Organism Cell Molecule Atom
Parts of the earth's air, water, and soil where life is found Biosphere Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy Community Populations of different species living in a particular place, and potentially interacting with each other Population A group of individuals of the same species living in a particular place Organism An individual living being Figure 3.3 Some levels of organization of matter in nature. Ecology focuses on the top five of these levels. See an animation based on this figure at CengageNOW. Cell The fundamental structural and functional unit of life Molecule Chemical combination of two or more atoms of the same or different elements Smallest unit of a chemical element that exhibits its chemical properties Atom Stepped Art Fig. 3-3, p. 52

Size of ecosystems Range from a puddle of water to an ocean
Do not have clear boundaries Not isolated from each other Can be natural or man made

Think about the school in terms of how life can be grouped:
Populations Communities Ecosystems

Are insect populations important to the health of human populations?
Which group needs the other more? Humans or insects?

Science Focus: Have You Thanked the Insects Today?
Pollinators Eat other insects Loosening and renewal of soil Reproduce rapidly (food source) Very resistant to extinction, fast evolutionary process

Do you think there is a useless population on earth?
Explain your answer by defining the term ‘useless’ first.

Active Figure: Levels of organization

Section Check Q1: Distinguish between a eukaryotic and a prokaryotic cell. Name an example of living organism that has them for each type. Q3: What % of all living species do we have information on? Which class of organism most likely has the greatest number of species? Q4: What are the main differences between a population, a habitat and a ecosystem? Name an example of each.

3-2 What Keeps Us and Other Organisms Alive?
Concept 3-2 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

What are the 4 majors parts (spheres) of the earth life support system?

The Earth’s Life-Support System Has Four Major Components
Atmosphere Troposphere – closest, weather, warmth, air Stratosphere - farther away from surface, ozone Hydrosphere Geosphere- includes interior, minerals, oil, soil Biosphere- all living things in all other spheres

Natural Capital Vegetation and animals Biosphere Crust Lithosphere
Atmosphere Biosphere Soil Rock Crust Natural Capital Lithosphere Mantle Biosphere (living organisms) Atmosphere (air) Figure 3.6 Natural capital: general structure of the earth showing that it consists of a land sphere, air sphere, water sphere, and life sphere. Core Mantle Crust (soil and rock) Geosphere (crust, mantle, core) Hydrosphere (water) Fig. 3-6, p. 55

What is a Biome?

Life Exists on Land and in Water
Biomes (land) regions of earth with one dominant type of environment (Deserts, plains, deciduous forests…) Aquatic life zones Freshwater life zones Lakes and streams Marine life zones Coral reefs Estuaries Deep ocean

Major biomes along 39th parallel in US
Average annual precipitation 100–125 cm (40–50 in.) 75–100 cm (30–40 in.) 50–75 cm (20–30 in.) 25–50 cm (10–20 in.) below 25 cm (0–10 in.) Denver Baltimore San Francisco St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Figure 3.7 Major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature. Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest Fig. 3-7, p. 55

Three Factors Sustain Life on Earth
One-way flow of high-quality energy beginning with the sun From sun through food cycle to environment exiting back into space Dictated by 2nd law of Thermo, high to low quality energy Cycling of matter or nutrients Earth is basically closed in terms of matter Nutrients must be recycled, in seconds or in centuries Gravity (law of gravity) How does gravity help sustain life on Earth?

How does gravity help? Allows earth to hold on to an atmosphere
Allows movement of materials, life on earth

How do you think the troposphere stays warm?

The name of the effect is ______________
How do you think this effects works? Is this effect natural or man-made?

What Happens to Solar Energy Reaching the Earth?
UV, visible, and IR energy (forms of electromagnetic radiation (waves)) Radiation Is absorbed by ozone Is absorbed by the earth Is reflected by the earth, as heat Some is trapped in troposphere The raising heat moves the air , creating wind

Energy flow to/from Earth
Solar radiation Reflected by atmosphere Radiated by atmosphere as heat UV radiation Lower Stratosphere (ozone layer) Most absorbed by ozone Troposphere Visible light Heat radiated by the earth Figure 3.8 Solar capital: flow of energy to and from the earth. See an animation based on this figure at CengageNOW. Heat Absorbed by the earth Greenhouse effect Fig. 3-8, p. 56

Natural Greenhouse Effect
Energy from sun is reflected back towards space as infrared radiation (felt as heat) Encounter greenhouse gases (CO2, CH4, No3- and O3) Causes gas molecules to vibrate more More vibration  greater KE and Heat Warmer atmosphere and surface

1) What if there was no greenhouse effect?
2) What would happen if the greenhouse effect is increased?

Too cold, or too hot

Active Figure: Energy flow from the Sun to Earth

Section Check Q5: How do the stratosphere and the troposphere differ? What are the main benefits humans derive from each? Q8: How are Biomes and Aquatic Life Zones similar? Q9: What are the 3 factors that sustain life on Earth? What the laws that relate to the factor?

Section Check: Green House Gasses
Q6: What are greenhouse gases and how do they affect life on the planet? Q10: What is the benefit of the ozone in the troposphere? What would be the result if it were removed? Q11: How is wind generated by solar energy? Q12: How do greenhouse gases keep the earth warm?

3-3 What Are the Major Components of an Ecosystem?
Concept 3-3A Ecosystems contain living (biotic) and nonliving (abiotic) components. Concept 3-3B Some organisms produce the nutrients they need, others get their nutrients by consuming other organisms, and some recycle nutrients back to producers by decomposing the wastes and remains of organisms.

Ecosystems Have Living and Nonliving Components
Abiotic : Non-living components Water Air Nutrients Rocks Heat Solar energy Biotic Living and once living

Major Biotic and Abiotic components of an Ecosystem
Precipitation Oxygen (O2) Carbon dioxide (CO2) Major Biotic and Abiotic components of an Ecosystem Producer Secondary consumer (fox) Primary consumer (rabbit) Figure 3.9 Major living (biotic) and nonliving (abiotic) components of an ecosystem in a field. See an animation based on this figure at CengageNOW. Producers Decomposers Water Soluble mineral nutrients Fig. 3-9, p. 57

Identify the autotrophs and heterotrophs (all levels, groups)

List of groups Autotrophs Primary consumers Secondary consumers
Tertiary (and higher) consumers Omnivores Decomposers Detritivores

Active Figure: Roles of organisms in an ecosystem

Range of Tolerance Lower limit of tolerance Higher limit of tolerance
No organisms Few organisms Few organisms No organisms Abundance of organisms Population size Figure 3.10 Range of tolerance for a population of organisms, such as fish, to an abiotic environmental factor—in this case, temperature. These restrictions keep particular species from taking over an ecosystem by keeping their population size in check. Question: Which scientific principle of sustainability (see back cover) is related to the range of tolerance concept? Zone of intolerance Zone of physiological stress Optimum range Zone of physiological stress Zone of intolerance Low Temperature High Fig. 3-10, p. 58

Several Abiotic Factors Can Limit Population Growth
Limiting factor principle Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance Principle of sustainability connection: population control

Producers and Consumers Are the Living Components of Ecosystems (1)
Producers, autotrophs Photosynthesis: sunlight-sugar Chemosynthesis: no sunlight- not sugar Consumers, heterotrophs Primary- feed off of plants Secondary- feed off of herbivores Third and higher level

What type of consumers are they
Insect B Insect C Insect A

Decomposers: release nutrients from dead bodies Mushrooms, Bacteria Detritivores- feed off of wastes and the dead Worms and Vultures

Aerobic respiration: uses oxygen to convert sugar (glucose) to CO2 + H2O + energy Anaerobic respiration, fermentation: does not use oxygen to convert sugar to energy

decomposers into plant nutrients in soil
Detritus feeders Decomposers Carpenter ant galleries Termite and carpenter ant work Bark beetle engraving Dry rot fungus Long-horned beetle holes Wood reduced to powder Figure 3.11 Various detritivores and decomposers (mostly fungi and bacteria) can “feed on” or digest parts of a log and eventually convert its complex organic chemicals into simpler inorganic nutrients that can be taken up by producers. Mushroom Time progression Powder broken down by decomposers into plant nutrients in soil Fig. 3-11, p. 60

The Main Structural Components of an Ecosystem

Active Figure: Matter recycling and energy flow

Animation: Energy flow in Silver Springs

Who are these guys?

Science Focus: Many of the World’s Most Important Species Are Invisible to Us
Microorganisms (Microbes) Bacteria Protozoa Fungi Some Benefits: Break down food in our stomachs Protect lungs Purify water Produce foods (bread, cheese, yogurt) Decomposers Phytoplankton take up CO2

Questions on 3-3 Q13 Distinguish between the abiotic and biotic components of an ecosystem. Q19 What is the difference between photosynthesis and chemosynthesis? Where does chemosynthesis occur on earth? Q15 List an example of a specific organism for each of the following categories: decomposer, secondary consumers, omnivores, producer and primary consumers.

3-4 What Happens to Energy in an Ecosystem?
Concept 3-4A Energy flows through ecosystems in food chains and webs. Concept 3-4B As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.

Energy Flows Through Ecosystems in Food Chains and Food Webs
Difference?

A Food Chain

Simplified Food Web in the Antarctic

Animation: Prairie food web

Active Figure: Rainforest food web

Animation: Diet of a red fox

Animation: Prairie trophic levels

Usable Energy Decreases with Each Link in a Food Chain or Web
Biomass: dry weight of all organic matter on a certain level Ecological efficiency: % of useable energy transferred from one level to next. 2-40%, 10% average Where does 90% go? Pyramid of energy flow

Usable energy available
10 Heat Tertiary consumers (human) Usable energy available at each trophic level (in kilocalories) Heat Decomposers Heat Secondary consumers (perch) 100 Heat Primary consumers (zooplankton) 1,000 Heat Producers (phytoplankton) 10,000 Figure 3.15 Generalized pyramid of energy flow showing the decrease in usable chemical energy available at each succeeding trophic level in a food chain or web. In nature, ecological efficiency varies from 2% to 40%, with 10% efficiency being common. This model assumes a 10% ecological efficiency (90% loss of usable energy to the environment, in the form of low-quality heat) with each transfer from one trophic level to another. Question: Why is a vegetarian diet more energy efficient than a meat-based diet? Stepped Art Fig. 3-15, p. 63

Some Ecosystems Produce Plant Matter Faster Than Others Do
Gross primary productivity (GPP) Rate producers solar energy into bio-mass with chemical energy Net primary productivity (NPP) GPP – energy needed by producers Ecosystems and life zones differ in their NPP Faster rate, more energy available to consumers

Understanding the difference between (GPP) and (NPP)
Lab

Estimated Annual Average NPP in Major Life Zones and Ecosystems
Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest Savanna Agricultural land Woodland and shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Figure 3.16 Estimated annual average net primary productivity in major life zones and ecosystems, expressed as kilocalories of energy produced per square meter per year (kcal/m2/yr). Question: What are nature’s three most productive and three least productive systems? (Data from R. H. Whittaker, Communities and Ecosystems, 2nd ed., New York: Macmillan, 1975) Lakes and streams Continental shelf Open ocean 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m2/yr) Fig. 3-16, p. 64

Questions on 3-4 Q22: Why can’t there be 16 trophic levels in a food chain or in food web? Q23: Why is a vegetarian diet more energy efficient than a meat based diet? Q25: Why are tigers few in number and the species vulnerable to premature extinction because of human activites? Q26 : Why are there so many insects in the world?

3-5 What Happens to Matter in an Ecosystem?
Concept 3-5 Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere, and human activities are altering these chemical cycles.

Nutrients Cycle in the Biosphere
Biogeochemical cycles, nutrient cycles Hydrologic Carbon Nitrogen Phosphorus Sulfur Connect past, present, and future forms of life

Water Cycles through the Biosphere
Natural renewal of water quality: three major processes Evaporation Precipitation Transpiration Alteration of the hydrologic cycle by humans Withdrawal of large amounts of freshwater at rates faster than nature can replace it Clearing vegetation Increased flooding when wetlands are drained

Hydrologic Cycle Including Harmful Impacts of Human Activities
Global warming Condensation Ice and snow Condensation Evaporation from land Evaporation from ocean Precipitation to land Transpiration from plants Surface runoff Increased flooding from wetland destruction Precipitation to ocean Runoff Lakes and reservoirs Reduced recharge of aquifers and flooding from covering land with crops and buildings Point source pollution Infiltration and percolation into aquifer Surface runoff Groundwater movement (slow) Ocean Aquifer depletion from overpumping Figure 3.17 Natural capital: simplified model of the hydrologic cycle with major harmful impacts of human activities shown in red. See an animation based on this figure at CengageNOW. Question: What are three ways in which your lifestyle directly or indirectly affects the hydrologic cycle? Processes Processes affected by humans Reservoir Pathway affected by humans Natural pathway Fig. 3-17, p. 66

Active Figure: Hydrologic cycle

Water cycle Lab

Biogeochemical Cycles lab

Science Focus: Water’s Unique Properties
Properties of water due to hydrogen bonds between water molecules: Exists as a liquid over a large range of temperature Changes temperature slowly High boiling point: 100˚C Adhesion and cohesion Expands as it freezes Solvent Filters out harmful UV

Carbon Cycle Depends on Photosynthesis and Respiration
Link between photosynthesis in producers and respiration in producers, consumers, and decomposers Additional CO2 added to the atmosphere Tree clearing Burning of fossil fuels

Carbon Cycle Carbon dioxide in atmosphere Respiration Photosynthesis
Burning fossil fuels Forest fires Diffusion Animals (consumers) Deforestation Plants (producers) Carbon in plants (producers) Transportation Respiration Carbon in animals (consumers) Carbon dioxide dissolved in ocean Decomposition Carbon in fossil fuels Marine food webs Producers, consumers, decomposers Figure 3.18 Natural capital: simplified model of the global carbon cycle, with major harmful impacts of human activities shown by red arrows. See an animation based on this figure at CengageNOW. Question: What are three ways in which you directly or indirectly affect the carbon cycle? Carbon in limestone or dolomite sediments Compaction Processes Reservoir Pathway affected by humans Natural pathway Fig. 3-18, p. 68

Active Figure: Carbon cycle

Nitrogen Cycles through the Biosphere: Bacteria in Action (1)
Nitrogen fixation Lightning (ionizes the nitrogen in air) Nitrogen-fixing bacteria and blue green algae(combine gas N2 and H to make ammonia) Nitrification : converted to ammonia ions- bacteria Then converted to proteins, nucleic acids, vitamins, amino acids- plants Products used by animals Denitrification : reverse process

Nitrogen Cycles through the Biosphere: Bacteria in Action (2)
Human intervention in the nitrogen cycle Additional NO and N2O Destruction of forest, grasslands, and wetlands Add excess nitrates to bodies of water Remove nitrogen from topsoil

Nitrogen cycle Nitrogen in atmosphere Denitrification by bacteria
Electrical storms Nitrogen oxides from burning fuel and using inorganic fertilizers Nitrogen in animals (consumers) Nitrogen cycle Volcanic activity Nitrification by bacteria Nitrogen in plants (producers) Nitrates from fertilizer runoff and decomposition Decomposition Uptake by plants Figure 3.19 Natural capital: simplified model of the nitrogen cycle with major harmful human impacts shown by red arrows. See an animation based on this figure at CengageNOW. Question: What are three ways in which you directly or indirectly affect the nitrogen cycle? Nitrate in soil Nitrogen loss to deep ocean sediments Nitrogen in ocean sediments Bacteria Ammonia in soil Fig. 3-19, p. 69

Active Figure: Nitrogen cycle

Annual Increase in Atmospheric N2 Due to Human Activities

Phosphorus Cycles through the Biosphere
Cycles through water, the earth’s crust, and living organisms May be limiting factor for plant growth Impact of human activities Clearing forests Removing large amounts of phosphate from the earth to make fertilizers

Phosphorous Cycle Processes Reservoir Pathway affected by humans
Natural pathway Phosphates in sewage Phosphates in fertilizer Plate tectonics Phosphates in mining waste Runoff Runoff Sea birds Runoff Phosphate in rock (fossil bones, guano) Erosion Ocean food webs Animals (consumers) Phosphate dissolved in water Phosphate in shallow ocean sediments Phosphate in deep ocean sediments Figure 3.21 Natural capital: simplified model of the phosphorus cycle, with major harmful human impacts shown by red arrows. Question: What are three ways in which you directly or indirectly affect the phosphorus cycle? Plants (producers) Bacteria Fig. 3-21, p. 71

Animation: Phosphorus cycle

Sulfur Cycles through the Biosphere
Sulfur found in organisms, ocean sediments, soil, rocks, and fossil fuels SO2 in the atmosphere H2SO4 and SO4- Human activities affect the sulfur cycle Burn sulfur-containing coal and oil Refine sulfur-containing petroleum Convert sulfur-containing metallic mineral ores

Sulfur Cycle Sulfur dioxide in atmosphere Sulfuric acid and Sulfate
deposited as acid rain Smelting Burning coal Refining fossil fuels Sulfur in animals (consumers) Dimethyl sulfide a bacteria byproduct Sulfur in plants (producers) Mining and extraction Uptake by plants Decay Sulfur in ocean sediments Figure 3.22 Natural capital: simplified model of the sulfur cycle, with major harmful impacts of human activities shown by red arrows. See an animation based on this figure at CengageNOW. Question: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle? Decay Processes Sulfur in soil, rock and fossil fuels Reservoir Pathway affected by humans Natural pathway Fig. 3-22, p. 72

Active Figure: Sulfur cycle

3-6 How Do Scientists Study Ecosystems?
Concept 3-6 Scientists use field research, laboratory research, and mathematical and other models to learn about ecosystems.

Some Scientists Study Nature Directly
Field research: “muddy-boots biology” New technologies available Remote sensors Geographic information system (GIS) software Digital satellite imaging

Some Scientists Study Ecosystems in the Laboratory
Simplified systems carried out in Culture tubes and bottles Aquaria tanks Greenhouses Indoor and outdoor chambers Supported by field research

Some Scientists Use Models to Simulate Ecosystems
Computer simulations and projections Field and laboratory research needed for baseline data

We Need to Learn More about the Health of the World’s Ecosystems
Determine condition of the world’s ecosystems More baseline data needed

Connected to the information presented in this chapter
Your Questions? Connected to the information presented in this chapter

UN Project Questions What are the main foods for the middle class and poor in your country? On what trophic level are the most common foods of the poor and middle class come from? List the main Biomes type that exist in your country. Using your textbook, determine the NPP for the major biomes. Describe some producers, herbivores, carnivores, decomposers and scavengers that are native to your country What are some of the human based effects on the major nutrient cycle?

Ecosystems: What Are They and How Do They Work?

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