1. Ecosystems: What Are They and How Do They Work?
Chapter 3
Dr. Wesam Al Madhoun

2. 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 will have three major harmful effects
Reduce biodiversity
Accelerate global warming
Change regional weather patterns

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

4. 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.

5. Cells Are the Basic Units of Life
Cell Theory: all living things composed of cells.
Eukaryotic cell: surrounded by membrane and has a distinct nucleus (a membrane bounded structure contain DNA)
Prokaryotic cell: surrounded by membrane but no distinct nucleus.

6. Structure of a Eukaryotic Call and a Prokaryotic Cell

7. Species Make Up the Encyclopedia of Life
Species: a set of individuals that can mate and introduce fertile offspring.
1.75 Million species identified
Insects make up most of the known species
Perhaps 10–14 million species not yet identified

8. Ecologists Study Connections in Nature
Ecology : study of how organism interact with their living environment of other organism and with their non living (a biotic) environment of soil, water and energy.
Levels of organization
Population: a group of individual of the same species living in the same place, same time.
Genetic diversity: genetic variation in a population.
Community: all the population of different species that live in a particular place.
Ecosystem: a community of different species interacting with each other and with nonliving environment.
Biosphere: consist of the parts of the earths, air water and soil where life is found.

9. 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

10. Population of Glassfish in the Red Sea

11. Genetic Diversity in a Caribbean Snail Population

12. Science Focus: Have You Thanked the Insects Today?
Pollinators
Eat other insects
Loosen and renew soil
Reproduce rapidly
Very resistant to extinction

13. Importance of Insects

14. 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.

15. The Earth’s Life-Support System Has Four Major Components
Atmosphere
Troposphere: 17 km above sea level at tropic, and 7 km at north and south poles “contain majority of the air that we breath”.
Stratosphere: km above earth surface.
Hydrosphere: consist of all the water on and near the earth surface.
Geosphere: consist of the earth’s intensely hot core, a thick mantle of rock, thin outer crust.
Biosphere: occupies atmosphere, hydrosphere and geosphere where life exist.

16. Vegetation and animals Biosphere Crust Lithosphere Mantle Biosphere
Atmosphere
Biosphere
Soil
Rock
Crust
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

17. Life Exists on Land and in Water
Biomes : large regions (forest, desert, grasslands) with distinct climate and certain species.
Aquatic life zones
Freshwater life zones
Lakes and streams
Marine life zones
Coral reefs
Estuaries
Deep ocean

18. Major Biomes along the 39th Parallel 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

19. What Happens to Solar Energy Reaching the Earth?
UV, visible, and IR energy
Radiation
Absorbed by ozone
Absorbed by the earth
Reflected by the earth
Radiated by the atmosphere as heat
Natural greenhouse effect

20. Solar radiation Lower Stratosphere (ozone layer) Greenhouse effect
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

21. 3-3 What Are the Major Components of an Ecosystem?
Concept 3-3A Ecosystems contain living (biotic) and nonliving (abiotic) components.
Concept 3-3B Autotrophs (self feeding, Heterotrophs (other feeders), Detritovores (feed on waste or dead bodies).

22. Ecosystems Have Living and Nonliving Components
Abiotic
Water
Air
Nutrients
Rocks
Heat
Solar energy
Biotic
Living and once living

23. Major Biotic and Abiotic Components of an Ecosystem

24. Oxygen (O2) Precipitation Carbon dioxide (CO2) 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
Water
Decomposers
Soluble mineral
nutrients
Fig. 3-9, p. 57

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

26. Range of Tolerance for a Population of Organisms
INSERT FIGURE 3-10 HERE

27. Producers and Consumers Are the Living Components of Ecosystems (1)
Producers, autotrophs
Photosynthesis: the way, energy enter most ecosystem
Chemosynthesis: producers (bacteria) convert inorganic compound to more complex nutrient without sun light.
Consumers, heterotrophs
Primary (plant eaters such as rabbits)
Secondary (meat eater, birds , frogs)
Third and higher level (tigers ,wolves)
Decomposers

28. Producers and Consumers Are the Living Components of Ecosystems (2)
Detritivores : feed on waste and dead bodies such as some insects and earth worms.
Aerobic respiration: use of oxygen to convert glucose (C6H12O6) back into carbon dioxide and water
Anaerobic respiration, fermentation: some decomposers get the energy they need by breaking down glucose in the absence of oxygen.

29. Science Focus: Many of the World’s Most Important Species Are Invisible to Us
Microorganisms
Bacteria
Protozoa
Fungi

30. 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.

31. Energy Flows Through Ecosystems in Food Chains and Food Webs
Food chain: a sequence of organism, each of which serves as a source of food or energy for the next.
Food web: a complex network of interconnected food chains.

32. Decomposers and detritus feeders
First Trophic
Level
Second Trophic
Level
Third Trophic
Level
Fourth Trophic
Level
Producers
(plants)
Primary
consumers
(herbivores)
Secondary
consumers
(carnivores)
Tertiary
consumers
(top carnivores)
Heat
Heat
Heat
Heat
Solar
energy
Heat
Figure 3.13
A food chain. The arrows show how chemical energy in nutrients flows through various trophic levels in energy transfers; most of the energy is degraded to heat, in accordance with the second law of thermodynamics. See an animation based on this figure at CengageNOW. Question: Think about what you ate for breakfast. At what level or levels on a food chain were you eating?
Heat
Heat
Decomposers and detritus feeders
Fig. 3-13, p. 62

33. Usable Energy Decreases with Each Link in a Food Chain or Web
Biomass: the dry weight of all organic matter contained in its organisms.
Ecological efficiency: the % of useable chemical energy transferred as biomass from one trophic level to the next
Pyramid of energy flow: cumulative energy loss.

34. Usable energy available
at each trophic level
(in kilocalories)
Heat
Tertiary
consumers
(human) 10
Heat
Secondary
consumers
(perch)
100
Heat
Decomposers
Heat
Primary
consumers
(zooplankton)
1,000
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?
Heat
10,000
Producers
(phytoplankton)
Fig. 3-15, p. 63

35. Some Ecosystems Produce Plant Matter Faster Than Others Do
Gross primary productivity (GPP): is the rate at which ecosystem producers (plants) convert solar energy into chemical energy as biomass found in their tissues.
Net primary productivity (NPP):
NPP = GPP – R. where R is energy used in respiration.
Ecosystems and life zones differ in their NPP

36. 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

37. 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.

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

39. 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

40. 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
Expands as it freezes
Filters out harmful UV

41. 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

42. 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

43. Nitrogen Cycles through the Biosphere: Bacteria in Action (1)
Nitrogen fixed – N 2 converted to nutrient by:
Lightning : electrical discharge in the atmosphere.
Nitrogen-fixing bacteria: in soil or plan roots.
Nitrification :is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates
Denitrification: is a microbially facilitated process of nitrate reduction that may ultimately produce molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products.

44. 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

45. Processes
Nitrogen
in atmosphere
Reservoir
Pathway affected by humans
Natural pathway
Denitrification
by bacteria
Electrical
storms
Nitrogen oxides
from burning fuel
and using inorganic
fertilizers
Nitrogen
in animals
(consumers)
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

46. Nitrogen input (teragrams per year)
300
Projected
human
input
250
200
Total human input
150
Nitrogen input (teragrams per year)
Fertilizer and
industrial use
100
Figure 3.20
Global trends in the annual inputs of nitrogen into the environment from human activities, with projections to (Data from 2005 Millennium Ecosystem Assessment) 50
Nitrogen fixation
in agroecosystems
Fossil fuels
1900
1920
1940
1960
1980
2000
2050
Year
Fig. 3-20, p. 70

47. 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.

48. Some Scientists Study Nature Directly
Field research: “muddy-boots biology”
New technologies available
Remote sensors
Geographic information system (GIS) software
Digital satellite imaging
2005, Global Earth Observation System of Systems (GEOSS) – integrate sensors, gauges and satellite that monitor earth, atmosphere and oceans

49. 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

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