This document provides an overview of key concepts about ecosystems, including: - Ecosystems are composed of biotic (living) and abiotic (nonliving) components that interact. - Energy from the sun flows through ecosystems via photosynthesis in producers and is lost at each trophic level. - Matter is recycled through ecosystems as organisms consume other organisms and their remains are decomposed. - Biodiversity provides resources and services that support all life on Earth.

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

2. Chapter Overview Questions
 What is ecology?
 What basic processes keep us and other
organisms alive?
 What are the major components of an
ecosystem?
 What happens to energy in an ecosystem?
 What are soils and how are they formed?
 What happens to matter in an ecosystem?
 How do scientists study ecosystems?

3. Updates Online
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac: Rescuers race to save Central American frogs. Blade
(Toledo, OH), August 6, 2006.
 InfoTrac: Climate change puts national parks at risk. Philadelphia
Inquirer, July 13, 2006.
 InfoTrac: Deep-Spied Fish: Atlantic Expeditions Uncover Secret Sex Life
of Deep-Sea Nomads. Ascribe Higher Education News Service, Feb
21, 2006.
 Environmental Tipping Points
 NatureServe: Ecosystem Mapping
 U.S. Bureau of Land Management: Soil Biological Communities

4. Core Case Study:
Have You Thanked the Insects
Today?
 Many plant species depend on insects for
pollination.
 Insect can control other pest insects by
eating them
Figure 3-1

5. Core Case Study:
Have You Thanked the Insects
Today?
 …ifall insects disappeared, humanity
probably could not last more than a few
months [E.O. Wilson, Biodiversity expert].
 Insect’s role in nature is part of the larger
biological community in which they live.

6. THE NATURE OF ECOLOGY
 Ecologyis a study
of connections in
nature.
 How organisms
interact with one
another and with
their nonliving
environment.
Figure 3-2

7. Universe
Galaxies
Solar systems Biosphere
Planets
Earth
Biosphere
Ecosystems Ecosystems
Communities
Populations
Organisms Realm of ecology
Communities
Organ systems
Organs
Tissues
Cells
Protoplasm
Populations
Molecules
Atoms Organisms
Subatomic Particles
Fig. 3-2, p. 51

8. Organisms and Species
 Organisms, the different forms of life on
earth, can be classified into different species
based on certain characteristics.
Figure 3-3

9. Other animals
Known species 281,000
1,412,000
Insects
751,000 Fungi
69,000
Prokaryotes
4,800
Plants
248,400
Protists
57,700 Fig. 3-3, p. 52

10. Case Study:
Which Species Run the World?
 Multitudes of tiny microbes such as
bacteria, protozoa, fungi, and yeast help keep
us alive.
 Harmful microbes are the minority.
 Soil bacteria convert nitrogen gas to a usable
form for plants.
 They help produce foods
(bread, cheese, yogurt, beer, wine).
 90% of all living mass.
 Helps purify water, provide oxygen, breakdown
waste.
 Lives beneficially in your body (intestines, nose).

11. Populations, Communities, and
Ecosystems
 Members of a species interact in groups
called populations.
 Populations of different species living and
interacting in an area form a community.
 A community interacting with its physical
environment of matter and energy is an
ecosystem.

12. Populations
A population is a
group of interacting
individuals of the
same species
occupying a specific
area.
 The space an
individual or
population normally
occupies is its habitat.
Figure 3-4

13. Populations
 Genetic diversity
 In most natural
populations
individuals vary
slightly in their
genetic makeup.
Figure 3-5

14. THE EARTH’S LIFE SUPPORT
SYSTEMS
 Thebiosphere
consists of several
physical layers that
contain:
 Air
 Water
 Soil
 Minerals
 Life
Figure 3-6

15. Oceanic Continental
Crust Crust
Atmosphere
Vegetation Biosphere
and animals Lithosphere
Soil Upper mantle
Rock Crust Asthenosphere
Lower mantle
Core
Mantle
Crust (soil
and rock)
Biosphere
Hydrosphere (living and dead
(water) organisms)
Lithosphere
Atmosphere
(crust, top of upper mantle)
(air) Fig. 3-6, p. 54

16. Biosphere
 Atmosphere
 Membrane of air around the planet.
 Stratosphere
 Lower portion contains ozone to filter out most of
the sun’s harmful UV radiation.
 Hydrosphere
 All the earth’s water: liquid, ice, water vapor
 Lithosphere
 The earth’s crust and upper mantle.

17. What Sustains Life on Earth?
 Solar
energy, the
cycling of
matter, and
gravity sustain
the earth’s life.
Figure 3-7

18. Biosphere
Carbon Phosphorus Nitrogen Water Oxygen
cycle cycle cycle cycle cycle
Heat in the environment
Heat Heat Heat
Fig. 3-7, p. 55

19. What Happens to Solar Energy
Reaching the Earth?
 Solarenergy
flowing through
the biosphere
warms the
atmosphere, eva
porates and
recycles
water, generates
winds and
supports plant
growth. Figure 3-8

20. Solar
radiation
Energy in = Energy out
Reflected by
atmosphere (34% ) Radiated by
UV radiation atmosphere
as heat (66%)
Lower Stratosphere
Absorbed (ozone layer)
by ozone Visible Troposphere Greenhouse
Light effect
Heat
Absorbed
by the Heat radiated
earth by the earth
Fig. 3-8, p. 55

21. ECOSYSTEM COMPONENTS
 Lifeexists on land systems called biomes
and in freshwater and ocean aquatic life
zones.
Figure 3-9

22. Average annual precipitation
100–125 cm (40–50 in.)
75–100 cm (30–40 in.)
50–75 cm (20–30 in.)
4,600 m (15,000 ft.)
25–50 cm (10–20 in.)
3,000 m (10,000 ft.) below 25 cm (0–10 in.)
1,500 m (5,000 ft.)
Coastal Sierra Great Rocky Great Mississippi Appalachian
mountain Nevada American Mountains Plains River Valley Mountains
ranges Mountains Desert
Coastal chaparral Coniferous Desert Coniferous Prairie Deciduous
and scrub forest forest grassland forest
Fig. 3-9, p. 56

23. Nonliving and Living Components of
Ecosystems
 Ecosystems consist of nonliving (abiotic) and
living (biotic) components.
Figure 3-10

24. Oxygen Sun
(O2)
Producer
Carbon dioxide (CO2)
Secondary consumer
Primary
(fox)
consumer
(rabbit)
Precipitation Producers
Falling leaves
and twigs
Soil decomposers
Water
Fig. 3-10, p. 57

25. Factors That Limit Population Growth
 Availabilityof matter and energy resources
can limit the number of organisms in a
population.
Figure 3-11

26. Lower limit of Upper limit of
tolerance tolerance
No Few Abundance of organisms Few No
organisms organisms organisms organisms
Population size
Zone of Zone of Optimum range Zone of Zone of
intolerance physiological physiological intolerance
stress stress
Low Temperature High
Fig. 3-11, p. 58

27. Factors That Limit Population Growth
 The physical
conditions of the
environment can
limit the
distribution of a
species.
Figure 3-12

28. Sugar Maple
Fig. 3-12, p. 58

29. Producers: Basic Source of All Food
 Mostproducers capture sunlight to produce
carbohydrates by photosynthesis:

30. Producers: Basic Source of All Food
 Chemosynthesis:
 Some organisms such as deep ocean bacteria
draw energy from hydrothermal vents and
produce carbohydrates from hydrogen sulfide
(H2S) gas .

31. Photosynthesis:
A Closer Look
 Chlorophyll molecules in the
chloroplasts of plant cells
absorb solar energy.
 This initiates a complex
series of chemical reactions
in which carbon dioxide and
water are converted to
sugars and oxygen.
Figure 3-A

32. Sun
Chloroplast
in leaf cell
Chlorophyll
H2O Light-dependent O2
Reaction
Energy storage
and release
(ATP/ADP)
Light- Glucose
CO2 independent
reaction
6CO2 + 6 H2O Sunlight C6H12O6 + 6 Fig. 3-A, p. 59

33. Consumers: Eating and Recycling to
Survive
 Consumers (heterotrophs) get their food by
eating or breaking down all or parts of other
organisms or their remains.
 Herbivores
• Primary consumers that eat producers
 Carnivores
• Primary consumers eat primary consumers
• Third and higher level consumers: carnivores that eat
carnivores.
 Omnivores
• Feed on both plant and animals.

34. Decomposers and Detrivores
 Decomposers: Recycle nutrients in ecosystems.
 Detrivores: Insects or other scavengers that feed
on wastes or dead bodies.
Figure 3-13

35. Scavengers Decomposers
Termite
Bark beetle Carpenter and
engraving ant carpenter
Long-
horned galleries ant work Dry rot
fungus
beetle
holes Wood
reduced
to Mushroom
powder
Time Powder broken down by decomposers
progression into plant nutrients in soil
Fig. 3-13, p. 61

36. Aerobic and Anaerobic Respiration:
Getting Energy for Survival
 Organisms break down carbohydrates and
other organic compounds in their cells to
obtain the energy they need.
 This is usually done through aerobic
respiration.
 The opposite of photosynthesis

37. Aerobic and Anaerobic Respiration:
Getting Energy for Survival
 Anaerobic respiration or fermentation:
 Some decomposers get energy by breaking
down glucose (or other organic compounds) in
the absence of oxygen.
 The end products vary based on the chemical
reaction:
• Methane gas
• Ethyl alcohol
• Acetic acid
• Hydrogen sulfide

38. Two Secrets of Survival: Energy Flow
and Matter Recycle
 An ecosystem
survives by a
combination of
energy flow and
matter recycling.
Figure 3-14

39. Abiotic chemicals
Heat
Heat (carbon dioxide, Solar
oxygen, nitrogen, energy
minerals)
Heat
Decomposers Producers
(bacteria, fungi) (plants)
Consumers
(herbivores,
Heat Heat
carnivores)
Fig. 3-14, p. 61

40. BIODIVERSITY
Figure 3-15

41. 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

42. Why Should We Care About
Biodiversity?
 Biodiversity provides us with:
 Natural Resources (food
water, wood, energy, and medicines)
 Natural Services (air and water purification, soil
fertility, waste disposal, pest control)
 Aesthetic pleasure

43. Solutions
 Goals,strategies
and tactics for
protecting
biodiversity.
Figure 3-16

44. The Ecosystem Approach The Species Approach
Goal Goal
Protect populations Protect species
of species in their from premature
natural habitats extinction
Strategy Strategies
Preserve sufficient •Identify endangered
areas of habitats in species
different biomes and •Protect their critical
aquatic systems habitats
Tactics Tactics
•Protect habitat areas •Legally protect
through private endangered species
purchase or
government action
•Manage habitat
•Eliminate or reduce
populations of
nonnative species •Propagate
from protected areas endangered
•Manage protected species in captivity
areas to sustain
native species •Reintroduce
•Restore degraded species into
ecosystems suitable habitats
Fig. 3-16, p. 63

45. ENERGY FLOW IN ECOSYSTEMS
 Foodchains and webs show how eaters, the
eaten, and the decomposed are connected to
one another in an ecosystem. Figure 3-17

46. First Trophic Second Trophic Third Trophic Fourth Trophic
Level Level Level Level
Producers Primary Secondary Tertiary
(plants) consumers consumers consumers
(herbivores) (carnivores) (top carnivores)
Heat Heat Heat
Solar
energy
Heat Heat
Heat Heat
Detritivores Heat
(decomposers and detritus feeders)
Fig. 3-17, p. 64

47. Food Webs
 Trophic levels are
interconnected
within a more
complicated food
web.
Figure 3-18

48. Blue whale Humans Sperm whale
Crabeater Elephant
seal seal
Killer whale
Leopard
seal
Adelie
penguins Emperor
penguin
Squid
Petrel Fish
Carnivorous plankton
Krill Herbivorous
plankton
Phytoplankton
Fig. 3-18, p. 65

49. Energy Flow in an Ecosystem: Losing
Energy in Food Chains and Webs
 Inaccordance with the 2nd law of
thermodynamics, there is a decrease in the
amount of energy available to each
succeeding organism in a food chain or web.

50. 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.
Figure 3-19

51. Heat
Tertiary Heat
consumers Decomposers
(human)
Heat
10
Secondary
consumers
(perch)
Heat
100
Primary
1,000 consumers
(zooplankton) Heat
10,000 Producers
Usable energy (phytoplankton)
Available at
Each tropic level
(in kilocalories)
Fig. 3-19, p. 66

52. 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.
Figure 3-20

53. Gross primary productivity
(grams of carbon per square meter)
Fig. 3-20, p. 66

54. Net Primary Production (NPP)
 NPP = GPP – R
 Rate at which
producers use
photosynthesis to
store energy minus
the rate at which they
use some of this
energy through
respiration (R).
Figure 3-21

55. Sun
Energy lost
Respiration and unavailable
to consumers
Gross primary
production Net primary
production
Growth and reproduction (energy
available to
consumers)
Fig. 3-21, p. 66

56.  What are nature’s three most productive and
three least productive systems?
Figure 3-22

57. 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/m2 /yr)
Fig. 3-22, p. 67

58.  Stratigraphy Background
 Study of rock (ohhh, exciting)
 A grouping exercise
 Rock layers provide a quick look at regional climates and geological events throughout
history
 Windows into climate conditions during specific times
 Ex. Of sedimentary rock layer: Grand Canyon (pre-cambian and Paleozoic)
 Rock-stratigraphic unit or rock unit
 Individual band with its own specific characteristics and position
 Formation: rock units stacked up vertically; composed of many rock units grouped into a
section with same physical properties (takes thousands to millions of years to create)
 Lithology
 Visual study of rock’s physical characteristics using a handheld magnifying glass or low-
power microscope
 Three Main rock type:
 Igneous, sedimentary, metamorphic
 Rock formations can be matched by their physical characteristics:
 Grain size and shape
 Grain orientation
 Mineral content
 Sedimentary structure
 Color weathering

59.  Igneous Rock
 Rock formed by the cooling and hardening of molten rock (magma), deep in the Earth, blasted out during
an eruption; 95% of the first 10 mi of crust
 six minerals: quartz, feldspar, pyroxene, olivine, amphibole, and mica
 (Si, Ca, Na, K, Mg, Fe, Al, H, O)
 Two type:
• Felsic: affected by heat (magma rising or friction b/t plates); lots of Si minerals (quartz and granite)
• Mafic: high levels of Mg and Fe containing minerals
 Sedimentary Rock
 Formed from rocks and soils from other locations compressed with the remains of dead organisms
 Fine-grained texture b/c they are layered or settled by water or wind
 Lithification: process that makes lithified soil (made of silt, sand, and organic compounds) by
compaction and cementation
 Diagenesis: process that lithifies sediments; controlled by temperature (200’C); unstable minerals
recrystallize into more stable matrix form or are chemically changed, like organic matter, into coal or
hydrocarbons.
• 1. Compaction, 2. cementation, 3. recrystallization, 4. chemical changes (ex oxidation and
reduction)
 Detritus: any type of rock that has been moved from its original location
 Metamorphic Rock
 Formed when rocks (igneous or sedimentary) originally of one type change into a different type by heat
and/or pressure
 3 main causes/forces: internal heat of earth, weight of overlying rock, and horizontal pressures from
previously changed rock
 Example: MARBLE and SLATE

60. SOIL: A RENEWABLE RESOURCE
 Soilis 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.

61. Soil Basics
 Renewable but very slowly (climate is factor)
 1 cm of soil can take 15-100 years to form
 Mixture of six components
1) Eroded rock
2) Mineral nutrients
3) Decaying organic matter
4) Water
5) Air
6) Living organisms (microscopic decomp)
 3 major roles of soil
 Provides Nutrients
 Filters water
 Stores water

62. 3 Soil Horizons
 (Horizon 0)
 Surface litter layer
 Freshly fallen/partially decomposed (leaves, twigs,
crop wastes, animal waste)
 Brown or black color
 Horizon A
 Topsoil
 Porous mix of partially decomposed organic matter
(HUMUS)
 Horizon B
 Horizon C

63. SOIL: A RENEWABLE RESOURCE
Figure 3-23

64. Wood
Oak tree sorrel
Lords and Dog violet Organic debris
ladies Grasses and builds up Rock
small shrubs fragments
Earthworm
Fern Millipede Moss and
Honey
fungus lichen
O horizon Mole
Leaf litter
A horizon
Topsoil
B horizon Bedrock
Subsoil Immature soil
Regolith
C horizon Young soil
Pseudoscorpion
Parent Mite
material Nematode
Root system
Actinomycetes
Red Earth
Mite Fungus
Mature soil Bacteria
Springtail Fig. 3-23, p. 68

65. 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.

66. Soil Profiles of the
Principal Terrestrial
Soil Types
Figure 3-24

67. Mosaic of
closely
packed
pebbles, boul
ders
Weak humus-
mineral mixture Alkaline,
dark,
Dry, brown to
and rich
reddish-brown
in humus
with variable
accumulations Clay, calciu
of clay, calcium m
and compounds
carbonate, and
Desert Soil Grassland Soil
soluble salts
(hot, dry climate) semiarid climate)
Fig. 3-24a, p. 69

68. Acidic
light-colored
humus
Iron and
aluminum
compounds
mixed with
clay
Tropical Rain Forest Soil
(humid, tropical climate)
Fig. 3-24b, p. 69

69. Forest litter leaf
mold
Humus-mineral
mixture
Light, grayish-
brown, silt loam
Dark brown
firm clay
Deciduous Forest Soil
(humid, mild climate)
Fig. 3-24b, p. 69

70. Acid litter
and humus
Light-colored
and acidic
Humus and
iron and
aluminum
compounds
Coniferous Forest Soil
(humid, cold climate)
Fig. 3-24b, p. 69

71. Some Soil Properties
 Soilsvary in the size
of the particles they
contain, the amount
of space between
these particles, and
how rapidly water
flows through them.
Figure 3-25

72. Sand Silt Clay
0.05–2 mm 0.002–0.05 mm less than 0.002 mm
diameter diameter Diameter
Water Water
High permeability Low permeability
Fig. 3-25, p. 70

73. 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.

74. The Water Cycle
Figure 3-26

75. Rain clouds
Condensation
Transpiration Evaporation
Precipitation Transpiration
to land from plants
Precipitation Precipitation
Evaporation
Surface runoff from land Evaporation
Runoff from ocean Precipitation
(rapid)
to ocean
Infiltration and Surface
Percolation runoff
(rapid)
Groundwater movement (slow)
Ocean storage
Fig. 3-26, p. 72

76. 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.

77. 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.

78. The Carbon Cycle:
Part of Nature’s Thermostat
Figure 3-27

79. Fig. 3-27, pp. 72-73

80. Effects of Human Activities
on Carbon Cycle
 We alter the
carbon cycle by
adding excess CO2
to the atmosphere
through:
 Burning fossil fuels.
 Clearing vegetation
faster than it is
replaced.
Figure 3-28

81. CO2 emissions from fossil fuels
(billion metric tons of carbon equivalent)
Year
Low
projection
High
projection
Fig. 3-28, p. 74

82. The Nitrogen Cycle:
Bacteria in Action
Figure 3-29

83. Gaseous nitrogen (N2)
in atmosphere
Food webs on land
Nitrogen fixation
Fertilizers
Uptake by Loss by
Uptake by autotrophs Excretion, death, autotrophs denitrification
decomposition
Ammonia, ammonium in soil Nitrogen-rich wastes, Nitrate in soil
remains in soil
Nitrification
Ammonification Loss by
Loss by leaching
leaching Nitrite in soil
Nitrification Fig. 3-29, p. 75

84. 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.

85. 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

86. Global nitrogen (N) fixation
(trillion grams)
Nitrogen fixation by natural processes
Year
Fig. 3-30, p. 76

87. The Phosphorous Cycle
Figure 3-31

88. mining Fertilizer
excretion Guano
agriculture
uptake by weathering uptake by
autotrophs autotrophs
Marine Dissolved leaching, runoff Dissolved Land
Food in Ocean in Soil Water, Food
Webs Water Lakes, Rivers Webs
death, death,
decomposition decomposition
sedimentation settling out weathering
uplifting over
geologic time
Marine Sediments Rocks
Fig. 3-31, p. 77

89. 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.

90. The Sulfur Cycle
Figure 3-32

91. Sulfur Water Acidic fog and
Sulfuric acid precipitation
trioxide
Ammonia Ammonium
Oxygen sulfate
Sulfur dioxide Hydrogen sulfide
Plants
Dimethyl Volcano
sulfide Industries
Animals
Ocean
Sulfate salts
Metallic Decaying matter Sulfur
sulfide
deposits
Hydrogen sulfide
Fig. 3-32, p. 78

92. 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.

93. 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.

94. HOW DO ECOLOGISTS LEARN ABOUT
ECOSYSTEMS?
 Ecologist go into ecosystems to observe, but
also use remote sensors on aircraft and
satellites to collect data and analyze
geographic data in large databases.
 Geographic Information Systems
 Remote Sensing
 Ecologists
also use controlled indoor and
outdoor chambers to study ecosystems

95. Geographic Information Systems (GIS)
A GIS
organizes, stores, an
d analyzes complex
data collected over
broad geographic
areas.
 Allows the
simultaneous
overlay of many
layers of data.
Figure 3-33

96. Critical nesting site
locations
USDA Forest Service
USDA
Private Forest Service
owner 1 Private owner 2
Topography
Habitat type
Forest
Wetland Lake
Grassland
Real world
Fig. 3-33, p. 79

97. Systems Analysis
 Ecologists develop
mathematical and
other models to
simulate the
behavior of
ecosystems.
Figure 3-34

98. Define objectives
Systems
Identify and inventory variables
Measurement
Obtain baseline data on variables
Make statistical analysis of
Data relationships among variables
Analysis Determine significant interactions
System Objectives Construct mathematical model
Modeling describing interactions among
variables
System Run the model on a computer,
Simulation with values entered for different
Variables
System Evaluate best ways to achieve
Optimization objectives
Fig. 3-34, p. 80

99. Importance of Baseline
Ecological Data
 We need baseline data on the world’s
ecosystems so we can see how they are
changing and develop effective strategies for
preventing or slowing their degradation.
 Scientists have less than half of the basic
ecological data needed to evaluate the status of
ecosystems in the United Sates (Heinz
Foundation 2002; Millennium Assessment 2005).