2. Learning Objectives
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. What is Ecology?
Ecology is …
the study of how organisms interact
with each other and with their
nonliving environment.
The study of connections in nature
5. Organisms and Species
Organisms – Any form of life
Species – Groups of organisms that resemble one
another in appearance, behavior, chemistry, and
genetic makeup
There are 4 million to 100 million species on Earth.
Most known species are microorganisms that are
too small to be seen with the naked eye.
10 million to 15 million other species
1.4 million species have been named (most are
insects)
6. 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
7. Populations, Communities, &
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.
8.
9. 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
11. The Four Spheres
Earth is our life support system.
Earth is made up of interconnected
spherical layers that contain air, water,
soil, minerals, and life.
Atmosphere (air)
Hydrosphere (water)
Geosphere (rock)
Biosphere (living things)
12.
13. The Atmosphere
A thin envelope of air around the planet.
The atmosphere is divided into four
layers based on temperature changes
that occur at different distances above
the Earth’s surface.
Troposphere
Stratosphere
Mesosphere
Thermosphere
14.
15. The Hydrosphere
Consists of earth’s water
Water can be found as liquid water, ice,
and water vapor.
Liquid water: surface and
underground
Ice: polar ice, icebergs, permafrost
Water Vapor: gas in the atmosphere
16. The Geosphere
The Earth can also be divided into layers based on physical
properties or chemical properties.
3 Layers (Chemical Properties):
Crust
Mantle
Core
5 Layers (Physical Properties):
Lithosphere
Asthenosphere
Mesosphere
Outer Core
Inner Core
17.
18. The Biosphere
All of Earth’s living things.
All of Earth’s ecosystems together.
22. Biosphere
Carbon Phosphorus Nitrogen Water Oxygen
cycle cycle cycle cycle cycle
Heat in the environment
Heat Heat Heat
Fig. 3-7, p. 55
23. Solar Energy
The flow of high-quality energy from the
sun through materials and living things
in their feeding interactions, into the
environment as low-quality energy, and
eventually back into space as heat.
Solar energy flows through the
biosphere, warms the atmosphere,
evaporates and recycles water,
generates winds, and supports plant
growth.
24. Solar Energy
About one-billionth of the sun’s output
of energy reaches the earth.
Much of the energy is reflected away or
absorbed by the chemicals, dust, and
clouds in the atmosphere.
25. 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
27. Biomes and Aquatic Life Zones
Life exists on land systems called
biomes and in freshwater and ocean
aquatic life zones.
Biome = The terrestrial portion of the
biosphere.
Aquatic Life Zones = Water parts of
the biosphere
28. Biotic and Abiotic Factors
Ecosystems consist of nonliving and
living components.
Biotic = living components
Producers
Consumers
Decomposers
Abiotic = nonliving components
29. 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
30. Factors that Limit Population Growth
Different species and their populations thrive under different physical
and chemical conditions.
Availability of matter and energy can limit the number of organisms in a
population.
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 optimum range of tolerance.
Precipitation/Amount of Water
Soil nutrients
Temperature
Sunlight
Salinity
Dissolved Oxygen Content
31.
32. Producers (Autotrophs)
Some organisms in ecosystems can
produce the food they need from
chemicals in their environment.
Photosynthesis
Chemosynthesis
33. Consumers (Heterotrophs)
Consumers get their food by eating or
breaking down all or parts of other
organisms or their remains.
Herbivores/Primary Consumers – eat
producers
Carnivores/Secondary Consumers – eat
herbivores
Tertiary Consumers – eat other
carnivores
Omnivores – eat both plants and
animals
34. Decomposers and Detritrivores
Decomposers
Specialized organisms that recycle
nutrients in ecosystems.
Digest or degrade living or dead organisms
into simpler inorganic compounds that
producers can take up form soil and water
to use as nutrients.
Detritrivores
Insects and other scavengers that feed on
the wastes or dead bodies of other
organisms.
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
37. Food Chains and Food Webs
Food chains and webs show how eaters, the
eaten, and the decomposed are connected to
one another in an ecosystem.
All organisms, whether dead or alive, are
potential sources of food for other organisms.
There is little matter wasted in natural
ecosystems.
Trophic Levels = Feeding Levels
38. 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
39. 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
40. Losing Energy in Food Chains and
Webs
There is a decrease in the amount of
energy available to each succeeding
organisms in a food chain or web. (2nd
Law of Thermodynamics)
Each trophic level contains a certain
amount of biomass.
Only a small portion of what is eaten and
digested is actually converted into an
organism’s biomass.
The amount available to each
successive trophic level declines.
41. Ecological Efficiency
The percentage of usable energy transferred as
biomass from one trophic level to the next.
It ranges from 2% to 40% or a loss of 60% to
98%.
10% ecological efficiency is typical
42. 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
43. Ecological Efficiency
Energy flow pyramids explain why the Earth can
support more people if they eat at lower trophic
levels by consuming grains, vegetables, and
fruits.
Food chains and webs rarely have more than
four or five trophic levels.
45. Biodiversity
A vital renewable resource is the biodiversity
found in the earth’s variety of genes, species,
ecosystems, and ecosystem processes.
4 Components
Functional Diversity
Ecological Diversity
Species Diversity
Genetic Diversity
46. Functional Diversity
The biological and chemical
processes such as energy
flow and matter recycling
needed for the survival of
species, communities and
ecosystems.
47. Ecological Diversity
The variety of terrestrial
and aquatic
ecosystems found in an
area or on the earth.
48. Species Diversity
The number of species
present in different
habitats.
49. Genetic Diversity
The variety of genetic
material within a
species or population.
50. Biodiversity Loss and Species
Extinction
Human activities are destroying and degrading
the habitats for many wild species and driving
some of them to premature extinction.
Sooner or later all species become extinct
because they cannot respond successfully to
changing environmental conditions.
Current extinction rates are 100 to 10,000 times
higher than natural extinction rates because of
human activities.
51. Biodiversity Loss and Species
Extinction
H = Habitat destruction and degradation
I = Invasive species
P = Pollution
P = human Population growth
O = Overexploitation (overhunting, over consumption)
52. 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
53.
54. In-Class Assignment
1. Read the Core Case Study on page 50.
2. Summarize the importance of insects in the
earth’s biodiversity.
3. Share with the class.
55. Solutions
Goals, strategies and tactics for
protecting biodiversity.
Figure 3-16
57. What is Soil? Why is it Important?
Soil is a slowly renewed resource that provides
most of the nutrients needed for plant growth
and also helps purify water.
Soil is a thin covering over most land that is a
complex mixture of eroded rock, mineral
nutrients, decaying organic matter, water, air,
and living organisms.
Soil forms when rock is broken down into
fragments and particles by physical, chemical,
and biological weathering.
58. What is Soil? Why is it Important?
Over hundreds to thousands of years various
types of life build up layers of inorganic and
organic matter on soil’s original bedrock.
Formation of 1 cm of soil can take from 15
years to hundreds of years.
Soil is the base of life on land.
Producers get the nutrients they need from soil
and water.
You are mostly composed of soil nutrients
imported into your body by the food you eat.
59. What is Soil? Why is it Important?
Soil helps cleanse water that flows through it.
Soil helps decompose and recycle
biodegradable wastes.
Soil helps remove carbon dioxide from the
atmosphere and stores it as carbon
compounds.
60. Mature Soils
Soils that have developed over a long time.
Arranged in soil horizons, each has a distinct
texture and composition.
Soil Profile – a cross-sectional view of the
horizons in a soil.
Most mature soils have at least three of the
possible horizons.
61. 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
62. Soil Layers
O Horizon – Surface Litter Layer
Freshly fallen or partially decomposed leaves
Twigs
Crop wastes
Animal Wastes
Normally brown or black
63. Soil Layers
A Horizon – Topsoil
Porous mixture of partially decomposed bodies of
dead plants and animals (Humus)
Inorganic materials such as clay, silt, sand
Fertile soil that produces high crop yields has a
thick topsoil layer with lots of humus.
Helps topsoil hold water and nutrients taken up
by plant roots.
64. Soil Layers
2 Upper Layers
Most plant roots and organic matter are located here
As long as vegetation anchors these layers, the soil will hold
water and release it as needed
Full of bacteria, fungi, earthworms, and small insects
The color of topsoil is a clue to its ability to grow crops.
Dark brown or black = rich in nitrogen and organic matter
Gray, yellow, red = low in nitrogen and organic matter.
65. Soil Layers
B Horizon – Subsoil and C Horizon – Parent material
Contain most inorganic matter
Broken down rock
Transported by water from the A horizon
66. 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
67. Soil
The spaces (pores) between the solid organic
and inorganic particles contain air and water.
Plants need the oxygen for cellular respiration.
Precipitation that reaches the soil percolates
through the soil layers and occupies many of
the soil’s open spaces or pores. (Infiltration)
As the water seeps down it dissolves various
minerals and organic matter in the upper layers
and carries them to lower layers. (leaching)
68. Soil Properties
Soils vary in the size of the particles they
contain, the amount of space between these
particles, and how rapidly water flows through
them.
Clay – Very small particles
Silt – Medium particles
Sand – Largest particles
Soil Texture – The relative amounts of the
different sizes and types of these mineral
particles.
69. 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
70. Mosaic of
closely
packed
pebbles,
boulders
Weak humus-
mineral mixture Alkaline,
dark,
Dry, brown to
and rich
reddish-brown
in humus
with variable
accumulations Clay,
of clay, calcium calcium
and carbonate, compounds
and soluble
Desert Soil Grassland Soil
salts
(hot, dry climate) semiarid climate)
Fig. 3-24a, p. 69
71. Acidic
light-colored
humus
Iron and
aluminum
compounds
mixed with
clay
Tropical Rain Forest Soil
(humid, tropical climate)
Fig. 3-24b, p. 69
72. 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
73. 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
75. Nutrient Cycles: Global Recycling
Global cycles recycle nutrients through the earth’s air, land,
water, and living organisms and, in the process, connect past,
present, and future forms of life.
Nutrients –the elements and compounds that organisms need to
live, grow, and reproduce
Biogeochemical Cycles
Water
Carbon
Nitrogen
Phosphorus
Sulfur
76. The Water Cycle
A vast global cycle collects, purifies,
distributes, and recycles the Earth’s fixed
supply of water.
Also called the hydrologic cycle.
Powered by energy from the sun and by
gravity.
84% of water vapor in the atmosphere
comes from oceans.
Most precipitation becomes surface runoff
77. Water’s 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.
78. 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
79. Surface Run Off
Replenishes streams and lakes
Causes soil erosion
Sculpts the landscape
Transports nutrients
80. Effects of Human Activities on the
Water Cycle
We alter the water cycle by…
Withdrawing large amounts of fresh water
Clearing vegetation and eroding soils
Polluting surface and underground water
Contributing to climate change
81. The Carbon Cycle
Carbon cycles through the earth’s air, water,
soil, and living organisms and depends on
photosynthesis and respiration.
Carbon is the basic building block of the
carbohydrates, fats, proteins, DNA, and other
organic compounds necessary for life.
The carbon cycle is based on carbon dioxide
(CO2)
83. The Carbon Cycle:
Earth’s Thermostat
If the carbon cycle removes too much CO2
from the atmosphere, the atmosphere will
cool.
If the carbon cycle generates too much CO2
the atmosphere will get warmer.
Even slight changes in the cycle can affect
climate and help determine the types of life
that can exist on various parts of the Earth.
84. The Carbon Cycle:
How it Works
Terrestrial producers remove CO2 from the
atmosphere.
Aquatic producers remove CO2 from the water.
All producers use photosynthesis to convert CO2
into complex carbohydrates (like glucose)
The cells in consumers carry out aerobic respiration.
They break down glucose and convert the glucose
back to CO2 for reuse by consumers.
The link between photosynthesis and aerobic
respiration circulates carbon in the biosphere.
85. The Carbon Cycle:
How it Works
Some carbon atoms take a long time to recycle.
Over millions of years, buried deposits of dead
plant matter and bacteria are compressed
between layers of sediment, where they form
carbon-containing fossil fuels.
This carbon is not released to the atmosphere
as CO2 for recycling until these fuels are
extracted and burned.
In the past 50 years, we have extracted and
burned fossil fuels that took millions of years to
form.
86. The Carbon Cycle:
The Role of Oceans
Some of the atmosphere’s carbon dioxide
dissolves in ocean water and the ocean’s
photosynthesizing producers remove some.
As the ocean water warms, some of the
dissolved CO2 returns to the atmosphere
Some ocean organisms build their shells and
skeletons by using dissolved CO2 molecules.
87. Effects of Human Activities on the
Carbon Cycle
We alter the carbon cycle by…
Clear trees and plants that absorb CO2
through photosynthesis faster than they can
grow back
Add large amounts of CO2 by burning fossil
fuels and wood.
Increased concentrations of can enhance the
planet’s natural greenhouse effect.
Global warming disrupts global food production
and wildlife habitats, alter temperature and
precipitation patterns, and raise the average
sea level in various parts of the world.
88. CO2 emissions from fossil fuels
(billion metric tons of carbon equivalent)
Year
Low
projection
High
projection
Fig. 3-28, p. 74
89. The Nitrogen Cycle
Different types of bacteria help recycle nitrogen through
the Earth’s air, water, soil and living organisms.
Nitrogen is…
The most abundant gas in the atmosphere
Crucial component of proteins, vitamins, nucleic acids
N2 cannot be absorbed and used directly as a nutrient by
multicellular plants or animals.
90. The Nitrogen Cycle
Two natural processes fix N2 into useful compounds
Lightning
Nitrogen Cycle
Nitrogen-fixing bacteria in soil and aquatic environments
convert (fix) gaseous nitrogen (N2 ) into ammonia (NH3)
which is later converted into ammonium ions (NH4+) that can
be used by plants.
Ammonia not taken up by plants undergoes nitrification.
Specialized soil bacteria convert the NH3 and NH4+ into
nitrite ions (NO2-) which are toxic to plants, and then to
nitrate (NO3-) ions which are taken up by the roots of plants.
Animals get their nitrogen by eating plants or plant-eating
animals.
91. The Nitrogen Cycle
Plants and animals return nitrogen-rich organic compounds
to the environment as wastes, cast-off particles, and
through their bodies when they die.
In ammonificiation, large numbers of specialized
decomposer bacteria convert organic material into simple
nitrogen-containing inorganic compounds such as ammonia
(NH3) and water-soluble salts containing ammonium ions
(NH4+).
In denitrification, nitrogen leaves the soil as specialized
bacteria in waterlogged soil and in the bottom sediments of
lakes, oceans, swamps, and bogs to convert NH3 and NH4+
back into nitrite and nitrate ions, then into nitrogen gas (N2)
and nitrous oxide gas (N2O). These gases are released to
the atmosphere to begin the nitrogen cycle again.
92. 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
93. Effects of Human Activities on the
Nitrogen Cycle
We add large amounts of nitric oxide (NO) into the
atmosphere when N2 and O2 combine as we burn
any fuel at high temperatures.
This gas can be converted to nitrogen dioxide gas
(NO2) and nitric acid (HNO3) which can return to
the Earth’s surface as acid rain.
We add nitrous oxide (N2O) to the atmosphere
through the action of anaerobic bacteria on livestock
wastes and commercial inorganic fertilizers applied
to soil.
This gas can warm the atmosphere and deplete
ozone in the stratosphere.
94. Effects of Human Activities on the
Nitrogen Cycle
Nitrate ions in inorganic fertilizers can leach through
the soil and contaminate groundwater.
This is harmful to drink, especially for infants and small
children.
We release large quantities of nitrogen stored in
soils and plants as gaseous compounds into the
troposphere through destruction of forests,
grasslands, and wetlands.
We upset aquatic ecosystems by adding excess
nitrates to bodies of water through agricultural runoff
and discharges from municipal waste systems.
95. Effects of Human Activities on the
Nitrogen Cycle
We remove nitrogen from topsoil when we harvest
nitrogen-rich crops, irrigate crops, and burn or clear
grasslands and forests before planting crops.
Since 1950 human activities have more than
doubled the annual release of nitrogen from the
terrestrial portion of the earth into the rest of the
environment.
This is a serious local, regional, and global
environmental problem that has attracted little
attention when compared to global warming and
depletion of the ozone layer.
96. The Phosphorus Cycle
Phosphorus is a key component of DNA and energy storage
molecules such as ATP in cells.
Phosphorus circulates SLOWLY through water, the earth’s
crust, and living organisms through the phosphorous cycle.
On a human time scale, much phosphorus flows one-way
from the land to the oceans.
Phosphate is found as phosphate salts containing phosphate
ions (PO43-) in terrestrial rock formations and ocean bottom
sediments.
As water runs over the phosphorus-containing rocks, it
erodes away inorganic compounds that contain phosphate
ions.
97. The Phosphorus Cycle
Phosphate can be lost from the cycle for long
periods of time when it washes from the land into
streams and rivers and is carried to the ocean.
Plants obtain phosphorus as phosphate ions
directly from soil or water and incorporate it in
various organic compounds.
Animals get their phosphorous from plants and
eliminate excess phosphorus in their urine.
Most soils contain little phosphate so it is the
limiting factor for plant growth on land unless
phosphorus is applied to the soil as fertilizer.
98. 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
99. Effects of Human Activities on the
Phosphorous Cycle
We mine large quantities of phosphate rock to
make commercial inorganic fertilizers and
detergents.
We reduce the available phosphate in tropical
soils when we cut down areas of tropical forests.
We disrupt aquatic systems with phosphates
from runoff of animal wastes and fertilizers and
discharges from sewage treatment systems.
Human activities have increased the natural rate
of phosphorous about 3.7 times since 1900.
100. The Sulfur Cycle
Sulfur circulates through the biosphere in the sulfur
cycle.
Much of the earth’s sulfur is stored underground in
rocks and minerals, including sulfate (SO42-) salts
buried deep under ocean sediments.
Sulfur enters the atmosphere…
As H2S and SO2 from volcanoes
As particles of sulfate salts from sea spray, dust
storms, and forest fires.
When produced by marine algae as dimethyl sulfide
(DMS).
101. 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
102. Effects of Human Activities on the
Sulfur Cycle
We burn sulfur-containing coal and oil to produce
electric power.
We refine sulfur containing petroleum to make
gasoline, heating oil and other useful products.
We convert sulfur-containing metallic mineral
ores into free metals such as copper, lead, and
zinc. This releases large amounts of sulfur
dioxide into the environment.
104. The Gaia Hypothesis
Some people have proposed that the Earth’s
various forms of life control or at least
influence its chemical cycles and other earth-
sustaining processes.
Named for the Greek goddess of the Earth.
First proposed in 1979 by English inventor
and atmospheric chemist James Lovelock
105. The Gaia Hypothesis
Life controls the Earth’s life-sustaining
processes. (Strong)
Life influences the Earth’s life-sustaining
processes. (Weak)
The Earth is an incredibly complex system that
sustains itself and adapts to changing
environmental conditions to reach an optimal
physical and chemical environment for life on
this planet.
106. How Do Ecologists Learn About
Ecosystems?
Ecologist go into ecosystems and learn what
organisms live there and how they interact, use
sensors on aircraft and satellites to collect data,
and store and analyze geographic data in large
databases.
Field Research
Geographic Information Systems
Remote Sensing
Ecologists use aquarium tanks, greenhouses,
and controlled indoor and outdoor chambers to
study ecosystems.
107. Geographic Information Systems
(GIS)
A GIS organizes, stores, and analyzes
complex data collected over broad
geographic areas.
Allows the simultaneous overlay of
many layers of data.
108. 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
109. Systems Analysis
Ecologists develop mathematical and other
models to simulate the behavior of ecosystems.
Can help us understand large and very complex
systems (rivers, oceans, forests, grasslands,
cities, and climate)
Researchers can change values of the variables
in their computer models to project possible
changes in environmental conditions, help
anticipate environmental surprises, and analyze
the effectiveness of various alternative solutions
to environmental problems.
110. 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
111. 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).
112. All things come from
earth, and to earth
they all return.
Menander, 342 -290 BC