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Ecosystems: What Are They and How Do They Work?Chapter 3
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?
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
Categories of Life
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)
Fig. 3-3, p. 52
Insects751,000
Other animals281,000
Fungi69,000
Prokaryotes4,800
Plants248,400
Protists57,700
Known species1,412,000
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.
Fig. 3-2, p. 51
Communities
Subatomic Particles
Atoms
Molecules
Protoplasm
Cells
Tissues
Organs
Organ systems
Organisms
Populations
Populations
Communities
Ecosystems
Biosphere
Earth
Planets
Solar systems
Galaxies
Universe
Organisms
Realm of ecology
Ecosystems
Biosphere
The Four Spheres
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)
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
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
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
The Biosphere
All of Earth’s living things.
All of Earth’s ecosystems together.
Everything is linked to everything else.
What Sustains Life on Earth?
3 Interconnected Forces
Solar Energy
The Cycling of Matter
Gravity
Fig. 3-7, p. 55
Nitrogencycle
Biosphere
Heat in the environment
Heat Heat Heat
Phosphoruscycle
Carboncycle
Oxygencycle
Watercycle
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.
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.
Fig. 3-8, p. 55
Absorbed by ozone Visible
Light
Absorbed by the earth
Greenhouse effect
UV radiation
Solarradiation
Energy in = Energy out
Reflected by atmosphere (34% ) Radiated by
atmosphere as heat (66%)
Heat radiated by the earth
Heat
Troposphere
Lower Stratosphere(ozone layer)
Ecosystem Components
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
Biotic and Abiotic Factors
Ecosystems consist of nonliving and living components.
Biotic = living components
Producers
Consumers
Decomposers
Abiotic = nonliving components
Fig. 3-10, p. 57
SunOxygen (O2)
Carbon dioxide (CO2)
Secondary consumer(fox)
Soil decomposers
Primaryconsumer
(rabbit)
PrecipitationFalling leaves
and twigs
Producer
Producers
Water
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
Producers (Autotrophs)
Some organisms in ecosystems can produce the food they need from chemicals in their environment.
Photosynthesis
Chemosynthesis
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
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.
Fig. 3-13, p. 61
Scavengers
Powder broken down by decomposers into plant nutrients in soil
Bark beetle engraving
Decomposers
Long-horned beetle holes
Carpenter ant
galleries
Termite and
carpenter ant work Dry rot
fungus
Wood reduced to powder
Mushroom
Time progression
Energy Flowin
Ecosystems
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
Fig. 3-17, p. 64
Heat
Heat
Heat
Heat
Heat
Heat Heat Heat
Detritivores (decomposers and detritus feeders)
First Trophic Level
Second TrophicLevel
Third Trophic Level
Fourth Trophic Level
Solar energy
Producers(plants)
Primary consumers(herbivores)
Secondary consumers(carnivores)
Tertiary consumers
(top carnivores)
Fig. 3-18, p. 65
HumansBlue whale Sperm whale
Crabeater seal
Elephant seal
Killer whale
Leopard seal
Adelie penguins Emperor
penguin
Petrel FishSquid
Carnivorous plankton
Krill Herbivorous plankton
Phytoplankton
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.
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
Fig. 3-19, p. 66
Heat
Heat
Heat
Heat
Heat
DecomposersTertiary
consumers(human)
Producers(phytoplankton)
Secondaryconsumers
(perch)
Primaryconsumers
(zooplankton)
10
100
1,000
10,000Usable energy
Available atEach tropic level(in kilocalories)
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.
Biodiversity
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
Functional Diversity
The biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities and
ecosystems.
Ecological Diversity
The variety of terrestrial and aquatic
ecosystems found in an area or on the earth.
Species Diversity
The number of species present in different
habitats.
Genetic Diversity
The variety of genetic material within a
species or population.
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.
Biodiversity Loss and Species Extinction
H = Habitat destruction and degradation
I = Invasive species
P = Pollution
P = human Population growth
O = Overexploitation (overhunting, over consumption)
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
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.
Solutions
Goals, strategies and tactics for protecting biodiversity.
Figure 3-16
Soil: A Renewable Resource
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.
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.
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.
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.
Fig. 3-23, p. 68
Fern
Mature soil
Honey fungus
Root system
Oak tree
Bacteria
Lords and ladies
Fungus
Actinomycetes
Nematode
Pseudoscorpion
Mite
RegolithYoung soil
Immature soil
Bedrock
Rockfragments
Moss and lichen
Organic debrisbuilds upGrasses and
small shrubs
Mole
Dog violet
Woodsorrel
EarthwormMillipede
O horizonLeaf litter
A horizon
Topsoil
B horizonSubsoil
C horizon
Parent material
Springtail
Red Earth Mite
Soil Layers
O Horizon – Surface Litter Layer
Freshly fallen or partially decomposed leaves
Twigs
Crop wastes
Animal Wastes
Normally brown or black
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.
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.
Soil Layers
B Horizon – Subsoil and C Horizon – Parent material
Contain most inorganic matter
Broken down rock
Transported by water from the A horizon
Fig. 3-23, p. 68
Fern
Mature soil
Honey fungus
Root system
Oak tree
Bacteria
Lords and ladies
Fungus
Actinomycetes
Nematode
Pseudoscorpion
Mite
RegolithYoung soil
Immature soil
Bedrock
Rockfragments
Moss and lichen
Organic debrisbuilds upGrasses and
small shrubs
Mole
Dog violet
Woodsorrel
EarthwormMillipede
O horizonLeaf litter
A horizon
Topsoil
B horizonSubsoil
C horizon
Parent material
Springtail
Red Earth Mite
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)
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.
Fig. 3-25, p. 70
0.05–2 mmdiameter
High permeability Low permeability
WaterWater
Clayless than 0.002 mm
Diameter
Silt0.002–0.05 mm
diameter
Sand
Fig. 3-24a, p. 69
Mosaic of closely packed pebbles, boulders
Weak humus-mineral mixture
Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts
Alkaline, dark, and rich in humus
Clay, calcium compounds
Desert Soil(hot, dry climate)
Grassland Soilsemiarid climate)
Fig. 3-24b, p. 69
Tropical Rain Forest Soil(humid, tropical climate)
Acidic light-colored humus
Iron and aluminum compounds mixed with clay
Fig. 3-24b, p. 69
Deciduous Forest Soil(humid, mild climate)
Forest litter leaf moldHumus-mineral mixtureLight, grayish-brown, silt loamDark brown firm clay
Fig. 3-24b, p. 69
Coniferous Forest Soil(humid, cold climate)
Light-colored and acidic
Acid litter and humus
Humus and iron and aluminum compounds
Matter Cycling in Ecosystems
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
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
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.
Fig. 3-26, p. 72
PrecipitationPrecipitation
Transpiration
Condensation
Evaporation
Ocean storage
Transpiration from plants
Precipitation to land
Groundwater movement (slow)
Evaporation from land Evaporation
from ocean Precipitation to ocean
Infiltration and Percolation
Rain clouds
RunoffSurface runoff
(rapid)
Surface runoff (rapid)
Surface Run Off
Replenishes streams and lakes
Causes soil erosion
Sculpts the landscape
Transports nutrients
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
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)
Fig. 3-27, pp. 72-73
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.
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.
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.
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.
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.
Fig. 3-28, p. 74
CO
2 em
issi
on
s fr
om
fo
ssil
fu
els
(bil
lio
n m
etri
c to
ns
of
carb
on
eq
uiv
alen
t)
Year
Lowprojection
Highprojection
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.
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.
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.
Fig. 3-29, p. 75
Gaseous nitrogen (N2)in atmosphere
Ammonia, ammonium in soil Nitrogen-rich wastes,remains in soil
Nitrate in soil
Loss byleaching
Loss byleaching
Nitrite in soil
Nitrification
Nitrification
Ammonification
Uptake by autotrophsUptake by autotrophsExcretion, death,
decomposition
Loss bydenitrification
Food webs on land
Fertilizers
Nitrogen fixation
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.
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.
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.
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 (PO4
3-) 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.
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.
Fig. 3-31, p. 77
Dissolvedin Ocean
Water
Marine Sediments Rocks
uplifting overgeologic time
settling out weatheringsedimentation
LandFoodWebs
Dissolvedin Soil Water,Lakes, Rivers
death,decomposition
uptake byautotrophs
agriculture
leaching, runoff
uptake byautotrophs
excretion
death,decomposition
mining Fertilizer
weathering
Guano
MarineFoodWebs
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.
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 (SO4
2-) 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).
Fig. 3-32, p. 78
Hydrogen sulfide
Sulfur
Sulfate salts
Decaying matter
Animals
Plants
Ocean
IndustriesVolcano
Hydrogen sulfideOxygen
Dimethyl sulfide
Ammoniumsulfate
Ammonia
Acidic fog and precipitationSulfuric acid
WaterSulfurtrioxide
Sulfur dioxide
Metallicsulfidedeposits
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.
The Gaia HypothesisIs the Earth alive?
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
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.
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.
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.
Fig. 3-33, p. 79
Critical nesting sitelocations
USDA Forest ServiceUSDA
Forest ServicePrivateowner 1 Private owner 2
Topography
Habitat type
LakeWetlandForest
Grassland
Real world
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.
Fig. 3-34, p. 80
SystemsMeasurement
Define objectivesIdentify and inventory variablesObtain baseline data on variables
Make statistical analysis of relationships among variables
Determine significant interactions
Objectives Construct mathematical model describing interactions among variables
Run the model on a computer, with values entered for differentVariables
Evaluate best ways to achieve objectives
DataAnalysis
SystemModeling
SystemSimulation
SystemOptimization
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).
All things come from earth, and to earth they all return.
Menander, 342 -290 BC
