2. ECOSYSTEM CONCEPTS
and ECOLOGY
Basic
Concepts and
Principles
2 Department of BIOLOGY, CAS‐UP Manila

3. • Earth is the only planet where there is life.
• Why does Earth have wind, clouds, and rain?
• Why does Earth have weather elements which
the moon and other planets do not have?
• The most important factors that make weather
changes possible are sun, air, and water
3 Department of BIOLOGY, CAS‐UP Manila

4. • Earth’s perfect size and mass,
crucial to a planet’s ability to
develop an atmosphere and
sustain life
• “Another fascina;ng
coincidence is that only
atmospheres with between ten
and twenty percent oxygen can
support oxida;ve metabolism
in a higher
organism” (Nature’s
Des+ny)
• Our exis;ng magne;c field
creates a kind of “force field”
around our planet, protec;ng
us from direct interac;on with
the sun’s solar wind—which
could blow away our
atmosphere and with it the
ability to sustain life
Department of BIOLOGY, CAS‐UP Manila 4

5. • Community of living things on the Earth
• Sum of all ecosystems on Earth
• Living organisms of the biosphere depend on
one another and on the other divisions of the
Earth’s physical environment:
– ATMOSPHERE (gaseous envelope)
– HYDROSPHERE (water supply)
– LITHOSPHERE (crust: soils and rocks
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6. • The Earth environment is the home (habitat)
of all forms of life including humans.
• All life forms depend on the proper
func;oning of our environment!
• To appreciate the intricacies and importance
of the environment, however, it is necessary
that certain ecological principles be explained
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Humans are biological
organisms, all our
activities have a bearing
on ecology
“Just as we humans are constrained by the laws of physics when we build airplanes and
bridges, we should also be constrained by the principles of ecology when we alter the
environment”

7. • Coined by Ernst Haeckel (1869)
• “oikos” – house
• “logos” ‐ study of
• EARTH is like a great estate in which the living organisms
and the physical environment interact in an immense and
complicated web of rela;onships
• ECOLOGY, then, is the study of the interac;ons among
organisms and between organisms and their physical
environment
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8. • Rela;onship with Ecology
– Study of the interrelationship between
living organisms and their animate and
inanimate environment
• Ecology is the basic tool of environmental science
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9. ECOSYSTEM – basic
unit and probably
the most
important concept
in ecology
Two Types of System:
1. Open system –
presence of inputs
and outputs
(maUer and
energy)
3. Closed system – no
exchange of maUer
and energy
(usually arXficially
made, e.g.
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10. • NEGATIVE FEEDBACK MECHANISM
– Brings the system back to the ideal state
– Devia;on‐counterac;ng inputs
• Homeosta;c Plateau ‐ min/max area within which the nega;ve feedback
mechanism can s;ll func;on
• POSITIVE FEEDBACK MECHANISM
– Increasing tendency to be away from setpoint
– Devia;on‐accelera;ng inputs
– Homeosta;c plateau exceeded
• Ex. Geometric increase in the popula;on
» Development of cancer and kidney stones
» Parturi;on or childbirth
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11. DO YOU THINK THIS IS AN
ECOSYSTEM?
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12. BIOTIC COMPONENTS ABIOTIC COMPONENTS
• Producers
– Green Plants
– Algae (Phytoplankton)
• Consumers
– Herbivores
– Carnivores
– Omnivores
• Decomposers
– Detri;vores
– True decomposers
– Bacteria and fungi
• Clima;c Factors
– Light
– Temperature
– Precipita;on
– Wind
– Humidity
• Edaphic Factors
– Soil Nutrients
– Soil Moisture
– Soil Ph
• Hydrological Factors
– Physicochemical factor Department of BIOLOGY, CAS‐UP Manila 12

13. THE ABIOTIC FACTORS
Department of BIOLOGY, CAS‐UP Manila 13

14. • Light affects the following ac;vi;es
– rate of photosynthesis (blue and red 420‐660 nm)
– flowering, dormancy, and leaf fall
– migra;on and hiberna;on
– nes;ng behavior
• Temperature
– direct effect on metabolism by controlling body chemistry and
reac;ons (inc T  inc rate of reac;ons)
– affects other environmental factors such as moisture
availability
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15. • Precipita;on/Moisture
– Water as a universal solvent, medium for biochemical
processes
– Very limi;ng in terrestrial environment; determines the type
of vegeta;on in a given environment
• Atmosphere/Wind
– Major reservoir of nutrients important to life
– Wind ac;on accelerates transpira;on process
– Strong winds may induce physical damage on plant structure
and distribu;on of seeds and small animals
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16. • Soil Content
– More nutrients in soil for plant growth means greater produc;vity
– “Law of the Minimum” by Justus von Liebig (1837), the growth
and survival of plants depend on the nutrient that is least
available
• Soil Moisture
– Increase water availability generally means greater produc;vity;
water is a raw material
• Soil Acidity
– determines the solubility and availability of essen;al inorganic salts
in the solu;on
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17. • Can modify the clima;c factors in the environment
especially light, temperature, moisture, and pressure
– Al;tude – drop of 5.5 ˚C per 1000 m increase
in al;tude
– Aspect – north‐facing slope and south‐facing slope
(low moisture, high T, high evapora;on)
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18. THE BIOTIC FACTORS
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19. • A groups of organisms that can use the energy in
sunlight to convert water and carbon dioxide into
Glucose (food)
• Autotrophs are also called Producers because they
produce all of the food that heterotrophs use
• Without autotrophs, there would be no life on this
planet
• Ex. Plants and Algae
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20. • Autotrophs that get their energy from
inorganic substances, such as salt
• Live deep down in the ocean where there is
no sunlight
• Ex. Bacteria and Deep Sea Worms
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21. • Organisms that do not make their own food
• Another term for Heterotroph is consumer
because they consume other organisms in
order to live
• Ex. Rabbits, Deer, Mushrooms
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22. • Scavengers/Detri;vores – feed on the ;ssue of dead organisms (both
plans and animals)
– Ex. – Vultures, Crows, and Shrimp
• Herbivores – eat ONLY plants
– Ex. – Cows, Elephants, Giraffes
• Carnivores – eat ONLY meat
– Ex. – Lions, Tigers, Sharks
• Omnivores – eat BOTH plants and animals
– Ex. – Bears and Humans
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23. 4 LAWS OF ECOLOGY
1. EVERYTHING IS CONNECTED TO EVERYTHING ELSE
2. EVERYTHING MUST GO SOMEWHERE
3. NATURE KNOWS BEST
4. THERE IS NO FREE LUNCH
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24. HOW DOES AN ECOSYSTEM
WORK?
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25. • Significance: makes energy available to all
components of the ecosystem
• Nature: “unidirec;onal linear flow”
» “Ma0er circulates energy dissipates”
• Two Laws of Thermodynamics – governs the
“one‐way” flow of energy through the
ecosystem
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26. • When a zebra eats the grass, it does not obtain all of the energy the grass
has (much of it is not eaten)
• When a lion eats a zebra, it does not get all of the energy from the zebra
(much of it is lost as heat)
• The two (2) previous examples of energy transfer show that no organism
EVER receives all of the energy from the organism they just ate
• Only 10% of the energy from one trophic level is transferred to the next –
this is called the 10% law
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27. • Grazing Food Chain
– starts from a green plant base then goes to grazing herbivores, and on to carnivores;
– most common in deep aqua;c systems but can also be found in terrestrial
• grass  cow  man
• phytoplankton  zooplankton  plank;vores  piscivores  cat  dog  “lasenggo” 
cannibals
• Detrital Food Chain
– from dead organic maper to microorganisms and then to detri;vores and their predators
– most common in terrestrial and shallow waters
• dead leaves  mites  carnivorous mites
• dung  bacteria  microbial consumers 
• Parasi;c Food Chain
– In which either the producer or consumer is parasi;zed
– Food passes to a smaller organism than a larger one.
• e.g. termites  Triconympha
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28. • Most organisms eat more the JUST one
organism
• When more organism are involved it is know
as a FOOD WEB
• Food webs are more complex and involve lots
of organisms
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No;ce that the
direc;on the
arrow points →
the arrow points
in the direc;on of
the energy
transfer, NOT
“what ate what”

29. • An ecological pyramid shows the rela;onship
between consumers and producers at
different trophic levels in an ecosystem
• Shows the rela;ve amounts of energy or
maper contained at each trophic level
• The Pyramid shows which level has the most
energy and the highest number of organisms
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30. Department of BIOLOGY, CAS‐UP Manila 30

31. • The total mass of the organic maper at each
trophic level is called biomass
• Biomass is just another term for poten;al
energy – energy that is to be eaten and used.
• The transfer of energy from one level to
another is very inefficient (10% Law)
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32. Biogeochemical Cycling in the
Ecosystem
All maper cycles...it is neither created nor
destroyed...
32 Department of BIOLOGY, CAS‐UP Manila

33. • Defined as the movement of elements and
compounds that are essen;al to life
– Materials are transported through organisms, the
atmosphere, water and land in a series of CYCLES
• “Bio” – life, par;cipa;on of organisms
• “Geo” ‐ abio;c environment as source of nutrients
• “Chemical” – nature of substances being cycled
“Biogeochemistry” (GE Hutchinson) Department of BIOLOGY, CAS‐UP Manila 33

34. • Gaseous type – the reservoir is the atmosphere and/
or hydrosphere (e.g. N2, CO2, O2)
• Sedimentary type – the reservoir is the Earth’s crust
(e.g. Phosphorus)
• Linkage type – the reservoir includes major pathways
in air, water, and crust (e.g. sulfur)
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35. • Pollu;on – accumulaXon of a chemical form that is higher
than the standards
• Non‐biodegradable substances – change to form new
chemical structure where no organism has yet to uXlize it
• ReducXon of the concentraXon of other chemical forms –
limits growth of the subsequent components of the cycle
• Eutrophica;on ‐ the channeling of a substance to other
pathways (greater amounts of phosphates in aquaXc
systems)
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36. • Flow of H2O
• Mediates nutrient cycle and as major energy
dissipa;on pathway
• Processes
– Precipita;on
– Run‐off and infiltra;on
– Evapora;on
– Condensa;on
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37. • Freshwater
– 3% of the world’s water supply
• More consump;on than supply
• Pumping waters from aquifers ‐ not a normal part of the water
cycle
• Garbage and wastes pollute the water and clog drainage systems
 induces flooding
• Asphal;ng – render the ground impervious to water  blocks
infiltra;on
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Pollu;on
– a change in transfer rate of water
and nutrients that can lead directly
or indirectly to a degradaXon of
human health or degradaXon of
plant and animal life

38. • Type: Gaseous (21%)
• Major Reservoir: Atmosphere
• Forms: Free and Molecular Oxygen
• Sources:
– Photosynthesis from producers
– PhotodissociaXon of Water Vapor
• Fate of Free O2:
1. Reach higher levels of trophosphere and reduced to ozone
(provides protecXon by filtering out the sun's UV rays)
2. May react with chemicals and organic compounds of the
earth’s crust
3. May be used up in cell respiraXon which release CO2 to be
used by autotrophs to produce more O2
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39. • CFC’s (chlorofluorocarbons) deplete ozone layer
“ozone hole”
• Eutrophica;on (nutrient enrichment from
agricultural and domesXc wastes) leads to depleXon
of oxygen in water
• Combus;on of fossil fuels and removal of vegetaXon
(deforestaXon) deplete the supply of oxygen in the
atmosphere
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40. • Type: Gaseous Cycle
• Major Reservoir : Atmosphere but also calcium carbonate in shells
and limestone, as well as fossil fuels
• Significance : Major element of organic compounds; building
blocks of all biomolecules
• Processes
– Photosynthesis removes CO2 while respiraXon and combusXon add CO2
to the atmosphere.
– CO2 from air and water combine to form bicarbonate (HCO3) – source of
carbon for aquaXc producers. Carbonic acid makes rainwater also slightly
acidic.
– Similarly, when aquaXc organisms respire, CO2 is released and combine
with water to form HCO3. HCO3 (water) = CO2 (air)
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41. Department of BIOLOGY, CAS‐UP Manila 41
The global carbon cycle includes the earth's atmosphere,
oceans, vegeta+on, soils and fossil fuels

42. • Increased u;liza;on and burning of fossil fuel
(oil, gas, coal) to run automobiles, industry,
and machineries
• Massive deforesta;on
• Waste incinera;on, etc
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CO2

43. • Type: Gaseous Cycle
• Major reservoir – ATMOSPHERE
• Importance – Essen;al for many biological
processes, cons;tutes part of proteins (amino
acids), in bases of nucleic acids that make up
DNA and RNA
• 79% of atmosphere is made up of nitrogen (N2)
but this is INERT
• It must be fixed for organisms to u;lize it
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44. • USE OF NITROGEN FERTILIZERS
– Human use of nitrogen fer;lizers causes runoff, leading to eutrophica;on in
aqua;c systems (e.g. eutrophica;on)
• NITRATES LEACHING INTO GROUNDWATER
– Nitrogen level in drinking water rises
– A large rise of nitrogen in drinking water supplies leads to
Methemoglobinemia / Blue‐Baby Syndrome
• NITROGEN OXIDES RELEASED THROUGH COMBUSTION
– Burning of fossil fuel + automobiles : source of nitrogen dioxide
– Ozone + PAN  Photochemical Smog
• LIVESTOCK RELEASE OF LARGE AMOUNTS OF AMMONIA (FROM WASTES)
– The ammonia released from wastes of livestock can have detrimental effects
on fish and other organisms
– There is reduc;on in diversity
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45. • Type: Purely Sedimental
• Major reservoir – Earth’s crust
• Gradual cycle ‐ It has no gaseous phase
– Phosphorous normally occurs in nature as part of phosphate ion.
– Most phosphates found as salts in ocean sediments or in rocks.
– Over ;me : geologic processes can bring sediments from ocean to
land, and weathering can bring it from land to ocean
• Importance
– Phosphorous cons;tuent of nucleic acids in DNA, and energy
currency of cell ATP.
– Phosphorous ‐also found in bones, in phospholipids which are found
in biological membranes.
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46. • Humans mine phosphate ores for use in
fer;lizer produc;on and detergents
• Human ac;ons could lead to
eutrophica+on of aqua+c systems which
cause algal blooms
• Algal blooms cause fish kills
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47. • Type: Sedimentary cycle with atmospheric
component
• Major reservoir – inorganic sulfur in rocks and fossil
fuel
• Biological Importance
– Sulfur is an important element in protoplasm
which is an important component of some amino
acids.
– Sulfur is part of proteins, vitamins and hormones
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48. • Humans produce sulfur dioxide from industry
and internal combus;on energy
• Sulfur dioxide can precipitate onto surfaces
where it can be oxidized to sulfate in the soil
which is toxic to some plants
• Sulfur dioxide can be oxidized to sulfate in
atmosphere as sulfuric acid which is a main
cons;tuent of acid rain
– Acid rain can affect chemical balance of lakes.
– It accelerates weathering in carbonate rocks.
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