Topic 8: Ecology Option C Part 1

Understandings
Statement Guidance
4.1 U.1 Species are groups of organisms that can potentially interbreed to produce
fertile offspring.
4.1 U.2 Members of a species may be reproductively isolated in separate populations.
4.1 U.3 Species have either an autotrophic or heterotrophic method of nutrition (a
few species have both methods).
4.1 U.4 Consumers are heterotrophs that feed on living organisms by ingestion
4.1 U.5 Detritivores are heterotrophs that obtain organic nutrients from detritus by
internal digestion.
4.1 U.6 Saprotrophs are heterotrophs that obtain organic nutrients from dead
organisms by external digestion.
4.1 U.7 A community is formed by populations of different species living together and
interacting with each other.
4.1 U.8 A community forms an ecosystem by its interactions with the abiotic
environment.
4.1 U.9 Autotrophs obtain inorganic nutrients from the abiotic environment.
4.1 U.10 The supply of inorganic nutrients is maintained by nutrient cycling.
4.1 U.11 Ecosystems have the potential to be sustainable over long periods of time.

Applications and Skills
Statement Guidance
4.3 S.1 Classifying species as autotrophs, consumers, detritivores or saprotrophs from a
knowledge of their mode of nutrition.
4.3 S.2 Setting up sealed mesocosms to try to establish sustainability. (Practical 5)
[Mesocosms can be set up in open tanks, but sealed glass vessels are preferable
because entry and exit of matter can be prevented but light can enter and heat
can leave. Aquatic systems are likely to be more successful than terrestrial
ones.]
4.3 S.3 Testing for association between two species using the chi-squared test with data
obtained by quadrat sampling. [To obtain data for the chi-squared test, an
ecosystem should be chosen in which one or more factors affecting the
distribution of the chosen species varies. Sampling should be based on random
numbers. In each quadrat the presence or absence of the chosen species should
be recorded.]
4.3 S.4 Recognizing and interpreting statistical significance.

Understandings, Applications and Skills
Statement Guidance
4.2 U.1 Most ecosystems rely on a supply of energy from sunlight
4.2 U.2 Light energy is converted to chemical energy in carbon compounds by
photosynthesis
4.2 U.3 Chemical energy in carbon compounds flows through food chains by means of
feeding. [Pyramids of number and biomass are not required. Students should be
clear that biomass in terrestrial ecosystems diminishes with energy along food
chains due to loss of carbon dioxide, water and other waste products, such as
urea.]
4.2 U.4 Energy released from carbon compounds by respiration is used in living
organisms and converted to heat.
4.2 U.5 Living organisms cannot convert heat to other forms of energy.
4.2 U.6 Heat is lost from ecosystems.
4.2 U.7 Energy losses between trophic levels restrict the length of food chains and the
biomass of higher trophic levels. [The distinction between energy flow in
ecosystems and cycling of inorganic nutrients should be stressed. Students
should understand that there is a continuous but variable supply of energy in
the form of sunlight but that the supply of nutrients in an ecosystem is finite and
limited.]
4.2 S.1 Quantitative representations of energy flow using pyramids of energy. [Pyramids
of energy should be drawn to scale and should be stepped, not triangular. The
terms producer, first consumer and second consumer and so on should be used,
rather than first trophic level, second trophic level and so on.]

Statement Guidance
C.2 U.1 Most species occupy different trophic levels in multiple food chains.
C.2 U.2 A food web shows all the possible food chains in a community.
C.2 U.3 The percentage of ingested energy converted to biomass is dependent on the
respiration rate.
C.2 U.4 The type of stable ecosystem that will emerge in an area is predictable based on
climate.
C.2 U.5 In closed ecosystems energy but not matter is exchanged with the
surroundings.
C.2 U.6 Disturbance influences the structure and rate of change within ecosystems.
C.2 A.1 Conversion ratio in sustainable food production practices.
C.2 A.2 Consideration of one example of how humans interfere with nutrient cycling
C.2 S.1 Comparison of pyramids of energy from different ecosystems.
C.2 S.2 Analysis of a climograph showing the relationship between temperature, rainfall
and the type of ecosystem.
C.2 S.3 Construction of Gersmehl diagrams to show the inter-relationships between
nutrient stores and flows between taiga, desert and tropical rainforest.
C.2 S.4 Analysis of data showing primary succession.
C.2 S.5 Investigation into the effect of an environmental disturbance on an ecosystem. Examples of aspects to
investigate in the ecosystem
could be species diversity,
nutrient cycling, water
movement, erosion, leaf area
index, among others.

EcologyEcology is the study ofis the study of
ecosystemsecosystems

Biosphere:Biosphere: the regions of the surface,
atmosphere, and hydrosphere of the earth
occupied by living organisms.

The Earth as seen from Saturn's rings
The Earth

EcosystemEcosystem is a compilation of both biotic and
abiotic factors, how organisms interact with
their environment.

What are the factors that effect an ecosystem like the
access to a watering hole below?
Abiotic (nutrients and energy)
Biotic individual organisms that live in that
ecosystem

Community = group of populations of different
species living close enough to interact
4.1 U.7 A community is formed by populations of different species living together and interacting with each other.

Population
• Includes all the members of a species found in a
given area.
• Ex: Elephant on a savannah
4.1 U.7 A community is formed by populations of different species living together and interacting with each other.

Individual Species a group of individuals
capable of interbreeding to produce fertile offspring

What is a Species?
There is only
one existing
human
species.
4.1 U.1 Species are groups of organisms that can potentially interbreed to produce fertile offspring.
Reminder from Topic 8 Evolution A species is a group of individuals
capable of interbreeding to produce fertile offspring.

4.1 U.2 Members of a species may be reproductively isolated in
separate populations.
• Reproductive isolation of populations occurs when barriers or
mechanisms prevent two populations from interbreeding,
keeping their gene pools isolated from each other.
• There are different types of reproductive isolation including
temporal, behavioral, and geographic

Factors that controlling an ecosystem
I. Energy (Open System)
II. Nutrients (Closed System)
III. Interactions between species

The ultimate energy source of the earth is the
sun

4.2 U.1 Most ecosystems rely on a supply of energy from sunlight
An open system makes it possible of maintain a stable ecosystem, with a lose of 90% of
all the energy input. Due to the Sun’s constant supply of energy back into the system.
I. Energy is an open system on Earth

Two Laws of Matter and
Energy
1.Matter and energy can not
be created or destroyed. The
law of conservation of matter
and energy.
2.When energy is changed
from one form to another
some is always degraded into
heat. Energy transfer is never
100% efficient.
3.On the Earth, 99% of all the
energy from the Sun is lost as
heat back out into the
atmosphere and out into
space.
4.2 U.1 Most ecosystems rely on a supply of energy from sunlight 4.2 U.2 Light energy is converted to chemical energy in carbon compounds by photosynthesis
ECOSYSTEMS AND ENERGY FLOW

Overview of energy & nutrient dynamics

Energy moves through
three basic classes of organisms:
1. Producers- include green plants and other photosynthetic
organisms that synthesize the organic nutrients that supply
energy to other members in the community.
2. Consumers- include all heterotrophic organisms. Organisms
that feed on green plants are primary consumers, or herbivores.
Secondary consumers, or carnivores, feed on other consumers.
3. Decomposers – are the organisms (saprophytes) that break
down wastes and dead organisms so that chemical materials are
returned to the environment for use by other living organisms.
4.1 S.1 Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.

Distinguish between
autotroph and heterotroph
• Autotrophs are capable of making their own
organic molecules from inorganic molecules
as a food source (a.k.a. producers);
Examples?
• Heterotrophs – cannot make their own food
and must obtain organic molecules from other
organisms (a.k.a. consumers); Examples?
4.1 U.3 Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods). 4.1 U.4 Consumers are heterotrophs that feed on living organisms by ingestion

Energy Flow Relationships
• For an ecosystem to be self-
sustaining, there must be a
flow of light energy from the
sun and chemical energy
between organisms. This
chemical energy is called
Biomass. This is the energy
available to organism in an
ecosystem.
• The pathway of energy flow
through the living
components of an ecosystem
are represented by food
chains and food webs.

4.2 U.2 Light energy is converted to chemical energy in carbon compounds by photosynthesis 4.1 U.9 Autotrophs obtain inorganic nutrients from the abiotic environment.
Photoautotrophs (“self feeders”) are the primary producers, and are
usually photosynthetic (plants or algae). They use light energy to synthesize
sugars and other organic compounds.

Chemoautotrophs utilizing inorganic compounds (without the aid of Sunlight)
such as hydrogen sulfide, sulfur, ammonium, and ferrous iron as reducing agents, and
synthesize organic compounds.

trophic levels
Show feeding
relationship.
Consumers (Can not make there own food)
ingest organic matter which is living or recently killed in the
food chains show below.

DecomposersTwo Types
• Detritivores (Ingest, then digest) ingests non-living organic matter
decomposing plant and animal parts as well as feces
• Saprotrophs (Digest first, then absorb) live in or on non-living matter,
secreting digestive enzymes into it and absorbing digestive products
SaprotrophsDetritivores
4.1 U.5 Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
4.1 U.6 Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.
Sow Bug Mushroom

4.2 U.3 Chemical energy in carbon compounds flows through food chains by means of
feeding C.2 U.1 Most species occupy different trophic levels in multiple food chains.
Trophic Levels: There are several hierarchical levels in an ecosystem, comprising
organisms that share the same function, the same nutritional relationship to the primary
sources of energy. Energy transfers from one organism to another are very inefficient.
Producer organisms (such as grass use radiation from the sun to make their food) and
ending at the top predator species (like a Lion), detrivores (like earthworms or woodlice),
or decomposer species (such as fungi or bacteria).

4.2 U.3 Chemical energy in carbon compounds flows through food chains by means of feeding C.2 U.1 Most species occupy different trophic levels in multiple food chains.
Chemical energy in carbon compounds flows through food chains by means of feeding.
•1º consumers feed on the producers. Only around 10%-20% of the energy from the producer is
passed on to the 1º consumers. The rest of the energy is lost as heat through cell respiration,
death and waste.
•2º consumers feed on the 1º consumers. Again only 10%-20% of the energy is passed on to the
next level, with the rest lost as heat through respiration, death, and waste.
•3º consumers feed on 2º consumers. 10%-20% is passed on to the tertiary consumer and the
rest is lost as heat, death and waste.

Energy transfer between trophic levels
is typically only 10% efficient
• Production efficiency:
only fraction of the
energy stored in food
pass to next level of
consumer
• Energy used in
respiration is lost as
heat
• Energy flows (not cycle!)
within ecosystems

4.2 U.7 Energy losses between trophic levels restrict the length of food chains and the
biomass of higher trophic levels.
Energy decreases in each successive
trophic level

Energy Flow Through
Ecosystems
4.2 U.7 Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels.

4.2 U.4 Energy released from carbon compounds by respiration is used in living organisms and converted to heat.
• Organisms need cellular energy for
cellular activities (MR. H GREN)
• ATP provides the energy needed for
these cellular activities
• ATP is produced through cellular
respiration, is an exothermic (heat is
produced as a waste product) and the
energy released is used in endothermic
phosphorylation reactions to create
ATP.
• ATP can be used quickly for the cellular
activities listed above.
• These reactions are 38% efficient,
therefore some of the energy produced
in these oxidation reactions is lost as
heat.
• *Burning gas in your car to move it
is about 25% efficient

4.2 U.5 Living organisms cannot convert heat to other forms of energy.
• Organisms can perform a variety of
energy conversions, such as light to
chemical energy during
photosynthesis, chemical energy to
KE during muscle contractions, chemical
energy to electrical energy in nerve
impulses and chemical energy to heat
energy in heat-generating adipose tissue
• Organisms cannot turn heat
energy into any other forms of
energy
• Heat resulting from cellular respiration
makes an organism warmer. Cold-
blooded organisms can become more
active, while warm blooded animals can
increase their rate of heat generation in
order to maintain their in internal body
temperature
• Eventually though, since heat passes
from warmer to colder bodies, all heat is
lost from the ecosystem

Energy Pyramid
•The greatest amount of energy in a community is present in the organisms that
make up the producer level.
•Only a small portion of this energy is passed on to primary consumers, and only a
smaller portion is passed on to secondary consumers (on average, only about 10%
of the energy).
•A pyramid of energy can be used to illustrate the loss of usable energy at each
feeding level.
4.2 S.1 Quantitative representations of energy flow using pyramids of energy.

I: food ingested by a consumer
A: a portion is assimilated across the
gut wall, convert nutrient to body
biomass (digestion, absorption)
E: remainder is expelled from the
body as waste products (egested
energy). animal excrete small portion
as nitrogen-containing compounds
(as ammonia, urea, uric acid)
(excreted energy)
R: of the energy assimilated, part is
used for respiration (respired
energy)
P: remainder goes to production
(new growth and reproduction)
C.2 U.3 The percentage of ingested energy converted to biomass
is dependent on the respiration rate.
Energy use is a complex process. Not all consumers have the same efficiency
A simple model of energy flow through consumer

Less then 0.5% of the Suns energy is converted into biomass. Only 5%
to 20% of that assimilated energy passes between trophic levels
Gross production: is the energy converted by plants into biomass
Net production: is the energy available to the heterotrophic component of the ecosystem
minus plant respiration during metabolic activities.
C.2 U.3 The percentage of ingested energy converted to biomass
is dependent on the respiration rate.
Net Production (NP) = Gross Production (GP) – Respiration (R)
or
NP = GP – R
Units = kJ m-2
year-1
Example: Calculate the values of net production using the equation above
•Gross Production = 809 kJ/m2
yr
•Respiration = 729 kJ/m2
yr
809-729 = 80
•Net Production = 80 kJ/m2
yr

C.2 U.3 The percentage of ingested energy converted to biomass is
dependent on the respiration rate.

1. High primary
productivity (by
producers) means
more energy is
available to the
ecosystem.
3. Higher the primary productivity and greater the
effeciency of energy transfer mean that more energy is
available at high trophic levels. This can support longer
the food chains, hence and more trophic levels
increasing net productivity. Ecosystems rarely have
more than 4 or 5 trophic levels.
2. The higher the
efficiency of
energy transfer
between trophic
levels the higher
the net productivity.
Energy transfer is
typically 10%.
Reasons for high net productivity of an
ecosystem
(4 trophic levels)
(5 trophic levels)

source of data:
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/NetProductivity.html
To understand
why analyze the
energy pyramids
of the different
ecosystems.
Net productivity of different ecosystems varies greatly

A food web is a diagram that shows how food chains are linked together into
more complex feeding relationships within a community. There can be more
than one producer in a food web, and consumers can occupy multiple positions
(trophic levels)
C.2 U.2 A food web shows all the possible food chains in a community.

Factors controlling a ecosystem
II.Nutrients (Closed
System)

I. Nutrient Cycles Through EcosystemsI. Nutrient Cycles Through Ecosystems
•Biogeochemical cyclesBiogeochemical cycles are cycles of matter
between the abiotic and the biotic components of
the environment
The carbon, nitrogen, and phosphorus cycles are
central to life on Earth
Carbon and nitrogen cycles have atmospheric
components, and cycle on a global scale
Phosphorus has no atmospheric component, and
cycles on a local scale
4.1 U.10 The supply of inorganic nutrients is maintained by nutrient cycling. C.2 U.5 In closed ecosystems energy but not matter is exchanged with the surroundings.

Energy Vs. Matter
•Energy is TRANSFERRED
– One-way flow of energy through food-chains and food webs.
• Energy from sun goes to plants, which then goes to consumers.
– Each trophic level loses ~90% of energy as heat.
– Only 10% of energy is used for life processes.
•Matter is TRANSFORMED
– This is why we have biogeochemical cycles.
– Only have a given amount of matter because Earth is a closed
ecosystem.
C.2 U.5 In closed ecosystems energy but not matter is exchanged
with the surroundings.

Very few types of organism play a role in
the cycling of nutrients
Saprotrophic Bacteria
cycle Nitrogen
Fungi Cycle Carbon

Carbon cycling
• Essential idea: Continued availability of carbon in
ecosystems depends on carbon cycling.

Carbon Cycle *
• The exchanged of
the element carbon
within the
biosphere. Or
geosphere,
hydrosphere, and
atmosphere of the
Earth.
• Carbon
interconnected by
pathways of
exchange with
these reservoirs is
mainly through
plants .

Remember what plantsplants
need…
4.3 U.1 Autotrophs convert carbon dioxide into carbohydrates and
other carbon compounds.
To make carbohydrates

4.3 U.3 Carbon dioxide diffuses from the atmosphere or water into autotrophs
• Autotrophs use carbon
dioxide for photosynthesis,
as the CO2 is depleted by the
autotroph, the concentration of
CO2 in the surrounding
atmosphere or water is greater
than inside the autotroph;
therefore a concentration
gradient is created
• Carbon dioxide diffuses
into the autotroph,
following the concentration
gradient created
• In aquatic organisms carbon
dioxide can diffuse directly into
the autotroph as all parts of the
plant are usually permeable to
CO2
• For land plants, carbon dioxide
diffuses through stomata
(openings on the bottom of the

4.3 U.7 Peat forms when organic matter is not fully decomposed because of
acidic and/or anaerobic conditions in waterlogged soils.
• In soils organic matter, e.g.
dead leaves, are
digested by saprotrophic
bacteria and fungi.
• Saprotrophs assimilate some
carbon for growth and release
as carbon dioxide during
aerobic respiration (requiring
O2).
• Waterlogged soils are an
anaerobic environment
leaving these organisms
unable to complete the
process.
• Large quantities of
(partially decomposed)
organic matter build up.
The organic matter is
compressed to form peat
Youtube video

• In soils organic matter, e.g.
dead leaves, are digested by
saprotrophic bacteria and
fungi.
• Saprotrophs assimilate some
carbon for growth and
release as carbon dioxide
during aerobic respiration
(requiring O2).
• Waterlogged soils are an
leaving these organisms
unable to complete the
process.
• Large quantities of (partially
decomposed) organic matter
build up. The organic matter
is compressed to form peat
• Digging Peat

http://commons.wikimedia.org/wiki/File:Coal_lump.jpg
The peat is compressed and heated over millions years eventually
becoming coal.
4.3 U.8 Partially decomposed organic matter from past geological eras was
converted either into coal or into oil and gas that accumulate in porous rocks.

4.3 U.7 Peat forms when organic matter is not fully decomposed because of
acidic and/or anaerobic conditions in waterlogged soils.
Saprotrophs assimilate some carbon for
growth and release as carbon dioxide during
aerobic respiration.
Aerobic respiration
requires oxygen
Waterlogged soils are an
Partial
decomposition
causes acidic
conditions
saprotrophs and
methanogens [4.3.U5] are
inhibited
Organic matter is only
partially decomposed
Large quantities of
(partially decomposed)
organic matter build up.
The organic matter is
compressed to form peat
http://commons.wikimedia.org/wiki/File:Peat-bog-Ireland.jpg
Organic matter

Coal Formation
•Increases in Artic ice formation, lead
to a reduction in sea-level during
the Carboniferous period.
•Lower sea level conditions created
costal swamps along all the
continents
•Trees appear in fossil record during
this period. Tree are able to grow
taller due to a new polysaccharide
(lignin) found in xylem tissue for the
first time.

Carboniferous
• Carboniferous period extended from 359 million years ago, to the
about 299.
• A time of glaciation, low sea level and mountain building. With many beds of
coal were laid down all over the world during this period.
• History’s Most Powerful Plant
4.3 U.8 Partially decomposed organic matter from past geological eras was converted either
into coal or into oil and gas that accumulate in porous rocks.

Carboniferous period
• The world’s large coal deposits
occurred during this time
period
Two factors
1. The appearance of bark-
bearing trees (containing bark
fiber lignin).
2. Lower sea levels
• Development of extensive
lowland swamps and forests.
• Large quantities of wood were
buried during this period.
• Animals and decomposing
bacteria had not yet evolved
that could effectively digest
the new lignin.

Basidiomycetes (fungi)
• Appear 290 million years ago. They can degrade it Lignin. The
substance is insoluble, to heterogeneous because of specific
enzymes, and toxic, they are one of the few organisms that can.
http://andreas-und-angelika.de/galleries/andreas/2014-
05_Autumn_Colours/photos/aka-Autumn-Colours-2014-04-
19__D8X7633.jpg

4.3 U.9 Carbon dioxide is produced by the combustion of biomass and
fossilized organic matter.
Fossil/Biomass fuel + O2 → CO2 + H2O
• When organic compounds rich in hydrocarbons are heated and
reach their ignition temperature in the presence of oxygen they
undergo combustion(burning). This is an oxidation reaction.
• The products of combustion are carbon dioxide and water

4.3 U.4 Carbon dioxide is produced by respiration and diffuses out of
organisms into water or the atmosphere.

4.3 U.5 Methane is produced from organic matter in anaerobic conditions by
methanogenic archaeans and some diffuses into the atmosphere or accumulates in
the ground.
• Methane is produced in anaerobic
conditions as a waste product by
bacteria (methanogenic
archaeans) who use organic acids
and alcohol to
produce acetate, carbon
dioxide and hydrogen, which is in
turn used to produce methane as a
waste product. These reactions
occur without oxygen in swamps,
wetlands and mangroves, in mud
along the banks of rivers and lakes,
and in the digestive tracts of
mammals and termites.
• In addition, large herds of domestic
cattle and sheep being raised
worldwide produce methane, which
is contributing to the greenhouse
effect http://pre13.deviantart.net/d828/th/pre/i/2012/156/0/e/herd_of_cows_by_yuvez
a-d52e16l.jpg

4.3 U.6 Methane is oxidized to carbon dioxide and water in the atmosphere.
• Methane is the main ingredient in natural gas. When you burn
methane the reaction involves oxygen gas from the
atmosphere to produce carbon dioxide and water
• When methane is actually released into the atmosphere
through the anaerobic reactions, it can persist in the
atmosphere for about 12 years, as it is naturally oxidized
by monatomic oxygen (O) and hydroxyl radicals (OH-
)
• This is why methane concentrations are not very great in the
atmosphere, even though large amounts are produced

4.3 U.10 Animals such as reef-building corals and Mollusca have hard parts
that are composed of calcium carbonate and can become fossilized in
limestone.
Some animals secrete
calcium carbonate
(CaCO3) structures to
protect themselves:
•Shells of mollusks
•Hard corals
exoskeletons

http://www.discoveringfossils.co.uk/chalk2.jpg http://www.discoveringfossils.co.uk/ammonite_nautilus.jpg
4.3 U.10 Animals such as reef-building corals and Mollusca have hard parts
that are composed of calcium carbonate and can become fossilized in
limestone.
• Hard corals produce their exoskeletons by secreting calcium carbonate and
mollusks have shells that contain calcium carbonate
• The calcium carbonate in alkaline or neutral conditions from a variety of
these organisms, settle onto the seafloor when they die
• Through lithification, these sediments form limestone. The hard parts of
many of these animals are visible as fossils in the limestone rock

4.3 U.2 In aquatic ecosystems carbon is present as dissolved carbon
dioxide and hydrogen carbonate ions.
CO2 + H2O → H2CO3 → H+
+ HCO3
–
CO2 + H2O → H2CO3 → H+
+ HCO3
–
• Carbon dioxide dissolves in water and some of it will remain as a dissolved
gas
• Some of the carbon dioxide will combine with water to form carbonic acid
CO2 + H2O <--> H2CO3.
• Carbonic acid can then disassociate to form H+
and HCO3
-
(H2CO3 <-->HCO3
−
+ H+
)
• This is reaction causes the pH decreases acidifying the ocean.
• Acidification of the water in the ocean and in rain reacts to release CO2 back
into the atmosphere.

Carbon Cycle
4.3 S.1 Construct a diagram of the carbon cycle.
Carbon cycle diagrams vary greatly in the detail they contain. This one shows not only the sinks
and the flows, but also estimates carbon storage and movement in gigatons/year.

4.3.S.1 Construct a diagram of the carbon cycle.
http://commons.wikimedia.org/wiki/File:Diagram_showing_a_simplified_representation_of_the_Eart
h%27s_annual_carbon_cycle_%28US_DOE%29.png
Carbon cycle diagrams vary greatly in the detail they contain. This one shows not
only the sinks and the flows, but also estimates carbon storage and movement in
gigatons/year.

You need to be able to produce a simplified carbon cycle. Use the
following sinks and flows (processes) to build a carbon cycle:
CO2 in the atmosphere
and hydrosphere
(oceans)
Carbon
compounds in
fossil fuels
Carbon compounds in
producers
(autotrophs)
Carbon compounds
in consumers
Carbon compounds
in dead organic
matter
Key:
Sink
Flux
n.b. some of the fluxes will need to be used more than once.
Cell
respiration
Photosynthesis
Combustion
Feeding
Egestion
Death
Incomplete
decomposition &
fossilisation

and hydrosphere (e.g.
oceans)
Carbon
compounds in
fossil fuels
Carbon compounds in
producers
(autotrophs)
Carbon compounds
in consumers
Carbon compounds
in dead organic
matter
Key:
Sink
Flux
Cellrespiration
Photosynthesis
Combustion
Feeding
Egestion
Death
Incomplete
decomposition &
fossilisation
Cell
respiration
Combustion
Cell
respiration Feeding
Death
Feeding

oceans)
Carbon
compounds in
fossil fuels
Carbon compounds in
producers
(autotrophs)
Carbon compounds
in consumers
Carbon compounds
in dead organic
matter
Key:
Sink
Flux
Cellrespiration
Photosynthesis
Combustion
Feeding
Egestion
Death
Incomplete
decomposition &
fossilisation
Cell
respiration
Combustion
Cell
respiration Feeding
Death
Feeding
Use the video to help
practise your drawing skills*
*this is a good resource, but there is one mistake in the video –
carbon is egested, when not digested by an organism, not
excreted.

4.3.S1 Construct a diagram of the carbon cycle.
oceans)
Carbon
compounds in
fossil fuels
Carbon compounds in
producers
(autotrophs)
Carbon compounds
in consumers
Carbon compounds
in dead organic
matter
Key:
Sink
Flux
Cellrespiration
Photosynthesis
Combustion
Feeding
Egestion
Death
Incomplete
decomposition &
fossilisation
Cell
respiration
Combustion
Cell
respiration Feeding
Death
Feeding
Extend your understanding:
1.Between which sinks would you add a flux showing volcanoes and the
weathering of rocks?
2.What additional sink would you add to show the role of corals and shellfish?
What additional flux would be needed?
3.In some environments water is unable to drain out of soils so they become
waterlogged and anaerobic. This prevents the decomposition of dead organic
matter forming peat deposits [4.3.U7]. Peat can be dried and burnt as a fuel.
Suggest how peat could be added to the carbon cycle.
4.Explain why fossil fuels are classified as non-renewable resources when the
carbon cycle indicates they are renewed (hint: refer to the pictorial carbon
cycle).
5.Diffusion is a flux that moves CO2 from the atmosphere to the hydrosphere
and back again. Taken together these fluxes are largest in the cycle suggest
why.

oceans)
Carbon
compounds in
fossil fuels
Carbon compounds in
producers
(autotrophs)
Carbon compounds
in consumers
Carbon compounds
in dead organic
matter
Key:
Sink
Flux
Cellrespiration
Photosynthesis
Combustion
Feeding
Egestion
Death
Incomplete
decomposition &
fossilisation
Cell
respiration
Combustion
Cell
respiration Feeding
Death
Feeding
The reminder of this presentation adds
detail and understanding to the carbon
cycle you have just learnt to draw.

C.2 A.1 Conversion ratio in sustainable food production practices.
In commercial (animal) food production, farmers measure the food conversion ratio
(FCR). It is a measure of an animal's efficiency in converting feed mass into the desired output.
For dairy cows, for example, the output is milk, whereas animals raised for meat, for example,
pigs the output is the mass gained by the animal.
mass of the food eaten (g)
(increase in) desired output (g)
(per specified time period)FCR =
http://en.wikipedia.org/wiki/Feed_conversion_ratio
Animal FCR
Beef Cattle 5 - 20
Pigs 3 - 3.2
Sheep 4 - 6
Poultry 1.4 - 2
Salmon 1.2 - 3
The lower the FCR the more efficient
the method of food production.
It is calculated by:

Essential idea: Soil cycles are subject to disruption.
C.6 The nitrogen and phosphorus cycles

Statement Guidance
C.6 U.1 Nitrogen-fixing bacteria convert atmospheric nitrogen to
ammonia.
C.6 U.2 Rhizobium associates with roots in a mutualistic relationship.
C.6 U.3 In the absence of oxygen denitrifying bacteria reduce nitrate in the
soil.
C.6 U.4 Phosphorus can be added to the phosphorus cycle by application
of fertilizer or removed by the harvesting of agricultural crops.
C.6 U.5 The rate of turnover in the phosphorus cycle is much lower than
the nitrogen cycle.
C.6 U.6 Availability of phosphate may become limiting to agriculture in the
future.
C.6 U.7 Leaching of mineral nutrients from agricultural land into rivers
causes eutrophication and leads to increased biochemical oxygen
demand.
C.6 A.1 The impact of waterlogging on the nitrogen cycle.
C.6 A.2 Insectivorous plants as an adaptation for low nitrogen availability
in waterlogged soils.
C.6 S.1 Drawing and labelling a diagram of the nitrogen cycle.
C.6 S.2 Assess the nutrient content of a soil sample.

Nitrogen is a key element in amino acids. Without nitrogen, a plant cannot make
amino acids. Without amino acids, a plant cannot synthesize proteins. Without
proteins, the plant cannot make new cells required for growth and repair.

Nitrogen Cycle
Key Chemical Ingredient: amino acids/proteins
• Earth’s atmosphere 80% nitrogen; unavailable to plants; cannot assimilate
• Nitrogen available to plants as
1. Ammonia (NH3)
2. Ammonium (NH4
+
)
3. Nitrate (NO3)
• Bacteria are essential to the nitrogen cycle
• Nitrogen gas in the atmosphere is very abundant, but is such a stable
molecule that bacteria are needed to break it apart and this process
consumes much energy
• Nitrogen enters ecosystems by atmospheric deposition (5-10%) or
Nitrogen fixation
• NH4
+
& NO3added to soil: dissolved in rain or fine dust (particulates)

Steps in Nitrogen CycleSteps in Nitrogen Cycle
• Five steps are involved in the nitrogen cycle
1. Nitrogen fixation Nitrogen must be fixed in order to be used
by plants, its atmospheric form (Rhizobium/Azotobacter).
2. Ammonification Ammonia (NH3) is made by decomposing
bacteria (Azotobacter/Rhizobium).
3. Nitrification For those plants who refuse to settle with
ammonia, they undergo nitrification. Bacteria (Nitrobacter )
convert most of the ammonia in soil to nitrite ions (NO3
-
)
4. Assimilation This is when plants absorb the substances
dropped off by nitrogen fixation and nitrification.
5. Denitrification If the nitrate ions choose not to assimilate
they leave the soil and are converted by specialized anaerobic
bacteria (Paracoccus) in water-logged soil, swamps, lakes back
into the atmosphere.

C.6 U.1 Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia.

http://commons.wikimedia.org/wiki/File:French_bean_plant_from_lalbagh_2336.JPG
• The Rhizobium and
Azotobacter bacteria
supply ammonia (fixed
from atmospheric
nitrogen) to the legume.
• The legume requires
ammonia for the synthesis
of amino acids.
• Removing nitrogen from
the air. Legume supplies
carbohydrates (glucose)
to the Azotobacter
bacteria. The bacteria use
the carbohydrates for
processes such as
respiration.
*Mutualism describes relationships between
organisms in which both organisms benefit.

http://commons.wikimedia.org/wiki/File:Nitrogen-
fixing_nodules_in_the_roots_of_legumes..JPG
• Rhizobium are
free-living in the
soil whereas
bacteria are often
not free-living but
live in a close
symbiotic
association in the
roots of plants such
as the legume
family.
• Legumes and the
Rhizobium grow
together to form
nodules on the
roots of the
legume.

C.6 U.3 In the absence of oxygen denitrifying bacteria reduce nitrate in the soil.
• Electron transport is a key
process in cellular respiration
• Oxygen or nitrate can be used
as an electron acceptor in
electron transport.
• Though oxygen is preferred in
oxygen poor conditions nitrate
is used and the process
releases nitrogen gas a product.
Denitrification reduces the availability of nitrogen compounds to
plants.
Nitrate (NO3
-
) Nitrogen (N2)
A chemical reduction process
carried out by bacteria
e.g. Paracoccus
http://microbewiki.kenyon.edu/index.php/File:P._Cloroaphis.jpg

C.6 A.1 The impact of waterlogging on the nitrogen cycle.
http://www.hampshirecam.co.uk/feb909_2.html

http://soer.justice.tas.gov.au/2009/image/1076/lan/id1076-p-SoilDegradationWaterlo-l.Jpg
• Soil can become inundated by water, waterlogged, through flooding or
irrigation with poor drainage.
• Waterlogging reduces the oxygen availability in soils.
• This encourages the process of denitrification by bacteria, e.g. Paracoccus.
• n.b. excess water in the soil also leads to greater leaching of nutrients, which leads
to nutrient enrichment of rivers and lakes and therefore to eutrophication.

C.6 A.2 Insectivorous plants as an adaptation for low nitrogen
availability in waterlogged soils.
http://botany.org/Carnivorous_Plants/
Drosera sp. - the Sundews
Find out more
• Modified leaves have evolved to trap insects.
• Enzymes are secreted to (extracellular) digest
the animal.
• The products of digestion are absorbed by the
modified leaves.
“Carnivorous plants have the most bizarre
adaptations to low-nutrient environments.
These plants obtain some nutrients by
trapping and digesting various invertebrates,
and occasionally even small frogs and
mammals. Because insects are one of the
most common prey items for most
carnivorous plants, they are sometimes called
insectivorous plants. It is not surprising that
the most common habitat for these plants is
in bogs and fens, where nutrient
concentrations are low but water and
sunshine seasonally abundant.”

http://i.telegraph.co.uk/multimedia/archive/01464/plant-5_1464520i.jpg
Insectivorous plants cannot be truly considered carnivorous as only nitrogen compounds
are absorbed. The plant still obtains it’s energy from light via photosynthesis.

adapted from: http://commons.wikimedia.org/wiki/File:Nitrogen_Cycle.jpg#mediaviewer/File:Nitrogen_Cycle.svg
On this diagram the pools (boxes) and fluxes (arrows) have been drawn on already. Add in the
processes and state the bacteria related to the some of the processes.
Rhizobium
free-living
nitrogen-fixing
bacteria in the
soil
Azotobacter
Mutualistic nitrogen-fixing
bacteria in root nodules
Nitrification (x2)
Nitrosomonas
Nitrobacter
Uptake (by active transport)
and assimilation by plants
Natural nitrogen
fixation by lightning
Application of fertilizers
containing nitrogen (fixed
by the Haber process)
Transfer by
the food
chain
Denitrification
Pseudomonas
Death &
decomposition
Ammonification
Excretion

free-living nitrogen-
fixing bacteria in the soil
Azotobacter
Mutualistic
nitrogen-fixing
bacteria in
root nodules
Nitrification
Nitrobacter
Uptake (by active
transport) and
assimilation by
plants
Natural
nitrogen
fixation by
lightning
Application of
fertilizers
containing
nitrogen (fixed by
the Haber process)
Transfer by
the food
chain
Denitrification
Pseudomonas
Death &
decomposition
Ammonification
Excretion
Nitrification
Nitrosomonas
Rhizobium

Essential idea: Soil cycles are subject to disruption.
We consume phosphorus through food produced with fertilizers. The women above is spreading
phosphorus by hand in her rice paddy to increase production..
Phosphorus cycles
http://www.futureearth.org/blog/2014-oct-16/can-we-build-sustainable-phosphorus-governance

C.6 U.4 Phosphorus can be added to the phosphorus cycle by application of
fertilizer or removed by the harvesting of agricultural crops.
• Phosphate is mined and
converted to phosphate-
based fertilizer – this
increase the rate of
turnover.
• The fertilizer is then
(transported great
distances and) applied to
crops . The processes
remove phosphorus from
the cycle in one location
and adds it to another.

C.6 U.5 The rate of turnover in the phosphorus cycle is much lower than
the nitrogen cycle.
http://commons.wikimedia.org/wiki/File:Phosphorus_cycle.png

C.6 U.5 The rate of turnover in the phosphorus cycle is much
lower than the nitrogen cycle.
The phosphorous cycle shows the various different forms in which phosphorous can
naturally be found.
•Certain rocks, e.g. Phosphorite, contains high levels of phosphate minerals.
Weathering of these rocks releases phosphates into the soil. Phosphates
are a form of phosphorus that can is easily be absorbed by plants entering the food
chains.
•The rate of turnover is relatively slow, compared with Nitrogen, as phosphate is
only slowly released to ecosystems by weathering.
•Organisms have a variety of uses for phosphate
 ATP
 DNA and RNA
 cell membranes
 skeletons in vertebrates

C.6 U.6 Availability of phosphate may become limiting to agriculture in the future.
• The demand for artificial fertilizer
in modern intensive farming is very
high.
• Consequently phosphate mining is
being carried out at a much faster
rate than the rocks can be
naturally formed and hence
replenished.
Impacts to agriculture of reduced
phosphate production are
potentially great.
• There are no sources of phosphate
fertilizer other than mining
minerals.
• There is no synthetic way of
creating phosphate fertilizers*,
though this may change in the
future.
*Yields per unit of farmland
would plummet without the
*Unlike ammonia which can be created by the
industrial conversion of plentiful supplies of
atmospheric nitrogen.
http://commons.wikimedia.org/wiki/File:Crop_spraying_near_
St_Mary_Bourne_-_geograph.org.uk_-_392462.jpg

http://commons.wikimedia.org/wiki/File:Phosphateproductionworldwide.svg
The graph is based on US Geological Survey data and shows world phosphate
production from mining.
World production has
varied greatly, but
overall there have been
smaller increases to
production after than
before 1980.
As the reserves of phosphate rock are depleted the production of phosphorous is likely to peak
and then decline. Though some sources the peak is likely to occur in in the next 30 years it is
difficult to judge particularly due to the fact new phosphate mineral deposits are still being
discovered.
millions of
Metric tons
C.6 U.6 Availability of phosphate may become limiting to agriculture in the
future.

C.6 U.7 Leaching of mineral nutrients from agricultural land into rivers causes
eutrophication and leads to increased biochemical oxygen demand.
• Rainfall leaches water-soluble
nutrients (e.g. phosphates,
ammonia and nitrates) from the
soil and carries them into rivers
and lakes.
• The nutrients can come either
from artificial fertilizers, natural
fertilizer such as manure or the
urine of livestock.
• Poorly drained, or waterlogged
soils encourages leaching of these
materials.
• An increase in nutrients in aquatic
ecosystems leads to
eutrophication a negative
environmental effect that could
include hypoxia, the depletion of
oxygen in the water, which may
cause death to aquatic animals.
Bellport Bay

http://commons.wikimedia.org/wiki/File:Potomac_green_water.JPG
An increase in nutrients in aquatic ecosystems leads to eutrophication

C.6 U.7 Leaching of mineral nutrients from agricultural land into rivers causes eutrophication
and leads to increased biochemical oxygen demand.
Red tide on Long Island has lead to eutrophication.

In summary:
•Algal growth is normally limited by the availability of nutrients such as
nitrates and phosphates
•Rapid growth in the algal populations occurs, these increases are called ‘algal
blooms’ also leading to an increase so naturally does the numbers of dead
algae
•the numbers of (saprotrophic) bacteria and microbes that feed on the dead
algae also increase
•an increase in biochemical oxygen demand (BOD) by the saprotrophic
bacteria results in deoxygenation of the water supply (reduced dissolved O2)
The consequences to organisms of low levels of dissolved oxygen:
•death or emigration of oxygen sensitive organisms (e.g. fish)
•proliferation of low dissolved O2 tolerant organisms
•reduction of biodiversity
•decrease in water transparency, i.e. an increase in turbidity stresses
photosynthetic organisms …
•… this in turn will affect the whole food chain
•increased levels of toxins and greater numbers of pathogens means affected
water is no longer suitable for bathing or drinking

C.6 S.2 Assess the nutrient content of a soil sample.
• A soil test will assess the present levels of major plant nutrients, soil
pH, micronutrients and provide an estimate of total soil lead.
• Once complete, recommendations will include the amounts of
limestone and fertilizer, if necessary, to meet the requirements of the
specific plant or crop being grown. If elevated soil lead levels are
indicated, appropriate information will be included with your results
to address this problem.

C.2 A.2 Consideration of one example of how humans interfere with nutrient cycling.
Humans practices can accelerate the flow of matter into and out of ecosystems.
This by implication (and often design) alters the nutrient cycling in ecosystems.
Biomass removed
during harvest from
the ecosystem
Phosphates and nitrates
run off adds to adjacent
aquatic ecosystems
Phosphates
added to the
agricultural
ecosystem
phosphates
added
to
the
agricultural
ecosystem
Phosphate
mined and
converted to
fertilizer.
Nitrate fertilizer
produced from
atmospheric
Nitrogen
(by the Haber process)
Agriculture
Harvesting of
crops
Water run-off
(leaching) from
agricultural fields
results in build-up of
phosphates and
nitrates in
waterways and leads
to eutrophication.

C.2 S.5 Investigation into the effect of an environmental disturbance on an
ecosystem.
Environmental disturbances are caused by natural or artificial
disruptions to a normal ecosystem, including:
•Fire breaks in bush lands or regions damaged by bushfires
•Outer boundaries of population settlements or regions bordering roads
•Dams and artificial rivers and creeks (e.g. irrigation sites)

ecosystem.
The effect of an environmental disturbance on an ecosystem can be
measured in a number of ways:
•Population density Species diversity and richness
•Presence and distribution of indicator species Canopy coverage and relative light
intensity
•Biomass
•Edaphic factors such as soil erosion (via depth), water retention (via drainage), pH and
nutrient content
Lost of topsoil due to mud slide Over hunting of a species

ecosystem.
Your investigation should compare a site undergoing secondary succession with a primary
ecosystem. This can be extended to look at the various stages of secondary succession if local
sites allow.
Ways of measuring the affect of
succession include:
•Species diversity
•Stem/Seedling density
•Biomass
•Canopy coverage / light
intensity at the surface
•Depth/Volume of leaf litter
•Soil nutrient levels
https://khorra.files.wordpress.co
m/2013/02/moving-glacier.jpg

Some Agents of Disturbance
•Fire
•Floods
•Drought
•Large Herbivores
•Storms
•Volcanoes
•Human Activity
C.2 U.6 Disturbance influences the structure and rate of change within
ecosystems.
Disturbances are events such as floods, fire, droughts,
overgrazing, and human activity that damage communities,
remove organisms from them, and alter resource availability

Primary Succession
•Begins in a place without any soil:
Sides of volcanoes
Landslides
Flooding
•First, lichens that do not need soil
to survive grow on rocks
•Next, mosses grow to hold newly
made soil
•Known as PIONEER SPECIES
Ecological Succession
•Natural, gradual changes in the types of species that live in an area
•Can be primary or secondary
•The gradual replacement of one plant community by another over time
ecosystems.

Secondary Succession
•Begins in a place that already has soil and was once the home of living
organisms
•Occurs faster and has different pioneer species than primary
succession
•Example: after forest fires
ecosystems.

Climax Community
•A stable group of plants and animals that is the end result of the
succession process
•Does not always mean big trees
– Grasses in prairies
– Cacti in deserts
ecosystems.

C.2 S.4 Analysis of data showing primary succession.
Use the examples to analyze data showing primary succession
http://wps.pearsoncustom.co
m/wps/media/objects/2128/21
79441/28_03.html

Biome is a geographical area that has a particular climate and sustains a specific
community of plants and animals (i.e. a type of ecosystem)
Biosphere is the total of
all areas where living things
are found (i.e. the totality of
biomes)
• The main factors affecting the distribution of biomes is temperature and rainfall
• These factors will vary according to latitude and longitude, elevation and proximity to the sea
• Temperature is influential because it affects the rate of metabolism – the phases in the life cycles
of many organisms are temperature dependent
• In the same way, the availability of fresh water (both in the soil and in rivers and lakes) is critical
to the growth and nutrition of organisms
• Rainfall and warmer temperatures are more common near the equator and less common at the
poles
http://ib.bioninja.com.au/options/option-g-ecology-and-conser/g2-ecosystems-and-biomes.html
C.2 S.2 Analysis of a climograph showing the relationship between
temperature, rainfall and the type of ecosystem.

The six major types of biome/ecosystem are outlined in the table below
Biome Temperature Rainfall Vegetation
Desert Hot (>30o
C)in the day
Cold (<0o
C) at night
Low Precipitation
Less than 30cm per year
Xerophytes
Adapted to water
conservation
Grassland Warm (20o
C-30o
C) Seasonal Droughts
Medium amount of rain
Grass with widely spaced
trees
Fires prevent trees from
invading
Shrub land Moderate (20o
C-30o
C) Rainy winters, dry
summers
Dry, woody shrubs
Regrow quickly
Coniferous Forrest
(Taiga)
Cold (0o
C-15o
C) Low Precipitation
Wet due to lack of
evaporation
Epiphytes, tall trees and
undergrowth
Large diversity in species
Tropical Rainforest Hot (20o
C-30o
C) High Precipitation
Over 250cm per year
Tundra Freezing (<0o
C) Little Precipitation Small close to the ground
(e.g. mosses)
Perennial plants grow in
the summer

The six major types of biome/ecosystem are outlined in the table below
Biome Temperature Rainfall Vegetation
Desert Hot (>30o
C)in the day
Cold (<0o
C) at night
Low Precipitation
Less than 30cm per year
Xerophytes
Adapted to water
conservation
Grassland Warm (20o
C-30o
C) Seasonal Droughts
Medium amount of rain
Grass with widely spaced
trees
Fires prevent trees from
invading
Shrub land Moderate (20o
C-30o
C) Rainy winters, dry
summers
Dry, woody shrubs
Regrow quickly
Coniferous Forrest
(Taiga)
Cold (0o
C-15o
C) Low Precipitation
Wet due to lack of
evaporation
Epiphytes, tall trees and
undergrowth
Large diversity in species
Tropical Rainforest Hot (20o
C-30o
C) High Precipitation
Over 250cm per year
Tundra Freezing (<0o
C) Little Precipitation Small close to the ground
(e.g. mosses)
Perennial plants grow in
the summer
You don’t have to remember the individual biomes …

http://cispatm.pbworks.com/f/1209212862/biome_graph.jpg
n.b. The biomes in regions within the dashed line are
strongly influenced by other factors (e.g. seasonality of
drought, fire, animal grazing).
A climograph is a diagram
which shows the relative
combination of temperature and
precipitation in an area.
This modified climograph (first
developed by Robert Whittaker)
shows the stable
ecosystems/biomes that arise
as a result of the relative
combination of temperature
and precipitation.
It is a graphical representation
of the biome summary table
(last slide).

http://cispatm.pbworks.com/f/1209212862/biome_graph.jpg
n.b. The biomes in regions within the dashed line are
strongly influenced by other factors (e.g. seasonality of
drought, fire, animal grazing).
A climograph is a diagram
which shows the relative
combination of temperature and
precipitation in an area.
This modified climograph (first
developed by Robert Whittaker)
shows the stable
ecosystems/biomes that arise
as a result of the relative
combination of temperature
and precipitation.
It is a graphical representation
of the biome summary table
(last slide).
… but, you do have to be able to analyze a climatograph

http://commons.wikimedia.org/wiki/File:Nutrient_cycle.svg
Gersmehl diagrams were first developed in 1976, by P.F. Gersmehl, to show the
differences in nutrient flow and storage/loss between different ecosystems
Nutrient inputs into the ecosystem:
•Nutrients dissolved in raindrops
•Nutrients from weathered rock
Nutrient outputs (losses) from the
ecosystem:
•Nutrients lost through surface runoff
•Nutrients lost through leaching

differences in nutrient flow and nutrient storage/loss between different ecosystems
Sinks for nutrient storage:
•Biomass (flora and fauna)
•Litter
•Soil

When used to analyze a particular
ecosystem:
•Diameter of sinks are proportional
to the mass of nutrients stored in
each sink
•the thickness of the arrows are
proportional to the rate of nutrient
flow
differences in nutrient flow and storage/loss between different ecosystems
Flows between the sinks:
•Littering (including withering, defoliation,
excretion, unconsumed parts left over,
dead bodies of animals, and so on) *
•Decomposition of the litter into inorganic
nutrients, which are then stored in the soil
•Nutrient uptake by plants
Human interactions are not considered – do not
confuse littering with dropping trash
*

• Litter (pine needles)
is the main store
• Slow rate of nutrient
transfer between
stores
• Soil is the main store
• Slow rate of nutrient
transfer between
stores (except for the
transfer from
biomass to litter)
• Biomass is the main
store (soil is nutrient
poor)
• Fast rate of nutrient
transfer between
stores
tagia
(temperate forest)
desert tropical rainforest
Image source: Allott, A. (2014). Biology: Course companion. S.l.: Oxford University
Press.
C.2 S.3 Construction of Gersmehl diagrams to show the inter-relationships between nutrient
stores and flows between taiga, desert and tropical rainforest.

C.2 U.4 The type of stable ecosystem that will emerge in an area is predictable based on
climate.
• The Coral Triangle is a geographical term used to describe the region that
possesses the world’s highest levels of marine biodiversity.
• The answer to why areas like the Coral Triangle harbor the world’s highest levels
of marine biodiversity begins not with the individual organisms,. Plate tectonics,
continental drift, and the advance and retreat of glaciersbut with stable
geologic processes that began hundreds of millions of years ago.
Glacial periods have covered the Earth with ice at least 21 different
times over the past several million years. During those time ice
never reached the coral triangle creating one of the most stable climate on
Earth.

C.2 U.4 The type of stable ecosystem that will emerge in an area is predictable
based on climate.
More than 2,500 species of
fish live in the Coral Triangle,
including the largest fish -
the whale shark, and
the coelacanth. It also
provides habitat to six out of
the world's seven marine turtle
species.
This great biodiversity is
thought to be due to an
extended period of little to
no climate change

C.2 U.4 The type of stable ecosystem that will emerge in an area is
predictable based on climate.
Borneo lowland rain
forest is a tropical and
subtropical of the large
island of Borneo located in
the Coral Triangle. It
supports approximately
10,000 plant species, 380
bird species and several
mammal species, which
include the Orangutan

• A new, unoccupied habitat (e.g., a lava flow or a severe landslide) goes through a
succession of communities based on the available abiotic factors and the
interactions that occur in a communities biotic.
• A stability of a community occurs after a period of time with the habitat reaching
what is called a climax community.
4.1 U.11 Ecosystems have the potential to be sustainable over long periods of time.
These giants
Redwood trees can
live to be 2,000 years
old and have graced
the planet for more
than 240 million
years.

Mesocosms
• Small, closed-off experimental systems set up as
ecological experiments
• Can be used to test effects of varying certain conditions
on ecosystem stability as well as the sustainability of
ecosystems

Bottle Biology

Example of Quadrat Sampling
•Plot-based (quadrat) methods are often used to study
populations of different species within a certain area.
•Quadrats are generally square sample areas marked out using a
framed structure.
4.1 S.3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling

Chi-Squared Test (X2
)
• Statistical tool used to determine how far data you observe
deviates from what you expect to observe
• For Chi test, the degrees of freedom is calculated as n-1, where
n represents the total number of levels (categories)

• To obtain data for the chi-squared test, an ecosystem should be chosen in
which one or more factors affecting the distribution of the chosen species
varies. Sampling should be based on random numbers. In each quadrat the
presence or absence of the chosen species should be recorded. The
collection of raw data through quadrat sampling was done in the North
Forest. Results are below.

O equals observed
E equals expected

To find the probability value (p) associated with the obtained Chi-square statistic
a. Calculate degrees of freedom (df)
df = (#rows-1)*(#columns -1) for an association
df= (# of outcomes – 1) for a theory
b. Use table of CRITICAL VALUES for Chi-square test to find the p value.
Chi-square statistic:

No Significant association Significant association
between means between means
P >0.05 P <0.05
X2
= 0.031
Since P>0.05, The is no significant associations between the means

Chi-Squared Testing
Compare the Chi-squared value with the Critical Value
Null Hypothesis (H0) :
If the X2
< CV, then ACCEPT the Null Hypothesis
(There is NO Association between the variables)
i.e. The two species are distributed independently
Alternative Hypothesis (H1):
If the X2
> CV, then FAIL TO ACCEPT the Null Hypothesis
(There is a significant Association between the variables)…aka
ACCEPT the Alternative Hypothesis
i.e. The two species are associated (either positively so they
tend to occur together or negatively so they tend to occur apart)

4.1 S.3 Testing for association between two species using the chi-squared test with data obtained by quadrat
sampling

Factors controlling a ecosystem
II. Nutrients (Closed System)

http://therainforestguide.weebly.com/
Essential idea: Community structure is an emergent property of an ecosystem.Essential idea: Community structure is an emergent property of an ecosystem.
C.1 Species and Community

Understandings
Statement Guidance
C.1 U.1 The distribution of species is affected by limiting factors.
C.1 U.2 Community structure can be strongly affected by keystone species.
C.1 U.3
Each species plays a unique role within a community because of the
unique combination of its spatial habitat and interactions with other
species.
C.1 U.4
Interactions between species in a community can be classified
according to their effect.
C.1 U.5
Two species cannot survive indefinitely in the same habitat if their
niches are identical.
C.1 A.1
Distribution of one animal and one plant species to illustrate limits of
tolerance and zones of stress.
C.1 A.2 Local examples to illustrate the range of ways in which species can
interact within a community.
C.1 A.3 The symbiotic relationship between Zooxanthellae and reef-building
coral reef species.
C.1 S.1 Analysis of a data set that illustrates the distinction between
fundamental and realized niche.
C.1 S.2 Use of a transect to correlate the distribution of plant or animal
species with an abiotic variable.

actors affecting the distribution of species:
Plants Animals
temperature
water
light (intensity/wavelength) breeding sites
soil pH food supply
soil salinity territory
mineral nutrient availability

Temperature Water Food
Body size (specifically SA:Vol
ratio) will determine an animal's
ability to conserve heat – a large
SA:Vol ratio means that heat is
easily lost to /gained from the
environment
Apart from drinking to maintain
cells’ osmotic balance water can
be required as a habitat,
transport medium, a place to lay
eggs, a source of dissolved
oxygen, food maybe filtered from
water (e.g. corals), and as a
coolant. [See 2.2 Water for
details]
Animals maybe specialized so
that they will only consume a
particular species of animal or
plant, e.g. the caterpillars of the
Small Tortoiseshell butterfly eat
only nettle plants.
Homeotherms (organisms that
maintain a stable internal body
temperature) can colonize a
wider range of habitats than
poikilotherms (internal
temperature varies considerably)
Seasonal or geographical
variation in food directly affects
abundance of the population
Detail on how the factors affecting the distribution of animal species:

Detail on how the factors affecting the distribution of animal species:
Breeding sites Territory
Breeding sites need to provide protection
for eggs, juveniles, and nesting adults.
Animals may mark territories, e.g. by
urinating or marking trees
Sites are often rich in food or other
resources necessary for juveniles, and
breeding adults
Territories can be established by
individuals, breeding pairs or groups
Juveniles may have specialized
environmental requirements different from
the adults, e.g. dragonfly nymphs live
underwater
Territories maybe temporary (e.g. just for
the duration of breeding cycle) or
permanent
Establishment of territories can lead to
intra-specific (within species) or inter-
specific (between species) competition

Example: Water
deep-sea vent, high
temperature and
pressure, no light,
organisms are
adapted to getting
there energy from
chemicals released
from the magma.

Food Supply: hypersaline lakeNutrient poor,
water is clear, oxygen rich; little productivity by
algae, relatively deep with little surface area.
Example: Water effect on the distribution of animals deep-sea mussels living on the
"shore" of the Brine Pool (extremely salty environment). These mussels use methane as
their primary source of food, but also filter small particles from the water.
http://oceanexplorer.noaa.gov/explorations/02mexi
co/background/mussels/media/brinepool.html

Intertidal Zone: Alternately submerged and
exposed by daily cycle of tides. Often
polluted by oil that decreases biodiversity.
Example: Waters effect on the
distribution of animals in the
intertidal zone. Mussel and star fish
have adapted to an environment of
harsh extremes.
Water and salinity
levels availability varies with the
tides. Intertidal zone's have high
exposure to the sun,
the temperature range can be
anything from very hot with fullhttp://people.stfx.ca/rscrosat/b
iology311/MUSSEL_SEASTAR

Temperature Water Light
Metabolic pathways are
controlled by enzymes, which
have optimal temperatures, too
high and the enzymes will
denature
Needed to maintain cell turgor Plants that grow in shade (lower
light intensity) contain more
chlorophyll, they have darker
green leaves
High temperatures increase the
rate of evaporation (and hence
transpiration)
Needed for photosynthesis and
respiration to occur
Plants, e.g. Kelp (algae), appear
brown, not green, and have
pigments that are adapted to
absorbing the blue wavelengths
as red wavelengths do not easily
penetrate water
Xerophytes, e.g. Cacti are
adapted to low water conditions,
hydrophytes, e.g. rice, are
adapted to waterlogged soils
Detail on how the factors affecting the distribution of Plant species:

Soil pH Soil salinity Minerals nutrient
availability
pH affects the availability
of mineral nutrients, e.g.
minerals can either be
bound more strongly in the
soil or leeched from the
soil more easily at different
pHs.
High salinity either makes
uptake of water (osmosis)
by plants more difficult, or
in extremes causes water
loss
Waterlogged soils
encourage denitrifying
bacteria and lower the
nitrogen availability to
plants
pH may affect the
decomposition of organic
matter, and hence the rate
at which nutrients are
(re-)cycled and made
available to plant
Halophytes, e.g. Mangrove
trees, are adapted to high
salinity soils
Weathering of rocks often
increases the availability of
nutrients in the soil
Detail on how the factors affecting the distribution of Plant species:

Tropical Forest: Vertical stratification with trees in canopy blocking light
to bottom strata, making light the limiting factor for those plant.

Desert: Sparse rainfall (less then 30 cm per year) makes water the limiting factor,
plants and animals. Both must adapt for water storage and conservation.

Temperate Rain Forest: Old growth forests nutrients are locked into the trees
making the soil nutrient poor.

Permafrost (Permanent frozen ground), bitter cold, low rain fall,
high winds and thus no trees. Has 20% of land surface on earth .

Keystone Species Concept
•In ecological communities there are little
players and big players. The biggest players of
all are referred to as keystone species.
•A keystone species may be defined as one
whose presence/ absence, or
increase/decrease in abundance, strongly
affects other species in the community.
•Evidence usually comes from addition or
removal experiments.
Example: Kelp forests (Keystone species: Sea
Otters)
• Can grow two feet per day
• Require cool water
• Host many species – high biodiversity
• Fight beach erosion
Kelp forests threatened by
• Sea urchins
• Pollution
• Rising ocean temperatures
Removal of the keystone in the arch
will cause the structure to collapse.

Keystone Species
Sea Otters: are a keystone species
in the kelp forests. They eat many
invertebrates, but especially sea
urchins. If there are too many sea
urchins, they will eat too much of
the kelp and destroy it.

Endangered Southern Sea Otter
Keystone species: plays a role affecting many other organisms in ecosystem
specifically sea otters eat sea urchins that would otherwise destroy kelp forests
• Kelp forests provide essential
habitat for entire ecosystem
•~16,000 around 1900
•Hunted for fur and because considered competition for abalone and shellfish
•1938-2008: increase from 50 to ~2760
•1977: declared an endangered species

http://www.vanaqua.org/files/1013/2018/0738/otter-eat.jpghttps://en.wikipedia.org/wiki/Mangrove
Red mangrove: This
tree grows along the
shoreline in the tropics
and its roots protect the
soil from erosion. The
roots also offer
protection to small
animals, including reef
fish.

Keystone modifier species, such as the Grizzly bears:
As predators, bears keep down the numbers of
several species, like moose and elk. They also carry
and deposit seeds throughout the ecosystem. Bears
that eat salmon will leave their dropping and the
partially eaten remains that provide nutrients such as
sulfur, nitrogen and carbon to the soil. https://www.pinterest.com/pin/330170216403151039/

Wolves: Are a top predator, wolves
are important in many habitats.
Wolves keep deer populations in
check and too many deer will eat
small trees, which leads to fewer
trees. In turn, there would be fewer
birds and beavers and the whole
ecosystem would change.
http://www.glogster.com/keishaa2014/el-parque-nacional-yellowstone/g-6m1qgcf75nvsgkiibvrkga0

ECOLOGICAL NICHE
•It is more than just the physical place (‘address’) where a species lives,
it also includes its role in the system (its “occupation / lifestyle”). It is
its total role in the ecosystem.
•A species functional role (“place”) in a community in relation to other
species which includes
Space and territory
Nutrition and feeding habits
Interactions and relationships with other organisms
Reproductive habits
Its role and impacts in the habitat or ecosystem
C.1 U.3 Each species plays a unique role within a community because of the unique
combination of its spatial habitat and interactions with other species.

Two types of Niche’s
•Fundamental Niche: the total range of physical, chemical and biological factors a
species can utilize / survive if there are no other species affecting it
•Realized Niche: the actual mode of existence, which results from its adaptations
and competition with other species. Because species never live under ‘perfect’
conditions but where an ‘acceptable’ ECOLOGIC SUM of conditions exists.
Competition II
Competition I
Competi
tion III
Realized Niche
C.1 S.1 Analysis of a data set that illustrates the distinction between fundamental and
realized niche.

C.1 U.4 Interactions between species in a community can be classified according to their effect.
Type of Interaction Sign Effects
mutualism +/+ both species benefit
commensalism +/0 one species benefits, one is
unaffected
competition -/- each is negatively affected
predation(includes herbivory,
parasitism)
+/- one species benefits, one harmed
Types of Species Interactions
An ecological community is a group of actually or potentially interacting
species, living in the same place
A community is bound together by the network of influences that species have
on one another.
There are four main classes of two-way interactions, and many possible
pathways of indirect interaction.

Mutualism is where two members of different species benefit
and neither suffers. Examples include rumen
termite/protazoa that digest cellulose

CommensalismCommensalism is an ecological relationship, in which one species
benefits from an association with another organism, while the other
organism receives no benefit, but is not harmed

• Predation are consumers the eat other consumers. Predators have evolved to
find, catch, kill, eat and digest it prey.
Anteater Ant

• Parasitism is the relation between the host and the parasite. The parasite
gains an advantage at the cost of the host, causing harm to the host which
may lead to death. Examples of parasites are some viruses, fungi, worms,
bacteria, and protozoa.
Bass
Lamprey

Herbivory
Primary Consumers that feed only on plant material. Considered
predators of plants. These relationships can be harmful or beneficial.
Ladybug and a caterpillar are examples of herbivories

Interactions Between Species (Two types)
•Competition is when two species need the same resource such as a
breeding site or food. It will result in the removal of one of the species.
There are two major types of competition

I. Intraspecific competition A form of competition in which individuals of the
same species compete for the same resource in an ecosystem. This tends to have a
stabilizing influence on population size. If the population gets too big, intraspecific
population increases, so the population falls again.

II. Interspecific competition A form of competition in which
individuals of different species compete for the same resource in an
ecosystem.

Competitive Exclusion
•No two species in a community can occupy the same
niche
Species A niche
Species B niche
C.1 U.5 Two species cannot survive indefinitely in the same habitat if their niches are identical. C.3 U.2 Competitive exclusion and the
absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive.

Principle of Competitive Exclusion
•Where two species need the same resources and will compete until one species is
removed.
•One would be more capable of gathering more resources or reproducing more
rapidly until the other was run out of existence.
•Experiments with paramecium populations in the lab of Ecologist G.F. Gause
demonstrated this concept scientifically.
*The niche concept was investigated in some classic experiments in the 1930s
by Gause. He used flasks of different species of the protozoan Paramecium,
which eats bacteria and yeast.
C.1 U.5 Two species cannot survive indefinitely in the same habitat if their niches are identical. C.3 U.2 Competitive exclusion and the absence of
predators can lead to reduction in the numbers of endemic species when alien species become invasive.
Experiment 1

P. aureliaP. aurelia
P. caudatumP. caudatum
• Conclusion: These two species of Paramecium share the same niche, so they
compete. P. aurelia is faster-growing, so it out-competes P. caudatum.
C.1 U.5 Two species cannot survive indefinitely in the same habitat if their niches are identical.

• In the second experiment he took P. caudatum and had it compete
with a second type of Paramecia. It is important to understand the
distribution in experiment 2.
• P. caudatum lives in the upper part of the flask because only it is
adapted to that niche and it has no competition. In the lower part of
the flask both species could survive, but only P. bursaria is found
because it out-competes P. caudatum.
Experiment 2
C.1 U.5 Two species cannot survive indefinitely in the same habitat if their niches are identical.
Conclusion: These two species of Paramecium have slightly different
niches, so they don't compete and can coexist.

C.1 A.1 Distribution of one animal and one plant species to
illustrate limits of tolerance and zones of stress.
Shelford's law of tolerance
A law stating that the abundance or distribution of an organism can be
controlled by certain factors (e.g. the climatic, topographic, and biological
requirements of plants and animals) where levels of these exceed the
maximum or minimum limits of tolerance of that organism.
http://www.ic.ucsc.edu/~wxcheng/envs23/lecture8/ecosystem

C.1 A.1 Distribution of one animal and one plant species to illustrate limits of
http://imgkid.com/purple-saxifrage.shtml
Purple Mountain Saxifrage:
Melting glaciers are indicators of
climate change, but when it comes
to biodiversity in the Alps, scientists
are more concerned about the fate
of fragile mosses and flowers.
Alpine plants are one group
expected to be highly susceptible to
the impacts of climate change

C.1 A.1 Distribution of one animal and one plant species to illustrate limits of
http://www.greenglobaltravel.com/wp-content/uploads/babyseaturtles.jpg
Sea Turtles: lay their eggs on
beaches, many of which are
threatened by rising sea levels.
Climate change also threatens the
offspring of sea turtles, as nest
temperature strongly determines the
sex: the coldest sites produce male
offspring, while the warmer sites
produce female offspring.
This nest-warming trend is reducing
the number of male offspring and
seriously threatens turtle populations.

C.1 A.2 Local examples to illustrate the range of ways in which species can interact
within a community.
Atlantic Silversides: With a life cycle said to be only two years, the young of last year
are now the breeders of this year. Having reached a size of 4'' to 5'', they begin returning
to the bay in late winter. As the waters warm they travel throughout the bay and middle
estuary, breeding as they go, eventually returning on the same path till exiting for the
inlet and surf in early July followed closely by Bluefish that pursued them into the bay.
For the rest of the year it's the young of the year they left behind that will dominate the
forage fish of the bay.

C.1 A.2 Local examples to illustrate the range of ways in which species can interact
within a community.
Bluefish, ranges in the western North Atlantic from Nova Scotia and Bermuda to
Argentina. They travel in schools of like-sized individuals as warm water migrants. They
generally move north in spring and summer to centers of abundance in the New York of
the Atlantic Silversides

coral reef species.
• The relationship between the
algae and coral polyp facilitates a
tight recycling of nutrients in
nutrient-poor tropical waters.
The coral provides the algae with:
• a protected environment - coral
polyps secrete calcium carbonate
to build the stony skeletons which
house the coral polyps (and
zooxanthellae)
• compounds they need for
photosynthesis
The algae provide the coral with:
• Oxygen
• helps the coral to remove wastes
• Supplies the coral with glucose,
glycerol, and amino acids
(products of photosynthesis)

Most reef-building corals have a
mutually beneficial symbiotic
relationship with a microscopic
unicellular algae called zooxanthellae
that lives within the cells of the coral
coral reef species.
http://felixsalazar.com/pages/2013/01/macro-reef-dwellers-a-retrospective/

Random Sampling
Using Quadrats to compare the population of plant or animal
species without requiring a complete count of an area. (Saves
time with a quick estimate of the numbers of a species in an
area.)
•The validity of results obtained from the various sampling
methods is dependent upon the adoption of random sampling
techniques
•Strategies for avoiding bias through random sampling utilise a
number of approaches – these include random sampling using a
grid
•A grid is created by laying out tapes at right angles to one
another to form the axes of the gridded area
•Pairs of random numbers are used to provide the coordinates for
locating quadrats
C.1 S.2 Use of a transect to correlate the distribution of plant or animal species
with an abiotic variable.

Quadrat is a frames, constructed from wood or metal, are used to
investigate the distribution of species
Subdivided quadrat frame
for determining % cover of
species
Square quadrat frame
for determining population
densities

Transects
•A transect is a line, created with string or a tape, along which systematic sampling is
performed
•Transects are particularly useful for sampling areas where there is a transition of
species from one habitat to another as environmental conditions change
•Transect studies are used to investigate gradients such as zonation on rocky shores
and changes in the species diversity across sand dunes
•A line transect is one in which all individual organisms touching the tape/string are
recorded
•The most commonly used belt transect involves laying a tape through the area of
study and sampling the population with quadrats positioned at regular intervals
alongside the tap

Belt transect Survey of a Dune System
A belt transect was used to investigate the distribution of three
species of grass commonly found on sand dunes
The transect line stretched from the high water mark to the
inland area and 1m x 1m quadrats were used to determine the
number of individual plants of each grass species along the
profile

Present the results as a bar chart

0
10
20
30
40
50
60
70
80
90
100
0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 55-60
Distance from high water mark (m)
Numberofplantsperm
2
Sand couch grass
Marram grass
Sand fescue

Bibliography / Acknowledgments

Topic 8: Ecology Option C Part 1

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