Ecology
2
What is Ecology?
Ecology is the study of how living
things relate to each other and
to their environment
Their environment refers to all the
conditions in which the
organism lives, which affect the
growth and development of
the organism.
3
What is an Ecosystem?
An ecosystem is a community of living
organisms interacting with one another
and their non-living environment within a
particular area.
The earth itself is a true ecosystem as no
part of it is completely isolated from the
rest.
**Ecosystem = Communities + Environment
4
Diversity of ecosystems
Woodland,
Hedgerow,
Seashore,
Marine,
Grassland,
Freshwater,
Tree, etc.
Can you name some more?
Ecosystems can be very large or very
small
5
To study an ecosystem
We divide the ecosystem into a
number of smaller, more
manageable areas (habitats).
Individual habitats are then
studied.
6
What is the Biosphere?
The biosphere is that part of the
earth inhabited by living
organisms, including land, ocean
and the atmosphere in which life
can exist.
It is the global ecosystem.
7
Relationships
in the
biosphere
8
What is a Habitat?
A habitat is the particular place
within the ecosystem where an
organism lives and to which it is
adapted
As a living organism (you) what is your
Habitat, Ecosystem and Biosphere?
9
Summary
 Biosphere
= that part of the earth and its
atmosphere in which life can exist
composed of ecosystems
 Ecosystems
= composed of communities
of organisms and their environment
 Communities
= populations of different
species of organisms
 Habitats
= is the place where an
organism lives and to which it is adapted
Learning check
10
1.
What is ecology?
2.
What is an ecosystem?
3.
What is the biosphere?
4.
What is a habitat?
11
Definition of Niche
A niche is the functional role of
an organism in an ecosystem.
A niche is a term describing the
relational position of a species or
population in an ecosystem.
12
Niche Explanation (cont’d)
This includes how a population responds to
the abundance of its resources and
enemies
(e.g. by growing when resources are
abundant, and predators, parasites and
pathogens are scarce)
and how it affects those same factors (e.g. by
reducing the abundance of resources
through consumption and contributing to
the population growth of enemies by falling
prey to them).
13
Niche Explanation (cont’d)
The abiotic (non-living) or physical
environment is part of the niche because
it influences how populations affect, and
are affected by, resources and enemies.
The description of a niche may include
descriptions of the organism's life history,
habitat, and place in the food chain.
14
Niche Explanation (cont’d)
No two species can occupy the same niche
in the same environment for a long time.
When plants and animals are introduced
into a new environment, they can occupy
new niches or niches of native organisms,
outcompete the native species, and
become a serious pest.
15
Lichens
Two lichens on a
rock, in two
different
ecological niches.
Can you explain
why they are
different niches?
Lichenes on a rock
Author: Johann Dréo
Date: 2005, august, 10
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Summary
For a species to maintain its population, its
individuals must survive and reproduce.
Certain combinations of environmental
conditions are necessary for individuals of
each species to tolerate the physical
environment, obtain energy and nutrients,
and avoid predators.
17
Summary cont’d
The total requirements of a species for all
resources and physical conditions
determine where it can live and how
abundant it can be at any one place.
These requirements are termed the
ecological niche.
Environmental
Factors
19
Environmental factors that
affect organisms
Abiotic
Biotic
Climatic
Edaphic
These are non-living factors
These are living factors
These are the average weather
conditions that affect the
community in an ecosystem
These refer to the soil
20
Abiotic factors
These are the non-living features of
an ecosystem (i.e. the physical
and chemical conditions) that
affect the community.
21
Abiotic factors include:
Temperature
Light
intensity
Air speed
Water current
Humidity
pH
Dissolved
oxygen
Salinity
Nitrate,
phosphate and
other plant
nutrients
22
Abiotic factors in a woodland
23
Biotic factors
These are the living features of
an ecosystem that affect the
other members of the
community.
24
Biotic factors include:
 Plants
for food and shelter
 Predators
 Prey
 Parasites and pathogens
 Decomposers
 Competitors
 Pollinators
25
Climatic factors
These are elements of the climate
(weather) that influence the life
and distribution of the organisms
that live in a particular
environment.
26
Climatic factors include:
 Temperature
 Rainfall
 Humidity
 Wind
 Light
intensity (including seasonal
variations)
 Day length
27
Edaphic factors
These are the physical, chemical
and biological characteristics
of the soil that influence the
community.
28
Edaphic factors include:
 Soil
type,
 Soil pH,
 Available (soil) water,
 Air and Mineral content,
 Humus,
 Soil texture and Structure.
29
Aquatic Environmental Factors
The following are also considered as
factors:
 Light penetration
 Currents
 Wave action
30
Learning check
1.
What is meant by abiotic factors? Give examples.
2.
What is meant by biotic factors? Give examples.
3.
What are edaphic factors? Give examples
31
Energy Flow
Ecosystems are unable to function unless
there is a constant input of energy from
an external source.
Where does this energy come from?
The Sun
32
The Sun
The sun is the
primary source of
energy for our
planet.
33
Energy Flow
is the pathway of energy transfer
from one organism to the next in an
ecosystem due to feeding, e.g.
along a food chain
Feeding allows energy to flow from
one organism to another in an
ecosystem.
34
Energy flow in the ecosystem
35
Food Chain
Is a flow diagram that begins with a plant
and shows how food/energy is passed
through a series of organisms in a
community.
Each organism feeds on the one before it.
A food chain ends when there is not
enough energy to support another
organism.
An example of a food chain:
grass  rabbit  fox.
36
A Grazing food chain
- is one where the initial plant is living e.g.
Grass  grasshoppers  frogs  hawks
Honeysuckle  aphids  ladybirds  thrushes
Seaweed  winkles  crabs  herring gulls
Phytoplankton  zooplankton  copepod 
herring
37
Grazing Food Chains
38
A Detritus food chain
- is one where the chain begins with dead
organic matter and animal waste (detritus)
e.g.
Detritus  edible crab  seagull
Fallen leaves  earthworms  blackbirds 
hawks
39
Food Web
This is a chart showing all the feeding
connections in the
habitat/ecosystem.
Constructed by showing the links
between all the interconnecting
food chains in the habitat.
Food Web
40
the interconnected food chains in an ecosystem
e.g.
A woodland food web
41
Construct a two food chains (4 ‘links’) from the above food
web
Another food web
42
What is the longest food chain you can construct from this
food web?
43
Producers
44
Producers are organisms capable of
making their own food by
photosynthesis, e.g. green plants.
Primary producers are the first
members of a food chain
Consumers
45
Consumers are organisms that feed on
other organisms. They cannot make their
own food. There are three types:
 Primary
consumers – feed on producers
 Secondary consumers – feed on primary
consumers
 Tertiary consumers – feed on secondary
consumers
46
Woodland food chain
Honeysuckle  aphids  ladybirds  thrushes
Producer
Primary
consumer
Secondary
consumer
Tertiary
consumer
Learning check
47
What is the primary source of energy?
2. Energy flow/transfer through an
ecosystem is achieved by …
3. What is meant by a Grazing food chain?
Give an example
4. Construct a simple food web
Two food chains e.g.
Plant  caterpillar  thrush  fox
Plant  earthworm  blackbird  fox
Combine them to form a food web
1.
Trophic Level
48
This refers to the position of an organism in
a food chain.
Plants are at the 1st trophic level (T1) and
Herbivores occupy the 2nd trophic level
(T2).
Carnivores that eat herbivores are at the
3rd trophic level (T3).
The 4th trophic level (T4) is often occupied
by the top carnivore.
49
Trophic levels
50
Pyramid of Numbers
A diagram that represents the numbers of
organisms at each trophic level in a food
chain.
Bottom layer is the largest and represents a
very large number of primary producers
The next layer smaller and represents a smaller
number of primary consumers
The next layer – the no. of secondary
consumers
The uppermost layer where there may be only
one tertiary consumer
51
Pyramid of Numbers
52
Learning check
Explain the following terms:
5.
Producer
Consumer
Primary Consumer
Secondary Consumer
Tertiary Consumer
6.
What is meant by trophic level?
1.
2.
3.
4.
53
To construct
a pyramid of numbers
1.
2.
3.
4.
Count the primary producers and place
them at the base of the pyramid
Count each consumer and include them
according to their status (primary or
secondary consumer) in the pyramid
The apex of the pyramid should include
tertiary or top carnivores
Draw the pyramid so that the area/volume
of each level is proportional to the number
of organisms found
Nutrient
Recycling
55
Nutrient Recycling
(1/3)
There is a limited amount of nutrients on earth e.g.
you are probably aware of the water cycle –
where water is constantly being recycled in
nature. There are similar cycles for all nutrients.
When plants and animals die, their nutrient
content is not wasted.
Bacteria and fungi decompose the remains and
release the nutrients back into the abiotic
environment (i.e. into the soil, nearby water and
air).
56
Nutrient Recycling
(2/3)
These nutrients are then taken up by other plants
and used to make new organic material.
This material is passed on down the food chains
and is reused by all the chain members.
When death occurs for these members, the
nutrients are again returned to the abiotic
environment and the cycling of nutrients
continues in this circular way.
Recycling nutrients within an
ecosystem
57
58
Nutrient Recycling
This ensures that there is no real longterm
drain on the Earth’s nutrients, despite
millions of years of plant and animal
activity.
In summary
Nutrient recycling is the way in which
elements are continuously being broken
down and/or exchanged for reuse
between the living and non-living
components of an ecosystem.
59
Carbon Cycle
Carbon forms part of all organic nutrients –
carbohydrates, fats and proteins.
Carbon dioxide is removed from the environment
by photosynthesis in plants, and under certain
conditions, over long periods of time, some of
these plants may form fossil fuels such as coal,
oil, peat and natural gas.
60
Carbon Cycle
Carbon dioxide is returned to the environment
by:
Respiration in plants, animals &
micro-organisms.
2. Decay caused by microorganisms.
3. Combustion i.e. burning fossil fuels
1.
61
The Carbon Cycle
(1/3)
62
Summary of Carbon Cycle
Click on the link below to see a summary of the
Carbon Cycle
The Carbon Cycle
For Animated Cycle click here
Flash
Shochwave
Click on this link to go to the next slide
63
The Nitrogen Cycle
All organisms need nitrogen for protein,
DNA & RNA manufacture
78% of the Earth’s atmosphere is nitrogen
gas, but it cannot be used in this form by
plants and animals.
Nitrogen gas must first be ‘fixed’, i.e.
changed to a suitable form (ammonia or
nitrate) before it can be used.
64
Nitrogen Fixation
♣
♣
♣
Nitrogen-fixing bacteria in the soil convert N2 gas
in the air into ammonia (NH3). This accounts for
the majority of all N2 fixation.
Lightening storms and fuel burning in car engines
produce nitrates, which are washed by rain into
the soil water.
Nitrates are absorbed by plant roots and
converted to plant protein.
65
The Nitrogen Cycle




Plant proteins are passed along food chains to
become animal protein.
When organisms die, their proteins are
converted to ammonia by bacterial
decomposition.
Nitrifying bacteria in the soil then convert
2_
ammonia (NH
_ 3) into nitrites (NO2 ) then into
nitrates (NO3 ).
Nitrates can be absorbed by other plants to
continue the cycle.
66
The Nitrogen Cycle

Denitrifying bacteria convert soil nitrates into N2
gas.
This is a loss of N2 from the cycle.
Only happens in anaerobic conditions
(when O2 levels are low) – due to flooding
or accumulation of sewage.

Nitrate also enters the cycle through the
addition of nitrogen rich fertilisers to the soil –
made industrially from nitrogen gas.
The Nitrogen Cycle
67
68
Summary of Nitrogen Cycle
Click on the link below to see a summsry of the
Nitrogen Cycle
The nitrogen cycle
For Animated Cycle click here
Flash
Shochwave
Click on this link to go to the next slide
Summary of Nitrogen Cycle
69
Nitrogen
in Air
1
8
Nitrite
NO2
7
6
5
Ammonia
NH3
4
5
Nitrate in
2
Plant Protein
Soil NO3
5.
1. Nitrogen Fixation &
Lightning
2. Absorbed by roots and
6.
used by plants –
Assimulation
7.
3. Animal feeding, digestion
& assimulation
8.
4. Excretion: urea 
Ammonia
Animal Protein
3
Death &
decomposition –
putrefying bacteria
Nitrification: NH3 
NO2
Nitrification: NO2 
NO3
Denitrification: NO3 
NO2  N
70
Learning check
1.
2.
3.
4.
5.
6.
7.
What is meant by nutrient recycling?
What process(es) remove Carbon dioxide from
the atmosphere?
What process(es) add Carbon dioxide to the
atmosphere?
Nitrogen gas must be ‘fixed’ – what does this
mean?
In what form is nitrogen absorbed by plants?
What is nitrification?
What do denitrifying bacteria do?
Human
Impact on
the
Environment
72
Pollution
Pollution is any human addition
(contamination) to a habitat or the
environment that leaves it less able to
sustain life.
It is the most harmful human impact and
affects air, fresh water, sea, soil and land.
Chemicals of human origin that harm the
environment are called pollutants.
Industrial/Air 73
Pollution
Agricultural
Pollution
– slurry, if it gets into a
river/pond
Some types of Pollution
Domestic
Pollution
River/Water
Pollution
74
Learning check
1.
2.
3.
Explain the difference between Pollution and
Pollutant.
List some types of pollution
CO2 is produced by all living things as a reuslt of
respiration. Is CO2 a pollutant? Explain your
answer.
75
Pollutants
: are produced by human activities
 CO2
from respiration is not a pollutant – :
excess CO2 from burning fossil fuels is
 SO2 from marshes & volcanoes is not – :SO2 from
factory chimney is
Some pollutants are normally present in an
environment, e.g. CO2, but levels are increased
by human activity.
Other pollutants never exist in an environment e.g.
oil slick, CFCs
76
From the Syllabus & Guidelines
The Syllabus states: “Study the effects of any
one pollutant.”
The Guidelines for Teachers states: “Give the
effects of one pollutant from any of the
following areas: domestic, agricultural,
industrial.” and
“Give an example of one way in which
pollution may be controlled in the
selected area.”
What follows is only a sample of the
pollutants available.
Effect of one pollutant from one area
- Agricultural, Industrial or Domestic
Area
Pollutant
Source
Effects
Washed or Formation of algal
Slurry &
Agricultural
leached
blooms and
Fertiliser
from land eutrophication
Forms ‘acid rain’
Sulphur
Burning
Industrial
dioxide
fossil fuels More detail later
Non-biodegradable
Domestic
Plastic bags Shopping Suffocate small
animals, Litter
77
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Eutrophication & Algal bloom
Eutrophication: a condition where lakes become
over-enriched with nutrients, resulting from
excess artificial fertilisers washed into rivers and
lakes.
There is a rapid increase in the growth of alga
(algal bloom) as they use up the nutrients.
When all the nutrients are used up the algae die
and are broken down by bacteria, which use up
the oxygen in the water resulting in the death of
aquatic organisms such as fish.
Control of Pollutants
in the selected area - Agricultural, Industrial or Domestic
Area
Pollutant
Control Measures
Agricultural
Slurry &
Fertiliser
Avoid spreading these:
• on wet, waterlogged, frozen
or steeply sloping land
• within 1.5m of any
watercourse.
Industrial
Sulphur
dioxide
Fit catalytic scrubbers in factory
chimneys
Plastic bags
Bag tax/levy. Reuse/Recycle
bags
Domestic
79
Ecological
impact of
one human
activity
Burning Fossil Fuels
81
Acidic oxides and acid rain
 All
rain is acidic – but not the same pH
- CO2 in the air dissolves in rainwater to form
carbonic acid – pH = 5.5 in unpolluted air
 Acid
rain refers to very acidic rain with a pH of 4.5 or
less
 Burning of fossil fuels releases acidic oxides into the
air, especially SO2 and nitrogen oxides (NOx)
 SO2 dissolves in rainwater to form sulphurous acid
(H2SO3) or reacts with particles in the air to form
sulphuric acid (H2SO4)
 The resulting rain is very acidic and can be carried
far by the wind
82
Effects of acid rain
 Reduces
soil pH
 Phosphorus (P) binds to soil particles and is
unavailable to plant roots
 Al becomes soluble and poisonous and with K, Ca
and Mg is washed (leached) from the soil into lakes
and water supplies
Soil is impoverished and fish die in highly mineralised
water. Why?
 Erodes limestone buildings
 Causes breathing difficulties – irritates the delicate
lining of the lungs
 Inhibits chlorophyll formation and burns the leaves
of plants
83
Dealing with acid rain
 Reducing
the quantity of fossil fuels
burned
 Using catalysts to treat chimney gases
(‘scrubbers’ are fitted to the insides of
chimneys)
 Catalytic converters fitted to modern cars
 Developing alternative ‘clean’ energy
sources
Learning check
84
1. What is acid rain?
2. How is acid rain formed?
3. List at least 4 of the effects of acid rain
85
What is Conservation?
**Conservation is the protection and wise
management of natural resources and the
environment.
Benefits of Conservation
1.
2.
3.
4.
Existing environments are maintained
Endangered species are preserved for
reproduction
The balance of nature is maintained
Pollution and its effects are reduced
One Conservation practice from
one of the following areas
Area
Agriculture
Fisheries
Forestry
Conservation Practice
Mixed farming, Crop rotation
Biological controls, Gene banks
Fishing Net size, Quotas, Re-stocking
Re-planting, Broadleaf/conifer mix
There is a need for continual monitoring of the
environment to ensure its protection and the wise
management of its natural resources.
86
87
Fisheries
One Conservation practice from one of the
following areas is required:
Fishing Net size
Quotas
Re-stocking
88
Fishing Net size
What is net mesh size?
This refers to how large or small the openings or spaces
enclosed by the threads of a net are.
 The
use of small-mesh nets can result in too many
young fish being caught
 Using larger meshed nets to allow the young to
escape, mature and reproduce
89
Go to next topic:
Waste Management
Different types of nets
Square mesh – does not
alter its shape under
tension – allows young
fish to escape
Diamond mesh netting (left) –
closes under tension (right) and
prevents young fish escaping
90
Fishing Quotas
What is a fishing quota?
A fixed proportion of the total allowable catch
allocated to each fishing nation.
This national quota allocation is further sub-divided into
quotas for specific areas, seasons, fisheries or
organisations, e.g. producers' organisations.
Why have quotas?
Over fishing has reduced fish stocks at sea
Fish quotas (maximum amount allowed to be caught)
have been assigned to different countries to ensure
that enough fish are left to replenish the stock.
91
Conservation and Fishing
Quotas
 Helps
to prevent the extinction of a fish
species
 Gradually increases fish stock and helps to
re-establish populations
 Attempts to maintain fishing at highest
possible levels
Go to next topic:
Waste Management
92
Re-stocking
What is the purpose of re-stocking?
To achieve a permanent increase in the sustainable
population of that species
Translocation of species into areas where they have
not naturally occurred is not encouraged
 Re-stocking attempts to maintain the balance in the
ecosystem
 Increases stocks for recreational fishing
93
Waste Management
What is waste management?
Waste management is the collection, transport,
processing, recycling or disposal of waste materials,
produced by human activity, in an effort to reduce
their effect on human health or local aesthetics or
amenity.
It also tries to reduce waste materials' effect on the
natural world and the environment and to recover
resources from them.
94
Waste Management
 Urban
rubbish is mostly dust, dirt, hair, paper, food
scraps, metal, glass and plastic.
 Traditional disposal has been to bury rubbish in
landfill sites or incinerate.
The area being filled has a rubberized landfill liner is in
place (exposed on the left).
This prevents leaching materials migrating downward
through the underlying rock.
95
Waste Management in Forestry
 Leaves
from coniferous trees should not be
allowed fall into rivers – make the water acidic
 Chemicals and fertilisers should not be allowed
run off into waterways - algal blooms and
eutrophication
 When trees are harvested only bare poles are
removed so a lot of tree debris (called brash) and
the stumps are left behind
96
Forestry solutions
 Waste
Management in the forestry sector is all
based on recycling.
 When the trees are harvested brash and the
stumps are left behind.
 The stumps are sprayed with a urea-type
compound which speeds up the decomposition
process
 The brash is either left to decompose on the forest
floor or collected and sold as a fuel source.
 In some of the larger sites the sawdust and debris
is sold on for conversion to fibreboard e.g. MDF
97
Problems with Waste Disposal
 Availability
of suitable landfill sites
 The toxic or polluting content of fumes from
incineration (CO2, other acidic oxides and dioxins –
produced from burning plastic)
 Decaying waste produces methane gas which
contributes to the “greenhouse gases”
 Harmful substances may leak into groundwater
supplies (wells, lakes, reservoirs)
 Plants and animals in rivers and lakes are killed
through direct poisoning or eutrophication
98
Possible solutions
 Lifestyle
changes and education programmes for
all ages are needed to alter the attitudes to
littering and waste minimisation and disposal
 Use
micro-organisms to degrade the rubbish and
produce fuel pellets
 Reduce
the use of paper and recycle more paper
 Biodegradable
materials (e.g. paper bags) should
be used in place of plastic ones.
99
Suggestions for waste
minimisation
 Reduce
– use less, minimise waste.
 Re-use
– use again, without changing but
maybe for a different purpose.
 Recycle
– change, recover some material
and use again.
100
Role of micro-organisms in Waste
Management
Composting is an aerobic process during which
micro-organisms decompose organic matter
into a stable substance called compost which
recycles all the nutrients required for plant
growth.
Since it is aerobic the organic waste mixture must
be turned and loosened to allow air into it.
This increases the size and number of air pores.
101
Micro-organisms in Waste Management
 Fungi
break down the ‘tougher’ materials in the
waste such as lignin and cellulose.
 Their
filamentous structure penetrates the
composting material and helps to improve
aeration and drainage in the compost heap.
 Temperatures
within a compost heap can reach
70°C as the bacteria and fungi work to
breakdown the material.
102
Vermicomposting
This is another method of recovering the nutrients
from organic waste, uses worms to consume the
food waste and utilizes the worm castings as
compost.
103
Role of micro-organisms in Pollution
Control
Composting can reduce environmental pollution
caused by disposal of organic wastes in landfills
and streams or by incineration.
Bacteria and fungi break down organic matter into
compost that recycles all the nutrients required for
plant growth.