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Senior Science
Preliminary Course
Stage 6
Local environment
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Number: 43176
Title: Local environment
Published by
Centre for Learning Innovation (CLI)
NSW Department of Education and Training
51 Wentworth Rd
Strathfield NSW 2135
_______________________________________________________________________________________________
_
Copyright of this material is reserved to the Crown in the right of the State of New South Wales. Reproduction or
transmittal in whole, or in part, other than in accordance with provisions of the Copyright Act, is prohibited without the
written authority of the Centre for Learning Innovation (CLI).
© State of New South Wales, Department of Education and Training 2008.
Contents
Introduction
Module overview ................................................................................. iii
Resources............................................................................................ iv
Icons .....................................................................................................v
Glossary............................................................................................... vi
Part 1: Features of ecosystems...........................................1–33
Part 2: Populations in ecosystems ......................................1–45
Part 3: Looking more closely at ecosystems .......................1–18
Part 4: Performing an investigation in an ecosystem ..........1–19
Part 5: Human environmental impact ..................................1–19
Part 6: Further investigations ..............................................1–21
Student evaluation of the module
Introduction
i
ii
Local environment
Module overview
Welcome to the module, Local Environment.
In this module, you will be doing fieldwork, theory and a range of
exercises and experiments. The module has been designed so that all the
necessary theory and background is placed in the first half of the module.
Towards the end of the module you will put your new skills and
knowledge into practice.
This module incorporates 30 indicative hours of study. It is divided into
six parts. You should spend at least five hours working on each part.
You may find it useful to keep a dictionary and a scientific dictionary
next to you while you work through the module. The glossary will
also help you to understand the meaning of the new words you will find.
These glossary words are shown in bold text when you first
encounter them.
Part 1 contains a large part of the theory and many of the new words and
terms you will encounter in this module. Once you are through Part 1,
do not be surprised to find that the other parts can be completed
more quickly.
You will perform your major fieldwork in Part 4 and complete the report
in Part 5. The content of Part 5 has been reduced to give you the time
you will need to complete your report.
In Part 6 you will investigate the impact of humans on ecosystems.
Here you will focus on some of the social issues along with the
biological issues of the activities of our species in ecosystems.
Good luck, we hope that you find Local Environment an interesting
introduction to ecology and your local environment!
Introduction
iii
Resources
Some of the best scientific research ever performed has been done with
surprisingly little equipment. The geneticist Gregor Mendel performed
his research with nothing much more than a spare garden bed, some
commonly available seeds, a small pair of scissors, a tiny paint brush and
a pen and paper. Yet Mendel’s research provided the foundations of
genetics, a very large branch of biology!
In this module you will use some very basic equipment, too. This is listed
below. You might like to gather this material now so that you have it
ready for your experiments.
What you will need
When
•
packet of tooth picks (or 3 boxes of matches)
Part 2
•
plastic bag
•
marker pen
•
30 cm ruler
•
pencil
•
pen, pencil, ruler, paper
•
protective clothing eg. hat, gloves, sunscreen
•
marking pegs
•
string
•
graph paper
•
thermometer
•
optional items (audiotape recorder, camera and
film, computer with spreadsheet and
wordprocessing programs, datalogger, soil test kit)
Part 4
Computer and internet access are needed for Parts 4 and 6.
iv
Local environment
Icons
The following icons are used within this module. The meaning of each is
written beside it.
The hand icon means there is an activity for you to do.
It may be an experiment or you may make something.
There is a safety issue that you need to consider.
There are suggested answers for the following questions at
the end of the part.
There is an exercise at the end of the part for you to
complete.
There is an activity that requires access to a computer.
You need to go outside or away from your desk for this
activity.
Introduction
v
Glossary
The following glossary provides the scientific meaning for many of the
terms used in this module, Local Environment.
The HSC examiner will expect you to understand the meaning of every
scientific term used. If you find a term that you do not understand then
look it up in a scientific dictionary or ask your teacher for assistance.
abiotic
Literally means not biotic (compare with the
definition of biotic below). The word abiotic is an
adjective used to refer to the non-living components
of an area or ecosystem. Air temperature, pH,
salinity, tides and wind and erosion are all examples
of abiotic factors.
abundance
Refers to number or how many. When biologists
use the term abundance they are usually referring to
the numbers of a particular species. For example,
'species X is more abundant than species Y' means
that there is a larger number of species X than
species Y.
acclimatise
To become accustomed to a new environment.
adaptation
Any characteristic that increases the chances of the
survival and reproductive success of any individual
or individuals that possess the characteristic.
Adaptations may be behavioural, physiological or
anatomical (structural).
Adaptations are the features favoured in the process
of natural selection.
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aquatic
Living in water. The term aquatic refers to both salt
and fresh water and can be used when referring to
organisms in oceans, lakes, rivers, ponds and
puddles. Kelp, coral and fish are all types of
aquatic organisms.
atom
The atom is the basic building block of matter.
Atoms consist of a central nucleus surrounded by
electrons. The nucleus, contains protons and
neutrons (not to be confused with the cell nucleus,
which is a totally different structure, but with the
same name).
Local environment
Electrons: are negatively charged particles that orbit
the nucleus. The electrons are shared or exchanged
between atoms during chemical reactions.
Protons: are positively charged particles located in
the nucleus. In an atom, the number of protons
equal the number of electrons to give the atom an
overall neutral charge.
Neutrons: are particles with no charge and are
located in the nucleus.
Introduction
biomass
The total living mass. Can be used to refer to the
total mass of a species, or group of organisms in an
area or at a particular trophic level.
biotic
Refers to the living elements of an area or
ecosystem. Biotic factors include predation,
organisms used as food sources, biological
disturbance such as burrows and parasitism.
brackish
Brackish water is slightly salty. The lower parts of
rivers entering the ocean are usually brackish where
ocean water mixes with the fresh river water.
carnivore
An animal that eats other animals.
chemical
compound
A chemical compound is formed by the chemical
combination of two or more atoms of different
elements. A compound formed from elements will
have its own distinct set of physical and chemical
properties that are usually different from those of
the component elements. For example, water is
made from the gaseous elements, hydrogen and
oxygen, but the resultant compound (water) is a
liquid.
community
A collection of populations.
competition
Rivalry for a resource.
concentration
The amount of a given substance in a stated unit of
a mixture or solution.
conductor
(thermal)
A thermal conductor is a substance that allows easy
passage of heat. Heat moves from an area of high
temperature to an area of lower temperature through
the thermal conductor. Metals are good thermal
conductors.
consumer
An organism that obtains its food from the organic
compounds from another organism. Herbivores,
carnivores, omnivores and parasites are all
consumers.
copulate
Unite in sexual intercourse.
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cull
To kill animals in an attempt to control numbers.
decomposer
Organisms involved in the decay process (breaking
down the dead remains and wastes of other
organisms) are decomposers. For example, fungi
and many bacteria are decomposers.
density
The mass per unit of volume.
desiccation
Drying or the removal of water
distribution
The geographic range of a species or group of
organisms.
diurnal
Daily. Can also mean day-time; during the day.
Diurnal organisms are active during daylight hours.
diurnally
Daily
diversity
In the biological sense, diversity refers to the
variety of organisms. For example, the Great
Barrier Reef exhibits a greater diversity of fish
species (some 1300 species) than Sydney Harbour
(some 450 species).
ecology
Study of the relationship between organisms and
their environment
ecosystem
The total of all biotic and abiotic factors in a
particular area, and the relationships between them.
electromagnetic
transmissions
Radiation consisting of waves associated with
linked electric and magnetic fields. Radio and
television transmissions are examples.
element
A pure substance made of only one type of atom.
Examples of elements include carbon (C), oxygen
(O), hydrogen (H), nitrogen (N), iron (Fe), calcium
(Ca), and sulfur (S). There are 92 naturally
occurring elements.
endemic
A species that naturally occurs within a particular
area.
environment
Surrounding things and conditions
excrement
Waste matter discharged from the body eg. faeces.
herbivore
An animal that eats plant material.
humus
Organic material found in soil that comes from the
decomposition of plants and animals.
insulate
Act as an insulator
insulator
(thermal)
A thermal insulator prevents the transmission of
heat. Many plastics are thermal insulators.
Local environment
Introduction
introduced
species
Any organism that is not endemic to an area.
Introduced species may be brought to a new area by
humans, or they may be introduced by natural
processes such as floating on logs across oceans to
a new location. In Australia humans have
introduced many species that have become pests eg.
European rabbits, privet, cane toads and pampas
grass.
ion
A charged particle. Atoms become ions by gaining
or losing electrons. Ions can combine with other
ions to form compounds. Because ions are formed
by gaining or losing electrons, ions may be either
positively or negatively charged.
legend
Explanation of symbols used in a diagram or map
macroscopic
Something that can be seen with the unaided eye.
matter
A special form of energy that has mass and exists in
both space and time.
molecule
The smallest unit of an element or compound. In
the case of elements, this may be a single atom eg.
in the case of inert (unreactive) gases such as neon
or more than one atom in the case of reactive
elements, eg. O2 (this indicates that the oxygen
molecule is made of two oxygen atoms).
mollusc
Molluscs make up the second largest phylum in the
animal kingdom. Molluscs have a muscular foot
and a mantle, and many have a shell. Garden snails
and octopus belong to this group.
natural selection
Survival of the fittest. Within a species, different
individuals have different combinations of genes.
Those with favourable gene combinations survive
to reproduce. Over time, unfavourable
characteristics are lost and the species changes
(evolves).
oscillate
To fluctuate or move to and fro as in a pendulum.
osmosis
Movement of water across a membrane which will
not allow passage of larger particles such as ions or
molecules larger than water
pandemic
A species that has world wide distribution.
pH
pH is a measure of acidity. pH is often measured
on a 1–14 scale. A pH below 7 is acid. A pH
above 7 is basic (alkaline). pH 7 is neutral.
photic zone
The region in which light penetrates water. Below
the photic zone there is no light because the light
has been absorbed by the upper layers of water.
ix
population
Collection of individuals belonging to the same
species within a defined area.
predator
An animal that kills and then feeds upon another
animal is described as a predator. A broader
definition of predator describes it as an organism
that feeds on another organism.
prey
The animal eaten by a predator. For example, the
osprey is an eagle-like bird that catches and eats
fish. The osprey is the predator and the fish is its
prey.
producer
An organism that can manufacture its own food
from raw materials by photosynthesis (or
chemosynthesis). All green plants are producers
because they manufacture their own food by
photosynthesis from carbon dioxide and water in
the presence of light. An autotrophic organism.
product
Substances produced by the chemical combination
of reactants. Products are written to the right of the
arrow in a chemical equation.
quadrat
A quadrat is a sample area, often a square, rectangle
or circle.
reactant
Substance which takes part in a chemical reaction.
Reactants are written to the left of the arrow in a
chemical equation.
species
The smallest unit of classification. A species
represents a potentially interbreeding group of
organisms that can produce fertile offspring.
Species are grouped into genera. When giving the
scientific name of a living thing we write the genus
name and then species name.
For example Crinia signifera. Here Crinia is the
genus name and signifera the species name. The
genus name is always capitalised.
x
substrate
Underlying layer; the layer of the earth that is
eroded or scoured by moving water or air
temperate
Regions of moderate temperatures are said to be
temperate. The majority of New South Wales has a
temperate climate for most of the year.
terrestrial
Living on land. The term terrestrial refers to
mountains, plains, caves and other environments on
land. For example, eucalypts, humans, kookaburras
and possums are all terrestrial organisms.
topography
Relief features of an area such as hills and gullies.
top-order
Carnivore that may eat other carnivores and
Local environment
Introduction
consumer
herbivores in a food web. The White Pointer shark
is a top order consumer.
transect
A line drawn across a study site along which
samples may be taken.
transmit
To convey or pass along.
trophic level
The relative position of an organism in a food
chain.
vegetation
Plants of a particular area or region.
viscosity
Thickness or resistance to movement of a
substance.
viscous
Having a high viscosity
wet sclerophyll
forest
Sclerophyll vegetation is hard leaved vegetation
such as eucalypts. A Eucalypt forest with an
understory and usually in a moist location is
referred to as wet sclerophyll forest.
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Senior Science
Preliminary Course
Stage 6
Local environment
Part 1: Features of ecosystems
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Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction ............................................................................... 2
Biotic and abiotic features ......................................................... 3
Terrestrial and aquatic environments ........................................ 5
Comparing abiotic characteristics.............................................. 6
Temperature variation......................................................................... 7
Heat conductivity ................................................................................12
pH .......................................................................................................12
Oxygen availability ............................................................................ 13
Desiccation .........................................................................................14
Availability of light...............................................................................15
Pressure .............................................................................................17
Availability of ions...............................................................................20
Availability of water ............................................................................21
Viscosity..............................................................................................23
Erosion and scouring .........................................................................24
Suggested answers................................................................. 27
Exercise – Part 1 ..................................................................... 33
Part 1: Features of ecosystems
1
Introduction
In this part, you will learn to:
•
describe the differences between abiotic and biotic features of the
environment
•
compare the abiotic characteristics of aquatic and terrestrial
environments
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
2
Local environment
Biotic and abiotic features
Environmental features can be divided into living (biotic) and non-living
(abiotic).
The term biotic refers to the living features of an area or ecosystem.
Biotic features include:
•
all the plants and animals in an area
•
the interrelationships between organisms (eg a kookaburra eating
an insect)
•
the results of the activities of organisms (eg burrows).
What are the biotic features of your local environment?
_________________________________________________________
_________________________________________________________
The term abiotic literally means not biotic. The term refers to the
non-living features of an area or ecosystem.
Examples of abiotic features are:
•
pH
•
air temperature
•
salinity
•
glaciation
•
tides
•
wind
•
erosion.
What are the abiotic features of your local environment?
_________________________________________________________
_________________________________________________________
Part 1: Features of ecosystems
3
Do you understand the meaning of the terms biotic and abiotic?
The table below lists factors (features) commonly found in the environment
in the left-hand column. You should indicate if each feature is either biotic
or abiotic in the right-hand column. If you do not get all of them correct,
re -read the information above before proceeding.
Environmental feature
Biotic/abiotic
pH
soil temperature
competition from members of a different species
competition from members of the same species
minerals in the soil
humus in the soil
water depth
soil disturbance from burrows
Check your answers.
4
Local environment
Terrestrial and aquatic environments
The term environment refers to the total set of conditions surrounding
an organism or group of organisms. Environments can be roughly
grouped into two types, terrestrial and aquatic.
Terrestrial environments are land based environments while aquatic
environments are water based environments. It may seem easy enough to
separate terrestrial and aquatic environments but as you are about to see,
it can sometimes be very difficult.
A number of environments are listed below. Next to each record indicate if
it is a terrestrial or aquatic environment.
Environment
Terrestrial/ aquatic
freshwater lake
eucalypt forest
sand dune
muddy bottom of ocean
the bed of a dry stream
the ice field of a glacier
tidal mangrove swamp that floods with
water at high tide but has no water at
low tide.
a puddle that exists by the side of a
road for 2 days after rain
Check your answers.
Part 1: Features of ecosystems
5
Comparing abiotic characteristics
Different environments can be described by differences in their abiotic
characteristics. For example, terrestrial environments usually have a
wider daily temperature variation than aquatic environments.
Abiotic features can vary within a particular environment.
For example temperatures vary seasonally (across a year) and diurnally
(across a day). Tides, wind speed, rainfall and light are other abiotic
features that can vary. Living things must be able to cope with changes
in the abiotic environment in order to live in a particular environment.
Think about your local environment. What abiotic factors vary in your
local environment over:
•
a day
______________________________________________________
•
a year?
______________________________________________________
Some abiotic factors of aquatic and terrestrial environments are discussed
in this section. These include:
6
•
temperature variation
•
heat conductivity
•
pH
•
oxygen availability
•
desiccation
•
availability of light
•
pressure
•
availability of ions
•
availability of water
•
viscosity
•
erosion and scouring.
Local environment
Temperature variation
As a general rule temperatures vary more widely on land than in water.
This is one of the important differences between temperature on land and
temperature in water. Look at the data in the table below.
Date
Minimum air
temperature
Maximum air
temperature
Minimum water
temperature
Maximum water
temperature
1 January
19°C
36°C
23°C
23°C
1 April
12°C
26°C
22°C
22°C
1 July
6°C
19°C
20°C
20°C
1 October
12°C
29°C
20°C
20°C
Selected temperature data for a coastal town on the New South Wales south
coast. The water temperature refers to ocean temperature.
Look at the maximum and minimum air temperatures for 1 January.
There is a 17°C difference between these two temperatures. Now look
at the maximum and minimum water temperatures for 1 January.
Water temperature did not vary.
The result for January has been put into the table below. Now it is your
turn. Calculate the variations for April, July and October. Put your results
into the table below.
Date
Air temperature
variation
Water temperature
variation
17°C
0°C
1 January
1 April
1 July
1 October
Diurnal air and water temperature variations.
Check your answers.
You can see that daily air temperatures vary more than daily water
temperatures.
Part 1: Features of ecosystems
7
Let’s now look at annual temperature variation. The highest maximum
air temperature is 36°C in January. The lowest air temperature is 6°C in
July. The annual air temperature variation shown in the table below is
30°C. This result is shown in the following table. Now it is your turn
to calculate the annual water temperature variation. Complete the
table below.
Annual air temperature
variation
Annual water
temperature variation
30°C
Check your answer.
Graph the temperature data shown in the top table on page 8. The graph
must be a line graph, not a bar graph. Remember to label the axes of your
graph and to give your graph a title.
40
35
30
25
20
15
10
5
0
January
April
July
October
Check your answer. Note that the maximum and minimum water
temperatures are superimposed upon each other because the plots are
almost identical.
8
Local environment
The size of water bodies
Bodies of water vary enormously in size. They include everything from
small puddles to oceans, tiny streams to rivers. Make a list of the types of
water bodies that occur in your local area.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Large bodies of water have less temperature variation than small bodies
of water. Look at the experiment below that was performed by a group of
Preliminary HSC students at a College of TAFE.
Aim
To compare the diurnal temperature variation of three different sized
bodies of water.
Method
A 10-litre plastic garden bucket and a 200-litre plastic child’s pool were
placed next to a large above-ground fibreglass pool. The above-ground
swimming pool had a diameter of 8 metres and was 1.5 metres deep.
The bucket and the child’s pool were filled with water from the large
swimming pool and left to stand for 24 hours. After standing for 24
hours, thermometers were put in the bucket, child’s pool and swimming
pool, and the maximum and minimum temperatures recorded for the
following 24-hour period.
A bucket, child's pool and swimming pool.
Part 1: Features of ecosystems
9
Result
Bucket
Child’s pool
Swimming pool
Minimum temperature
9°C
10°C
13°C
Maximum temperature
14°C
13°C
13.5°C
Diurnal temperature variation
5°C
3°C
0.5°C
Water temperature in the bucket, child’s pool and swimming pool.
Discussion
The smaller the body of water, the greater the diurnal temperature
variation. This is biologically significant. Organisms living in larger
bodies of water (such as oceans) would experience less temperature
variation than those living in smaller bodies of water (such as ponds
and puddles.)
Significance of temperature differences
By now you are probably curious to know if the temperature variations
you have seen in water and on land are important to living things.
Think about how temperature variations might effect aquatic organisms
such as fish or terrestrial organisms such as kangaroos. Now read on and
see if you can find some answers to these questions.
Terrestrial organisms usually have to cope with a wider range of
temperature variation than do aquatic organisms.
Terrestrial organisms can have adaptations to cope with the large
diurnal temperature variations. For example, most kangaroo species feed
during the evenings and early morning and rest in the shade during the
heat of the day. This behaviour is an adaptation that reduces the range of
temperatures to which the kangaroo is exposed. You will find out more
about adaptations later in this module.
Aquatic organisms rarely experience rapid temperature changes.
Large temperature change has not been part of most aquatic
environments so natural selection has not acted to make most aquatic
organisms resistant to temperature changes.
10
Local environment
Temperature differences, aquatic reptiles and sex
Turtles lay their eggs in sand. The temperature of the sand will
determine the sex of the offspring. In green turtles, if the average sand
temperature during the incubation period is greater than 29°C, the
hatchling will be female. If the average sand temperature is below 29°C,
the hatchling will be male.
Crocodiles show a similar relationship between egg temperature and sex.
Temperature differences and fish
Look at the information below provided by a pet shop that sells goldfish.
When the pet shop sells them, the goldfish is placed into a small plastic
bag with some of the water from the tank in which they are swimming.
Some oxygen gas is placed into the bag. Then the bag is tightly sealed
before the fish is handed over to the customer.
Place this bag unopened into the tank for 30 minutes. This will
allow your fish to acclimatise to the temperature of your tank.
After 30 minutes open the end of the plastic bag and gently pour
water and fish into your aquarium.
WARNING: Rapid temperature changes can kill goldfish. When
changing aquarium water do not replace more than half the volume
of water at any one time.
1
Having read the above instructions, would you assume that the
natural habitat of goldfish and similar species has a wide or a narrow
temperature variation?
_____________________________________________________
_____________________________________________________
2
A sudden 10°C change in water temperature would be sufficient to
kill most goldfish, yet most goldfish live in aquariums where the
annual temperature variation is in the order of 10°C. Why does the
annual temperature variation not affect the fish?
_____________________________________________________
_____________________________________________________
_____________________________________________________
Part 1: Features of ecosystems
11
3
Under what conditions may fish experience rapid temperature
changes in the ocean?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
Heat conductivity
Water is a better conductor of heat than air. The significance of this
difference is that water transmits heat to and from aquatic organisms
more quickly than air does to and from terrestrial organisms.
This means that body heat is lost more easily to water than to air.
Although terrestrial organisms may experience a wider temperature
range, the heat changes are poorly conducted to the terrestrial organism.
The lower conductivity of air is one abiotic factor that assists terrestrial
organisms to survive wide temperature variations.
Aquatic mammals (such as seals) have layers of blubber to insulate them
from the surrounding water to reduce the loss of their body heat to the
surrounding water.
Of course, the general principles we have seen above apply to humans
too. On a hot day a dip in some cool water will conduct a lot of heat
away from the body - very pleasant! How do humans insulate
themselves against heat loss on a cold day?
pH
The term pH refers to acidity/alkalinity. The pH is often measured on a
1–14 scale. A pH of 7 is neutral, pH lower than 7 is acid and a pH
greater than 7 is alkaline.
1
7
more acid in this direction
14
more alkaline in this direction
A pH scale shows relative acidity and alkalinity.
12
Local environment
Most living things occur in environments that are either neutral or close
to neutral. Pollutants that alter the pH of an environment can harm the
organisms that live there. For example, when water falls on coal dumps
an acid run-off is created. This acid run-off can kill plants.
Oxygen availability
There is a higher concentration of oxygen in air than in water.
Most aquatic organisms have adaptations to overcome the low
availability of oxygen in water. Look at the table below. You will notice
that the concentration of oxygen in air is much higher than in water.
Concentration
Air
Salt water
Fresh water
21%
0.4% - 0.8%
0.5% - 1%
Comparison of oxygen concentrations in air, salt water (ocean surface) and
fresh water. Concentration is volume of gas compared with volume of water as
a percentage.
Water near the surface has a higher concentration of oxygen than water at
depth. There are two reasons for this:
•
Water at the surface is in contact with the oxygen in the air.
Waves and breaking water help to dissolve additional oxygen into
the water. Deeper water is calm with no opportunity for breaking
water to increase the oxygen content.
•
Oxygen is slow to diffuse (spread) through water. The deeper the
water, the longer it takes oxygen to diffuse from the surface to
the bottom.
Temperature also affects oxygen availability in water. Less oxygen can
dissolve into hot water than into cold water.
A similar pattern can be seen in the solubility of other gases from
the atmosphere:
Part 1: Features of ecosystems
13
Gas formula and name
Solubility of gas in water (g per L)
20°C
40°C
60°C
oxygen O2
0.043
0.031
0.023
nitrogen N2
0.019
0.014
0.010
argon Ar
0.059
0.042
0.030
carbon dioxide CO2
1.69
0.97
0.58
Solubility of atmospheric gases in water at different temperatures.
Hot water is a pollutant when released into aquatic environments.
Thermal power stations such as those near Lake Macquarie on the New
South Wales central coast have been criticised for releasing heated water
into the shallow lake. Over the years the power stations have caused
significant increases in water temperatures, particularly in the southern
part of the lake. This hot water can kill fish and plants.
What harmful biological effects might hot water have on the lake?
Write down your ideas.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answers.
Desiccation
Desiccation is a word that refers to drying or the removal of water.
You have probably come across desiccated substances such as
desiccated coconut, which can be found in the cooking section of most
general stores.
Desiccation is a factor of terrestrial environments but not a factor of
aquatic environments. On land the rate of desiccation increases when:
14
•
temperature and wind speed increase
•
humidity and cloud cover decrease.
Local environment
Most terrestrial organisms have adaptations to reduce desiccation – for
example, eucalypt leaves have a waxy covering on the leaf surface.
The question below occurred in a Trial HSC examination in a New South
Wales high school. See if you can work out the answers based on what you
already know about abiotic factors. The exam question had 8 lines provided
for the students to write their answers. We have provided the same space for
you to write your answer.
The gills of an eel are external to the body cavity while the lungs of a
mouse are within the body cavity.
1
Explain the importance of the gills being external in the eel.
_____________________________________________________
_____________________________________________________
2
Explain the importance of the lungs being internal for the mouse.
_____________________________________________________
_____________________________________________________
3
The gills of an eel have a proportionally larger surface area than the
lungs of mouse. How would you explain this observation in terms of
adaptation to the environment?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Availability of light
Light penetrates air better than it penetrates water.
Light does not penetrate more that 100 m, even in clear water.
Photosynthesis only happens in the presence of light. This means that
aquatic plants can only survive in the top 100 metres of the ocean (even
less in muddy or turbid water). The zone of light penetration is called the
photic zone.
Land plants are not restricted by the ability of light to penetrate air.
However, other factors (such as shade created by other plants or reduced
light availability in caves) can have an effect.
Part 1: Features of ecosystems
15
sun
area of light penetration
– the photic zone
The photic zone.
Water depth and the colour of light
Two observations about light penetration in water are:
•
As water depth increases, light availability decreases.
•
As white light enters the water, some of the colours making up the
white light are absorbed at a shallower depth than others.
It was shown that species with green pigments (green algae) were able to
photosynthesise best in the near-white light at the surface. Those with
red pigments (red algae) had an advantage at greater depths.
Early studies suggested that marine algae (seaweeds) were adapted to the
changing colour of light with depth. The hypothesis was that the
different types of algae (red, green, brown) were distributed according to
the colour of light available.
We could leave our story here except for one important point: later
studies have gathered additional evidence that clearly demonstrates that
the hypothesis was wrong!
There is no doubt that some algae can photosynthesise better in the light
available at certain depths than other algae. However, this factor is not
important in determining the distribution of algae. As it turns out, other
factors such as currents, the type of substrate for attachment and
competition are the factors determining distribution.
16
Local environment
It is an important aspect of science that you must always be prepared to
re-test and to accept that existing theories may be disproved later. It is
also important to realise that many factors act on living things. You may
find a contributing factor, but a combination of other factors may be
more important to the organism.
If you read more widely, you will no doubt encounter the old idea that
the colour of light at depth in the photic zone regulates the distribution of
algae that grow there. The fact that it is still common to find such ideas
in textbooks is a lesson in the importance of making sure that you get
information that is recent and that you check your information from
several sources.
There are many ideas that were at one time thought to be correct, but that
were disproved later. Who can forget such great ideas as the Earth being
flat or that atoms could not be split? You might like to make a list of
other ideas that have been disproved. Go on, do it now. You will
probably be surprised at how many you can think of within a space of
just a few minutes.
Pressure
Pressure is an important physical factor for living things. Let’s start by
revising some of the physics and chemistry of pressure that you have
learned in your previous studies in science, before we examine the
biological significance of pressure. Many of the ideas we discuss in this
module depend upon ideas from chemistry, physics and geology.
The various areas of science are linked. It is common to study ideas
from other branches of science in order to understand biological ideas.
Pressure changes and boiling point
The following experiment is often demonstrated to students.
A glass of water is taken from a tap. A thermometer is placed into the
glass and the temperature recorded. The water is not boiling. It is
ordinary cold water from a tap.
The glass of water is then placed under a bell jar connected to a vacuum
pump. The pump is turned on and the air begins to be removed from the
bell jar. The pressure inside the bell jar decreases.
After a little time the water begins to boil vigorously. When the
temperature is checked on the thermometer, it is exactly the same as it
was at the start. Cold tap water is boiling.
Part 1: Features of ecosystems
17
bell jar
thermometer
temperature 17∞C
glass
water
a Temperature of tap water
in glass is measured.
temperature 17∞C
water boiling
b Temperature remains the
same but after pressure
reduced water boils.
Tap water boils after air pressure is reduced.
We conclude that the temperature at which water boils decreases as
pressure decreases.
Mountaineers have great difficulty in getting hot liquids to drink at high
altitudes because liquids boil at such low temperatures near the top of
high mountains. Aircraft passengers also experience a similar problem.
The pressurised cabin of an aircraft is at much lower pressure than air
pressure at sea level. Therefore, liquids boil at lower temperatures and
tea and coffee are served warm rather than very hot.
Pressure changes and solubility
At low pressure less gas remains dissolved in a liquid than at high
pressure. Examine an unopened bottle of lemonade at room temperature.
The liquid inside the bottle is not bubbling. Now remove the top to
release the pressure within the bottle—it begins to bubble. When the
pressure is reduced some of the carbon dioxide gas dissolved in the liquid
is released.
Those of you who have travelled by air and ordered a carbonated drink
may have noticed how quickly the drink bubbles when opened—and how
quickly the drink flattens. The pressure inside the aircraft cabin is low,
so more gas is released from the drink than at sea level.
18
Local environment
Pressure and living things
There are lower limits of pressure under which no living things can
survive. If pressure is too low, water in cells would boil (become a gas)
making it impossible for life to continue. Likewise, at very low pressure
it is difficult to keep gases dissolved in blood to provide sufficient
oxygen for the requirements of cells.
Pressure variation on land and in water
Air pressure changes very slowly as height above sea level increases.
Water pressure increases rapidly with depth.
For every 10 metres of depth in seawater, the surrounding pressure
increases by one atmosphere in (an atmosphere is equal to the air
pressure at sea level). This means that at 10 metres the surrounding
pressure is double the air pressure at sea level. A scuba diver diving to a
depth of 30 metres will experience pressure four times greater than that
in air at sea level. By comparison, a 30-metre change of altitude in air
would have a negligible effect on pressure.
Lets see what you can remember about pressure. A spearfisherman takes a
deep breath at the surface and snorkels down to 10 m. At 10 m the pressure
is double that at the surface and the gas in his lungs compresses to half the
volume it had at the surface.
1.
The spearfisherman continues to hold his breath and then swims
back to the surface. What will be the volume of gas in his lungs
when he reaches the surface?
_____________________________________________________
_____________________________________________________
2.
The spearfisherman makes a second dive to 20 m. What will be the
volume of the gases in his lungs when he reaches 20 m? You can
assume that he started with both lungs full of air at the surface.
_____________________________________________________
_____________________________________________________
Check your answers.
Part 1: Features of ecosystems
19
Availability of ions
Ions occur in both terrestrial and aquatic environments. However, to
be available to living things, ions need to be dissolved in water.
Aquatic organisms have a good availability of ions because they are
bathed in water the whole time. Terrestrial organisms must get ions from
those dissolved in water. The table below shows some common ions.
Ion
Use (function)
magnesium (Mg2+)
Structural element of chlorophyll in plants.
nitrate (NO3–)
Source of water soluble nitrogen for plants. Nitrogen is
an important element in all proteins.
calcium (Ca2+)
Bone-building in vertebrates.
phosphate (PO43–)
Structural component of nucleic acids in genetic
material.
iron (Fe2+)
Structural element of haemoglobin in blood.
Some common ions required by organisms.
Different aquatic environments can have different types and different
quantities of ions. Seawater has more ions dissolved in it than
freshwater. Where rivers enter the ocean, there will be a zone of
brackish water where the fresh river water mixes with the ocean.
The distribution of aquatic organisms can be limited by the ions
available. For example, coral occurs in temperate oceans. Coral is
intolerant of brackish water and sediment so it does not occur in areas
where rivers run into the ocean.
Marine fish rarely swim upriver into freshwater because the ion
concentration in the water will be lower than the ion concentration in
their body tissues. Too much water will move into their cells by
osmosis. For a similar reason freshwater fish rarely move down rivers
into oceans. The ion concentration of salt water is higher than the ion
concentration in the tissues of freshwater fish. In salt water, freshwater
fish lose water from their cells by osmosis. Large increases or decreases
of the amount of liquid in cells can cause the death of fish.
20
Local environment
Complete the table below. Predict if water will enter or leave the body cells
of the organisms listed. State a reason for each prediction.
Situation
Water movement
goldfish in its natural freshwater
environment
goldfish placed in sea water
tailor (a marine fish) in its natural
environment
tailor placed into fresh water
goldfish in brackish water
tailor in brackish water
Check your answers.
Availability of water
All organisms require a supply of water. Water is the solvent in which
the majority of cellular reactions occur. Most organisms have a
significant percentage of their body weight comprised of water.
Water is more readily available for aquatic organisms than terrestrial
organisms. Terrestrial organisms usually have adaptations to conserve
the water in their cells. For example, humans have skin to prevent water
loss and Australian eucalypts have waxy leaves to conserve water.
Part 1: Features of ecosystems
21
Water for support
You have probably floated in water at some time. Your body floats in
water because the average density of the human body is generally a little
less than the density of water.
Would it be easier to float in:
1
salt water or fresh water? ________________________________
2
air or water? __________________________________________
Check your answer.
Aquatic organisms are better supported by water than terrestrial
organisms are supported by air because air is much less dense than water.
It is common for terrestrial organisms to have stronger support structures
than aquatic organisms. For example, terrestrial vertebrates usually have
a much stronger bone structure than found in aquatic vertebrates such as
fish. Many terrestrial plants have woody tissue that provides support.
Woody tissue is rarely found in plants in aquatic environments.
Swim bladders
Some aquatic species have adaptations to adjust their body density.
This allows them to maintain their depth without having to swim to
maintain position.
A swim bladder is an organ found in many fish that allows them to alter
average body density. The fish can add or subtract gas to the swim
bladder much like a scuba diver adding and subtracting gas to a
buoyancy compensator (vest) to maintain depth.
The position of the swim bladder is critical to the balance of the fish.
In the yellow perch (Perca flavescens), the fish’s centre of gravity is
below the swim bladder. This allows the perch to keep effortlessly in the
upright swimming position.
However, the swim bladder is not as well placed in all fish. In pikes (fish
of the genus Esox), the centre of gravity is above the swim bladder.
Pikes must continually use the movements of their fins to maintain an
upright position.
22
Local environment
Here is an optional activity for warmer weather. Take a small kickboard to a
swimming pool, river, dam or lake. The kickboard will be your artificial
swim bladder.
Get into the water and lay on the board face down. The board should be
placed so that your chest is resting on the board. Now try to push the board
down into the water. Pushing the board down will dramatically alter the
centre of gravity and you should find it very difficult to stay floating face
down.
You will come to appreciate how difficult pikes must find staying upright
in the water!
Viscosity
The word viscosity refers to the thickness or resistance to movement of a
substance. Cold honey is said to have a higher viscosity or to be more
viscous than hot honey. Water has a higher viscosity and thus is more
viscous than air. Aquatic organisms live in a more viscous environment
than terrestrial organisms.
It is more difficult to move through water than it is to move through air.
If you have ever walked in waist-deep water, you will have experienced
this problem yourself.
Aquatic organisms that move quickly through water often have
streamlined shapes to reduce the effect of the viscosity of water.
The torpedo shape of dolphins and seals is a classic shape for fastmoving aquatic organisms. Of course, many organisms have no need of
fast movement in water, so these will not necessarily have a streamlined
body shape. For example, seahorses are not streamlined: they move very
slowly and live in fast currents. They can wrap their tails around
seaweed to avoid being swept away.
Terrestrial organisms that move quickly show a different set of
adaptations compared to fast-moving aquatic organisms. For these
organisms, the viscosity of air is not a problem. However, friction with
the ground is a problem.
The horse is a typical fast-moving terrestrial animal. Its legs are
proportionally long and its hoof is a modified finger, which provides
minimal ground contact when moving. The long legs of a horse provide
a long stride, so that the number of ground contacts the animal must
make over a given distance is reduced.
Part 1: Features of ecosystems
23
Here is an optional activity for you to try.
1
Get a small bottle of honey at room temperature. Place a spoon into
the honey and time how long it takes to sink to the bottom of the jar.
2
Remove and clean the spoon. Place the jar of honey into a
refrigerator for a day and repeat the experiment.
3
Find an empty jar of a similar size to your honey jar. How long does
it take the spoon to sink in water?
Erosion and scouring
Erosion is an important abiotic factor in many terrestrial Australian
environments. Inappropriate farming methods in the past greatly
increased the rate of soil erosion. Overgrazing and land clearing
removed cover plants and increased erosion rates. Soil erosion is a
serious problem because many Australian environments produce soil at a
slower rate than soil is removed by erosion.
In the marine environment, scouring by currents can remove sand and
mud which make suitable habitats for invertebrates such as burrowing
molluscs. In rivers, scouring during floods can:
•
alter river courses
•
remove existing soft sediment habitats
•
wash organisms living in these habitats downstream or even out to
sea.
Substrate can be removed in both aquatic and terrestrial environments.
Wind, water and ice can be responsible for erosion and scouring on land.
In aquatic environments water movement (current) is almost the sole
source of scouring. Ocean currents and the movement of water in rivers
can move large quantities of sediment over considerable distances.
The greater the water or wind speed, the greater the size of particles that
can be moved. The maximum particle size that can be moved by wind
is smaller than the maximum particle size that can be moved by water.
Ice can move much larger particles than either wind or water. In fact, it
is common for glaciers to move house-sized boulders.
The settling of small particles occurs much more quickly in air than in
water. This is because air is less viscous than water.
24
Local environment
Would you like to be a kid again? Here is your chance with this optional
activity.
Go outside on a wet day and watch water moving down a soil bank or
unpaved gutter. Do areas covered in vegetation erode as quickly as areas
that are not covered in vegetation? Some careful redirecting of water
will quickly test this!
Of course, you do not have to wait for rain. If you do not have water
restrictions in your area then you may be able to have some satisfying
fun using a hose.
If you were to take over a farm with a small stream flowing through the
property, would you want to encourage or discourage vegetation growing
on the banks of the stream?
Turn to the exercise at the back of this part. There is a summary for you to
complete which compares abiotic factors in aquatic and terrestrial
environments.
Part 1: Features of ecosystems
25
26
Local environment
Suggested answers
Biotic and abiotic features
Environmental feature
Biotic/Abiotic
pH
abiotic
soil temperature
abiotic
competition from members of a different species
biotic
competition from members of the same species
biotic
minerals in the soil
abiotic
humus in the soil
biotic
water depth
abiotic
soil disturbance from burrows
biotic
Part 1: Features of ecosystems
27
Terrestrial and aquatic environments
28
Environment
Terrestrial/ aquatic
freshwater lake
aquatic
eucalypt forest
terrestrial
sand dune
terrestrial
muddy bottom of ocean
aquatic*
the bed of a dry stream
terrestrial#
the ice field of a glacier
terrestrial^
tidal mangrove swamp that floods
with water at high tide but has no
water at low tide
terrestrial†
a puddle that exists by the side of a
road for 2 days after rain
aquatic
*
even though some organisms are living in the mud rather than in the water
#
until it rains and the stream flows again
^
even though ice is frozen water
†
This is very difficult. Mangroves are terrestrial plants that can survive
flooding. Many aquatic organisms such as fish feed near their roots at
high tide. Those organisms living totally in the water are aquatic, while
others are terrestrial. Mangrove swamps are usually considered as
terrestrial environments that flood regularly.
Local environment
Temperature variation
Date
Air temperature
variation
Water temperature
variation
1 January
17°C
0°C
1 April
14°C
0°C
1 July
13°C
0°C
1 October
17°C
0°C
Temperature variation
Annual air temperature
variation
Annual water
temperature variation
30°C
3°C
40
35
Maximum air temperature (∞C)
30
25
Maximum water temperature (∞C)
20
Minimum water temperature (∞C)
15
10
Minimum air temperature (∞C)
5
0
January
Part 1: Features of ecosystems
April
July
October
29
Temperature differences and fish
1.
The natural habitat of goldfish would have a narrow temperature
variation.
2.
Annual temperature changes would occur slowly during the passing
of the seasons. Such changes are slow enough not to place undue
stress on the fish. It is the rate of temperature change rather that the
total temperature change that is important.
3.
Cold ocean currents and the outflow of rivers into the ocean can
produce areas in which temperature rapidly changes. (You may like
to think about how fish can overcome the rapid temperature changes
in these areas.)
Oxygen availability
There are a number of potentially harmful biological effects:
•
Increased water temperature will reduce the amount of oxygen that
can be dissolved into water. So oxygen availability to organisms
will decrease.
•
The increased temperature will not necessarily suit the organisms
that live there. Existing organisms may be forced to move or die.
In Lake Macquarie the availability of many commercial fish species has
decreased in the areas of heated water in the lake. Close to the outlet
where water temperatures are hottest, the number of species found has
decreased.
Desiccation
30
1
The eel is not affected by desiccation and is able to hang the gills
directly into the water to remove oxygen.
2
The mouse lives in a desiccating environment and would dehydrate
rapidly if the large surface area of the lungs were exposed to air.
Unlike skin, lungs are not water proof and can lose moisture.
3
The larger proportional surface area of the eel’s gill allows more
efficient removal of oxygen. This larger surface area compensates
for the eel living in an environment with a low oxygen availability.
Local environment
Pressure and living things
1.
The volume of gas will be the same as when he started. Both lungs
full of air. As the spearfisherman swims down, the gas compresses.
When he swims back to the surface the gas expands as it
decompresses.
2.
At 20 metres the pressure is three times that of the surface.
The volume of gas will be one third of that at the surface.
Availability of ions
Situation
Water movement
goldfish in its natural
freshwater
environment
Water moves in very slowly because the goldfish's body
tissues have a slightly lower water concentration than fresh
water.
goldfish placed in sea
water
Water moves out of the goldfish's cells rapidly because the
concentration of water in the fish's cells is higher than the
surrounding water. The liquid in the goldfish's cells is not as
salty as the surrounding water.
tailor (a marine fish) in
its natural
environment
Water moves out very slowly because the concentration of
water in the fish's cells is a little higher than the surrounding
water.
tailor placed into
freshwater
The fluids in the tailor’s cells are saltier than the surrounding
water. Water would move rapidly into the tailor's cells because
the concentration of water outside the fish is much higher than
the concentration inside the fish.
goldfish in brackish
water
Brackish water is saltier than the fish's cells. The
concentration of water inside the fish is therefore higher than
the surrounding fluid so water moves out of the fish.
tailor in brackish water
The brackish water is less salty than the liquid in the tailor's
cells. Water will move into the tailor.
Water for support
1.
It is easier to float in salt water than fresh water because salt water is
denser than fresh water.
2.
It is more difficult to float in air than it is in water.
Part 1: Features of ecosystems
31
32
Local environment
Exercise – Part 1
Exercise 1.1
Name: _________________________________
Complete the table for abiotic factors below. You will compare (show
how each is similar or different) each factor for terrestrial and aquatic
environments. This is a useful exercise, because you are often asked to
summarise similarities and differences.
Abiotic factor
Comparison
Terrestrial
Aquatic
availability of ions
availability of oxygen
availability of water
conductivity
desiccation
light penetration
pressure
support
temperature
viscosity
Part 1: Features of ecosystems
33
Gill Sans Bold
Senior Science
Preliminary Course
Stage 6
Local environment
Part 2: Populations in ecosystems
0
20
I
er
b
to T S
c
O EN
g
in D M
t
a
r EN
o
p
or AM
c
n
2
Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction ............................................................................... 3
Distribution and abundance....................................................... 4
Distribution............................................................................................4
Abundance............................................................................................7
The importance of distribution .............................................................9
The importance of abundance.............................................................9
Short and long term consequences of competition ................. 11
Long term consequences: natural selection and evolution ..............11
Sampling ................................................................................. 13
Why biologists make estimates .........................................................13
Techniques of sampling .....................................................................14
Capture/recapture and tagging/marking practical.............................21
Quadrat sampling practical ................................................................22
The flow of energy and matter................................................. 25
Energy.................................................................................................25
Matter..................................................................................................25
Defining an ecosystem.......................................................................26
Matter and energy flow ......................................................................26
Trophic levels .....................................................................................32
Part 2: Populations in ecosystems
1
Important cycles in ecosystems ............................................... 33
Water cycle.........................................................................................33
Carbon/oxygen cycle .........................................................................34
Nitrogen cycle ....................................................................................35
Photosynthesis and respiration................................................ 36
Photosynthesis...................................................................................36
Respiration .........................................................................................37
Suggested answers ................................................................. 39
Exercise – Part 2 ..................................................................... 43
2
Local environment
Introduction
In this part, you will be given opportunities to learn to:
•
identify the factors determining the distribution and abundance of a
species in each environment
•
describe and explain the short and long term consequences on the
ecosystem of members of the same species competing for resources
•
explain the need to use sampling techniques to make population
estimates when total counts cannot be made.
•
discuss the importance of the cycling of materials in ecosystems
•
describe the flow of matter through a natural ecosystem using the
water, carbon/oxygen and nitrogen cycles
•
identify uses of energy in organisms
•
describe the flow of energy through a natural ecosystem.
In this part you will be given opportunities to:
•
perform a first hand investigation using transect, random quadrat,
capture-recapture and tagging/marking methods to make estimates of
real or simulated populations of organisms and use the available
evidence to discuss the advantages and disadvantages of these
methods.
•
identify data sources, gather and process information from first-hand
and secondary sources to construct food chains and food webs to
illustrate the flow of matter and energy and use the available
evidence to discuss the relationships between different organisms in
the ecosystem.
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
Part 2: Populations in ecosystems
3
Distribution and abundance
In many ecological studies it is important to determine:
•
how many organisms are in an area – abundance
•
where the organisms occur – distribution.
How many and where found will be important questions for you to
answer in your ecological study later in this module.
Distribution
Distribution is the geographic range of a species or group of organisms.
There are many terms to help describe distribution, but perhaps the two
most helpful are endemic and pandemic.
Endemic and pandemic species
An endemic species is one that naturally occurs only within a particular
area. For example, the budgerigar is a small parrot endemic to Australia.
Budgerigars can be found in captivity in many other countries, but they
are not endemic to these places. Other organisms endemic to Australia
include kangaroos, koalas, eucalypts and the Gouldian finch.
Think about the plants and animals in your local area. Which ones are
endemic?
A pandemic species is spread worldwide, or at least is very widespread.
Humans are probably the only species that comes close to having a
worldwide distribution, but many others are certainly very wide spread.
Pandanus plants, for example, are very widely spread in the tropics.
Pandanus has a fruit that can float large distances in the ocean, making
the colonisation of widely spread islands and continents possible.
4
Local environment
Many gulls and terns have a large distribution related to their extensive
flight over water and their ability to feed at sea. They can also rest by
floating on the water.
Factors relating to distribution
As you will have probably realised, it is one thing to identify distribution,
but it can require a lot of thought and research to find out why the
organisms occur within this distribution. When you do your fieldwork
later in this module, you should think about the possible reasons
for distribution.
Let’s look at the distribution of the bacterium, Escherichia coli. E. coli is
abundant in the digestive tract of humans and is very closely associated
with the distribution of humans. The relationship between the
distribution of the two species is used to trace the entry of human wastes
into streams and oceans. Wherever you get human waste, you also get
high levels of E. coli. Counts of E. coli are one of the most common
tests performed to record the levels of human waste in water.
Recording distribution
When you are studying an area such as a park or bushland reserve it is
not sufficient just to record if a species is endemic or pandemic.
More detailed information is required.
Ecologists will usually make a map to show the location of the major
plants and the regions in which particular animals are found. These maps
are very useful because distribution is often related to biotic and abiotic
features within an environment.
Look at the two maps on the next page that were made by a student
studying the local area. One map shows only the major topographic
features and the other shows the major vegetation types for the
same area.
Part 2: Populations in ecosystems
5
Maps of a student's local area.
6
Local environment
1
List the topographic features shown in the student's map above.
_____________________________________________________
_____________________________________________________
2
Does any of the vegetation seem to be related to particular
topographic features?
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
If you were to list the main topographic features of your local area, what
features would you include?
_________________________________________________________
_________________________________________________________
_________________________________________________________
Abundance
Abundance refers to the numbers of individuals. Abundance is not
necessarily related to distribution. For example, Dugong dugon, the
dugong, has a wide distribution in calm coastal waters about the
northern coast of Australia, but has a low abundance (hunting has
reduced numbers.)
Abundance can be determined by making estimates of the population
size. Estimates will be dealt with later in this module.
In the fieldwork you will do later, you may decide to determine the
abundance of a species. Once the abundance is determined, you will then
need to consider any factors that relate to this abundance or any
particular significance that may be attached to the figures.
Let’s look at some examples.
Part 2: Populations in ecosystems
7
Seasonal variation in abundance
During migration or breeding some species will have a greater abundance
in a particular location than at other times of year.
The wedge-tail shearwater, Puffinus pacificus, is found in very large
numbers between November and May on many islands and some coastal
areas of Australia. The abundance is very high. When visiting these
same areas in June–October, the abundance is very low. There is a
seasonal abundance related to breeding.
Abundance related to a biotic factor
When the prickly pear, Opuntia stricta, was released into Australia few
organisms ate it. The prickly pear spread rapidly to many parts of
Australia, overgrowing natural plant communities and taking over
valuable agricultural land. The abundance of prickly pear was very high.
The CSIRO released the cactoblastis moth, Cactoblastis cactorum, that
ate prickly pear. Within 12 months the majority of prickly pear had been
eaten: prickly pear abundance had decreased in response to being eaten.
Answer the following questions. Both questions are designed to make you
think about the information given in the two examples above.
1
You have found out that wedge-tail shearwater number varies
seasonally in some Australian islands. November to May the
abundance is high in these islands, while June to October the
abundance is low on the islands.
If you were to estimate the total abundance of wedge-tail
shearwaters worldwide in July, would you expect this number to be
the same as the total number worldwide in May?
Explain your answer.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
8
Local environment
2
Draw a graph to represent the change in prickly pear abundance
from the day cactoblastis was first released until one year later.
Add a line to represent what you would have expected to see happen
to cactoblastis abundance as well.
Number of prickly pear
Use the axes lines following.
0
1
Time (years)
Check your answers.
The importance of distribution
Wide distribution is usually beneficial to a species. If members of a
species die in one location due to changed conditions, then there will be
others in different locations able to survive and continue the species.
Species with restricted distributions face extinction if the few places they
are able to live become unsuitable. For example, the Wollemi pine
(Wollemia nobilis) currently has a very small distribution and is restricted
to a single location in the Blue Mountains to the west of Sydney. If this
single location was damaged, the pine could become extinct.
Part 2: Populations in ecosystems
9
The importance of abundance
High abundance is generally beneficial to a species because it provides a
large gene pool and enables the species to maintain a large genetic
variability. High genetic variability is very desirable to enable species to
cope with the changes in environments over time.
10
Local environment
Short and long term consequences of
competition
Long term consequences: natural
selection and evolution
Members of the same species compete for resources such as shelter,
mates and food. Those able to get sufficient of these resources are able
to live and reproduce.
Natural selection and evolution result from competition for resources.
Those with favourable characteristics will be more likely to survive and
reproduce than those with less favourable characteristics. Over time,
natural selection will select the favourable characteristics and reject
the less favourable characteristics. The species will change (evolve) as
a result.
In some cases, evolution allows a species or group of organisms to
make use of a food source not previously available to them.
For example, before the evolution of jaws, most fish groups were filter
feeders. They sieved microorganisms from the water and used them
as food. With the evolution of jaws, fish were able to kill and eat
larger prey.
When a species evolves to be able to use a new source of food, the food
organism will be reduced in numbers. Sometimes the food organism will
also evolve in response to the new selection pressure. For example,
trilobites became a food source for jawed fish. In response to this new
source of predation, many groups of trilobites evolved the ability to
roll–up. When trilobites rolled-up, their soft under surface was protected
and only their armored shell was exposed.
The balance of different species within the ecosystem will change over
time as species evolve to suit their changing conditions.
Part 2: Populations in ecosystems
11
The short-term consequences
You have seen that the long-term consequence of members of the same
species competing for a resource is evolution. The short-term
consequences for some members of a species include:
•
death or shortened life span
•
reduced numbers of offspring.
The Australian magpie
The Australian magpie, Gymnorhina tibicen, is a territorial bird.
Only those with a nesting site will breed. The nesting site is within a
territory in which the birds feed. Those able to get and defend a territory
and nesting site are able to breed and maintain a food supply. The other
birds are not able to breed and are forced to feed from less desirable
areas. In times of food shortage, magpies with territories are better able
to survive than those without.
You will look more closely at the relationship between a species and a
food resource when you learn about predator-prey relationships later in
this module.
Make a summary of the long-term and short-term consequences of
competition.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your summary against the notes above.
12
Local environment
Sampling
Why biologists make estimates
Ecologists often need to quantify abundance and distribution.
For example, ecologists are often asked to work out the numbers of a
rare species or even of pests to help work out management plans for
these organisms.
In a large area it is not feasible to count every organism and to map its
location. For example, if you needed to determine the total number of
grey kangaroos in New South Wales or if you wanted to know how many
blades of grass were on a lawn, it would not be practical to count every
kangaroo and every blade of grass. To overcome this problem,
ecologists will sample a known percentage of the area and then multiply
to make an estimate of the total number. The formula most commonly
used is:
total number = number found in area sampled X
100
percentage area sampled
In a study to estimate the total number of Crinia signifera (a species of frog)
in a marsh, a biologist sampled 5% of the total area. A total of 127 Crinia
signifera were located in the sample area. Use the formula given above to
estimate the total number of Crinia signifera in the marsh.
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
Part 2: Populations in ecosystems
13
Techniques of sampling
The selection of the area or areas to sample is one of the most difficult
decisions facing the ecologist. The ecologist must determine the size of
the sample, as well as deciding whether the sample will be selected
randomly or non-randomly. In addition, a sampling technique must be
chosen (quadrat, transect, capture/recapture or tagging/marking.)
You will have trouble in making some of these choices when you do
your fieldwork later in this module. To assist your decision making
process, each of the options for taking a sample are discussed below.
Sample size
The larger the percentage of the total area sampled, the more accurate the
estimate will be. Sampling 30% of an area, for example, will provide a
more accurate result than sampling 10% of an area. A 100% sample is
the most accurate, but constraints of time and cost mean that a smaller
sample is generally taken.
Number of samples
Once the size of the sample has been decided, you must determine how
many samples to take. For example, if 10% of the area is to be sampled,
should it be a single sample of 10%, ten 1% samples, two 5% samples or
even five 2% samples?
The decision about the number of samples will depend upon a number of
factors. For example, if you use many small sample areas it is possible to
scatter your samples over a wider area.
However, if you are sampling large organisms such as eucalypts, you
will need each sample to cover an area big enough to include a number of
plants for study.
Both sample size and sample number provide much discussion and
argument in scientific circles. It is never an easy decision to make,
as you will find out when you attempt your own field study later in
this module.
14
Local environment
Random site selection
As the name suggests, you choose the site(s) to sample randomly.
The advantage of this method is that you are not influenced by your own
prejudice in site selection. For example, in choosing a site you may be
influenced by factors such as the inconvenience of working in an area
with large numbers of stinging nettles or you may prefer to work on flat
ground rather than on a steep slope. Random site selection removes such
possible sources of bias.
A common method of random sampling is to obtain a map of the site
and place a grid across the map. Each grid square has a number.
Grid numbers are selected at random (numbers placed into a hat).
Those that are drawn are the ones to be sampled. For smaller areas, a
wire square can be thrown into the sample area. Everything that falls
inside the square is sampled.
The disadvantage of this method is that organisms are not distributed
evenly, and so it is possible that your randomly chosen samples will not
give a true representation of either number or distribution. Consider the
diagram below.
A
B
C
D
E
F
G
H
I
J
1
dam
2
3
4
5
6
7
8
9
10
cattle
sample
Paddock with ten selected random samples shown (shaded).
Part 2: Populations in ecosystems
15
If you were asked to determine the number of cattle in the paddock
above, you could run into problems using a random sample method.
The paddock is shown during drought. The randomly selected samples
are spread across the whole paddock, but none include any cattle.
Based on the ten selected samples alone, you would determine that there
were no cattle in the paddock. The cattle are clustered about the water
source and the random sample method does not take this into account.
Similar situations can lead to misinterpretation. An example is explained
below:
•
During drought in western New South Wales many animals feed
close to roads because the box drains at the side of roads are moister.
The vegetation will continue to grow despite the drought. The
vegetation attracts herbivores such as kangaroos.
•
The increased number of herbivores at the roadside increases the
number of road kills.
•
The increased number of road kills attracts larger numbers of
carnivores such as eagles.
•
As the drought worsens, population numbers decrease and those
remaining move closer to the roads.
•
Because of the large number of animals at the roadside, motorists
commonly report these animals to be in plague proportions during
drought when in fact the populations are in decline.
Without a sample that accurately represents the situation, it is easily to
come to incorrect conclusions.
Think about the factors which affect plant distribution (water availability,
soil type and so on). How might these factors affect the decisions you make
about where to sample? You might like to look at the student maps we saw
earlier that showed topographic features as well as vegetation distribution.
When should you use random samples?
Random samples are best used when you do not want to influence the
choice of the sample site and when organisms are evenly distributed
across an area.
Non-random samples
In a non-random sample you choose which areas to sample.
This overcomes the problem of non-random distribution of organisms
and allows ‘typical’ areas to be selected.
16
Local environment
Let's consider a couple of ways in which we could apply a non-random
sample to the problem of the cattle in the paddock shown on page 14.
If you look carefully at the diagram, you will see that the cattle occur in
ten grid squares and that there are no cattle in the other 90 squares.
Given this information, you could choose your squares in a semi-random
manner to reflect this distribution. You could choose one of the grid
squares with cattle present at random and choose nine of the grids
without cattle at random.
Another, and perhaps simpler possibility in this case, is to only sample
the ten grid squares in which cattle occur. Given that ten squares are to
be sampled, this method would give you the exact number of cattle.
Of course, you do not need to modify your result mathematically in this
case because you have counted the entire population.
When should you use a non-random sample?
Non-random samples are best used when organism distribution is to be
taken into account.
Transect
A transect is a line drawn across a study site. In the field the line is
usually identified by running a string line across the site or by taking a
compass bearing from an identified starting point. Transects are very
useful for identifying changes in distribution and abundance across a site.
There are two types of transect: line transect and strip transect.
Line transect
When using a line transect you only sample organisms that fall on the
line of the transect. For long transects it is common to only sample part
of the transect, for example by only recording organisms occurring in
every tenth metre.
A line transect and a strip transect are shown on the following page.
Compare the two types of transects. What is the difference between the
two? Which transect might you use?
Part 2: Populations in ecosystems
17
line transect
strip transect
m
strea
plan view of site
large eucalypt
melaluca
marsh
grasses
Line transect compared with a strip transect
Strip transect
In a strip transect a transect line is placed across a site. Another line is
run parallel to the transect line and everything within the two lines is
sampled. This provides a strip within which to sample.
There are many variations on strip transects. For example, some
ecologists only record data for part of the strip (eg. recording the strip in
every tenth metre in long transects). Others will record a square metre
from either side of the line at regular intervals.
18
Local environment
line parallel to transect line
transect line
distance in metres
Below is a diagram showing variations of strip transect design.
sample
area
a Sampling the strip
at regular intervals.
sample
area
b Sampling either
side of the line
at regular intervals.
sample
area
c Alternating sample
at regular intervals.
Some options for strip transects.
Quadrat
A quadrat (pronounced kwod-rat) is a sample area, often a square,
rectangle or circle. It is usual to have a number of quadrats of identical
dimensions within an area. Quadrats can be assigned either randomly or
non-randomly. In the field a quadrat is usually defined by placing a
string line about the quadrat boundaries.
Quadrats are used to measure distribution and abundance and are
particularly useful when wanting to sample a range of locations
across a site.
Refer to page 14 to see quadrats placed at random across a site using a
grid reference.
Part 2: Populations in ecosystems
19
Capture/recapture and tagging/marking
Capture/recapture is a method used to estimate numbers in populations of
moving organisms. The technique is used almost exclusively with
macroscopic animals eg. fish and birds.
In capture/recapture a known number of animals are captured live and
tagged. These are then released.
After time has been allowed for the released animals to move back
into their populations a sample of animals are again captured alive.
The number of tagged and the number in the recaptured sample is
recorded. The ratio of tagged recaptured to number in sample equals the
ratio between the number originally tagged and the total population
number.
number recaptured with tag
number originally tagged
=
number in recaptured sample
total population
Rearranging the formula to estimate the total population
total population =
number in recaptured sample
number recaptured with tag
number originally tagged
Accuracy is improved by initially tagging a large number of animals and
by repeating recapture a number of times and averaging the results. It is
most important that tagged animals are released where they were found
or that time is allowed for animals released in one location to spread
amongst the total population before a sample is taken.
Thiara balonnensis is a small marsh snail found in northern New South
Wales and southern Queensland. An ecologist captured 250 Thiara
balonnensis and placed a small spot of mauve coloured nail varnish onto
each shell. The varnish was almost indistinguishable on the brown
shell and did not expose the tagged snails to any additional chance
of predation.
Each tagged snail was released exactly where it had been found.
After one week 200 snails were recaptured. Of the 200 snails recaptured,
only 20 were tagged snails.
1
Why did the ecologist wait a week between marking the snails and
doing the recapture?
______________________________________________________
______________________________________________________
______________________________________________________
20
Local environment
2
Estimate the abundance of the Thiara balonnensis population.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Practical work is a mandatory part of your course. The two practicals
following are to be completed and then reported on in the send-in
exercise at the end of this part.
Capture/recapture and
tagging/marking practical
Aim
To estimate the number of toothpicks in a packet by using capture/recapture
and tagging/marking.
You will need:
You will need a packet of toothpicks (three boxes of matches is a
reasonable substitute for toothpicks), a marker pen and a plastic bag
for this practical.
Method
1.
Mark the end of 20 toothpicks with a marker pen.
2.
Place all the toothpicks (marked and unmarked) into a plastic bag.
3.
Shake the bag.
4.
Without looking into the bag, remove 20 toothpicks at random.
Record the number of marked toothpicks in your sample.
5.
Replace all of the toothpicks into the bag.
6.
Repeat steps 3, 4 and 5 twice more so that you have three sets of
recapture data.
Part 2: Populations in ecosystems
21
Results
For each of the samples estimate the total number of tooth picks in the
packet. Put your results into a table like the one below.
Sample
number
Number of
toothpicks in sample
1
20
2
20
3
20
Number of coloured
toothpicks in sample
Average the number of coloured toothpicks and use this number to
estimate the number of toothpicks in the packet.
Discussion
There are a number of aspects of this experiment that reflect good
scientific method. For example, the experiment is repeated a number of
times (why do we do this?) and the result of the three samples is
averaged (why do we do this?). If you are not sure why these are done
read the section on Experiment design skills in the Science resource
book.
Quadrat sampling practical
Aim
To estimate the total number of symbols in the figure on the following page
titled ‘Birds’. Use 10 quadrat samples.
You will need
A ruler, pencil and the figure titled ‘Birds’ on page 22.
Method
You are to use 10 quadrats to estimate the total number of symbols in the
graphic. Each quadrat must represent 1% of the total area of the sample.
This is an area of 1 cm2 on the graphic. Your 10 samples will, therefore,
represent 10% of the total area.
1.
22
Decide how to place your samples (random or non-random).
Local environment
2.
Draw your quadrats onto the diagram. You must draw them to scale.
(You can draw squares that have each side 1 cm long.)
3.
Count the number of symbols in each quadrat.
Result
1.
Construct a table to show the number of symbols in each quadrat.
2.
Estimate the total number of symbols in the birds graphic on page 22.
Show all your calculations.
Discussion
Did you choose a random or non-random distribution of quadrats? Why?
100 m
Name two things you could do to improve the reliability of your results.
100 m
Birds.
Now do Exercise 2.1 to report on the two practical activities that you have
just completed.
Part 2: Populations in ecosystems
23
If you have access to a computer connected to the Internet, you may like to
visit the web site Africam.
This site has placed cameras at a number of waterholes in Africa. Every 30
seconds or so each camera takes a photograph. The best times to log onto
this site if you live in Eastern Australia is early in the afternoon (dawn at the
African waterholes).
The Africam site is interesting for ecologists because you can determine the
times of day the waterholes are most commonly used by animals, as well as
determining the times of day most commonly used by particular species.
You can access this site by going to the following address:
http://www.lmpc.edu.au/science. From here go the section for Senior
Science, 8.5 Local Environment, where the link is listed.
24
Local environment
The flow of energy and matter
Before you can begin to understand the flow of energy and matter
through an ecosystem you must first have a working knowledge of
energy and matter. In this first section you will review these ideas.
Energy
Work is done when energy is released. There are many different types of
energy such as heat, light, kinetic (energy of motion) and potential
(stored) energy. You will no doubt remember many of these from your
previous studies in science.
Energy cannot be created and it can not be destroyed. However, energy
can be converted into other types of energy.
Energy is important to organisms. Food provides a source of chemical
energy. This chemical energy can be converted into other forms of
energy useful to the organism such as heat energy and kinetic energy
(for movement.)
Matter
Matter is the word we use to refer to the stuff from which things are
made. Matter has mass.
Within food webs, matter (food) moves from one organism to another.
We can also measure biomass, the mass of living matter. For example,
the biomass of plants in a particular area is generally much higher than
the biomass of herbivores that feed upon the plants. Can you think of
any reasons why this may be so? We will return to this idea later in
the module.
Part 2: Populations in ecosystems
25
Defining an ecosystem
An ecosystem is the total of all biotic and abiotic factors in a particular
area and the relationships between them. For example, in a desert
ecosystem, an ecologist is referring to all the plants, all the animals and
all the relationships between these organisms, as well as the non-living
aspects of environment such as temperature.
Other levels of organisation
There are many levels of organisation in ecosystems. At one of the
lowest levels there are individuals. A collection of individuals of the
same species within a defined area is called a population. Collections of
populations form a community of organisms.
Matter and energy flow
Food chains
An ecologist noticed that the berries on the blueberry ash (a type of tree)
in his garden were eaten by sugar gliders that visited the tree at night.
One night while the ecologist was observing the sugar gliders, a powerful
owl captured and killed one of the gliders. The owl took the body to a
near-by tree where it ate its victim. The diagram below is a simple food
chain that explains the observations and indicates the relationship
between the organisms involved.
blueberry ash
sugar glider
powerful owl
Food chain showing the feeding relationship between blueberry ash, sugar
gliders and powerful owls
Notice in the figure above that the arrows point in the direction of energy
flow. When drawing a food chain you must always have the arrows
pointing in the direction the energy (food) has moved.
26
Local environment
All food chains start with a primary producer. In this food chain the
primary producer (autotroph) is the blueberry ash.
Here is a quick check to see if you can make a simple food chain.
Read the paragraph below and make a food chain to describe
the relationships.
The blackfish eats a variety of green algae. One natural predator of the
blackfish is the tailor. Tailor are carnivorous fish that are a particular
threat to smaller blackfish.
_________________________________________________________
Check your answer.
Food webs
A food web is a method of showing a number of relationships at the same
time. Let’s return to the sugar glider example above. Blueberry ash is
not the only food source for sugar gliders. They eat many other things
including the flowers of eucalypts and the sap that can be found on the
trunks of wattle.
Powerful owls also eat more than just sugar gliders. For example, they
also eat mice. Mice eat grains (grass seeds) amongst other things in
their diet.
Look at the diagram below. It shows the relationships described above.
grains
blueberry ash
mouse
sugar glider
powerful owl
eucalypts
wattle
Simple food web.
If a living thing is not eaten by something else, then it will eventually die
and decay. To make a food web we need to take decay into account.
The diagram on the next page shows how this food web can be modified
to take into account the decay relationships.
Part 2: Populations in ecosystems
27
mouse
grass
sugar glider
blueberry ash
powerful owl
eucalypts
wattle
decay
More complex relationships between a group of organisms.
When drawing food webs you must take care not to cross the lines
because this can make your diagram confusing. Arrows point in the
same direction as they do in food chains–in the direction that
energy moves.
Sometimes ecologists infer relationships. For example, an area may have
kookaburras and worms present. The ecologist knows that kookaburras
eat worms, but has not actually seen the kookaburra eat a worm at the
site being studied. To indicate that it is likely that worms are being eaten
by kookaburras a dotted line is drawn in the food chain or food web.
worm
kookaburra
Inferred relationships are linked with dotted lines.
If you decide to draw a food web or food chain as part of your fieldwork
you may find it useful to use inferred relationships (dotted lines.)
Study the information below and then draw a food web to describe the
relationships.
An ecologist made a list of every relationship between organisms that he
observed at a site. The list is shown on the next page.
28
Local environment
Organism
Eaten by
fig tree
fruit bat
fig tree
silver eye (a type of bird)
silver eye
hawk
grass
mouse
mouse
hawk
Grass
European rabbit
The ecologist did not see anything eat the rabbits, but he has read in a
book that hawks often eat the smaller young rabbits. There is an inferred
relationship between the rabbit and the hawk. All of the organisms that
are not eaten eventually die and decay.
Check your answers.
Part 2: Populations in ecosystems
29
Biomass pyramids
Biomass is the total living mass of organisms. Biomass can be used to
refer to the total mass of a species, or group of organisms in an area.
You may determine the total biomass of all organisms in an area or the
biomass of a single species.
If you estimated the biomass of herbivores, carnivores and primary
producers in a community, a pyramid like the one below could be drawn.
This biomass pyramid is
based on qualitative data.
It simply shows that the
total living mass (biomass)
of top-order consumers is
less than that of carnivores.
The biomass of carnivores
is less than the biomass of
herbivores. The biomass
of herbivores is less than
the biomass of primary
producers upon which they
feed.
top
order
consumer
carnivores
herbivores
primary producers
A biomass pyramid based on qualitative data.
If a quantitative study was made a biomass pyramid could provide more
detail:
biomass in grams
2g
tertiary consumers
10 g
secondary consumers
40 g
consumers
820 g
producers
A biomass pyramid based on quantitative data.
Energy pyramids
Only about 10% of all the energy stored by the primary producers is
passed on to the herbivores. Likewise, only 10% of total herbivore
energy is passed to the carnivores, and only 10% of total carnivore
energy reaches the top-order consumers.
30
Local environment
Let’s look at this in a different way. Of all the energy available in
primary producers:
10% of this reaches herbivores
1% reaches carnivores
0.1% reaches top-order consumers.
The figure below shows reduction of energy passed along the food chain.
1/
10
size of
primary producer
energy
passed to
herbivores
1/
10
size of
herbivores
1/
10
size of
carnivores
energy
energy
passed to passed to
carnivores top order
consumer
energy in primary producers
Now let’s think about the producers and herbivores. Producers use much
of the energy stored in their cells in respiration and growth. This energy
used by the producers cannot be passed on to herbivores.
The herbivores eat the producers, but they do not eat all the producers.
Some producers remain uneaten and will eventually die and decay.
The energy used by the producers and the uneaten individuals accounts
for about 90% of all the energy available in producer cells. This is why
only 10% of the total energy is passed on to herbivores.
A careful quantitative study of a community could produce an energy
pyramid such as this:
21
383
3368
20810
second order carnivores
first order carnivores
herbivores
producers
Pyramid of energy (kJ/m2/year)
Part 2: Populations in ecosystems
31
10 000 units of energy are needed each day to support a small group
of carnivores. If less than 10 000 units of energy are available, the
carnivores will die. The carnivores are part of a simple food chain
which is shown below:
primary producer fi herbivore fi carnivore
The total energy in the herbivores is 100 000 units.
1
Will the carnivores survive? Explain your answer.
______________________________________________________
______________________________________________________
2
List the use of energy in organisms.
______________________________________________________
Check your answers.
Trophic levels
When referring to organisms as primary producers, herbivores,
carnivores and top-order consumers or producers, herbivores, first order
carnivores and second order carnivores, we are really dividing living
things into trophic levels.
A trophic level is the relative position of an organism in a food chain.
(Trophic comes from the Greek word trophos meaning ‘food’.)
Plants which are able to convert light energy from the sun into chemical
energy are at the bottom trophic level of all food chains because they
support all of the other trophic levels. All these other trophic levels
obtain energy by obtaining chemicals from the bodies of lower
trophic levels.
The energy flows in one direction only from producers to herbivores
to carnivores.
The energy is not recycled. No energy is returned to the sun.
However, energy from the sun can be trapped and stored, unused in fossil
fuels such as coal and oil, for hundreds of millions of years.
32
Local environment
Important cycles in ecosystems
Many materials are cycled within ecosystems. Cycles are important
because they allow substances to be reused. Many of the cycles in
ecosystems include both biotic and abiotic factors in the cycle.
This allows living things access to abiotic factors that they require
for life.
You will now look briefly at three cycles that you may have encountered
in your previous studies in science.
Water cycle
condensation
precipitation
er land
inds ov
ist w
o
m
ev
ap
or
at
io
precipitation
n
evaporation
transpiration
water run-off
absorption
sea
percolation
Water cycle
To help you better understand this cycle, take a pencil and trace the path of
the water around the cycle. Will the water stay longer in some parts of the
cycle than others?
Part 2: Populations in ecosystems
33
Carbon/oxygen cycle
solar energy
enables
green plant to carry
on photosynthesis
carbon dioxide (CO2) in the air
industrial
burning
of fuel
plant
respiration
volcanoes
burning
of coal
and
wood
oxygen
animal
respiration
eating
animal waste
animal death
plant death
decay by bacteria and fungi
Carbon/oxygen cycle
Trace the path of carbon and oxygen around this cycle. Locate the parts of
the cycle where carbon exists as solid compounds and the parts of the cycle
where it is combined with oxygen to form carbon dioxide gas.
The carbon/oxygen cycle shows a balance between:
•
CO2 absorbed by photosynthesis
•
CO2 released by respiration and the burning of fossil fuels
•
O2 released by photosynthesis
•
O2 absorbed in respiration and the burning of fossil fuels.
Current trends to reduce forests and increase the use of fossil fuels mean
that less oxygen and more carbon dioxide is produced. This will reduce
the oxygen levels in the atmosphere and increase the carbon dioxide
content. It is predicted that even small increases in the amount of carbon
dioxide in air will lead to increased temperatures on Earth.
You will look more closely at respiration and photosynthesis in one of
the following sections of this module.
34
Local environment
Nitrogen cycle
lightning
nitrogen gas in atmosphere N2
nitric acid
HNO3
nitrogen-fixing
bacteria in soil
and root nodules
of legumes
nitrates
NO3–
denitrifying
bacteria
plant
death
nitrifying
bacteria
nitrites
NO2–
ammonium
salts NH4+
animal animal waste, for
death
example, urea
(NH2)2CO
decomposition by
bacteria and fungi
ammonia gas
in soil NH3
Nitrogen cycle.
All living things require nitrogen to make important substances such as
proteins and enzymes. Only a few bacteria can use nitrogen gas directly
from the atmosphere. All other living things must use chemical
compounds that contain nitrogen for their nitrogen requirements. If it
were not for nitrogen-fixing bacteria, life would probably cease to exist
on Earth.
How well can you remember the three cycles above? Quick now. Grab a
piece of paper and draw the water cycle, carbon/oxygen cycle and nitrogen
cycle. Do not look at the notes you have just read. When you have finished
you can check your answers against the diagrams in the notes above.
Part 2: Populations in ecosystems
35
Photosynthesis and respiration
The life processes, photosynthesis and respiration, have important roles
in sustaining ecosystems. These will now be discussed in more detail.
Photosynthesis
The sun is essential to life on Earth. The sun provides the light energy
that is converted into chemical energy for use by living things in the
process of photosynthesis. You have already seen that photosynthesis:
•
has been important in the development of our current atmosphere
•
is a factor in the carbon/oxygen cycle.
Photosynthesis is important because it is the main process by which raw
materials (abiotic factors) can be made into high-energy compounds that
can provide a food source for organisms.
Light energy is converted into chemical energy during photosynthesis.
The low-energy compounds water and carbon dioxide are changed into
high-energy sugars in the process.
The word equation for photosynthesis is given below. The equation
should be familiar to you already since you had the opportunity to study
it earlier in this module.
carbon dioxide + water
in the presence
of light
glucose + oxygen + water
Word equation for photosynthesis.
Primary producers start each food chain. It is the energy from the sugars
created in photosynthesis that is passed along food chains. What is the
ultimate source of the energy of sugars made by photosynthesis?
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Local environment
Respiration
Respiration is the process by which energy is released from food. It is a
chemical process that occurs in all cells of all living things.
When respiration stops, life stops. A word equation for the process of
respiration is given below.
food + oxygen
energy + carbon dioxide + water
Word equation for respiration
Mainly chemical energy and heat energy are released in this process.
Food is a high-energy reactant. Carbon dioxide and water are two
low–energy products.
Respiration is more complex than the word equation above indicates.
The process does not release energy in a single step. Respiration is a
reaction with many steps. Each step releases a little energy. One of the
advantages of this is that the rate of energy release can be better
controlled to prevent overheating of cells.
Respiration is important in ecosystems because of the by-products,
carbon dioxide and water. The global rate of carbon dioxide
production must be equal to the global rate of oxygen release by
photosynthesis. If an imbalance occurs the levels of oxygen and carbon
dioxide in the atmosphere will change, with potentially disastrous
consequences for ecosystems.
Answer the following questions in the space provided. The questions have
been written to make you think carefully about the application of some of
the things you have already learned. You can expect that your HSC
examiners will also write questions that will require you to apply what you
have learned to real situations.
1
Miriam says that respiration is a process that releases energy in cells,
but Marnie says that respiration is breathing rate because her doctor
always times her breathing rate when she needs to determine
Marnie’s respiration rate. Who is correct, Miriam or Marnie?
Explain your answer.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Part 2: Populations in ecosystems
37
2
Clearing of land for agriculture has decreased the rate of
photosynthesis, but has provided significantly more food for
humans, to support population increases. Explain the significance of
land clearing for agriculture to the carbon/oxygen cycle.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
3
Justin purchased a bag of lawn food from a nursery. The sign on the
bag says ’All the food your lawn needs. Just apply one handful per
ten square metres every six weeks.’ The list of bag contents
indicates that the bag contains only inorganic minerals.
When Justin’s friend Robert read the details on the bag he said that
the label on the bag was incorrect because there was no plant food in
the bag.
Is Robert correct or incorrect? Explain your answer.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
You have now finished Part 2. In the next part of this module you will
look more closely at population sizes. Move on to Part 3 now. Do not
wait for the send-in exercises to be returned before moving to the
next part.
38
Local environment
Suggested answers
Recording distribution
1
The map shows the following topographic features: a hill, a ridge
and a stream.
2
You may infer a number of relationships from these maps. First, the
wet sclerophyll forest is related to the presence of water. It occurs
close to the stream. The second inference is that the basalt creates
soils that favour the Xanthorrhoea (the grass tree) or that the slope of
the hill provides favourable habitats for this plant. Finally, dry
sclerophyll forest is related to the areas away from water on welldrained sandy soils.
Abundance related to a biotic factor
1
The worldwide total would increase each year after the hatching of
the eggs and then gradually decrease until the following season's
breeding season.
In the case of the islands, the birds live there for only part of the
year. For the remainder they live elsewhere. If you only sampled
the islands you would get the mistaken impression that numbers rise
and fall dramatically on a seasonal basis.
However, worldwide figures for July and May should be
approximately the same. May is at the end of the breeding season so
all the newly hatched birds for that season would be included in the
total. Likewise, in July, numbers should not be dramatically
different since only a small percentage would have died from natural
causes in the period May-July.
Part 2: Populations in ecosystems
39
Your graph should look something like this:
Number of prickly pear
2.
cactoblastis decrease
with falling food supply
cactoblastis
increase
0
1
Time (years)
Why biologists make estimates
total number
=
127 X 100/5
=
127 X 20
=
2540 frogs
Capture/recapture and tagging/marking
1
Even though the snails were replaced where they were found, it is
important to allow them to mix fully into the population.
2
total population
= 200 ¥ 250
20
= 2500
Food chains
green algae fi blackfish fi tailor
40
Local environment
Food webs
fruit bat
fig tree
silver eye
hawk
mouse
grass
rabbit
decay organism
Biomass pyramids
1
The carnivores will not survive. Only 10% of primary producer
energy is available to herbivores (10 000 units) and only 10% of
that is available for carnivores (1000 units). This is 9000 units less
than required.
Note: In real life the carnivores will most likely eat most of the
herbivores and then run out of food and die. We will look at this in more
detail later in the module.
2
You probably identified uses such as respiration, growth,
reproduction and movement.
Respiration
1
Mirriam is correct and Marnie is incorrect. When human cells
respire, they use oxygen gas. The higher the rate of respiration, the
greater the amount of oxygen that is needed. When respiration rate
is high, breathing rate will also be high because more oxygen is
needed. Breathing rate goes up when the respiration rate goes up.
2
When photosynthesis decreases, less carbon dioxide is converted
into oxygen and sugars. Less oxygen production means that more
carbon dioxide will occur in the atmosphere.
3
Robert is correct. Green plants make their own food by
photosynthesis. Justin's ‘plant food’ is just a bag of trace elements.
Plants need small quantities of trace elements, just as humans need
small quantities of vitamins and minerals in their diet. The trace
elements in the bag would be low energy compounds, while food is
made of high energy compounds such as sugars.
Part 2: Populations in ecosystems
41
42
Local environment
Exercise – Part 2
Exercise 2.1
Name: _________________________________
Sampling practical reports
Present a written account of both practicals: Capture/recapture and
tagging/marking and Quadrat sampling. Each practical must be written
under the headings ’Aim’, ’Method’, ’Result’ and ’Discussion’.
The Aim must clearly state the purpose of the experiment. It must not
include other information such as results. To help you, both experiments
have a suggested Aim which you may copy if you wish.
The Method outlines what you did. You must not put any results in your
Method. You may like to reword the Methods provided in the
instructions for each practical.
The Result outlines what you found. Both practicals suggest how to
present your results.
The Discussion is where you interpret your results and where you
comment upon your experimental method. There is no need to comment
on your experimental results for these experiments, but you will need to
comment on aspects of the experimental method. Suggestions are given
in the practicals above.
Each practical must be written in one page or less. Please turn to the next
two pages to write up these reports. A copy of the ‘Birds’ figure is
supplied so that you can show the quadrats.
Space has been restricted for two reasons. Firstly, it forces you to think
about what you are writing. You must choose your words carefully and
write clearly in order to write in a restricted space. Secondly, it is part of
the examination preparation that we have built into these learning
materials. Exams at this level provide both restricted space and time in
which to complete you answer. By answering in a restricted space you
are practicing an important examination technique.
Part 2: Populations in ecosystems
43
Catpure/recapture and tagging/marking practical
report
44
Local environment
100 m
Quadrat sampling practical report
100 m
Part 2: Populations in ecosystems
45
Gill Sans Bold
Senior Science
Preliminary Course
Stage 6
Local environment
Part 3: Looking more closely at ecosystems
0
20
I
er
b
to T S
c
O EN
g
in D M
t
a
r EN
o
p
or AM
c
n
2
Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction................................................................................ 2
Getting ready ............................................................................. 3
Choosing a field study area ................................................................ 3
Observations and recording................................................................ 3
Trends in population sizes ......................................................... 4
The role of decomposers ........................................................... 6
Definition and role................................................................................ 6
Adaptation ................................................................................. 8
Defining adaptation.............................................................................. 8
Adaptation and ecology..................................................................... 10
Types of adaptation........................................................................... 10
Suggested answers ................................................................. 13
Exercise – Part 3 ..................................................................... 15
Part 3: Looking more closely at ecosystems
1
Introduction
In this part you are going to look at populations in more detail. You will
also look at the adaptations of some organisms to their environment.
After this you will be putting your ecological knowledge to the test by
doing some field investigations of your own.
In this part, you will be given opportunities to learn to:
•
examine trends in population sizes for some plant and animal species
within an ecosystem
•
outline factors that affect numbers in predator and prey populations
•
explain the importance of the role of decomposers in the local
ecosystem
•
identify and describe adaptations of a plant and an animal from the
local ecosystem.
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
2
Local environment
Getting ready
It is time for you to apply some of the things you have learned in this
module to a community of organisms in your local area.
Choosing a field study area
To study an ecosystem you do not need a large area. Something the size
of a backyard, a small park or even a vacant block of land would be large
enough for a study area. The area does not need to be natural bushland,
you could use an outdoor concreted carpark if needed! This said, an area
of natural bush, a park, garden or backyard would no doubt provide a
more pleasant and interesting place to work.
Once you have chosen your field study area, you will need to organise a
couple of spare hours to go to the site to make your observations so that
you can answer the questions below.
Equipment
You will need a pen and paper to record your data. It is always a good idea
to take a clipboard so that you have something firm to support the paper
when writing.
Observations and recording
Turn to Exercise 3.1 at the back of this part to find out what you must do.
Part 3: Looking more closely at ecosystems
3
Trends in population sizes
The abundance of a predator species is related to the abundance of its
prey. The more prey available as a food source, the greater the number
of predators that can be supported. If the abundance of food (prey)
decreases, fewer predators can be supported and predator abundance
will decrease.
Look at the graph below which shows a theoretical predator/prey curve.
Number
prey
tor
da
e
r
p
0 x
y
z
Time
Theoretical predator/prey curve.
Make an analysis of the graph above by writing down the important events
shown on the curve. Write your comments on the graph.
Check your answers.
The predator and prey will continue to oscillate over time in response
to increases and decreases in abundance of each species.
Although numbers oscillate over time, the abundance of prey does not
return to its pre-predation level.
4
Local environment
Predator–prey relationships have been used to control some pests in
Australia. This is called biological control. For example, European
rabbits were introduced into Australia and soon became a pest.
Their abundance was highest in the southern parts of the continent.
The European rabbit had few natural predators so a virus, Myxoma, was
introduced into the population in 1950.
The result was similar to that seen in the theoretical predator prey curve
shown earlier. European rabbit numbers decreased rapidly. Within a
short time rabbit abundance was reduced to very low levels. The rabbit
population fluctuates slightly from time to time, but has not returned to
its pre-predation level.
The Myxoma virus has never been very effective in very dry areas
because mosquitoes are the main carriers of the Myxoma virus between
rabbits. Another virus, the Calicivirus was recently introduced to
Australia by CSIRO. Calicivirus has dramatically reduced the number of
rabbits in very dry areas of Australia.
Cactoblastis has successfully reduced the numbers of prickly pear, just as
Myxoma and Calicivirus have successfully kept rabbit numbers low.
Part 3: Looking more closely at ecosystems
5
The role of decomposers
You have already looked at decomposers, organisms that carry out decay,
in food webs and in cycles.
Now you will now investigate the role of decomposers in more detail.
Definition and role
Any organism that breaks down the dead remains and wastes of
another organism is a decomposer. Bacteria, fungi and moulds are
common decomposers.
Why do you think decomposers are important in ecosystems?
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
You may find it useful to review cycles such as the nitrogen cycle at this
point. You should be able to find the roles of decomposers in some of
the cycles you previously studied.
6
Local environment
Evidence of decomposer activity
When you visit your field study site, you should take the opportunity to
look for evidence of decomposers. Although many decomposers are
microscopic, their activity is usually evident.
One of the best places to see decomposer activity is in leaf litter.
The litter contains leaves and dead organisms. The topmost layer will
contain the freshly deposited material and will show little evidence of
decay. However, as you dig down through the layers you will find
evidence of the breakdown of leaves.
The litter becomes darker in colour with depth and is then called humus.
You will often find white, yellow and red flecks of moulds and fungi.
The nutrient-rich lower layers of leaf litter will also usually contain a
wide range of small insects, worms and other invertebrates that are living
off the nutrients being released by the decay process.
If you have a garden or bushland nearby that has leaf litter, it would be well
worth your while to take a break now and go and have a careful look at the
leaf litter. Find a place where the litter is deep and gently remove the litter
layer at a time. You will be amazed at the things you can find!
It would be a good idea to wear gloves (scorpions, centipedes and spiders
are commonly found in leaf litter) and to take a hand lens if you have one to
magnify the smaller organisms that you find. You may also find a small
garden fork useful for digging in the leaf litter.
Part 3: Looking more closely at ecosystems
7
Adaptation
Can you remember any adaptations of living things to factors in their
environment? Can you identify and describe adaptations of a plant and
animal from your local ecosystem? To help you to be able to do these
things as part of your fieldwork you will need to learn a little about
adaptations first.
Defining adaptation
An adaptation is any behavioural, physiological or anatomical
(structural) characteristic that increases the probability of the survival
and reproductive success of any individual or individuals that possess
the characteristic.
Adaptations are the features favoured in the process of natural selection.
You must be very careful with your use of the term adaptation.
The reason that care is required is that the word has two meanings:
a common English meaning and a biological meaning. Consider
the following:
Some plants are dormant. Many have adapted to freezing conditions
in their native lands by dropping their leaves.
The implication of the passage above is that the currently existing plants
have changed, within their own life time, to suit the freezing conditions.
It is similar to Lamarck’s idea that giraffes got long necks by stretching
for food.
If you replace the word plant with the word species in the first sentence
you get:
Some species are dormant. Many have adapted to freezing conditions
in their native lands by dropping their leaves.
8
Local environment
The sentences are now biologically correct. The implication now is that
species have adapted (over time) and this is consistent with current views
of biological evolution.
Remember, individuals do not adapt, only species can adapt.
Using the term adaptation correctly can be very tricky.
Even experienced scientists occasionally make mistakes. Practice in
using the term correctly is required.
Read each of the following sentences. Decide which sentences are
biologically correct and which are incorrect. Rewrite the incorrect
sentences so they are biologically correct.
1
The red kangaroos of western New South Wales have adapted to the
dry conditions by resting in the shade during the heat of the day.
______________________________________________________
______________________________________________________
______________________________________________________
2
The gliding membrane found in sugar gliders is an adaptation that
allows gliding flight between trees.
______________________________________________________
______________________________________________________
______________________________________________________
3
The species Crinia signifera has adapted to life in the shallow fresh
water of ponds, streams and puddles.
______________________________________________________
______________________________________________________
______________________________________________________
4
Insectivorous plants have adapted to living in soils with low
quantities of nitrates by capturing insects as their source of nitrates.
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
Part 3: Looking more closely at ecosystems
9
Adaptation and ecology
Adaptations are important in interspecific competition (competition
between two different species). The species with the most suited
characteristics to a particular environment will usually be at an
advantage. If two species compete in an ecosystem for a resource, the
better adapted species will usually win the contest. This is particularly
important when the resource is limited.
You have already studied the case of privet moving into clearings and
becoming established at the expense of native species. In this case, the
resource for which the plants were competing was space. The adaptation
of rapid growth rate in privet places it at an advantage to the native
species that grow at a slower rate.
When you perform your fieldwork later in this module, you may find that
certain species in your study area have adaptations that place them at an
advantage to other species. These adaptations may be related to higher
abundance or greater distribution of the species that have the adaptations.
The evolutionary significance of adaptation
You will remember something of Charles Darwin’s ideas of biological
evolution from your previous studies of science.
Darwin put forward the idea of survival of the fittest. Organisms with
characteristics that are favourable to the environment in which they live
will survive. Those with unfavourable characteristics either die or
reproduce less than the others. Over time unfavourable characteristics
are removed and favourable characteristics are retained by the species.
When environments change, different characteristics will be favoured
and so species will change.
Types of adaptation
There are three major types of adaptation: behavioural, structural and
physiological. These are outlined on the following pages.
10
Local environment
Behavioural
Any behaviours that give a species an advantage to either survive or
reproduce is a behavioural adaptation. Mating displays, defence of
territory, aggressive displays and the formation of groups (herds of cattle,
schools of fish) are all examples of behavioural adaptations.
The red kangaroo rests in the shade during the heat of the day and feeds
in the cooler early evening and early morning. Animals that do this are
called twilight feeders. The twilight feeding of the red kangaroo is a
behavioural adaptation of the species that conserves water because the
animal only moves about in unsheltered areas during the cool of the day.
Can you think of any behavioural adaptations that you have seen. If you
are a pet owner you will no doubt be able to think of many examples!
Structural
Structural adaptations are anatomical features of a species that improve
its chances of survival and reproduction.
Some European, South American and Australian orchids are pollinated
by male insects that attempt to copulate with the flowers. The flowers
of these orchids have highly modified petals (an anatomical adaptation)
that make them represent a ‘dummy female’ to the male insect.
The Australian orchid genus Cryptostylis has at least five species in the
genus that are pollinated by male wasps. When the male wasp attempts
to mate with the flower he is covered in pollen. When the wasp attempts
to copulate with another of the orchids, pollen is transferred.
This structural adaptation of the genus Cryptostylis offers considerable
advantages to the orchid. The male wasp is attracted only to orchids that
resemble a female wasp, and so the likelihood of the insect transferring
pollen to a member of the same species of orchid is very high.
When insects such as bees transfer pollen, they visit numerous species of
plants each day. Therefore, bees are less likely to transfer pollen
between members of the same species than the wasp.
You should always take care when describing an adaptation to be
specific. Consider the sentence below that was written as part of an
examination answer by a student:
The wings of birds are a structural adaptation to flight.
Part 3: Looking more closely at ecosystems
11
The problem is that not all birds fly. Penguins, for instance, use their
wings to move through water, while the wings of an emu do not
allow flight.
A better response would have been:
The large wing span of albatross is a structural adaptation that allows
this species to have prolonged flight.
Physiological
Physiological adaptations are the hardest to observe in the field because
they are adaptations related to the body chemistry of a species.
The rat kangaroo of central Australia produces highly concentrated urine.
The species has very efficient kidneys that remove most of the water
from urine. This conserves the rat kangaroo’s water. This is an example
of a physiological adaptation that assists the species to live in areas of
low water availability.
Now complete Exercise 3.2 at the back of this part.
You have now completed Part 3. You should start Part 4 as soon as
possible. Part 4 is the start of your own study on your local area.
12
Local environment
Suggested answers
Predator–prey relationships
•
In the graph the prey has no predator at time 0 and consequently has
high numbers.
•
At time x, a predator is introduced.
•
Because of the abundant food, the predator numbers begin to
increase while the prey numbers decrease.
•
At time y, predator numbers peak, but prey number continues to
decrease. At this point, the food source for the predator is becoming
scarce. Predators begin to die from insufficient food and predator
numbers begin to decrease.
•
At time z, predator numbers have reached a low. The prey has less
predation and has begun to increase in number.
The role of decomposers
Decomposers are important in ecosystems because without them the dead
bodies and wastes of organisms would accumulate. By breaking down
these materials, decomposers prevent accumulation and release nutrients
trapped in the bodies and wastes for recycling. The recycled materials
are an important source of atoms for other living things bodies.
Defining adaptation
1
This sentence is not biologically incorrect. It implies that the red
kangaroos currently in western New South Wales have changed
rather than the species having changed. The sentence could be
rewritten as follows:
The red kangaroo species of western New South Wales has adapted to the dry
conditions by resting in the shade during the heat of the day.
Part 3: Looking more closely at ecosystems
13
2
This sentence is biologically correct. The sentence says that they
have an adaptation. Because there is no implication that they have
developed the adaptation within their own life span the sentence is
biologically accurate.
3
This sentence is biologically correct. The sentence clearly refers to
the species adapting.
4
This sentence is very similar to the example given in your notes and
is incorrect. The sentence could be rewritten to make it biologically
correct as follows:
Insectivorous plant species have adapted to living in soils with low quantities of
nitrates by capturing insects as their source of nitrates.
14
Local environment
Exercises – Part 3
Exercises 3.1 to 3.2
Name: _________________________________
Exercise 3.1 Observations and recording
1
Draw a simple map to show the location of your site, on your own
paper. If your site is within a town, it should include the name of the
town and nearest cross street. If your site is not inside a town, it
should indicate the nearest town to the site.
Attach your map to this page.
2
Make a table that lists at least two primary producers, two herbivores
and one carnivore that you found at your site. Common names can
be used, but be sure to indicate the type of organism because
common names can be confusing. For example, you may see a
paddymelon (a type of kangaroo)—but in many parts of New South
Wales a paddymelon is a small bitter melon (a vine). If you indicate
the type of organism, confusion can be prevented.
Part 3: Looking more closely at ecosystems
15
3
Make a food chain that includes some of the organisms in the list
you developed for question 2. You may show inferred relationships
if this is easier to do.
______________________________________________________
4
16
Make a simple food web for the organisms in your sample area. You
may include organisms that you would infer to be present, but that
you did not see when you visited the site. For example, if you
visited your site by day you would be unlikely to see the bats that
visit the site by night. The names of inferred organisms are to be
written in red on your food web. Organisms you observed at the site
are to be written in blue.
Local environment
Exercise 3.2
1
Define the term adaptation. Use two examples of adaptations to help
to explain the meaning of the term.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
2
Name two organisms in your local area and describe one adaptation
of each. You must be sure to name the organisms, clearly indicate
the adaptations and explain the advantage offered by each
adaptation.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
3
What is the role of decomposer organisms in the ecosystem?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Part 3: Looking more closely at ecosystems
17
4
You have been appointed as the scientific officer in a national park.
The park manager is concerned that the numbers of Pseudophryne
bibroni, a small frog, may be declining in the park. As scientific
officer it is your job to see if Pseudophryne numbers are declining.
How would you go about this task?
______________________________________________________
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______________________________________________________
______________________________________________________
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Gill Sans Bold
Senior Science
Preliminary Course
Stage 6
Local environment
Part 4: Performing an investigation in an ecosystem
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Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction ............................................................................... 2
Choosing a site ......................................................................... 3
How to present a report............................................................. 5
Length and format ................................................................................5
Illustrations............................................................................................5
Report sections ....................................................................................6
The field study........................................................................... 9
What will you be doing? .......................................................................9
What will you need? ...........................................................................10
Measuring abiotic variables ...............................................................10
Suggested answers................................................................. 13
Appendix ................................................................................. 15
Exercise – Part 4 .................................................................... 19
Part 4: Performing an investigation in an ecosystem
1
Introduction
It is time for you to perform your field investigation. You will need to
spend about six hours in the field collecting data before you can begin
writing your report. The field report is assessable and must be submitted
at the end of Part 5 after you conclude the fieldwork in this part.
In this part you will be given opportunities to learn to:
•
explain trophic interactions between organisms in the local
ecosystem using food chains, food webs and pyramids of biomass
and energy where appropriate
In this part you will be given opportunities to:
•
process secondary information to identify OH&S issues to identify
potential sources of physical, chemical and biological risk before
undertaking investigation of a local terrestrial or aquatic
environment
•
plan, choose equipment or resources for, and perform a field study of
a local terrestrial or aquatic ecosystem to:
–
measure abiotic variables in the ecosystem being studied using
appropriate instruments and where possible combine with
recorded values and relate this to the distribution of organisms
–
estimate the size of a plant and an animal population in the
ecosystem using transects and/or random quadrat techniques
–
gather data to describe the distribution of the plant and animal
species whose abundance has been estimated
–
use available evidence to describe observed trophic interactions
between two plant and two animal species found in the area..
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
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Choosing a site
If you rush out into the field without reading this section first, you do so
at your own peril! The information below outlines what you must do and
how to write it up.
You need an area of natural bushland, park, reserve, large garden, pond,
rock platform, stream or backyard to use as a study site. You may like to
use the area you used for your exercise at the end of Part 2 or you may
like to choose a different site. The choice is yours.
Your site must be local and it must be the type of location in which you
can perform your field measurements. It is unlikely, for instance, that
your local park gardener would approve of you walking across
flowerbeds in order to lay a transect or quadrat as part of your study.
How many site visits are required?
The choice of the number of visits you make is up to you. It is possible
to get enough information to write a good report with just one visit.
However, you may decide to make several visits to compare data over a
number of days. The decision will depend upon the time you have
available and the types of activities you perform as part of the
investigation you are required to design yourself.
You can carry out a virtual excursion through the Internet before setting
out on your own field study trip. Go to http://www.lmpc.edu.au/science
Senior Science, 8.5 Local environment. Click on Virtual mangrove
excursion – visit this as preparation for the field study trip.
Remember to respect any ecosystem that you study. The
community is alive. If you turn over a stone or a log, make sure
you return it to the way it was. Do not collect specimens unless it
is necessary. Disturb the environment as little as possible.
Part 4: Performing an investigation in an ecosystem
3
You do not send your report on a field study of a local terrestrial or
aquatic ecosystem until the end of Part 5.
At the end of Part 5 you also need to complete an exercise on:
•
existing human environmental impacts and
•
potential human environmental impacts
on the local ecosystem. Keeps this in mind and perhaps write down a
few relevant observations whilst at the site.
Now would be a good time to get an overview of how this major activity is
covered in Parts 4 and 5. Scan through the contents of Parts 4 and 5 so that
you have a better idea of what is involved in this open-ended investigation.
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Local environment
How to present a report
Read this information in this section before you start your field study.
This information outlines what your report must look like, the length and the
sections into which it is divided.
Length and format
Your report may be either handwritten or wordprocessed. No marks will
be awarded for neatness (although it must be legible or we will not mark it
at all), so the choice is yours. However, do not waste hours persevering
with a computer if you are not familiar with a wordprocessing package
already. You are being marked on your ability to perform and record an
ecological investigation, not on your ability to tame a computer.
Your report is to be a maximum of 1500 words. That equates to about
three pages of A4 typing or about six pages of handwriting. If you
exceed 2000 words, your teacher will return the report unmarked and ask
you to cut it down and resubmit.
Sticking to the length is very important because it forces you to be
concise and to think out each sentence carefully. Two past HSC
examiners consulted when writing this module said that practice in
writing concisely was essential practice for students preparing for the
HSC examination.
Illustrations
All diagrams, graphs and charts are to be done by hand.
Computer–generated graphs are not permitted. The reason for this is that
you will not have access to a computer to draw graphs in an examination.
So you need to practice doing these by hand.
Part 4: Performing an investigation in an ecosystem
5
You may want to include photographs that you have taken at your site.
These may be presented as photographs pasted into the report or as a
digital image inserted via your wordprocessor. You may only use
photographs that you have taken at the site yourself. Pictures from
books, magazines, pamphlets or the Internet are not to be included.
Only include pictures that are directly relevant to your report. Do not
include pictures simply to improve the report’s appearance. Marks will
be deducted for pictures not directly related to your field study.
Tables may be done either by hand or on a wordprocessor.
Report sections
Your report is to be divided into sections. Each section must commence
on a new page. The sections must be as follows:
•
Safety and risk management
•
Introduction
•
Methods
•
Results
•
Discussion
In addition your report should have a cover page.
There is an explanation below of what you must include in each of the
sections.
Safety and risk management
You must identify potential risks (physical, chemical and biological)
before you undertake your investigation of the local terrestrial or aquatic
environment.
This means that you must think about possible dangers before you do
your work. For example, you are already aware of the possibility of
spiders, scorpions and centipedes in leaf litter.
Now complete Exercise 4.1 at the back of this part.
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Local environment
In addition to the safety aspects, you should also consider laws and
regulations that apply to your site. For example, many native plants are
protected and you can be fined large amounts of money for picking them.
In some parks you will be required to stay on the tracks, while you will
no doubt need to get permission to work on privately owned land.
List the regulations that apply to your site. You should present the
regulations in point form. A sample is given in the Appendix.
Introduction
Your introduction must include:
•
a few sentences to describe the type of site (bushland, park, pond)
•
the location of your site
•
a sketch map of your site showing the main features of interest as
well as the approximate dimensions of your site
•
a list of the things you set out to do at the site (your aim(s) ).
Your introduction should be less than 250 words in length.
Methods
The methods section must only contain details of how you undertook
each part of the investigation. All results must be put in the result section
of your report.
To make it easy to follow your report, each method should be written
under its own sub-heading. (eg Measurement of air temperature). In the
results section you would have a corresponding heading (eg Air
temperature results). A sample of how to present your methods is given
in the Appendix.
The methods outline how you performed each aspect of your
investigation.
Your investigation must include the following:
•
measurement of at least two abiotic factors in your area (eg air
temperature, water temperature, soil pH)
•
estimation of the size of a plant population and the size of an animal
population in the ecosystem using transects and/or random quadrats
techniques. You must provide information on the method used, the
number of samples taken, the area of each sample and the total area
of the site
Part 4: Performing an investigation in an ecosystem
7
•
recording of the distribution of both the plant species and the animal
species whose population sizes have been estimated. This could be
done on a sketched map of the area using a legend with appropriate
symbols for the plant and the animal
•
recording of a list of the common plants and animals you observed at
your site
•
description of observed trophic interactions between two plant and
two animal species by drawing a food web or food chains
•
description of the relationship between a plant and at least one
animal by drawing a pyramid of biomass and energy
•
descriptions of the adaptations of one plant and one animal
Results
This section must include the results for each investigation. Do not
interpret the results here, that must be done in the discussion.
You should put your results into tables, graphs and charts where possible.
A sample of the way to set out your results is given in the Appendix.
Discussion
In the discussion you analyse your results and justify decisions you made
during the study. Each point you make should be placed under a separate
subheading in the discussion. You must include at least the following in
your discussion:
•
how you estimated the population sizes
•
explanation of why you chose the sample method used to determine
abundance (transect, random quadrats) and an indication of any
advantages or disadvantages in using this method
•
how you recorded the distribution
•
explain observations that were evidence for trophic interactions and
pyramid construction
•
food chains or a food web based upon some of the list of plants and
animals you observed at the site
•
any further studies that could be done at your site.
A sample food web can be seen in the Appendix.
8
Local environment
The field study
Now you are just about ready to go out into the field to investigate an
ecosystem. Before you start you need to be clear on what it is you will be
doing and what you will need to take with you. This is what you will be
finding out in this section.
What will you be doing?
Firstly, think about what you are aiming to do in this field study.
Next, make a list of all the things that you must do when you are actually
doing your field study.
These activities will better prepare you for your investigation. Now you
may need to read through the information in the previous section again.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answers.
Part 4: Performing an investigation in an ecosystem
9
What will you need?
List all the materials and equipment you will need for your field study.
1
What will you need to take into the field?
_____________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
2
What equipment and materials will you need to complete your
report?
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
Check your answers.
Measuring abiotic variables
You must measure at least two abiotic variables in your local area study.
The factor that you measure does not need to be complex. Here are three
possibilities for abiotic factors that could be measured. Others are
discussed in the section titled Changes to abiotic factors in your
Part 5 notes.
10
Local environment
Temperature
Air temperature can be measured with a kitchen wall thermometer.
If you do not have one, then you may be able to borrow one.
The thermometers can be purchased very cheaply from most
supermarkets and hardware suppliers.
Soil temperature can also be measured with the same thermometer, but
you need to be careful not to break the end of the thermometer. A tip is
to make a thermometer size hole in the soil using a stiff piece of wire.
Put the end of the thermometer into the hole and wait a minute or two
before taking the reading.
pH
Soil pH can be measured with a soil test kit. If you know a keen
gardener in your area, you may be able to borrow one to test your soil
sample. It is not worth the expense of purchasing a pH kit for this
exercise.
Turbidity
If you are investigating water at your site, then turbidity may be of
interest. All you need is a plastic tube or tall bottle. Place a large black
cross onto the bottom of the tube and sit the tube on white paper. Pour in
water until the black cross can not be seen when looking down the tube.
Measure the depth. The more turbid the water, the shallower the water
will be in the tube when the cross disappears.
Part 4: Performing an investigation in an ecosystem
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12
Local environment
Suggested answers
The field study
During the investigation you must:
•
consider your health and safety
•
identify potential sources of risk
•
observe laws and regulations
•
observe then sketch the features of the site
•
describe the site
•
measure at least two abiotic factors (variables) at the site
•
estimate the population size of one plant and one animal species
•
describe the distribution of the plant and animal species whose
abundance has been estimated
•
list the common plants and animals in the area
•
observe and describe trophic interactions between two plants and
two animals species
•
observe adaptations of a plant and an animal
•
record observations as text, tables, diagrams or photographs.
1
Essential items would include: pen, pencil, ruler, paper, gloves, hat,
sunscreen, marking pegs, string, thermometer
Optional items could include: audiotape recorder, camera and film,
datalogger, soil test kit
2
For your report you will need: pen, pencil, ruler, graph paper or
computer with spreadsheet program and word processing program,
paper.
Part 4: Performing an investigation in an ecosystem
13
14
Local environment
Appendix
There are a number of legislative requirements that may apply to you
when you are on your field study. For example:
•
You cannot pick protected species of plants.
•
You can not pick plants in a National Park.
•
You cannot trespass on privately owned property. You must ask
permission.
Are there any other laws that you need to be aware of?
Introduction
The site
The study area was a one hectare area of bushland on the Western side of
Blue Gum reserve. The reserve was established in 1974 to provide a
green-belt to buffer a near-by housing estate.
Site location
Blue Gum reserve is near the intersection of Woomera and
Billabong streets, 3.5 km west of the Post Office, Blue Gum Ridge,
New South Wales.
(We have not included a map in this sample. This is just to give you an
idea of how to set-out the report.)
Part 4: Performing an investigation in an ecosystem
15
Aim
The main aim of this study was to compare the vegetation close to
the housing estate with the vegetation further inside Blue Gum Park.
A number of local environmental groups have reported weeds
encroaching the reserve because of urban activities.
You may have several aims that could be listed under this heading.
The introduction above uses less than 130 words. The captions included
on your map of the area are not included in the word count.
Methods
You would place each method under its own sub heading. Two samples
are given below.
Measurement of air temperature
Air temperature was measured at three different sites (shown on map).
Temperature was recorded at ground level and 1 metre above ground
level using a thermometer. Measurements were taken at 9am, 12pm
and 3pm.
Measurement of soil temperature
Soil temperature was taken at a depth of 5 cm using a thermometer.
Temperature was measured at the same sites and times as air
temperature.
Remember that you must also describe the methods that you used to
measure or record the following:
•
abundance (population size)
•
distribution
•
list of plants and animals.
Results
You will need one sub heading for each set of results. Sub headings in
the results section should match-up with the sub-headings you used in the
methods. This makes it easy to follow your findings. Don’t forget to put
in your results for abundance, distribution, animals and plants present.
16
Local environment
Measurement of air temperature
Words included in tables and charts are not included in the word count.
Temperature (°C)
Site
9am
12pm
3pm
Site 1 ground level
14
18
21
1 metre above site 1
12
19
22
Site 2 ground level
14
18
21
1 metre above site 2
12
17
22
Site 3 ground level
14
18
21
1 metre above site 2
12
19
24
Measurement of soil temperature
Temperature (°C)
Site
9am
12pm
3pm
Site 1
11
11
11
Site 2
11
11
11
Site 3
11
11
11
Your report will also include your results for abundance, distribution
and your list of animals and plants.
Discussion
The results (not actually shown here) show that there are a large number
of weed species close to the housing development. These weeds appear
to have colonised disturbed areas on the periphery of Blue Gum reserve.
The majority of the reserve is free of weeds, except along the edges of
tracks and in clearings created by fallen trees.
Part 4: Performing an investigation in an ecosystem
17
The air temperature varied more than the soil temperature but this did not
appear to affect the distribution of weeds.
fruit bat
fig tree
silver eye
hawk
mouse
grass
rabbit
decay organism
A sample food web.
top
shark carnivore kookaburra
Water
Land
carnivores
brown snake
fish
herbivores
field mice
zooplankton
autotrophs
phytoplankton
grasses
Samples of biomass pyramids
You would discuss any other general observations here such as:
18
•
how you estimated the population sizes
•
explanation of why you chose the sample method used to determine
abundance (transect, random quadrats) and an indication of any
advantages or disadvantages in using this method
•
how you recorded the distribution
•
observations that were evidence for trophic interactions
•
a food chain or food web and a biomass/energy pyramid based upon
some of the list of plants and animals you observed at the site
•
any further studies that could be done at your site.
Local environment
Exercise – Part 4
Exercise 4.1
Name: _________________________________
Exercise 4.1 Risk assessment
In this exercise you need to provide a list of potential risks and your
solution or management strategy.
The table below lists some of the potential risks that may exist in the
environment that you will be studying. Add any other risks that could
be in your environment. List management strategies that will reduce
these risks.
Potential risk
Management strategy
spider, centipede and scorpion
bites
Wear gloves when handling leaf litter.
cuts from handling sword grass
Wear gloves. Basic medical kit
packed.
Part 4: Performing an investigation in an ecosystem
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Gill Sans Bold
Senior Science
Preliminary Course
Stage 6
Local environment
Part 5: Human environmental impact
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Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction ............................................................................... 2
Human environmental impact.................................................... 3
Changes to the environment................................................................3
A sample field study report........................................................ 5
The students’ human impact report.....................................................5
Problems and solutions ........................................................... 10
Nitrates................................................................................................10
Dryland salinity ...................................................................................11
Reduced genetic diversity..................................................................12
Suggested answers................................................................. 15
Exercises – Part 5 ................................................................... 17
Part 5: Human environmental impact
1
Introduction
In this part you will be given opportunities to learn to:
•
outline energy flow and cycling of matter in the local ecosystem
studied
•
describe the effects of a range of human impacts on the local
environment.
In this part, you will be given opportunities to:
•
process and analyse information to prepare a report on the field
study undertaken using an appropriate reporting style.
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
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Human environmental impact
You have seen earlier in this module that the biotic features of the
environment can alter abiotic factors as well as other biotic factors.
Humans have made large changes to the environment because of
their activities.
Changes to the environment
The scale of the changes made by humans is much smaller than the
changes created by green plants. Plants converted 20% of the
atmosphere to oxygen–the most significant change to affect both biotic
and abiotic factors on Earth in the past two billion years. The release
of oxygen by plants is still the most significant biotic factor in
Earth’s ecosystems.
Activities of humans
Human activities have had significant effects on the environment only
over the past 10 000 years. In the past 100 years alone, our species has
been linked to the extinction of up to 1 000 000 species of plants and
animals and the modification of the majority of habitats on the planet.
The human effect may be insignificant next to photosynthesis, but we do
at least qualify as the cause of one of the major extinction events in
Earth history!
You will look at a case study and a sample field study report to give you
a feel for the types of biotic and abiotic changes humans can cause.
There is some suggested reading listed in the reference section at the
back of the module. It is not compulsory and it will not directly help you
study for your HSC. However, if you are interested in learning more
then these books will provide you with a very interesting read.
Part 5: Human environmental impact
3
Tick off the human activities that you have observed in your local area.
Human impact
Present
Absent
Human impact
Land clearing
Fire
Grazing
Air pollution
Pasture improvement
Water pollution
Irrigation
Land pollution
Introduced species
Smog
Fertilisers
Heavy metals
Pest control
Mining
Machinery
Erosion
Urbanisation
Weed infestation
Transport
Die-back
Fishing
Sand-mining
Population expansion
Landfill
Present
Absent
Case study: Prawning in the Gulf
The Gulf of Carpentaria has one of the major fisheries in Australia..
Traditional trawler methods of prawning have been to drag a heavily
weighted net across the sandy bottom. The disturbance of the net causes
the prawns living on the bottom to jump. When they jump, they are
caught in the net.
Unfortunately, this method of prawning flattens the bottom and destroys
habitats. The method of prawning reduces prawn abundance. To help
overcome the problem the length of the prawning season has been
reduced to lessen the damage to habitats.
4
Local environment
A sample field study report
You are required to measure abiotic factors. You have probably already
recorded a number of abiotic factors as part of your field study. Below is
the report of an experiment conducted by a group of TAFE students who
investigated water from two Sydney streams. One stream was located in
a natural environment and the other was in an urban environment and had
been used for dumping cars.
You will notice that the students who submitted this experimental writeup have done a good job. They worked in a team of three students and
shared the data collection and writing tasks. They wrote a first draft
which they discussed with their teacher and then corrected the draft to
get the final copy below. We have only made one change to their
report – we have word processed their report but not removed spelling
errors. The original was hand-written.
This experiment covers a number of factors that you may not be able to
test with the chemicals and equipment available to you as a distance
education student. The results indicate human impact on one of the
environments tested.
The students’ human impact report
Aim
To compare a number of abiotic factors from a stream in a natural
environment and a heavily polluted stream in an urban environment.
Part 5: Human environmental impact
5
Method
The temperature of the water and the bottom sediment was recorded
using a digital thermometer
The pH of water was measured using a pH meter. A digital read-out
indicates the pH.
A dampened lead acetate paper was placed over a sample of water taken
from each stream to measure sulfides. The paper was allowed to stand
for 20 minutes and then any discolouration noted.
Turbidity was measured by slowly pouring a water sample from each site
into a tube. The bottom of the tube had a white base with a black cross.
The depth at which the cross could not be seen through the water was
recorded.
Dampened turmeric paper was placed over a water sample from each site
to detect the presence of ammonia.
Results
Environment
Sediment
temperature (°C)
Water temperature
(°C)
stream (urban)
18
18
stream (natural)
14
15
Temperature of streamwater from different environments.
Environment
pH
stream (urban)
8.6
stream (natural)
6.9
The pH of streamwater from different environments.
6
Local environment
Environment
Sulfides
stream (urban)
present
stream (natural)
absent
The presence of sulfides in streamwater from different environments.
Environment
Turbidity
stream (urban)
22 cm
stream (natural)
cross still visible at 1 m
The turbidity of streamwater from different environments.
Environment
Ammonia
stream (urban)
present
stream (natural)
absent
The presence of ammonia in streamwater from different environments.
Discussion
The results for the stream in the urban environment indicate that it
is polluted.
The pH of the urban stream is alkaline. The pH of 8.6 is higher than
most freshwater organisms can survive and may help to explain why we
saw very few plants and animals in the urban stream. The natural stream
had a pH that is suitable for most living things and it had many different
plants and animals living in the water.
The sulfides in the urban stream could have come from a number of
sourses such as car exhaust gasses dissolving into the water and
fertilisers put onto a near-by sporting field. The method used to test
sulfides does not show how much sulfide was present—the test we used
just indicates presence or absence. Our experimnent could be improved
by using a test for sulfides that could indicate how much was present.
The urban stream was much more turbid than the natural stream.
This would mean that photosynthesis could only happen in the top few
centimetres of the urban stream because light does not penetrate very far
Part 5: Human environmental impact
7
because of the turbidity. The turbidity of the urban stream is probably
caused by urban run-off that enters the stream from drains.
The ammonia test is a presence/absence test like the sulfide test.
Ammonia should only occur in very small quantities in most natural
environments. As the results show, the level of ammonia in a natural
stream is not sufficient to be recorded by this test. If we assume that the
natural stream result represents a normal result for ammonia, then the
result for the urban stream is greater than normal. Ammonia could be
introduced into the urban stream from a fertiliser factory up stream, from
the rotting of dead animals in the stream or from some detergents that
enter the water from run-off.
The temperature results indicate that the urban stream was warmer than
the natural stream. These results are not reliable because they were
recorded in two different places on two different days and local weather
conditions may be the cause of the difference.
The experiment above found a number of abiotic factors that were
possibly altered by human activity. Humans have altered many abiotic
features in the environment. For example car exhausts release sulfur
compounds, carbon dioxide and carbon monoxide. Exhaust gases have
been linked to acid rain, minor changes in atmospheric gases, depletion
of the ozone layer and lung diseases in humans.
The experiment written up by the students above was well done.
However, there were still a number of areas that could be improved.
In this activity, you will rewrite some of the experiment to improve
the presentation.
Answer the questions below.
1
Look at the section on pH in the discussion section of the student’s
report. The students have done well to show that the urban stream
has a pH higher than that suitable for life. However, they have not
indicated where the alkaline material may have come from. If you
look at the section on ammonia in the discussion, you should be able
to locate the source of the alkalinity. Rewrite the section on pH to
include a source for the stream alkalinity.
______________________________________________________
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8
Local environment
2
Look at the section on sulfides in the discussion. When writing
scientific reports you must write in the third person–you are not
allowed to use I, we, me, you and us in your writing. Here you are
going to improve the section the students wrote on sulfides by
removing those words.
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Part 5: Human environmental impact
9
Problems and solutions
Nitrates
Nitrates are compounds found in fertilisers and human and animal
excrement. When fertilisers, sewage and animal wastes enter rivers
nitrate levels increase. Some of the effects of nitrates entering Australian
river systems include:
•
bacterial blooms. Cyanobacteria (often incorrectly called blue-green
algae) release toxins into the water that kill fish and other animals.
•
increased water plant growth. Many water plants increase in size
and number in the presence of nitrate and this growth can clog
waterways reducing water flow.
Nitrates are one of the most important pollutants of Australian inland
waterways. Cyanobacterial blooms have resulted in the death of
livestock and have even made town drinking water unsafe for short
periods in some areas.
Solutions to the problem include:
•
better treatment of sewage entering the rivers.
•
keeping livestock and feedlots (yards where large numbers of stock
are kept and fed before sending to market) away from the edges of
rivers.
•
reduced use of fertilisers.
Do you have cyanobacterial blooms in your area? If so, what do you
think causes them?
_________________________________________________________
_________________________________________________________
10
Local environment
Dryland salinity
The irrigated farm lands along the Murray and Darling rivers is some of
the most important agricultural land in Australia. Agricultural practices
have included the clearing of native vegetation and irrigation using river
water. These agricultural practices have resulted in some of the soil
becoming so saline that it is now unusable for farming.
The effect of rising groundwater
The original vegetation in most of the areas experiencing salinity
problems was trees and shrubs with deep roots. Transpiration rates were
high and saline groundwater was only found deep in the soil. The high
transpiration rate of the native vegetation helped to prevent ground water
from rising to the surface. When native vegetation was removed and
replaced with crops the transpiration rate was decreased which allowed
more water to be added to the ground water.
Another factor was the addition of water. By pouring water into the soil
during irrigation, water was added to ground water causing it to rise.
Eventually ground water has risen to the level of the crop roots.
The plants die when the salty water reaches the roots and salty patches
appear on the soil.
The river water itself is also a problem. The seeping of ground water and
fertilisers into the rivers mean that farmers are irrigating with water that
is slightly saline to start with. As ground water rises, rivers become more
saline and the water used for irrigation has even more salt in it.
Solutions to salinity
There is no short-term answer to dryland salinity. It has taken many
years for ground water to rise, and it will take many more before it can
fall to its original levels. Some solutions have been to:
•
plant salt tolerant plants with high transpiration rates
•
use drip irrigation methods. Drip irrigation drops water at the roots
of the cultivated plants. Instead of watering a whole paddock, only
the plants themselves are watered. This reduces the water used in
irrigation.
Part 5: Human environmental impact
11
Reduced genetic diversity
Humans have reduced the genetic diversity of organisms by reducing the
number of species and by modifying and selecting genes.
Species reduction
Destruction of habitat eg. by land clearing, has been the major cause of
species reduction. The replacement of natural ecosystems, which have
many species, with agricultural ecosystems, that have few species, has
caused the extinction of many species. For example, the Bridle Nailtail
Wallaby, Onychogalea fraenata, was once common but has declined
dramatically since European settlement and land clearing in Queensland.
The Bridle Nailtail is now only found in a very restricted area near the
town of Dingo in Queensland.
The species reduced or made extinct by land clearing are unintended
victims of human activities. However, some species have been
deliberately hunted to extinction. The Dodo of Mauritius and the
Tasmanian Tiger are probably the best known examples. The Tasmanian
Tiger, Thylacinus cynocephalus, was shot to stop Tasmanian Tigers from
eating livestock. Some species of whales face extinction through
whaling. Numerous game animals throughout the world including tiger
and elephant are under threat from hunters.
Genetic modification
The reduction of population sizes means that gene pools of reduced
species are smaller. If a smaller variety of genes are available, a species
is less able to cope with natural selection in changing environments.
This can hasten the extinction process.
One of the major concerns among biologists is the reduced genetic
diversity of commercial crop species. Plant breeders produce plants with
the most desirable set of characteristics for a market. Features such as
high yield, quick growth, resistance to low rainfall, the ability to survive
high temperatures and disease resistance are highly prized among
breeders. Once a suitable plant has been produced, it is usually
replicated by cloning, a process that makes plants that are genetically
identical to the original. This results in many crops being genetically
identical and the original genetic variation of the species is lost.
If environmental conditions change these plants would have insufficient
variation to survive the natural selection process.
12
Local environment
Answer the following questions. The questions are typical of the type of
questions you would be expected to answer in examinations in this subject.
1
List three ways agricultural practices in Australia have had an impact
on biotic and abiotic features of the environment.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
2
Name one species that is either endangered or extinct because of
human activities. What human activity has caused this species to
become either extinct or endangered?
_____________________________________________________
_____________________________________________________
3
Name two abiotic features of the environment and explain how you
would test for them.
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________
Check your answers.
Turn to Exercise 5.1 to report about human environmental impact on the
local ecosystem you have just studied.
Part 5: Human environmental impact
13
14
Local environment
Suggested answers
Discussion
1
The pH of the urban stream is alkaline. The pH of 8.6 is higher than
most freshwater organisms can survive and may help to explain
why there were very few plants and animals in the urban stream.
The natural stream had a pH that is suitable for most living things
and it had many different plants and animals living in the water.
A possible cause of the alkaline water is the detergent entering the
water upstream.
Notice that the ‘we saw’ has also been removed from this rewritten
answer. Did you notice this incorrect presentation?
2
The sulfides in the urban stream could have come from a number of
sources such as car exhaust gases dissolving into the water and
fertilisers put onto a nearby sporting field. The method used to test
sulfides does not show how much sulfide was present—the test used
just indicates presence or absence. The experiment could be
improved by using a test for sulfides that could indicate how much
was present.
Reduced genetic diversity
The answers below are sample answers only. You may have different
answers depending upon the examples you selected.
1 • Land clearing has destroyed natural habitats and leads to reduced
numbers of species.
• Irrigation and land clearing are linked to dryland salinity.
The rising of saline ground water has killed plants in some
irrigated areas.
• Run-off of fertilisers and animal waste has increased nitrates in
rivers and streams. This increase is linked to bacterial blooms and
increased growth of water plants.
Part 5: Human environmental impact
15
2
The Tasmanian tiger (Thylacinus cynocephalus) was shot to prevent
it from eating livestock.
3
16
Feature
How tested
air temperature
thermometer held in air.
water pH
pH meter. The meter provides a digital read-out
of pH.
Local environment
Exercises – Part 5
Exercises 5.1 to 5.3
Name: _________________________________
Exercise 5.1: Human environmental impact on the
local ecosystem
In Part 4 you completed a field study of a local terrestrial or aquatic
ecosystem. This exercise requires you to list existing and potential
human impacts on that local ecosystem.
There is no need to go back to the ecosystem site unless you wish to.
Observations that you made during your field study may enable you to
list some existing human environmental impacts.
a) Existing human environmental impacts on the local ecosystem:
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Your study in this part of examples of human environmental impact and
changes in environments you have learnt about should enable you to
predict potential human impacts.
b) Potential human environmental impacts on the local ecosystem:
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Part 5: Human environmental impact
17
Exercise 5.2: Energy flow and cycling of matter in
the local ecosytem
In Part 2 you learnt that:
•
energy flow was in one direction from plants to herbivores to
carnivores
•
cycling of matter, such as water, carbon, oxygen and nitrogen, was
between the living and non-living world and not in one direction.
Outline this for the local ecosystem by drawing two diagrams:
a) Energy flow in the local ecosystem.
b) Cycling of matter in the local ecosystem.
18
Local environment
Exercise 5.3: Field study report for a local terrestrial
or aquatic ecosystem
Attach your report for the field study that you carried out in Part 4.
Part 5: Human environmental impact
19
Gill Sans Bold
Senior Science
Preliminary Course
Stage 6
Local environment
Part 6: Further investigations
0
20
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Senior Science Stage 6 Preliminary Course
Water for living
Plants
Humans at work
Local environment
• Features of ecosystems
• Populations in ecosystems
• Looking more closely at ecosystems
• Performing an investigation in an ecosystem
• Human environmental impact
• Further investigations
Contents
Introduction ............................................................................... 2
Use of the local environment..................................................... 3
Over the last 50 years..........................................................................3
Local government regulations .............................................................3
Points of view ............................................................................ 5
We all think differently..........................................................................5
Creating a survey .................................................................................7
The impact of science and technology .................................... 10
Those emissions ................................................................................10
Do we need it? ...................................................................................11
Congratulations ....................................................................... 13
Suggested answers................................................................. 15
Additional resources................................................................ 17
Exercises – Part 6 ................................................................... 19
Part 6: Further investigations
1
Introduction
By the end of this part, you will be given opportunities to learn to:
•
identify features of the local environment which may vary in
importance for different groups in the local society
•
discuss views that different groups in the local society have on
human impact on the local environment
•
outline some criteria for local government regulations concerning
zoning of the land for uses such as
–
domestic housing
–
units
–
schools
–
public transport facilities
–
commercial developments
–
primary produce
–
industry.
At the end of this part, you will be given opportunities to:
•
perform a first-hand investigation to gather information by surveying
local residents and discuss concerns about human impact on the local
area
•
process, analyse and present information from secondary sources to
trace the use of the local environment over the last 50 years.
© Board of Studies NSW Senior Science Stage 6 Syllabus November 2002.
The most up-to-date version is to be found at
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/index.html
2
Local environment
Use of the local environment
Over the last 50 years
This is a short research project. You should spend no more than two hours
doing your research.
Trace the use of your local environment over the last 50 years. What human
activities occurred in your area 50 years ago? Do the same activities occur
today? Has the use of the local environment changed?
You can use newspaper items, council reports, environmental reports and
books on your local area to help. If there is a council library in your area
then you should be able to locate the information there.
If you are fortunate enough to have relatives who have lived in the area
over the past 50 years, then you could talk to them. Relatives or friends
with a first-hand knowledge are valuable sources of information.
Turn to the exercises at the end of this part. Complete Exercise 6.1 by
recording information you found out about the changes to your local
environment over the last 50 years.
Local government regulations
Local government provides various regulations for the use of land.
Land is usually ‘zoned’ which means that all land in a particular area
will have rules applied governing the types of activity that can occur.
For example, if land is zoned as rural then the council would not
approve the development of a housing estate or heavy industrial
complex. Of course, councils may re-zone land from time-to-time to
allow different activities to occur.
Part 6: Further investigations
3
For each zoned area local governments have sets of regulations that
apply to the activities in the area. For example, the regulations
governing the shops and businesses in a town centre are usually
different to the regulations governing residential areas. There are
usually different regulations for domestic housing, units, schools,
public transport facilities, commercial developments, heavy industry
and rural lots.
Lets look at a particular case. A resident in a residential area of a
suburb of Sydney had a large in-ground pool in the back yard. The pool
was legally installed and had council approval. In a residential area,
such pools are for the enjoyment of the occupants of the residence and
their friends. The owner of the pool decided to help teach the children
of some friends how to swim. It was so successful that soon other
parents wanted the owner to teach their children to swim too.
The owner decided to charge fees and began to run learn to swim
classes. The learn to swim classes were soon stopped by the local
council because the pool was in a residential area which was not zoned
for commercial activity.
Within some zones additional rules apply to some properties that do not
apply to others. For example, in many areas residences that back onto
bushland are able to make limited firebreaks on council owned land or
reserves to protect their properties during the summer months.
Local government regulations are important because it is through these
regulations that communities can manage the impact of human
habitation on local ecosystems. State and federal government laws are
also important in establishing rules for regulating the impact of humans
on the environment.
If you do not know the local government area you live in, or are
interested in finding out about another area in New South Wale, go to
http://www.dlg.nsw.gov.au/ for the Local Government Directory.
This directory provides web site addresses for NSW local councils.
Go to your local council, council library or web site address to
investigate the rules that apply to the street or area in which you live.
What type of development is allowed in the zoning of your area?
Are there any special rules that apply to your area?
Complete Exercise 6.2 by reporting on your local government’s
regulations that apply to the zoning of land.
4
Local environment
Points of view
We all think differently
Not everyone has the same views. In this section, we will look at two of
the features of the environment that may vary in importance for different
groups in society.
Space
Different groups within a community usually have different points of
view on natural bushland. Consider these views about a 400 hectare area
of public land outside a rural town in New South Wales.
Peter, member of the local conservation group:
‘This is only a small area of natural bush. All the other land around
here has been turned into farms so this is the only place where native
plants and animals get a fair chance. The conservation group would
like the State Government to declare it a reserve and to limit access to
the place. On the weekends, a lot of the young blokes from the town
rip around the bush on their bikes. If something isn’t done to protect
it soon this little bit of natural bush will be destroyed.’
Doug, father of a 17 year old trail bike rider:
‘We need a safe place for our kids to ride their bikes. You can’t go
riding on the farms around here because of the livestock and fences.
If a kid hit one of those fences in the paddocks the wire would kill or
injure them. The only place is the public land outside the town. It’s a
good spot for the kids. They are far enough out of town so the noise
does not annoy the residents and the plants and animals don’t seem to
mind. We’ve seen all sorts of native birds and animals down there so
the bikes don’t seem to have scared anything away. These greenies
don’t know what they are talking about. They just want to lock the
place up so that no one can use it.’
Part 6: Further investigations
5
Michelle is the president of the local netball club. The club currently
uses two courts at the local high school but these are not enough for her
club’s needs. Michelle would like to have 1.0 ha of the crown land
allocated to her club so that they can make a new set of netball courts.
What arguments might Michelle have in favour of this proposal?
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Check your answer.
Access to resources
There have been many confrontations between the Australian mining
industry and conservation groups. Some of the bitterest arguments have
occurred when mining companies have proposed mining in national
parks. Lets look at the way each side argues.
Mining
6
•
Mining is one of the most important primary industries in Australia.
Without mining, Australia would have serious financial problems
because thousands of jobs depend either directly or indirectly on the
industry. Mining is a major source of export earnings for Australia.
•
Mining has disturbed less than 0.5% of the total land area of
Australia. The land that is disturbed is re-vegetated after the mining
operation so on a national scale the disturbance to habitat is tiny.
Farming and urban development are far more damaging to the
environment than mining yet few people say that these activities
should stop.
•
You must put a mine down where there is something to mine.
Viable mineral deposits such as gold do not occur just anywhere.
Telling miners to look elsewhere is not a solution if some of these
important resources happen to be in a national park.
Local environment
Conservation
Less than 1% of Australia’s total land surface is National Park.
These areas have been put aside to preserve aspects of the natural
environment. If you allow mining then the areas are no longer natural
and it defeats the purpose of having the park. Likewise, if mining is
allowed, what other types of use for parkland may follow?
•
The miners are greedy. They can explore for minerals over 99% of
the country but insist that they must have access to the National
Parks too. National Parks must be considered as a valid land use and
given the same consideration as other land users.
•
Mining activity is not just restricted to a small area. The actual mine
sites are small, but the run-off enters rivers and the surrounding bush
can be damaged by encroaching weeds. More vehicles use nearby
roads and often small towns spring up close to park boundaries
putting more pressure on the natural environment.
•
Mining activity in a national park may last 10-50 years. After that,
the miners move out. However, the species they have destroyed do
not always move back. In many parks, rare plants and animals are in
grave danger of extinction. You cannot have an area set aside for
conservation and then allow mining.
Make a list of issues for your local area that involve differences in
community opinion about the use of space and resources. If you get the
opportunity to read various points of view on a local issue, be sure to
look at the language used. Often words can be used to convey a biased
or an emotional description. The trick is to tell the truth without
mentioning arguments that might harm your case.
Creating a survey
If you want to know the opinions of a large group of people, one of the
best ways to find out is to ask them.
A survey can be used to get the data you need. A good survey:
•
is short (people will not want to spend a long time answering a
survey)
•
easy to read
•
has the questions you want answered included in the survey
•
should be easy to determine results.
Part 6: Further investigations
7
Open or closed questions?
An open question allows the person answering the survey the opportunity
to express their opinion in their own words while a closed question offers
the choice of a limited set of answers.
Think about these two survey questions:
Question 1:
Do you think a shopping centre should be built
next to Endeavour Park YES/NO
Question 2:
Are you in favour of the new shopping centre
being built next to Endeavour park?
Question 1 requires just a yes or no answer. You will get a clear-cut
result and will know the percentage of people in favour and the
percentage against.
Question 2 allows the person to answer in their own words.
Question 1 is a closed question and has the advantage of a clear yes/no
result. The disadvantage is that anyone with a different opinion
eg. a person who does not care if the shopping centre goes up next to
Endeavour park or not, will have trouble in answering the question.
Question 2 is open. The advantage is that the person answering can
explain their thoughts. The disadvantage is that it is much harder to
analyse your results.
Interpreting your result
Ten people were surveyed using question 1 and ten people were surveyed
using question 2. Here are the results:
Question 1
•
6 YES; 3 NO
Question 2
8
•
No
•
Yes
•
Yes
Local environment
•
Only if there is enough parking
•
It will make it easier for elderly residents to shop
•
Yes, if there are going to be child minding facilities
•
I think it will be a disaster for the plants and animals in the local
park
•
There will be too many cars in the streets and it will make it difficult
for local residents to use the park.
•
The extra jobs created by the shopping centre will help the young
people of our area.
•
I am in favour of the development because we have needed better
shops in our town
As you can see, question 1 gives a clear result, but question 2 has found
out something about the things that have lead people to their particular
opinion. How would you determine the result of question 2?
Now it is your turn to write a short survey. You will make a survey
form and send it in to your teacher. You do not have to survey people.
The purpose is to design the survey questions only.
Turn to Exercise 6.3 to record your survey questions.
Purpose
The purpose of your survey is to find out if people in your local area
are concerned about the impact of humans and technology on the
local environment.
The survey questions
Your survey must have at least 10 questions and no more than
15 questions. The survey must be no longer than two A4 pages.
You can use either open or closed questions or a mixture of open and
closed questions in your survey.
Take your time designing the survey. It is not easy to write a
good survey.
Part 6: Further investigations
9
The impact of science and technology
What one person thinks is an advance, the next person may consider a
backward step. Here you will be introduced to just two of the many
issues. We have purposely left each issue unresolved so that you can
think about the issues. You will no doubt be able to add to the list from
issues raised in your local community.
Those emissions
Electricity and mobile telephones can be considered as beneficial to the
community because they supply energy and communications.
However, not everyone has been happy with these technological
developments. Some claim that the high tension power cables and
mobile telephones have electromagnetic transmissions that are
dangerous to humans.
One of the more interesting demonstrations provided by the opponents of
high tension power lines passing near houses in a northern Sydney
suburb was a neon tube that glowed when placed under the power lines.
Power cables are held about 15 metres from the ground by large steel
pylons. The demonstration was done by a person standing on the ground
under the pylons. The tube was earthed, and there was sufficient
electromagnetic radiation for the tube to glow.
There is no doubt that both mobile telephones and high tension power
lines have electromagnetic emissions. The argument is whether these
emissions are dangerous. Two arguments appeared in the letters to the
editor in the local newspaper in the week following the demonstration of
the glowing neon tube. The arguments are summarised below.
10
Local environment
Argument 1
If a neon tube can glow under these wires, housing should not be placed
too close because the electromagnetic radiation could be damaging to
human brain cells. There is electromagnetic radiation released by atomic
bombs and it is known to have harmful effects.
Argument 2
We are exposed to electromagnetic radiation all the time. The same
people who are complaining happily have radios, microwave ovens and
televisions in their homes. The argument about nuclear weapons is silly
because the levels of electromagnetic radiation under the power lines is
thousands of times less than the radiation from an atomic device.
Do we need it?
For some, each new technology is an advance. For others, many
technologies are just technology for the sake of technology. Read about
the technologies below. Consider the arguments that you could use to
support each one, then think of the arguments against the technology.
The revolving toilet seat cover
The toilets in a large shopping centre in the Sydney suburb of Chatswood
come with a fitted paper cover on the toilet seat. At the press of a button,
the paper cover rotates to provide a fresh paper cover on the seat.
The covers are on the seats for reasons of hygiene and ensure a clean seat
for each user.
The popcorn maker
A popcorn maker is an electrical item used for making popcorn in the
home. Just add the ingredients using the measure supplied, put on the lid
and turn on the power. No more overflowing pots. The measures
supplied mean that the correct amount of corn is added to just fill the
popcorn maker when all the corn has popped.
Part 6: Further investigations
11
Plate warmer
When serving food in restaurants, it is common to pre-warm the plates so
that food does not cool too quickly. This allows the chief to prepare the
meals for a whole table before sending them out from the kitchen.
Meals may stand for five or more minutes while others are prepared, but
everyone gets a hot meal.
A domestic plate warmer has been released onto the market that will
warm 10 plates or bowls at a time. It is an electric device that is a little
smaller than a microwave oven.
12
Local environment
Congratulations
You have now completed the Local environment module.
The knowledge and skills you have gained will form an important base,
which will help you in your studies of other units in this course.
Hopefully your local area study has given you a new insight to your local
area.
Part 6: Further investigations
13
14
Local environment
Suggested answers
We all think differently
Michelle may have used the following points in her argument. Did you
think of any others?
•
The club only wants 1.0 ha of land – that is just 1/400 of the total
reserve area so it is not likely to have a major impact.
•
People attending matches could enjoy the surrounding bushland
while they were there. Picnickers and walkers would have far less
impact on the bush than the bikes.
•
There is plenty of room to park and it will relieve traffic congestion
around the school when they have district tournaments.
Part 6: Further investigations
15
16
Local environment
Additional resources
Carson, Rachael (1962) Silent Spring Boston: Houghton Mifflin.
Carson’s book is a classic. It was written at a time when some people
were just beginning to realise the damage that pesticides and mining
practices could cause—not just to the environment, but to humans as
well. Her book is easy to read and has some truly amazing evidence.
Suzuki, David (1997) The Sacred Balance: Rediscovering our place in
nature, Allen and Unwin.
Suzuki’s book is a harder read, but covers more recent issues. It is sad to
see that some of these issues are the same that Carson had alerted us to
over 30 years before! An interesting aspect of Suzuki’s book is that he
has clearly identified overpopulation (overabundance) of humans as a
major concern. Suzuki’s book is dedicated to his parents, wife and
five children.
Part 6: Further investigations
17
18
Local environment
Exercises – Part 6
Exercises 6.1 to 6.3
Name: _________________________________
Exercise 6.1: Changes over the last 50 years
In this activity you will be finding out about your local environment, and
in particular the use of it over the last 50 years. Spend no more than two
hours gathering information.
You should find out information such as:
•
What human activities occurred in your area over the last 50 years?
•
What sort of human activities occur today that might affect your
local environment?
•
Has the use of the local environment changed?
Uses of the environment might include: urban development, industrial
activities, mining, agriculture, recreation.
Present this information in a way that you prefer. This may be as a tape
recording, written report with photographs, newspaper file and so on.
Attach this page to your presentation.
Part 6: Further investigations
19
Exercise 6.2 Local government zoning
This is a short research exercise. Spend around one to two hours on this.
In this activity you must find out the following.
•
What type of development is allowed in the zoning of your area?
•
Are there any special regulations that apply to your area?
•
Areas can be zoned for domestic, commercial or industrial use.
What does mean? What restrictions apply?
Go to your local council or council library and investigate the zoning
regulations that apply to the area in which you live. Complete a short
report on the rest of this page.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
20
Local environment
Exercise 6.3: Survey questions
Write your survey questions on this page. Your teacher will return the
survey with indications of the appropriateness of your questions.
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
Part 6: Further investigations
21
Student evaluation of the module
Name: ______________________
Location: _____________________
We need your input! Can you please complete this short evaluation to
provide us with information about this module. This information will
help us to improve the design of these materials for future publications.
1
Did you find the information in the module clear and easy to
understand?
_____________________________________________________
2
What did you most like learning about? Why?
_____________________________________________________
_____________________________________________________
3
Which sort of learning activity did you enjoy the most? Why?
_____________________________________________________
_____________________________________________________
4
Did you complete the module within 30 hours? (Please indicate the
approximate length of time spent on the module.)
_____________________________________________________
_____________________________________________________
5
Do you have access to the appropriate resources? eg a computer, the
internet, scientific equipment, chemicals, people that can provide
information and help with understanding science
_____________________________________________________
_____________________________________________________
Please return this information to your teacher, who will pass it along to
the materials developers at OTEN – DE.
SSCPRE 43176 Local environment
Learning Materials Production
Open Training and Education Network – Distance Education
NSW Department of Education and Training