Dhruv EM 0680 Revision Notes
Topic 10: Fieldwork
• How to carry out a biodiversity sampling exercise (any species):
grid the field / use GPS coordinates;
use a stated method to randomly choose quadrat sites e.g. random number generator;
run a transect line perpendicular to the investigation site / tape (mark even distances);
quadrat size stated, e.g. 1 m2, 25 cm2, 50 cm2;
use of a compass / graduated tape for a transect;
count (all species in the quadrat / every nth distance close the transect) + each species;
take an average of results;
record results in a, table / tally chart and use book / key to identify;
scale up for whole area / described scaling;
repeat on different days / environmental conditions / months;
compare and average / remove anomalies.
• Methods of measuring insect biodiversity:
Pitfall trap: glass jar buried into soil with hole (allow water to drain), sloping edges (avoid
water running) and covering (different materials)
Benefits: small insects otherwise rarely seen, can be left out for long periods, cheap
Problems: harm animals; large animals will not be captured; will only capture few species;
can be eaten by predators / can eat each other; organisms can starve; trap fills up;
Pooters: cup with two tubes with one meshed (prevent swallowing/suck in), replaced
(avoid disease), check after sample (so don’t die / eat each other), water (resp. product)
Benefits: target a particular insect, no harm to organism, can be observed
Problems: time consuming, only insects can be seen, small insects, small area, move.
Transects: systematic sampling
Suitable length: 100-200m + material: long tape measure or string + use: run across area,
every nth distance marked
Issues – species may not be close to the line / clustered; biased method; not
representative; the animals may move;
Quadrats: random sampling
Suitable sizes: m2, 25cm2, 50cm2 + material: open frame and grid + use: random
placement and count
Issues – fly or move; could be counted more than once; camouflaged / difficult to identify
or see; hide during the day / only be active at night / nocturnal / ORA; only be present
certain times of year / may migrate.
• Measuring the health of a species:
Record
-age -sex -mass -length -colour / appearance -shape / key details / patterns on skin.
• Questionnaires:
Questionnaires can be oral or written to gain information from an individual or a group of
individuals
Should have:
Same gender sampled / equal;
More questions;
Yes/No questions as much as possible;
Give instructions;
Random selection;
Rural and urban;
, 2
Issues?
May not be returned;
Questions may be poorly worded;
May be biased / not a correct sample size;
People may not tell the truth;
Why were questionnaires not returned?
described hot not the target audience;
declined the survey / did not want to do it;
unavailable / too busy working / lack of time;
unwell / had died;
did not speak the same language (as the questionnaire);
illiterate / could not read;
questionnaires lost (in post);
Why locals?
local knowledge of, where species are / when species active;
many people can help;
low cost;
large amount of data can be collected;
data can be collected quickly;
raises awareness of the animal.
• Experiments and data handling:
• plan fieldwork investigations and do them safely:
Should select –
Suitable location, time, species, apparatus, sampling team, sample size / area / method;
Hazards –
student should not be disturbing an endangered species;
difficult to count at night / move during day / active / nocturnal or diurnal;
hard to see / camouflaged;
dangerous to do fieldwork in the dark;
dangerous to do fieldwork in certain areas due to harmful species, conditions, etc;
Pilot survey –
test whether questions are, suitable / clear;
identify any problems with the questions;
test whether sampling methods are suitable;
check that answers can be easily analysed.
• suggest an aim or testable hypothesis based on scientific understanding:
Link an independent variable to a dependant variable under suitable controls.
• identify the independent and dependent variables:
Independent variable – the variable that must be changed
Dependant variable – the variable that must be measured as a result of the changing IV.
, 3
• identify control variables that should be kept constant and describe how and explain why
variables should be kept constant:
Species, volume used, mass used, temperature, concentration, length, area, humidity,
age of species, size, location, etc. should be maintained as a constant when IV changed
To have a control – describe the factor that needs to be compared with / to see the effect
of the independent variable.
• suggest an appropriate number and range of values for the independent variable:
a good investigation should have 3 variations of the same independent variable.
• describe the scientific method for an investigation, including a suitable control where
appropriate: change IV, keep CV constant and measure DV (volume of gas released,
length, number of species, mass, colour, etc.)
• identify apparatus from diagrams or descriptions, draw, complete or label diagrams of
apparatus, explain use of common apparatus, suggest improvements:
• hand lens • humidity/moisture meter • light meter • metre ruler • pH meter • pitfall trap •
pooter • quadrat: open frame and grid • 30cm ruler • sweep net • transect: long tape
measure or string • tray for hand-sorting + see apparatus page.
• identify risks and suggest safety precautions, describe and explain hazards and safety
precautions, suggest improvements:
Sample a safe area, risk harms the person sampling / environment – select an alternative
apparatus / similar species / find a way to reduce the risk = (e.g. use dilute acid instead of
concentrated – corrosive, sample a local park rather than the dense jungle – venomous
species, etc.)
• select the most appropriate apparatus, sampling technique and sampling strategy for the
task and justify the choices made, suggest improvements:
Random (method where equal chances of everyone in target population being picked)
How can this be carried out?
-Coordinate gird and dividing area
-Quadrat placement
-Random selection (e.g. phone book, etc.)
USING A RANDOM NUMBER GENERATOR (points on a grid selected, sample nearby)
Advantages:
Eliminates bias as all have an equal chance of being selected
Can be used when there is a large sample area and systematic would take too long
Disadvantages:
Chance to miss species if they are clustered / species are usually randomly distributed so
poor representation in case a cluster is missed
Some areas in the random sample may not be accessible
Systematic (method where every Nth name is selected from target population)
How can this be carried out?
Every nth person, number, house, location, distance, etc. +/ along a transect line (tape)
-Advantages
Samples taken evenly over whole sample area
Simple to replicate investigation (to check data)
-Disadvantages
Can miss species if they are clustered / species must be randomly distributed / movement
Not representative
Risk of bias (from choosing sample intervals) + Difficult to sample such a large area.
, 4
• describe and explain techniques used to ensure the accuracy of observations and data:
repeat / compare average;
can take an average; data more representative; highlights anomalous results; improves
reliability.
• describe how to record the results of an investigation, take sufficient observations or
measurements, including repeats and replicates where appropriate:
Tally / table / etc.
• record observations and measurements systematically, for example in a suitable table or
tally using appropriate units (always in the header):
Either independent variable and then dependent variable
Or independent variable and then dependant variable in sets
Or independent variable and then dependent variable with controls.
• describe how to process the results of an investigation to form a conclusion:
Link the observation on the DV as the IV changes and write a sentence linking the
relationship (mentioning under which conditions the findings are true – control).
• process data, including calculations or graph plotting, using a calculator as appropriate,
present data graphically:
Bar chart Histogram
Can be normal or divided bar
chart.
Frequency of a category with
bars not touching. Frequency of varying categories.
Bars should touch each other.
Pie chart Line graph
(Frequency of each category /
sample size) x 360 = angle.
Rank wise starting at noon (plot For continuous data that is changing.
outward lines to normal). Lines joined from x to x.
Should have a clear key for each Equal scaling.
sector.
Topic 10: Fieldwork
• How to carry out a biodiversity sampling exercise (any species):
grid the field / use GPS coordinates;
use a stated method to randomly choose quadrat sites e.g. random number generator;
run a transect line perpendicular to the investigation site / tape (mark even distances);
quadrat size stated, e.g. 1 m2, 25 cm2, 50 cm2;
use of a compass / graduated tape for a transect;
count (all species in the quadrat / every nth distance close the transect) + each species;
take an average of results;
record results in a, table / tally chart and use book / key to identify;
scale up for whole area / described scaling;
repeat on different days / environmental conditions / months;
compare and average / remove anomalies.
• Methods of measuring insect biodiversity:
Pitfall trap: glass jar buried into soil with hole (allow water to drain), sloping edges (avoid
water running) and covering (different materials)
Benefits: small insects otherwise rarely seen, can be left out for long periods, cheap
Problems: harm animals; large animals will not be captured; will only capture few species;
can be eaten by predators / can eat each other; organisms can starve; trap fills up;
Pooters: cup with two tubes with one meshed (prevent swallowing/suck in), replaced
(avoid disease), check after sample (so don’t die / eat each other), water (resp. product)
Benefits: target a particular insect, no harm to organism, can be observed
Problems: time consuming, only insects can be seen, small insects, small area, move.
Transects: systematic sampling
Suitable length: 100-200m + material: long tape measure or string + use: run across area,
every nth distance marked
Issues – species may not be close to the line / clustered; biased method; not
representative; the animals may move;
Quadrats: random sampling
Suitable sizes: m2, 25cm2, 50cm2 + material: open frame and grid + use: random
placement and count
Issues – fly or move; could be counted more than once; camouflaged / difficult to identify
or see; hide during the day / only be active at night / nocturnal / ORA; only be present
certain times of year / may migrate.
• Measuring the health of a species:
Record
-age -sex -mass -length -colour / appearance -shape / key details / patterns on skin.
• Questionnaires:
Questionnaires can be oral or written to gain information from an individual or a group of
individuals
Should have:
Same gender sampled / equal;
More questions;
Yes/No questions as much as possible;
Give instructions;
Random selection;
Rural and urban;
, 2
Issues?
May not be returned;
Questions may be poorly worded;
May be biased / not a correct sample size;
People may not tell the truth;
Why were questionnaires not returned?
described hot not the target audience;
declined the survey / did not want to do it;
unavailable / too busy working / lack of time;
unwell / had died;
did not speak the same language (as the questionnaire);
illiterate / could not read;
questionnaires lost (in post);
Why locals?
local knowledge of, where species are / when species active;
many people can help;
low cost;
large amount of data can be collected;
data can be collected quickly;
raises awareness of the animal.
• Experiments and data handling:
• plan fieldwork investigations and do them safely:
Should select –
Suitable location, time, species, apparatus, sampling team, sample size / area / method;
Hazards –
student should not be disturbing an endangered species;
difficult to count at night / move during day / active / nocturnal or diurnal;
hard to see / camouflaged;
dangerous to do fieldwork in the dark;
dangerous to do fieldwork in certain areas due to harmful species, conditions, etc;
Pilot survey –
test whether questions are, suitable / clear;
identify any problems with the questions;
test whether sampling methods are suitable;
check that answers can be easily analysed.
• suggest an aim or testable hypothesis based on scientific understanding:
Link an independent variable to a dependant variable under suitable controls.
• identify the independent and dependent variables:
Independent variable – the variable that must be changed
Dependant variable – the variable that must be measured as a result of the changing IV.
, 3
• identify control variables that should be kept constant and describe how and explain why
variables should be kept constant:
Species, volume used, mass used, temperature, concentration, length, area, humidity,
age of species, size, location, etc. should be maintained as a constant when IV changed
To have a control – describe the factor that needs to be compared with / to see the effect
of the independent variable.
• suggest an appropriate number and range of values for the independent variable:
a good investigation should have 3 variations of the same independent variable.
• describe the scientific method for an investigation, including a suitable control where
appropriate: change IV, keep CV constant and measure DV (volume of gas released,
length, number of species, mass, colour, etc.)
• identify apparatus from diagrams or descriptions, draw, complete or label diagrams of
apparatus, explain use of common apparatus, suggest improvements:
• hand lens • humidity/moisture meter • light meter • metre ruler • pH meter • pitfall trap •
pooter • quadrat: open frame and grid • 30cm ruler • sweep net • transect: long tape
measure or string • tray for hand-sorting + see apparatus page.
• identify risks and suggest safety precautions, describe and explain hazards and safety
precautions, suggest improvements:
Sample a safe area, risk harms the person sampling / environment – select an alternative
apparatus / similar species / find a way to reduce the risk = (e.g. use dilute acid instead of
concentrated – corrosive, sample a local park rather than the dense jungle – venomous
species, etc.)
• select the most appropriate apparatus, sampling technique and sampling strategy for the
task and justify the choices made, suggest improvements:
Random (method where equal chances of everyone in target population being picked)
How can this be carried out?
-Coordinate gird and dividing area
-Quadrat placement
-Random selection (e.g. phone book, etc.)
USING A RANDOM NUMBER GENERATOR (points on a grid selected, sample nearby)
Advantages:
Eliminates bias as all have an equal chance of being selected
Can be used when there is a large sample area and systematic would take too long
Disadvantages:
Chance to miss species if they are clustered / species are usually randomly distributed so
poor representation in case a cluster is missed
Some areas in the random sample may not be accessible
Systematic (method where every Nth name is selected from target population)
How can this be carried out?
Every nth person, number, house, location, distance, etc. +/ along a transect line (tape)
-Advantages
Samples taken evenly over whole sample area
Simple to replicate investigation (to check data)
-Disadvantages
Can miss species if they are clustered / species must be randomly distributed / movement
Not representative
Risk of bias (from choosing sample intervals) + Difficult to sample such a large area.
, 4
• describe and explain techniques used to ensure the accuracy of observations and data:
repeat / compare average;
can take an average; data more representative; highlights anomalous results; improves
reliability.
• describe how to record the results of an investigation, take sufficient observations or
measurements, including repeats and replicates where appropriate:
Tally / table / etc.
• record observations and measurements systematically, for example in a suitable table or
tally using appropriate units (always in the header):
Either independent variable and then dependent variable
Or independent variable and then dependant variable in sets
Or independent variable and then dependent variable with controls.
• describe how to process the results of an investigation to form a conclusion:
Link the observation on the DV as the IV changes and write a sentence linking the
relationship (mentioning under which conditions the findings are true – control).
• process data, including calculations or graph plotting, using a calculator as appropriate,
present data graphically:
Bar chart Histogram
Can be normal or divided bar
chart.
Frequency of a category with
bars not touching. Frequency of varying categories.
Bars should touch each other.
Pie chart Line graph
(Frequency of each category /
sample size) x 360 = angle.
Rank wise starting at noon (plot For continuous data that is changing.
outward lines to normal). Lines joined from x to x.
Should have a clear key for each Equal scaling.
sector.
