Ecological Fieldwork:
Quantitative Survey A study to measure the distribution, population, frequency or cover of a species.
Display of Results Graphs, histograms, bar charts, pie chart, flow charts and maps can give a much clearer report of the survey results.
Mandatory Activities
Identification Using a Key
The field key below is a dichotomous key.
It is a sequence of pairs of statements only one of a pair applies to the organism you to identify.
1 (a) Animal with backbone 2
(b) Animal without backbone 3
2. (a) Covering of feathers 4
(b) Covering of hair 5
3. (a) Tough hard outer body 6
(b) Soft body 7
4. (a) Red feathers covering upper chest - Robin
(b) Large black and white - Magpie
5. (a) Dog-like, long bushy tail - Fox
(b) Long ears, short white tail - Rabbit.
6. (a) Three pairs of legs - Insect
(b) Four pairs of legs - Spider
7. (a) Segmented body - Earthworm
(b) Unsegmented - Slug
Conduct a Quantitative Survey of Plants, e.g., distribution of daisies
- Method: Line Transect (x3)
- Set a measuring tape straight across the habitat in the direction of change in an influential environmental factor e.g. soil water, pH, and nitrogen content.
- On a map of the habitat mark the trace of tape - this is a line transect.
- Walk beside the line and indicate, on the map, the position of each daisy plant touched by the line.
- Repeat the process twice more from other start positions.
- Combine the results to establish the daisy distribution.
- Relate the distribution to the variation of the environmental factors.
- A map is an appropriate mode for the display of the results.
Conduct a Quantitative Survey of Animals, e.g., fieldmouse population
Day 1
- Capture field mice using small mammal traps.
- Record the number of captured mice e.g. 20.
- Mark each with a dab of red paint on the belly surface.
- Release each at their capture site.
- Allow time for the mice to readjust to normal conditions.
Day 2
- Capture field mice as before.
- Record the number captured e.g. 18.
- Record the number of recaptures (marked mice) e.g. 6.
- Return the mice to the habitat at their capture site.
Calculation: Population = (Day 1 Captures x Day 2 Captures) divided by Number of Recaptures
= (20 x 18) divided by 6
= 60 mice
Determining the Frequency of a Plant Species
- Method: many random quadrats e.g. 100.
- Randomly pick quadrat sites within the habitat.
- At each quadrat record the plant species present.
- For each species record the number of quadrats is was found in.
- This number is its frequency if a hundred quadrats were used.
Frequency is the percentage occurrence of a species with a large sample of randomly chosen quadrats.
Suitable Quadrat Size: 1/4 m2 (0.25 m2 ).
Frequency is displayed clearly as a bar chart.
Determining the Percentage Cover of Sedentary Species
- Method: pin-frame.
- Set out a straight transect line across the habitat.
- Place the pin-frame beside the line at the start.
- Push down each pin, to the ground, and record the species touched.
- Move the frame to the next half-metre and repeat.
- Record the total number of pins used.
- For each species record the number of ‘hits’.
- Calculation: Percentage Cover = Number of ‘Hits’ x 100
Total Number of Pins
Percentage cover is the proportion of ground screened or occupied by a species.
Percentage cover is distinctly presented as a pie chart or histogram.
Investigation of Abiotic Factors (Three Mandatory Activities)
Soil pH
- Air-dry the soil - leave exposed to air until constant mass.
- Sprinkle a small pinch of soil onto a white plate.
- Add universal indicator solution until soil is quite wet.
- Thoroughly mix the soil and the universal indicator.
- Press the mixture so some indicator oozes out.
- Match the indicator colour to a colour on the pH chart.
- The number on the matching colour is the soil pH.
Percentage Soil Water
- Using a scales find the mass of an evaporating dish, e.g. 15g.
- Find the mass of the dish plus fresh soil, e.g. 55g.
- Subtract to calculate the mass of the fresh soil, e.g. 40g.
- Dry the soil in an oven at 1008C until constant mass.
- Find the mass of the dish plus the dry soil, e.g. 45g.
- Mass of Soil Water = (ii) - (v) = 10g.
- Calculation: Percentage Soil Water = Mass of Soil Water x 100
Mass of Fresh Soil
= 10g x 100
40g
= 25%
Soil Temperature
- Temperature can simply be measured with a soil thermometer.
Adaptations of Organisms to their Environment
An adaptation is a feature that suits the organism to its environment. Adaptations are solutions to a problem.
Examples of Adaptations (see also competitive, predator and prey adaptations.)
- Needle-like mouth parts of aphids tap food from the phloem of the plant.
- Ladybird warning colouration: releases toxic fluids to deter predators.
- Grass shoot tips are at or below ground: adaptation to survive grazing.
- Field mice are nocturnal: predator avoidance.
Collection Methods in Ecological Studies (Mandatory Activity) Make sure to be able to draw a diagram of each of the following
- Small Mammal Trap
- Pitfall Trap
- Cryptozoic Trap
- Pooter
- Net: sweep net, insect net, plankton net or fish net.
- Tullgren Funnel
