Ecology 3 (Study of an ecosystem)

Question 1

List the steps involved in a ‘habitat study’.

Answer 1

1. Map the habitat.
2. Identify the organisms present.
3. Estimate the number of organisms.
4. Measure the abiotic factors.
5. Present info.

Question 2

Give one instrument used for identifying organisms in a habitat (include labels).

Answer 2

A pooter.

(Diagram switches mouthpiece and inlet, can be used either way however flexible tube makes collecting easier).

Question 3

What is the difference between a qualitative and a quantitative survey?

Answer 3

1. A qualitative survey records the presence/absence of an organism in a habitat.
2. A quantitative survey records the amount of an organism present in a habitat.

Question 4

How would you carry out a quantitative survey of plants?

Answer 4

1. I would throw a quadrat, at random, 10 times within the habitat.
2. I recorded the space taken up (% cover) or the presence/absence of the plant (frequency) in the grids of the quadrat.
3. To calculate % cover of the plant, I would estimate the % coverage for each of the 10 trials, then find the average.
4. To calculate the frequency of the plant in the habitat, I would use the following formula:

Times the plant appeared x 100

Total no. of throws 1

Question 5

How would you carry out a quantitative survey of animals in a habitat?

Answer 5

1. I would use the capture-recapture method, firstly capturing a set amount of a species.
2. They are marked in such a way that does not put the organism at a disadvantage (nail varnish on snail shell) and released.
3. After a few days, I would return to the habitat and collect the same number of organisms of that species as I had on the first day.
4. Using the following formula, I could estimate the population size of the species in the habitat:

(Captured 1st visit) x (Captured 2nd visit)

Total no. of organisms marked 2nd visit

Question 6

Name three possible abiotic factors in a grassland ecosystem.

Answer 6

1. Light intensity (measured in lux, measured w/ light meter).
2. Soil pH (measured with soil pH meter).
3. Climate (measured with thermometer).