Investigating Abundance

Question 1

Define Abundance

Answer 1

no. of individuals of a species in a given area at a given time

Question 2

Name the two types of quadrat

Answer 2

point and frame

Question 3

What three factors should you consider when planning an investigation

Answer 3

Size of the Quadrat ( larger species = larger quadrat/large number of small better than a small number of large ones)

Number of Samples( larger=more reliable but must balance with time available)

Position of Each Quadrat ( must be random)

Question 4

Describe how you would use a quadrat to collect a sample.

Answer 4

layout tape measure @ right angles
obtain co-ordinates randomly by a computer generator
place quadrant at the intersection of each pair of co-ordinates and record the species in it

Question 5

Other than quadrats what else could be used?

Answer 5

Belt transect

Question 6

What are belt transects useful for?
How are they made?
How are they used?

Answer 6

Useful along a line of succession or for species that don’t move
made by stretching string or tape across the ground in a straight line
Use a frame quadrat laid alongside then moved its own length and repeated

Question 7

What is the equation to work out the estimated population size?

Answer 7

total number of Individuals in 1st x 2nd sample/ number of marked individuals in the recaptured sample

Question 8

What is a method to find a population size?

Answer 8

mark-release-recapture

Question 9

What assumptions are made from the mark-release-recapture method?

Answer 9

The proportion of marker to unmarked in 2nd sample is = to the whole population
The marked individuals in the 1st capture distribute themselves evenly amongst the reminder of the population
The population has a definite boundary so no emigration or immigration
There are few if any deaths and births
Method of marking is not toxic or increase the chance of predation
Mark is not lost during the investigation

Question 10

How do the assumptions made in proportional sampling differ from those
made in mark-release-recapture?

Answer 10

1. No assumption that organisms are uniformly distributed;

2. Size of total area / size of sampled region not required;

Question 11

Give one assumption about the animals caught that is made in both methods.

Answer 11

Animals are from / all part of the same population;