4. Investigating Diversity

Question 1

Outline a method the ecologists could have used to determine the plant species richness at one site.

Answer 1

1. A method of selecting sampling sites at random:
2. Use of quadrat.
3. Identify (plant) species (at site / in each quadrat) OR

Count number of (different plant) species (at site / in each quadrat),

Question 2

Describe how you would use quadrats to determine whether a particular plant species has a clustered or a random distribution.

Answer 2

use of random numbers to place quadrats; number of individuals counted in large number of quadrats; little variation random, large variation - clustered;

Question 3

Measuring Abundance

Answer 3

Question 4

Method for Random sampling

Answer 4

Lay out 2 tape measures at right angles along two sides of the study area
Obtain a series of co-ordinates using a random number generator or tables
Place quadrat at intersection of co-ordinates and record species within it
Calculate a mean value
Multiply the number of quadrats that would fit in the entire area by the mean to give you an estimate for the total.

Question 5

Sampling can be random or systematic

Answer 5

Random and systematic sampling avoid bias.

This means the data collected will be representative and valid.

Question 6

How useful are quadrats

Answer 6

Adv-

Manageable
Portable
Used to make species comparisons in different areas of habitat e.g. north and south facing

Disadv-

Difficult to use with tall vegetation or on rough ground
Unsuitable for use with mobile animals