Quadrat Sampling (Lecture 7)

Question 1

What is quadrant sampling most suitable for?

Answer 1

Sessile or stationary animals, or mobile animals captured on film.

Question 2

What must you consider when determining the optimal quadrant size and shape?

Answer 2

1. Statistical: Precision, lowest variance

2. Ecological: Organisms/habitat scale

Question 3

What two factors effect estimates of quadrant sampling?

Answer 3

1. Edge effect - The more edge there is the more decisions need to be made on weather a species is in or outside the sample area.
2. Standard Error - Frame size. Smaller frames have smaller SE
   * *these two need to be weighed against each other**

Question 4

Why do smaller frames have a smaller SE?

Answer 4

Smaller frames require more samples and as “n” increases, the SE decreases. (inverse relationship)

Question 5

What is the purpose of nested quadrants?

Answer 5

1. Accounts for ecological scale; mosses are much smaller than shrubs or trees
2. Determine minimum area to sample.

Question 6

How is the minimum area to sample determined?

Answer 6

Number of species increases as sample size increases, to a certain point. When this data is plotted, where the plateau occurs is the minimum area to sample.
aka Species Area Curve

Question 7

What are some recommendations for quadrant sampling?

Answer 7

1. Read up on the habitat and organisms you are sampling to determine if a common frame size is used.
2. Determine the minimum area to sample
3. Lots of samples!
4. Circular quadrants have the least edge.
5. Rectangular quadrants are best for patchy environments. (more likely to hit some veg)