The study of the spatial distribution of vegetation often makes use of random samples of “quadrats,” rectangular plots of fixed size placed at random over the sampling region (e.g., a field or forest). The number of plants of each type occurring within each quadrat is then counted. In one such study, an investigator counted the number of white pine seedlings growing in eighty 10 m×10 m  quadrats to test whether the distribution of pine seedlings in the forest was random, clumped, or dispersed. She obtained the following counts:

a. If the null hypothesis of a random distribution of pine seedlings across the forest is correct, to what theoretical probability distribution should the observed frequencies of quadrats containing a given number of seedlings conform?

b. Carry out a formal test of the null hypothesis.

c. If the null hypothesis is rejected in part (b), determine whether the spatial distribution of seedlings is clumped or dispersed.

Transcribed Image Text:

Number of seedlings 00 11 22 33 Number of quadrats 4747 66 55 88