GLEASON: SOME APPLICATIONS OF THE QUADRAT METHOD 25 
quadrat to be used is determined first by the general character of 
the vegetation, using a small one, one square meter, for dense 
closed vegetation, and a larger one, two meters square, for open or 
irregular associations. The quadrats may be marked out by 
four stakes connected by a line of proper length, or they may be 
estimated by the eye with sufficient accuracy for all practical use. 
The optimum size can be ascertained after an examination of the 
preliminary results, and the survey can be repeated with a better 
size of quadrat if the first is unsatisfactory. The number to be 
counted depends upon the visible uniformity of the association, 
on the area covered by it and on the time available. If possible, 
one hundred are counted. 
The first one is located anywhere. The others are located 
successively in a pre-decided relation to the first, thereby obviating 
any element of personal choice. Thus they may be in a straight 
line and separated by ten paces each, so that the whole strip of 
one hundred would be one kilometer long; or they may be in a 
Square, but similarly separated, so that the area examined would 
be approximately 100 meters square; or any other arrangement of 
separate or contiguous quadrats may be used, depending upon 
the configuration of the association. 
For the first quadrat, the species are listed and the figure 1 
placed after each in a single vertical row. For the second, the 
figure 2 is placed after the 1 for all those species which occur also 
in the second quadrat, and new names followed by the figure 2 
are added for the additional species. The process is continued to 
completion, when it is seen that some of the species occur in a 
Majority of the quadrats and others in a few or only in one, and 
the common species are distinguished from the rare ones as the 
work proceeds. 
At the conclusion of the count, the results are summarized and 
the ratio between the total number of quadrats and the number 
in which a particular species occurs is expressed as a percentage 
Which is known as the frequency index, here abbreviated to FI. 
Thus, the frequency index of a common species may be as high as 
100 and most associations show certain species with FI 90 or 
more, while others are as low as I. 
Obviously not every species of the association will appear in 
