Earth Partnership for Schools
WOODLAND RESTORATION INTERACTIVE WORKSHOP > HOW TO RESTORE WOODLAND AT YOUR SCHOOL > STUDY THE SITE > INVENTORY EXISTING WOODLAND > TREE INVENTORY
Percent Frequency = the percent of quadrats in which the species is found. Frequency shows how common or uncommon a plant species is in an ecosystem. This measure can be used to rank the species from common to rare.
Abundance = the number of individual trees of a species found in all quadrats combined.
Total basal area = the sum of all the basal areas of the individual trees of a species,where the basal area of a tree is equal to p ( diameter ) 2.
- Have students construct a DBH tape by relating circumference and diameter.
- Have students figure out the frequency, abundance, and basal area of each species measured (use notes above). Then look at which species are the dominant ones on the site, based on each of these three measures.
- Compare the composition of the forest you measured with the composition of an original Wisconsin forest, as described in the book Vegetation of Wisconsin. (Note that Vegetation of Wisconsin uses scientific names for species).
- Identify the biggest tree on the site; the smallest. By looking at which trees are small, think about what the forest might look like in 50 or 100 years.
Instructions for calculating frequency:
Calculate the percent frequency for each species by dividing the total number of quadrats where that species was found (#quadrats) by the total number of quadrats sampled, then multiply by 100.
For example, if red oak was present in 6 of 12 quadrats, the percent frequency for red oak would be:
6 X 100 = 50%
Download the following files to conduct your inventory: