Frequency of occurrence

Frequency of occurrence of an aquatic plant is an estimate of the relative abundance of specific aquatic plants. Here is one procedure to determine the frequency of occurrence:

A number of evenly-spaced locations are chosen around a shore (usually 10 per lake, but up to 30 locations in a large lake). Locations are selected so that they will give a reasonable representation of the vegetation present in the waterbody.
At each location, a visual inventory is performed in each of three areas - the emergent plant zone, the floating-leaved plant zone, and the submersed plant zone.
The frequency of occurrence is the percentage of locations at which a particluar plant was seen. For example, if ten locations were sampled and the plant maidencane was seen at four of them, the frequence of occurrence of maidencane would be 40% (that is, 4 divided by 10, then multiplied by 100%).

The information on this page was derived in part from the following publication of
Florida Lakewatch of the University of Florida Department of Fisheries and Aquatic Sciences.
This booklet may be downloaded in its entirety as a PDF file by clicking here.
Scroll down till you see the Circular 101 icon.

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A collaboration of the Center for Aquatic and Invasive Plants, University of Florida, and the Invasive Plant Management Section of the Florida Fish and Wildlife Conservation Commission.