Materials: Meter stick or measuring wheel, twine or rope to mark your boundary, pencil and paper
1. Given a specific environment - green field, forest, garden, ect., hypothesize what size square plot would be a representative sample for plants found in that area.
2. Share hypotheses with the class. Assign each group a unique area size to sample. You may even want to assign groups sample sizes that differ by powers of two. It depends on how open-ended you want to conduct the activity.
3. Have different groups survey the types and number of species found in their sample size.
4. Construct a data table with the following headings: Plot area, Number of Species, and Cumulative Species.
5. Pool data with other groups and plot Cumulative Species vs. Area on a graph. From the graph you will notice a clustering of data. At some point, you will increase the area, but won’t gain many new species. At this point, the sample size may be determined by extrapolating the area value on the x-axis.
1. To mathematically determine the exact area, you may use a graphing calculator to plot your points. Then using the function for best fit line, have the calculator draw the best-fit line. The formula for this line should have the general equation:
S = cAz where S represents the total number of species observed, A represents the optimal area and c and z represent constants fitted to the data. (c is similar to the slope of the line
and z > 1)
3. See if your calculated sample size is generalizable for other types of habitats.
Horn, H. S. (1993). Biodiversity in the backyard. Scientific American
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