Shannon-Weiner Diversity Index

Field Exercise

The diversity index is a common way of showing that diversity is not just numbers of different species, but how well each of these species is represented in different "habitats".  In class you used previously collected data to practice calculating the index. In this field exercise, you will collect and calculate data that you collected.

Procedure:

1-     Take some index cards. Bait some with something sweet (honey), and
some with tuna (cat food). Place each pair near each other  at the sites you choose.

2-     Place the cards in different locations (near trees, in the grass, near the building’s
foundation, etc.) and pin them to the ground so they don’t blow away.

3-     Approximate the moisture level or wetness of your areas and use the CBL’s to determine the temperature of each site.  List any other differences in the habitats, biotic or abiotic, that you can measure or describe, that may help you in your analysis at the end of the experiment.

4-     Leave the cards for 24 hours, and then collect them.

5-     Slip each card into a zip-lok type bag. The bags can then be placed in the
refrigerator or freezer until you are ready to make your counts.

6-     Count the number of species, and number of individuals of each
species. It isn't necessary to identify the species, just agree among
yourselves what different types are.there. A hand lens may help in the identification.

7-     Remember, the most common equation is:  H = -sum(p_ilnp_i)

8-     You can go further by cutting different sized pieces of plywood, setting
them out in different locations, and a week later collecting all of the
invertebrates that you find under each board. Do the same calculations of
"H" for different areas. This should show something about the effect of
habitat size on diversity.

Questions:

1-     Compare the species for each set of cards.  Is there a preference for one type of food over the other?   Does the S-W Index support this? 

2-     Is there a difference in the Index’s from one location to another?  Describe what is different between the habitats.  How do you think the moisture, temperature and any other biotic or abiotic factors influenced your results?