Name: ______
Date: ______
Environmental Science
Biodiversity of Habitats Activity
Introduction
When scientists speak of the variety of organisms (and their genes) in an ecosystem, they refer to it as biodiversity. A biologically diverse ecosystem, such as an old growth forest or tropical rain forest, is healthy, complex and stable. Nature tends to increase diversity through the process of succession.
The opposite of biodiversity is referred to as monoculture, or the growing of one species of organism, such as a lawn, a wheat field or cornfield. Because all of the species are identical, there are few complex food webs and disease can spread quickly. Monoculture often requires extensive use of pesticides and herbicides (to fight nature's tendency to diversify communities) and is very labor and energy intensive. Humans often try to reduce diversity because it is easier to harvest a crop if it all contains the same species, but this obviously creates serious problems.
This activity illustrates how to use math to calculate the diversity index of a selected habitat. The habitats we will simulate are tropical rain forests, coniferous (pine) forests, deciduous (leafy) forests, deserts, grasslands and wheat fields. The different organisms living there will be represented by colored beads. The closer to 1 the diversity index is, the more diverse and healthy the habitat is.
Prediction
Which habitat will have the greater diversity index? Why?
Procedure
1. Obtain a “habitat” for your lab group from the front lab table. The habitat is represented by a labeled film canister.
2. Record the habitat type on your data table.
3. CAREFULLY open the canister and remove 10 beads from your film canister. DO NOT DUMP OUT ALL OF THE BEADS.
4. Count and record in “Trial #1” how many beads of each color you have in your sample.
5. Return the beads to the film canister and seal it.
6. GENTLY shake the canister.
7. Repeat steps #3-6 for “Trial #2” and “Trial #3”, recording your results each time.
8. Seal the canister and return it to the front lab table.
9. Calculate the diversity index for each Trial as follows: # colors (species) ÷ 10
10. Average the three Trials together and record the Diversity Index for that habitat in your data table.
11. Repeat steps #1-10 for all six habitats.
Data
# of different colors / Trial 2
# of different colors / Trial 3
# of different colors / Diversity Index
(average of trials/10)
Questions
1. Why do you think you would need to use more insecticides if you were farming in a monoculture? Explain why this is good or bad.
2. Imagine you owned a piece of forest and you decided to cut down the variety and replant with only one type of tree. What would happen to much of the wildlife that was adapted to that forest? Will this same fate happen to all the wildlife? Explain.
3. If you wanted to help local wildlife, what could you do to the landscaping around your own home?
4. Many species can only live or reproduce in one type of forest. The spotted owl is an example - it can only live and successfully reproduce in old growth forests (big, old cedars, hemlocks, etc.). If these old growth forests are cut down, it's unlikely this owl will survive. Environmentalists call this an "indicator" species." Why do you think it’s called an “indicator”? Should we be concerned about only one species? Explain.