Down, Dung and Dirty
Barbara Fendley and Carolyn Hayes
1991 Woodrow Wilson Biology Institute
Introduction
Human populations are not static. Migrations occur into
and out of ecosystems. Communities change over time with
populations being dependent on the resources in that
environment. For example, rural communities are
agriculturally diversified based on their natural resources
and land configurations. Demographic changes are a
reflection of succession which takes place in human
populations. New groups of people move in and replace the
original inhabitants of a community.
Dung cultures can serve as models for the observation of
succession stages. In a short time students can observe the
changes seen in succession and the biodiversity of a
community through its species richness and evenness.
Objectives:
- Students will be able to identify stages of succession on dung cultures.
- Students will be able to graph biodiversity of each succession stage using species richness and evenness.
- Students will be able to utilize the terms: succession, species richness, biodiversity and species evenness.
MATERIALS
- horse, goat, or cow dung
- plastic cocktail cup
- paper towel
- plastic wrap
- rubber band
PROCEDURE
- Place a dampened paper towel in the bottom of the cup.
- Place a sample of dung on the paper towel.
- Cover with plastic wrap and secure with a rubber band.
- Poke holes with a probe for oxygen.
- Place in a warm area with diffused-light.
- Start observations on the following day and continue every day for at least two weeks. (Note: Water may need to be added through the holes if necessary.)
Analysis Questions
- Make a graph which illustrates when each fungi first appears. Be sure that the graph also indicates the disappearance of each fungus if that occurs.
- Identify which type of fungus would be classified as pioneer organisms.
- Identify which type(s) of fungus(i) make up the climax community.
- Note any morphogical structures that appeared to change as succession occurred.
- Hypothesize why the above changes took place. (see question #4)
- Make a time line illustration of the various fungi that appeared on the dung. This represents species richness.
- Make a bar graph which is representative of species evenness. (This is the relative abundance of each species.)
Alternatives
- Collect dung from animals with varying diets.( i.e. fed with hay, grain, or pasture) Compare the types of fungi present in the different food sources.
- Place the dung cultures in various temperatures to note the effects on the stages of succession.
- Place the dung cultures in different light sources to note the effects on the stages of succession.
REFERENCES :
Mycology Lab Manual, Walter J. Sundberg, Southern Illinois University.
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