In terms of biomass, fungi generally dominate the soil microbiota (2-5 tons per hectare in a temperate grassland). Fungi grow as heterotrophic, microscopic filaments known as hyphae. These hyphae form colonies of visible fluffy mycelium on substrates that provide adequate nutrition (e.g. a grass stem, malt media) When not biologically active, fungi can persist in the soil as spores. The sampling procedure outlined below will allow you to determine fungal diversity in the upper 5 cm of soil and how the composition of this decomposer community responds to fire. You will, however, need to refine the details of the sampling regime for your sites during the first week.

1. Collect two 300 g soil sample from each location.

2. In the CERA lab, set up a dilution series using 10 g of each sample in 100 ml of water. The concentration of soil in your final dilution should be 0.001g soil/100 ml.

3. Pipette 0.5 ml of five of your dilutions on to the malt media provided. How many replicates of each dilution should you use?

4. Spread the liquid evenly on the media with the glass rods ("hockey sticks") provided.

5. Seal the plates with Parafilm and bring them back to Grinnell for incubation at 25 C. (While most soil fungi are not pathogenic, you probably should not open the petri plates again.)

6. Check the plates 2-4 days later for defined colonies. How can you differentiate species? Can this method be used to obtain a measure of fungal density in the soil?

7. Outline the sampling procedure for your detailed studies of fungal decomposer diversity next week. Prior to week 2, notify your instructor regarding the amount of media you require.

In community ecology, disturbances are temporal changes in the physical environment (e.g., storms, fires, and floods) that disrupt communities, usually by removing individuals (or parts of individuals) from them. Disturbances can affect community structure by (1) temporarily changing physical conditions that affect the performance of individuals and the dynamics of populations, and (2) by opening up space, making it available for colonization by species that may not have been community members, or that may have been rare prior to the disturbance. Thus, periodic disturbance -- if it is not too intense or too frequent -- may increase species diversity in communities (see your text's discussion of the "intermediate disturbance hypothesis").

Prior to old-world settlement of North America, periodic fire was an important kind of disturbance in tallgrass prairie. Today, studying the consequences of fire for community structure and ecosystem processes is one of the central issues in tallgrass prairie ecology. Prairie restorers use proscribed (i.e., planned, set, and controlled) fire as a management tool in restoration projects. This has been done intensively at CERA, especially over the last decade or so. No one yet, however, has collected experimental data at CERA on how fire affects aspects of the physical environment or on the biological response to those changes. That's your mission. Researching the results of prairie studies elsewhere will help you formulate hypotheses and prepare your posters.

6 March 1997 In an area of restored prairie immediately NW of the lab building, equal numbers of 20 m x 10 m strips were either burned or left as unburned controls. The dispersion of treatments is uniform, with alternating burned and unburned plots. Mown strips separate adjacent experimental plots.

6 March 1998 The burned plots were burned again.

To minimize trampling of the experimental plots, each experimental plot has been divided into 5 m x 4 m sections, one for each lab day. Take only one sample per week per plot (from a random location) within your 5 m x 4 m section, and tread lightly to get in and out.

Group 5 -- Sample T_air , RH, maximum windspeed, and light intensity in each replicate of the two treatments, on both weeks, with vertical profiles.

Group 6 -- In week 2, sample T_{soil ,Y soil} , and collect a soil sample in each replicate of the two treatments. In week 3, calculate soil nitrogen and phosphorus concentrations, using the soil test kit.

Group 7 -- Sample above-ground necromass (week 1) and above-ground biomass (week 2) in each replicate of the two treatments.

Group 8 -- Sample plant density, diversity, and plant height in each replicate of the two treatments, in both weeks.

Group 9 -- Weeks 2 and 3. Identify arthropods from the previous week's funnel collection.

Group 10 -- Week 2: Sample fungal diversity in 4 replicates of the 2 treatments, using the procedure you designed last week. Week 3: Obtain measures of morphospecies diversity. Can you figure out how to measure abundance as well?

For this final exercise, you will present the results of your field-ecology project in the form of a poster, prepared by your research group. Work together with your group members to decide how to communicate your findings effectively. We can provide you with one piece of poster board (approx. 55 x 70 cm). That area should be sufficient. Oversized posters should not exceed twice the base area.

Here are some guidelines.

1. The order of presentation in the poster should resemble that of a scientific paper. That is, it should include Title, Authors, Introduction, Methods, Results, Discussion, Acknowledgments and References Cited sections. Please refer to the hand-out about writing scientific papers to review what belongs in these sections (although most of you have mastered this by now).

2. Although posters resemble papers in their overall outline, merely pasting a scientific paper onto a poster board does not make a good poster -- it makes a bad poster. Your poster needs to grab your classmates' and instructors' attention, and it must communicate its message while being observed from 50 cm or so away. Consider whether: (a) your text is large enough to be legible; and (2) the graphs and/or tables you use to summarize your results are visible from a considerable distance. Use a large font, and say what you have to say without extraneous words.

3. For ideas about poster design, you may find it useful to examine faculty and student scientific posters currently on display in the building.

Your poster should be COMPLETED by the beginning of next week’s lab period. The posters are intended to be hung in the wrap-around section of the Noyce Science Center, on the first floor. There will be two viewing sessions per lab period. During each session, half the groups will stand by their posters and answer questions from classmates, TAs, and instructors. 40 points of your grade will be based on the quality of your poster and your ability to answer questions about your project.

Because of the close relationships among the various projects, it is important that you learn what the other groups discovered. During the session in which you are free to circulate, you should read the other posters and ask questions of the authors. The general results and conclusions of the posters in your session are fair game for the final exam. In addition, for the final 10 points of your grade, you should write a short (1-2 pp.) review of one of the other posters. If you worked in the aquatic communities, pick one of the prairie posters. If you worked in the prairie, pick one of the aquatic posters. The short review is due at the end of the lab period. Begin the review with a brief summary of the poster, and then address the following questions:

1. Is the hypothesis clearly stated, and is it discussed in light of what is already known about the question?
2. Does the background material presented allow you to understand the study's rationale?
3. Are the methods appropriate for answering the question addressed?
4. Are the methods adequately described (so that another member of the class could repeat the study)?
5. Are the data succinctly summarized in the text and clearly presented in tables and/or figures?
6. Does the discussion relate the results to other published (or unpublished) findings?