Purpose:

To survey the soil organisms of a selected area and determine their relative abundance

Materials:

• Field Guides
• Coffee can
• Materials for Berlese Funnel (see diagram)
• Plastic sample bags (large enough for soil samples)
• Tweezers
• Magnifying glass
• Microscopes

Procedure:

1. Over the course of the study, collect at least twenty soil samples in locations that include as many habitats as possible from the field area. It will also be necessary to spread the sample sites out as much as possible. The most productive samples usually come from moist, shaded areas with abundant leaf litter covering the ground. Samples must be processed the same day that they are collected.
2. To collect samples, use a coffee can with the bottom removed so that both ends are open (record the volume of the coffee can used). Press the can into the soil until its top is level with ground level. Then remove all of the soil within the can and place in a sample bag. Label and plot the location of each sample on a map or an aerial photo ( an overlay may be used in to minimize possible mistakes in plotting sample locations).
3. After collecting the sample, cave in the walls of the hole left by the can and level the area as best as possible. This will prevent any small animals from falling in and getting trapped.
4. At home place the soil sample in a tray and remove any large organisms and identify to order using the attached keys and other sources in the classroom (It may be necessary to place some in a killing jar first - see handouts for preparation of killing jars). Then group the individuals in each order based on similarities in appearance. This is determining the morphospecies of each order. Record the number of individuals of each morphospecies. Once a morphospecies is defined, make sure its use is consistent for all of the organisms collected during the project. Make a verbal description of each morphospecies when first encountered (See example below).
5. If the organisms from the previous step are arthropods, it will be necessary to pin and prepare one individual of each morphospecies as described in the attached handouts. These specimens will form a very important reference collection. Be sure to protect this collection with crushed mothballs. Put the mothballs in a small, perforated envelope and securely attach it to the inside of the box. In addition to the information described in the attached handouts, be sure to indicate on each pin label from which collection point each specimen came and to which morphospecies it belongs. If it is not possible to pin the insects within a day of collecting them, put them in a freezer until it is possible. Do not throw away extra individuals but rather store them in a freezer at home or at school. These will need to be turned in at the conclusion of the project. All pinned / prepared specimens (in a properly prepared storage box) for each collection point will be turned in at each raw data due date.
6. Then follow the steps for removing smaller soil organisms as described on the diagram "Plate VI: Collecting Soil Insects or Nematodes Using the Berlese Funnel Technique". Use half of each sample for collecting soil arthropods and half of the sample for collecting nematodes and protists. Identify collected organisms to as specific level as possible with the attached keys end other sources in the classroom. Determine the morphospecies for these organisms as described in the previous step (also see example below). Be sure to record the number of individuals of each morphospecies in each soil sample (It will be necessary to devise some quantitative method for counting the protists and nematodes). The study of the organisms collected with the Berlese Funnel will require the use of microscopes in the classroom. Sketch all of these organisms as seen under the microscopes (Be sure to include the magnification at which they were viewed).
7. As a minimum, analyze the data based on the diversity of each order or class, the number of individuals in each order or class, and the number of individuals of each morphospecies. In addition, it would be interesting to see if there are correlations between the data and factors such as temperature, vegetation, soil characteristics, etc.
8. No soil or specimens should be thrown away. All of this material needs to be turned in with the final project.
9. If the soil samples are not yielding many organisms, try making an infusion by placing some dry grass from the area in a jar of spring water. After 3 days start examining the water for any microorganisms. Then follow all appropriate steps as described above.