Exercise 6. Soil Diversity Jan Kerwin F. Codiniera1, Juan Miguel L. Franco1, Van Alvin U. Gambalan1 Juan Carlos D. Maranan1 1 Department of Biological Sciences, College of Science, University of Santo Tomas, España Manila
Abstract A Berlese funnel setup was used in this experiment in order to assess the soil diversity of a given soil sample, which includes identification and statistical data regarding the arthropod community present. Results show that 2 soil termites were found present in the soil sample used. Computations for statistical data show that the values for density and relative density were 7.69x10-3 and 100, respectively. Abundance was measured to have a value of 2 while both the relative abundance and Simpson’s Index of Diversity have a value of 1. Shannon-Wiener Index of Diversity was also computed, having a value of 1.39. The possible causes for this low diversity are the type of soil used, presence of moisture in the setup, and unavailability of fixatives for preservation.
1992). The setup works by simulating a temperature gradient over the sample such that the organisms inside the sample would move away from the high temperature. Doing so will lead them to fall to the collecting vessels and will be able for examination later on. This setup was done to (1) be able to learn techniques for assessing density, diversity, relative abundance , and rank abundance of leaf litter arthropod community and to (2) be able to sort, identify, and count the arthropods from the soil samples. Methodology Constructing a Berlese funnel Two 2-Liter soda bottles were used as the body of the Berlese funnel. Approximately four inches were cut off from the first bottle and the funnel was removed. The second bottle is the opposite as the part with the funnel was retained. A mesh or net was placed on the opening of the funnel and the funnel was placed inverted into the other half-bottle, which served as a specimen collector and contained water.
Introduction
Checking for Soil Diversity
A simple way of assessing how healthy a soil sample from a certain area is by examining the different living organisms that can be extracted from the sample alone. An efficient method of extracting living organisms is with the use of the Berlese funnel setup. First tested in 1905, Antonio Berlese constructed a method wherein a hot water jacket is used as a heat source. It was then later modified in 1918 by Albert Tullgren by using an electric bulb to replace the hot water jacket and an iron sheet drum to create a heat gradient. (Imes
Soil was gently placed inside the Berlese funnel. The soil must be broken up first as to have an even consistency to allow any arthropods to emigrate from the soil. Annelids, such as earthworms, should be removed because mucus secretions can impede the movement of other organisms. Afterwards, a lamp is placed near the top of the Berlese funnel as to stimulate the warming of the soil surface. As a result, organisms would try to move away from the heat and towards the bottom near the funnel where they will fall. The water should be
replaced every 16 hours or so. Methylene blue or ethanol was used as a fixative after Fig. 1 Berlese – funnel method set-up
indicate a healthy soil because they are agents of organic matter decomposition and are important to nutrient recycling. Only two soil mites of the same species were confirmed to be observed.
each replacement of the water.
Results and Discussion
The loam soil utilized in this experiment was a topsoil from a newly potted plant. During the identification of organisms captured using the Berlese funnel using a dissecting microscope, we observed that there were only few numbers of microarthropods present. We identify these microarthropods as soil mites. The presence of these mites
Fig. 2 Soil mites under dissecting microscope
A possible factor contributing to this low diversity of organisms found is the the soil used since it was collected from a newly potted plant, the organisms must not have settled to their usual location. Another factor would be that the soil used was not completely dry and therefore may have prevented some organisms to fall from the funnel. Furthermore, there were no fixative readily available for use so there might have been organisms like nematodes present but immediately dessicated since a fixative was not applied. The Berlese funnel method gives an inaccurate result of the biodiversity of the soil since it only works on dry soil and can only capture organisms that do not easily dessicate and are mobile.
Conclusion The Berlese funnel setup is a technique for assessing the diversity of organisms found present in a particular soil sample. The application of this technique showed that there were two organisms, which were identified as soil mites, present in the soil sample used for the experiment.
References (1) Imes, R. (1992). Practical Entomologist: A fireside book. New York, NY: Simon and Schuster. (2) Gonçalves, M. F., & Pereira, J. A. (2012).
The results for the computation of statistical data in this experiment is shown in figure 3. The value of density gives an idea of how much of the organisms is found in an area while the abundance shows how many of the species is found in the sample. However given all those values, they may have been irrelevant since there were only two organisms found of the same species. Abundance and Diversity of Soil Arthropods in the Olive Grove Ecosystem. Journal of Insect Science, 12, 20. http://doi.org/10.1673/031.012.2001
Fig. 3 Computation for species diversity
