Decomposition of terrestrial leaf litter in soil microcosms: An investigation for use in the classroom

Using investigative activities in the biology classroom can enable students to discover new information and to gain experience with the process of science. This scholarly activity involved designing an investigative laboratory activity dealing with leaf litter decomposition and the soil community. The two main objectives for the laboratory activity were (1) to give students experience with the process of science and (2) to introduce students to decomposition and to the soil community. Decomposition is an important process but is not commonly dealt with in general biology courses. An understanding of decomposition can facilitate comprehension of other ecological topics such as nutrient cycling and ecosystem productivity. In developing the activity, soil microcosms were designed and experiments were carried out in the microcosms to investigate the decomposition rate of deciduous leaf litter from two species and coniferous leaf litter from one species. The influence of decomposition on the soil community, on soil nutrient levels and on soil pH was also investigated during the experiments. One of the experiments was carried out as a laboratory activity by a group of students. Evaluations were used to solicit student feedback about the activity.;Deciduous leaf litter decomposed at a faster rate than coniferous litter during the experiments. Several types of fungi and invertebrates were isolated from the microcosms at the end of the experiments. The decomposition of leaflitter had minimal effects on the soil community and on soil nutrient levels and pH. The consistency of data gathered during the decomposition experiment indicated that it was useful in a classroom setting. Student feedback was used as a basis for modifications to the laboratory activity. Inquiry teaching methods which included more student involvement in the design and implementation of the experiment were incorporated into the initial handout which accompanied the activity. An instructional guide was also designed to provide teachers with background information on decomposition and the soil community, and to describe the procedures involved in building the microcosms and conducting the experiment in a classroom.