Laboratory design to simulate complexity of forest floor for studying the role of fauna in the soil processes

Summary We developed a technique for simulating the complexity of the soil system under controlled laboratory conditions. Removable microcosms were inserted in a homogeneous substrate soil in a large plastic box. This macrocosm was sealed, except for an inlet and outlet for air flow, and an aperture for collecting leachates. The system can be designed and manipulated in various ways according to the needs of a particular experiment. Respiration and nutrient fluxes can be measured either from the whole macrocosm or separately from the microcosms. We have performed three experiments in order to evaluate the role of animals in the soil processes. A set of macrocosms was constructed from components of coniferous forest soil. These were partially sterilized by freezing and then thawing, and re-inoculated with (1) microbes alone, or (2) microbes and fauna. The animal populations became well established, average densities per area approaching those in natural forest soils. However, there were considerable differences in community structure between the experiments. The sterilization did not eliminate microfauna; nematodes reproduced to high densities in the control macrocosms.