Dispersal of microarthropods in forest soil

This experiment was a part of a research on the soil community in anthropog enous birch stands in Finland. In that study it was found that communities of Collembola are similar in birch stands of different origin (cultivated f ield or spruce forest), while the communities of Oribatida are essentially different. When compared to original spruce forest, the communities of both groups are different. Cultivation eliminates the populations of most microarthropod species, that have to disperse after reforestation from the surrounding areas. The aim o f the experiment was to study the ambulatory dispersal of soil microarthrop ods. It was carried out in plastic boxes filled with an intact block of def aunated surface soil taken from a birch stand that was established ca. 30 y ears earlier on a cultivated field. A strip of intact spruce forest soil wa s placed at one end of the boxes to harbour the source populations. At the opposite end we placed a row of pitfall traps. Soil samples were taken ever y two weeks at increasing distances from the source soil using a metal core r, and animals were extracted in a high gradient apparatus. The pitfalls we re also emptied every two weeks. The experiment lasted for ten weeks. Pitfall and soil sample data gave an estimation of the maximum dispersal ra te for each species or genus. The distance that the populations could poten tially disperse in 30 years (age of the stand) indicated that some, but not all of the species could have actively migrated to the central parts of th e birch stand (30 m).