Activity-stimulating phenomena caused by field-disturbance in the use of pitfall-traps.

The influence of several mechanical field disturbances, when using pitfall-traps for activity determinations, is analysed. The disturbances result in higher catches of surface-dwelling Collembola; the animals being stimulated to higher locomotory activity.The disturbance by walking in the field results in a multiple of the control catch. This effect lasts for about 1 hour.The digging-in effect lasts for about two days but more or less different for the various species. The cause is sought in the CO2 production in the soil, which is considerable after soil disturbances. The reaction of Collembola to rather high CO2 concentrations in the air results in an increase of the locomotory activity.Another interpretation, namely attraction to CO2 sources, could not be demonstrated.