Effects of soil temperature and moisture on the feeding activity of soil animals as determined by the bait-lamina test

Abstract

The aim of the study was to determine the effect of soil temperature and moisture on the feeding activity of soil fauna. To measure this activity, we conducted two short-term (14 days) experiments using the bait-lamina method. In experiment 1, the enchytraeid Cognettia sphagnetorum was added to defaunated mor humus. The experiment included incubations at four temperatures (−4, 5, 14, and 24 °C) and three moisture regimes (220, 260, and 300% of dry weight). No feeding activity was detected at −4 °C, but at other temperatures the bait-laminae were perforated, and the number of baits consumed increased with time. Because of variable animal survival and because of the rather low bait consumption, the effect of temperature and moisture on the feeding activity was unclear. In experiment 2, intact soil cores were either pre-treated at −21 °C or were not treated until being placed at −4, 5, 14 and 24 °C and two moisture regimes. The pre-treatment at −21 °C killed all meso- and macrofauna except collembolans and mites. Despite high densities of collembolans and moderate densities of mites at 24 °C in the pre-treated cores, there was no bait perforation. In the non-frozen cores, there was no feeding activity at −4 °C, but the activity increased with temperature up to 24 °C. The study showed that the bait-laminae were perforated by the activity of soil-living animals. Bait perforation seemed to be dependent on animals like enchytraeids and lumbricids and to a lesser degree collembolans and mites. The feeding activity measured by the bait-laminae increased with temperature, whereas the effect of soil moisture was less evident.