Earthworm populations of experimental birch plots on a Calluna podzol

Abstract

Experimental plots set up by G. W. Dimbleby to test the effect of birch on the soil of a podzolized heather moor were sampled for earthworms after 8, 10 and 27 yr. Of 213 worms collected, one was Dendrobaena octaedra (Savigny, 1826) and the remainder were Bimastos eiseni (Levinsen, 1884). No worms were found on the heather control plots and a single specimen only was taken on plots screefed and sown with Molinia. The population density on plots treated with birch litter, taking 1 yr with another, averaged approximately 1.7 worms m −2 with a biomass < 1 g m −2. On the Callunetum surrounding the experimental plots worms were sampled by a trapping method. Only B. eiseni was found. On the Callunetum and on the experimental plots worm numbers were correlated with the calcium content of the 0–3 cm soil horizon. Parts of the experimental site and surrounding Callunetum are subject to intermittent waterlogging. The development of the earthworm population in these areas appears to be restricted by occasional reducing conditions in the upper organic horizon.