Surface movements of earthworms in agricultural land

MATHER, J. G., & O. CHRISTENSEN, 1988. Surface movements of earthworms in agricultural land. Pedobiologia 32, 399-405. The dispersal rates of earthworm populations within the soil habitat have previously been considered, especially in relation to the colonisation of grass land. However, even though the most rapid and effective mode of population spread is likely to occur across, rather than below, the soil surface, quantitative data concerning the distances travelled by individual earthworms when above ground remain sparse. Here, the surface trails of earthworms in agricultural land are investigated and it is demonstrated that individuals of Lumbricus terrestris are able to cover considerable distances (ranging from 3.8m to 19.3m) during a single surface foray. The data illustrate important aspects of earthworm behaviour, particularly their ability to explore and sample surrounding areas, as well as their potential for migrating rapidly between habitats of varying suitability and for colonising new areas. Furthermore, the investigation suggests that earthworm surface trails can be related to agricultural practice. Thus, it is here proposed that surface movement patterns have potential as a sensitive and convenient method for indicating the short- and Jong-term ecological effects of changes in habitat conditions. This proposal has application for the concept of environmental monitoring through bio-indication.