Earthworms of an urban cemetery in Preston: General survey and burrowing of Lumbricus terrestris.

Abstract

Cemeteries in the UK are predominantly represented by grassland areas which have a variety of origins. Each can act as a haven for wildlife and numerous studies have looked at the flora and fauna present and in particular lichens associated with gravestones which offer chronological assessment. However, very few studies have looked at invertebrates in such settings and surprisingly, few if any have investigated earthworms - given the folklore associating these animals with the decomposition of human remains in the soil. This investigation set out to identify which species of earthworm were present in an urban cemetery in Preston and to discover how deep the animals were burrowing and indeed, if they were capable of burrowing to a depth of 2 metres – the depth at which bodies are usually buried. Nine species of earthworm were found, representing all three ecological categories, epigeic, endogeic and anecic. Burrow configurations were measured through casting with polyurethane resin. Vertical burrows of clitellate Lumbricus terrestris penetrated to a mean depth of 0.49 m (maximum 0.59 m), a function of soil type and water table. Where previous land use had created a relatively impervious layer below the soil surface, complex branched burrows of L. terrestris were found. These were significantly (p<0.001) shorter (mean depth 0.21 m) but confirmed the behavioural flexibility that this species of earthworm is known to exhibit. The presence of a healthy earthworm community in the grassland of the cemetery may well assist ecosystem services, but assistance with decomposition of human remains is unlikely.