Earthworms from soils developed after 80 years under tree monocultures at Holt Down, Hampshire, UK

Abstract

Experimental research from the 1980s showed that tree species influenced soil development where stands of beech (Fagus sylvatica) and small-leaved lime (Tilia cordata) respectivey started to develop a podzolic soil and a brown forest soil after 50 years from near identical origins. Evidence of earthworms was reported but no detail provided. Current work re-examined these soils and a further adjacent spruce (Picea abies) plantation and specifically sampled for earthworms. Standard soil and litter measurements were made, and earthworms were collected by a combined digging and hand-sorting, plus vermifuge technique. The soil surface below lime was covered with Mercurialis perennis, but deep leaf litter was present below beech, with needle cover below spruce. Significantly more earthworms were present below lime, at a density of 29 m−2, when compared with beech (<2 m−2) with spruce intermediate (11 m−2), with a significantly greater earthworm biomass below lime. Of 8 earthworm species collected, more than 70% were from below lime, including Aporrectodea longa, Lumbricus terrestris, A. caliginosa, Octolasion cyaneum and L. rubellus. Those below spruce were mainly Dendrobaena octaedra and only A. longa was found below beech. These observations, after 80 years of differential soil development below tree stands, clearly show continued interactive influences on soils of monoculture tree species with associated ecosystem engineering earthworms.