The development of sustainable earthworm populations at Calvert landfill site, UK

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AbstractEarthwormsAllolobophora chloroticaandAporrectodea longawere inoculated into Calvert landfill site in spring 1992, in conjunction with the planting of two tree speciesAlnus glutinosaandAcer pseudoplatanus. Monitoring has taken place over a period of 11 years. Sampling in 2003 revealed that earthworm distribution no longer equated to the inoculation treatments; the worms had spread extensively. The presence ofA. glutinosahad a significant effect (p<0ċ01) on earthworm number (mean density 198 m−2) and biomass (34 g m−2) compared to plots whereA. pseudoplatanushad been planted and subsequently died (mean density 118 m−2; biomass 21 g m−2). Results suggest that tree presence may be critical to earthworm community development.In 2002, the spread ofA. chloroticafrom the original points of inoculation had reached 60 m with the highest recorded population density at 108 m−2with a mass of 18ċ6 g m−2.A. longawas recorded at a distance of 132 m from the nearest point of inoculation with the highest recorded population density at 70 m−2with a mass of 49ċ3 g m−2, 10 m from the original inoculation grid. Other species recorded (and % of total) wereAporrectodea rosea(0ċ9)Lumbricus castaneus(7ċ4),Eiseniella tetraedra(21ċ5) andLumbricus rubellus(4ċ5). The two inoculated species,A. chlorotica(40ċ4) andA. longa(25ċ3), accounted for two thirds of the earthworms found on site. The highest earthworm community density was 213 m−2with a mass of 73ċ9 g m−2at 10 m from original point of inoculation.In 1999, treatments of surface organic matter (OM), in the form of composted green waste, and rotavation were applied to non‐replicated plots of 50 m2with the effects on earthworm distribution and abundance recorded in 2002. Addition of OM alone led to an increase in number and mass (331 m−2; 95 g m−2) compared to the control (233 m−2; 51 g m−2), while rotavation alone (111 m−2; 36 g m−2) had a detrimental effect over the given time period.This long‐term monitoring programme has demonstrated the development of sustainable earthworm communities on a landfill site. Natural nutrient accumulation and addition of OM on or into the soil‐forming material appeared to assist this process. This work may help to inform post‐capping treatment at similar landfill sites Copyright © 2004 John Wiley & Sons, Ltd.