Sustainability of earthworm communities in translocated grasslands: the first decade after runway 2 construction at Manchester airport

Abstract

Construction of a second runway at Manchester Airport led to a £17 million environmental mitigation package concerned with habitat restoration, relocation of species and translocation of valuable habitat components. One major concern was for legally protected vertebrate species (Meles meles and Triturus cristatus) affected by these works. To this end, a monitoring programme was established to assess earthworm communities (potential prey for the protected animals) within areas of translocated grassland. Major upheaval of soils can have negative consequences on soil biota, so integration of translocated turf with receptor subsoil was essential. The work reported here relates to continued monitoring of 4 specific translocated grassland areas. Digging and hand sorting of soil from replicated plots of 0.1 m2, followed by vermifuge (mustard) application was used to extract earthworms. Monitoring took place on an annual basis during the same week of October from 1998-2007. Twelve species of earthworm were located, representing three ecological groups. Recorded densities ranged from 4 to 427 earthworms m-2. Similarly, biomasses ranged between 2 and 110 g m-2. Significant differences can be ascribed to type of translocation undertaken (turf transfer or soil alone) and also between grassland sites (low lying, slopes, hillocks) and across years. Meteorological data suggests that the most significant environmental aspect during the decade of monitoring was rainfall, having its greatest negative effect on earthworms in 2003. Earthworm community composition has been dynamic over this time period.