The potential of restored landfill sites for biodiversity conservation in the UK

Loss of biodiversity has been in the forefront of conservation issues worldwide since the last century. Biodiversity conservation through restoring degraded habitats or creating new habitats is advocated in the UK Biodiversity Action Plan. Newly created grasslands on restored landfill sites are semi-natural habitats that could support a number of species. However, it is unknown whether these re-created habitats represent a significant resource in terms of biodiversity conservation though poor quality soil was being used for restoration. A multi-taxon approach was applied to examine the biodiversity potential of these novel habitats. Plants (vascular plants and bryophytes), invertebrates (carabid beetles and land snails), and vertebrates (birds) were studied on nine restored landfill sites and paired reference sites in the East Midlands region of the UK during 2007 and 2008. Plant species data were collected by random quadrats along two 100m transects from each site; carabid beetles were censused by pitfall traps; land snails were investigated by hand searches along the transects; and bird species were assessed using point counts. Effects of restoration were investigated by examining species richness, diversity or abundance of studied taxa and also how habitat quality and landscape factors determined species composition on restored landfill sites. A total of 170 plant species (162 vascular plants and 8 bryophytes), 37 carabid beetle, 17 land snail and 12 bird species were found in the studied sites. Species richness and diversity or abundance of studied taxa on restored landfill sites were found to be equal to or above that of reference sites. Compositional differences were found between taxa on restored landfill sites and their corresponding reference sites. Though vegetation composition including NVC plant communities on restored landfill sites was rather homogeneous compared to reference sites, restored landfill sites were found to support a number of nationally decreasing native plant species and of common species of other taxa and also a number of Red List bird species such as Skylark (Alauda arvensis), Grey partridge (Perdix perdix), Lapwing (Vanellus vanellus), Tree sparrow (Passer montanus) and Starling (Sturnus vulgaris). Habitat quality and landscape variables were found to be significant predictors for different species. Underlying soils were found to be an important factor in determining the heterogeneity of the plant communities within the study area which in turn dictates suitability of habitat for other taxonomic groups. A lack of congruency between taxa supports the incorporation of a multi-taxa approach into restoration plans. Management in terms of cutting or mowing of these landfill sites were found to have varying influences on different taxa. Moreover, restored landfill sites had less disturbance than reference sites as there was restricted access to dog walkers and for recreational purposes. This may be one of the main factors that could enhance the richness and abundance of a number of taxa, especially bird species. Management of these landfill sites should be targeted on species-specific goals as these sites can play a significant role in Local Biodiversity Action Plans. Overall, this study indicates that restored landfill sites have potential biodiversity conservation value in a complex modified human landscape.