An Investigation into the successful establishment of a hay meadow community on clay capped landfill.

Abstract

There is a pressing need to develop means of creating habitats that can contribute to the conservation of species threatened by loss of existing natural and semi-natural habitats. Decommissioned landfill presents excellent opportunities for the creation of a number of habitat types. However, landfills are often sealed with a compacted clay cap which not only creates harsh growing conditions and poor soil quality but also results in an impoverished soil fauna making it a challenging environment in which to effect rapid habitat creation. It is currently unclear to what extent the established principles of hay meadow creation are transferable to clay capped landfill. This thesis considers the creation of a hay meadow community and focuses on three properties that are influential in their development and that can be manipulated in experimental conditions: the soils, vegetation and micro-topography. It also explores methods of accelerating the establishment of a hay meadow community, thus encouraging a rapid green cover to provide shelter on the inhospitable bare soil to encourage seedling recruitment as well as addressing potential conflicts with public acceptability of landscape changes during restoration. Soil was identified as being the key factor in the successful establishment of a hay meadow community and the introduction of micro-topographic undulations as having the potential to increase the botanical diversity. Attempts to accelerate the colonisation of the clay cap through the introduction of earthworms were unsuccessful although a hypothesis to address the potential conflict between science and socio-cultural factors was made. This involves the swift establishment of a green cover across the site through the addition of topsoil and ameliorant, the sowing with fast-growing grass species and the creation of small patches of habitat with sown assemblages of species based on semi-natural counterparts.