Heathland Restoration Techniques: Ecological Consequences for Plant-Soil and Plant-Animal Interactions

We compare the soil and plant community development during heathland restoration on improved farmland when achieved through soil stripping with that achieved through soil acidification. We also test the potential for toxic metals to be made more available to plant and animal species as a result of these treatments. Acidification with elemental sulphur was found to be more effective than soil stripping for establishing an ericaceous sward despite the high levels of phosphate still present within the soil. However, both soil acidification and soil stripping were found to have the potential to increase the availability of potentially toxic metals. Acidification increased uptake of both aluminium and zinc in two common plant species Agrostis capillaris and Rumex acetosella and decreased the abundance of surface active spiders. The potential consequences for composition of restored heathland communities and for functioning of food chains are discussed. 1. Introduction The restoration of lowland heath is an important facet of heathland conservation, as restored heathlands can ameliorate the effect of habitat fragmentation and so reduce the risk of extinction debt [1]. Much heathland has been destroyed through agricultural intensification during the second half of the last century [2, 3]. Consequently, there has been considerable long-standing interest in methods for the restoration of heathland on improved agricultural land [4–14]. Such restoration requires a reversal of the increased soil pH and nutrient availability that is effected during agricultural improvement so that ericaceous and acid grassland species are not outcompeted by large-growing mesotrophic grasses. Successful approaches have been based on either physically removing the improved topsoil [15, 16] or chemically amending it by, for example, adding sulphur to reduce pH and macronutrient concentrations [17, 18]. Whilst it is encouraging that some heathland restoration attempts based on either soil removal or soil acidification are successfully establishing ericaceous covers, the evaluation of successful habitat restoration should encompass a far broader assessment of the extent to which the communities and ecological processes of the restored ecosystems show similarity with those of target, established ecosystems [19]. This is particularly true for heathland restoration, as an important aim is often to provide habitat for higher trophic level protected species such as stone curlew (Burhinus oedicnemus), nightjar (Caprimulgus europaeus), and sand lizard (Lacerta agilis) that can have significant