Agriculturally unimproved chalk grasslands represent an important semi-natural habitat of high conservation importance, both in the UK and north-western Europe (Willems 2001; WallisDeVries et al. 2002; Woodcock et al. 2005). While there are many types of chalk grassland, these lowland habitats are known to support a particularly diverse flora, rich in forbs, including many rare or declining species (Gibson and Brown 1991; WallisDeVries et al. 2002). The invertebrate community associated with chalk grasslands is diverse (van Swaay 2002; WallisDeVries et al. 2002; Woodcock et al. 2005), and similarly includes many threatened species, perhaps the most widely recognised of which are the butterflies (van Swaay 2002). Traditional management of chalk grasslands is typically characterized by low intensity grazing, normally by sheep, although hay cutting is also used in some situations (Gibson and Brown 1991; Willems 2001; WallisDeVries et al. 2002). Without the removal of a relatively large proportion of the annual primary production, succession of the grassland will occur to either scrub / woodland or coarse species-poor grassland types (Gibson and Brown 1991).
Agricultural intensification by the application of inorganic fertilisers or excessively high grazing rates combined with the conversion of chalk grasslands to arable cultivation have resulted in the large scale loss and degradation of this species-rich habitat type across northwestern Europe (Blackstock et al. 1999; Willems 2001). This decline in both the quality and quantity of calcareous grassland has meant that of c. 400 plant species associated with this habitat, approximately 42 % are now considered to be threatened (reviewed in WallisDeVries et al. 2002). Similarly, although less well documented, the invertebrates of chalk grasslands have also undergone massive population declines in response to these changing patterns of land use and management (Steffan-Dewenter and Tscharntke 2002; van Swaay 2002). Reversing this trend requires multiple approaches, including the protection of remnant patches of chalk grassland, as well as the re-establishment of species-rich chalk grassland on either agriculturally-improved grassland or ex-arable land (Willems 2001; WallisDeVries et al. 2002; Walker et al. 2004). In this paper we will focus on the last of these, the re-creation of chalk grassland on land that has been converted to arable agriculture within the last 60 years. Here, re-creation is used to refer to the re-establishment of a grassland community on land that was no longer covered by a permanent grass sward of any type. The re-creation of chalk grassland will serve a number of potential purposes. For example, it will increase the overall area of this habitat type and so reduce the effects of fragmentation and patch isolation. Similarly if used strategically it may also provide buffer zones reducing the impacts of edge effects in remnant grassland patches (Bakker and Berendse 1999; Steffan-Dewenter and Tscharntke 2002). In the UK such re-creation schemes are now incorporated as part of agri-environmental policy, and as such are associated with financial reimbursement to support farmers for income forgone (DEFRA 2005).
The re-creation of chalk grasslands has been achieved by a wide variety of approaches, all of which can be broadly classified as promoting either the introduction of target plant species or promoting their subsequent establishment and persistence (Bakker and Berendse 1999; Willems 2001; Walker et al. 2004). The introduction of target plant species, i.e. those considered typical of chalk grasslands, has been achieved by direct sowing of commercially available seeds or the introduction of local provenance seeds collected using a variety of methods, including vacuum harvesting (e.g. Stevenson et al. 1997), brush harvesting (Morgan and Collicutt 1994; Edwards et al. 2007) or hay spread directly onto the site (Jones et al. 1999; Edwards et al. 2007). The sowing of a seed mix can have agronomic advantages over natural regeneration by reducing the establishment of undesirable pernicious weeds (Willems 2001; Bakker et al. 2003). Promoting establishment and persistence of species once they have been introduced using these methods falls into two main phases. The first is preperation prior to seed introduciton. This include practices such as the reduction of soil nutrients by soil stripping or growing unfertilised crops (Walker et al. 2004; Edwards et al. 2007) or the creation of germination niches by low levels of soil disturbance (e.g. Woodcock et al. 2008). Secondly, once seeds have been introduced, extensive grazing or mowing regimes have been used to both reduce the dominance of some plant species while continuing to reduce soil fertility by the removal of this above ground biomass (Willems 2001; Walker et al. 2004).
This study investigates the effects of management practices used to introduce plant species during the re-creation of chalk grassland on ex-arable land. We compare two fundamentally different approaches that while promoting the establishment of plants, have fundamentally different goals. The first approach is the sowing of a simple commercially available seed mix of grasses that are intended to control the pernicious weeds by the rapid establishment of grass cover. The second approach considers two methods that introduce local provenance seeds typical of chalk grasslands, namely hay spreading and the sowing of brush harvested seeds. The impact of these management practices on the re-creation of chalk grassland was assessed for both plant and phytophagous beetle assemblages. Phytophagous beetles were chosen in addition to the plants as they are a functionally diverse component of grassland fauna that represent a major proportion of the total abundance and species composition of grassland invertebrates (Woodcock et al. 2005; Woodcock et al. 2006; Woodcock et al. 2007).
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