Is the combination of topsoil replacement and inoculation with plant material an effective tool for the restoration of threatened sandy grassland?

Abstract

Question: Is it possible to restore dry calcareous inland sand ecosystems with their characteristic plant community structure within a 4-yr period by means of combined abiotic-biotic techniques (topsoil replacement, inoculation with raked/mown plant material from target areas)? Location: Upper Rhine valley, Germany. Methods: Two 4-year experiments were carried out on former arable land, each in the proximity of a reference area bearing a similar complex of threatened sandy grasslands (experiment 1: fine-scale; experiment 2: landscape scale). In both experiments we used nutrient-poor deep-sand substrate (abiotic approach), raked/mown inoculation material from target areas and grazing as management tool (biotic and management approach). The vegetation of the restoration and donor areas was sampled once a year and analysed by non-metric multidimensional scaling (NMDS) ordination and target-species ratios. Mixed linear models were calculated to determine effects of grazing (experiment 1) and year (both experiments). Results: NMDS revealed a continuous development of the restored sites towards the corresponding donor sites. Similarly, target-species ratios of the restored sites tended towards the ratios of the donor sites. To date, grazing effects have mainly been structural: reduction of a carpet-forming pleurocarpous moss species and of litter. In addition, cover of target species in relation to total plant cover was significantly enhanced by grazing in the last two study years. Conclusions: The combination of nutrient-poor substrate, inoculation with raked/mown plant material and grazing proved to be a very effective restoration method for dry base-rich sand ecosystems. After 4 yr the restored plant communities serve as well-developed parts of a habitat network. Nomenclature: Wisskirchen & Haeupler (1998) for vascular plant species, Koperski et al. (2000) for bryophytes and Scholz (2000) for lichens.Abbreviations: NMDS 5 non-metric multidimensional scaling; TSR qual 5 qualitative target-species ratio; TSR quant 5 quantitative target-species ratio.Eichberg, C.

Soil disturbance as a restoration measure in dry sandy grasslands

“…Ploughing or deep perturbation (mixing of the soil), on the other hand, creates a more intensive disturbance by turning the soil over, burying the nutrient rich top-soil. Top-soil removal and sod-cutting, during which the vegetation and the nutrient-rich top-soil are removed to a depth of 30-40 cm (de Graaf et al 1998;Röder and Kiehl 2006;Kiehl and Pfadenhauer 2007;Eichberg et al 2010), have a much greater potential for reducing nutrient availability and increasing the pH than rotovation and ploughing.…”

“…There will be a natural accumulation of nutrients and organic matter (Eichberg et al 2010), which will be further accelerated by atmospheric nitrogen deposition (Roem and Berendse 2000). This nutrient accumulation is a threat to all sandy grasslands, while calcareous sandy grasslands face the additional threat of decalcification and subsequent acidification of the topsoil (Olsson et al 2009).…”

“…Several studies have been published on their diversity and possible restoration, in particular in Germany and Sweden (e.g. Röder and Kiehl 2006;Kiehl and Pfadenhauer 2007;Eichberg et al 2010;Schnoor and Olsson 2010;Ö dman et al 2011). In Sweden for example, less than 50 ha of xeric sand calcareous grasslands remain (Olsson 1994;Tyler 2005).…”

“…It is recognised that soil disturbance and removal can be a successful restoration measure for sandy types of dry grasslands (Eichberg et al 2010;Faust et al 2011;Jentsch et al 2009;Ö dman et al 2011). This review focuses on anthropogenic soil disturbances such as rotovation (breaking up the soil), ploughing, sod-cutting, deep soil perturbation and top-soil removal, and their usefulness as restoration measures with respect to their effects on the soil nutrient content, the CaCO 3 content of the top soil and the vegetation of sandy grasslands.…”

“…Of particular interest is the threatened habitat xeric sand calcareous grassland (Natura 2000 code 6120, 2002/83/EC Habitat Directive), which is home to a large number of red-listed and endangered species of vascular plants (Mattiasson 1974;Olsson 1994;Eichberg et al 2010), bryophytes (Tyler 2005), fungi (Hansson and Jeppson 2005;Olsson et al 2010) and invertebrates (Ljungberg 1999). During the past century there has been a decrease in the area and species richness of these grasslands, caused mainly by changes in land use (Tyler 2003;Mattiasson 2009;Eichberg et al 2010), and they are further threatened by acidification (Olsson et al 2009;Mårtensson and Olsson 2010) and nutrient enrichment (Tyler 2005;Storm and Süss 2008;Mårtensson and Olsson 2010). There are 423 sites with xeric sand calcareous grasslands listed in the EUNIS database (European Environment Agency 2011), occurring in 11 European countries; Germany and Poland hold the highest number of sites.…”