Carly J. Stevens, Cecelia Duprè, Edu Dorland, Cassandre Gaudnik, David J. G. Gowing, Martin Diekmann, Didier Alard, Roland Bobbink, Emmanuel Corcket, J. Owen Mountford, Vigdis Vandvik, Per Arild Aarrestad, Serge Muller, and Nancy B. Dise. Year. Grassland species composition and biogeochemistry in 153 sites along environmental gradients in Europe. Ecology 92:1544.

INTRODUCTION

Large scale surveys on environmental gradients proven to be valuable to formulate and test hypotheses (e.g., Manel et al. 2000; Kleinebecker et al. 2008; Maskell et al. 2010). Data from such surveys provide a means of assessing actual impacts of global change drivers, testing of models at a large scale, and providing insights into regional biodiversity patterns (Manel et al. 2000).

This data paper documents the species composition and soil and plant tissue biogeochemistry of 153 acid grasslands in the Atlantic biogeographic region of Europe. Grasslands surveyed belonged to the alliance Violion caninae (Schwickerath 1944) and are typically grass dominated, with Agrostis capillaris L. and Festuca ovina sensu lato L. being most common and abundant. Sedge, rush, shrub and forb cover is variable, common species include Luzula campestris (L.) DC., Potentilla erecta (L.) Räuschel and Galium saxatile L. Bryophytes are commonly found in the grassland sward, particularly in the UK, with the species most frequently found being Rhytidiadelphus squarrosus. Grasslands were sampled in 10 countries including Ireland, Isle of Man, Great Britain, France, Belgium, the Netherlands, Germany, Norway, Denmark, and Sweden. The acidic grasslands visited were selected in a stratified manner to cover the range of atmospheric nitrogen (N) deposition in north-western Europe, and sites in the vicinity of local point sources of N (e.g., large pig or poultry farms up to 1 km away) were avoided. All of the grasslands were managed by grazing or cutting and none were fertilized. Areas within the grassland that belonged to other plant communities or were strongly affected by animals (e.g., stock feeding areas), tracks and paths, or were in the rain shadows of trees or hedges were excluded from the survey. At each site five randomly placed replicate 2 × 2 m quadrats were sampled within a 1 ha sampling area. Within each quadrat, all vascular plants and bryophytes were identified to species level and their cover was estimated. A total of 397 species were found in the 153 sites (335 species of vascular plant and 62 species of bryophyte). Two topsoil samples were collected from each quadrat at a depth of 0–10 cm below the litter layer and bulked to make one sample per quadrat. Subsoil samples were collected from the centre of the quadrat from a depth of 20 – 30 cm or, in shallower soils, as deep as was possible. Soils were analyzed for pH in water, metal concentrations, nitrate and ammonium concentrations, total carbon and N, and Olsen extractable phosphorus. Aboveground plant tissues were collected from within the 1 ha sampling area for three species: Rhytidiadelphus squarrosus, Galium saxatile and Agrostis capillaris and analyzed for percentage N, carbon and phosphorus. Site physical characteristics, including location, altitude, aspect and slope, are also collated.

This data set (or parts thereof) has already been used to publish a number of research papers focusing on the effects of N deposition on the species composition and biogeochemistry of grasslands (Stevens et al. 2004; Stevens et al. 2006; Fraser and Stevens 2008; Stevens et al. 2009a; Stevens et al. 2009b; Duprè et al. 2010; Stevens et al. 2010a; Stevens et al. 2010b; Stevens et al. in press-a; Stevens et al. in press-b). However, the sampling of a well-defined habitat across a large spatial scale and the methodological consistency of the data also provide unique opportunities to investigate spatial and biogeographic patterns further.

METADATA

CLASS I. DATA SET DESCRIPTORS

A. Data set identity: Biodiversity of European Grasslands – Impact of Nitrogen Deposition (BEGIN) Acid Grassland Survey.

B. Data set identification code: Not applicable (N/A)

C. Data set description

Principal Investigators:

Professor David Gowing, Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.

Professor Nancy Dise, Department of Environmental and Geographical Science, Manchester Metropolitan University, Manchester M1 5GD, UK.

Dr Carly Stevens, ([email protected]) Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.

Abstract: This data set consists of vascular plant and bryophyte species composition and plant and soil biogeochemical data from 153 acid grasslands located in the Atlantic biogeographic region of Europe. Data were collected between 2002 and 2007. The grasslands all belong to the Violion caninae association and were managed by grazing or cutting but had not received fertilizer inputs. These data provide plant composition from five randomly located 2 × 2 m quadrats at each site with all vascular plants and bryophytes identified to species level with cover estimates for each species. Topsoil and subsoil were collected in each quadrat, and data are provided for pH, metal concentrations, nitrate and ammonium concentrations, total carbon and N, and Olsen extractable phosphorus. Aboveground plant tissues were collected for three species (Rhytidiadelphus squarrosus, Galium saxatile, and Agrostis capillaris), and data are provided for percentage N, carbon, and phosphorus. These data have already been used in a number of research papers focusing on the impacts of atmospheric N deposition on grassland plant community and biogeochemistry. The unique data set presented here provides the opportunity to test theories about the effect of environmental variation on plant communities, biogeochemistry, and plant–soil interactions, as well as spatial ecology and biogeography.

D. Key words: Acid grasslands; Atlantic region of Europe; plant tissue chemistry; soil chemistry; species composition.

CLASS II. RESEARCH ORIGIN DESCRIPTORS

A. Overall project description

Identity: Survey of acid grasslands in the Atlantic region of Europe.

Originators:

Professor David Gowing, Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.

Professor Nancy Dise, Department of Environmental and Geographical Science, Manchester Metropolitan University, Manchester M1 5GD, UK.

Dr Carly Stevens, ([email protected]) Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.

Period of Study: Data were initially collected from 64 sites in the UK in 2002 and 2003. This was extended to a larger international survey in 2007 including sites in 10 countries.

Objectives: The BEGIN project aimed to investigate the impacts of atmospheric nitrogen deposition on species composition and biogeochemical cycles.

Sources of funding: The BEGIN project was funded by the European Science Foundation through the EURODIVERSITY-programme, and national funds were provided by DFG (Germany), NERC (United Kingdom) and NWO (The Netherlands) and INRA, ADEME and Aquitaine Region (France). Data collected in 2002/3 was funded by The Open University, Ferguson Trust, and NERC.

Abstract: see above.

B. Specific subproject description

Site description

Site type: Survey of 153 acid grasslands in the Atlantic region of Europe covering various management types.

Geography:The study area covered Ireland, Isle of Man, Great Britain, France, Belgium, the Netherlands, Germany, Norway, Denmark, and Sweden. The most northerly site was located north of Bergen in Norway and the most southerly site was located in south-west France, close to the Spanish border, the most easterly site was located near Halmstad in southern Sweden and the most westerly site in Galway, western Ireland. Altitude ranged from 4 to 812 m above sea level.

Habitat: Acid grasslands belonging to the Violion caninae association.

Geology: Various.

Watersheds/hydrology: N/A.

Site history: various, although all sites were managed either by cutting or grazing and had not received fertilizer additions.  Grasslands in the vicinity of point sources of N (e.g., large pig or poultry farms) were avoided.

Climate: mean annual maximum daily temperature ranged from 6.8 to 18.8 ºC, mean annual minimum daily temperature ranged from 0.6 to 10.2 ºC, and mean annual rainfall ranged from 498 to 1971 mm (MARS 2009).

2. Sampling design

Design characteristics: Sites were selected in a stratified manner to cover the range of ambient N deposition in Europe and climatic gradients. Where possible grasslands surveyed were selected at random from national data sets of grassland extent or protected sites held by conservation agencies although in a number of regions the limited number of grasslands and sampling restrictions meant that this was not possible. This was particularly true in Norway, Sweden, Denmark, and Germany.

Data collection: One hundred and fifty three Violion caninae grasslands were surveyed. To ensure consistent community selection across the geographic gradient, a list of indicative or dominant species of the community was drawn up of which at least five had to be present at each of the survey sites. These were all species which typically have a high constancy in the community and/or occur at cover greater than 20%. The indicative or dominant species used for site selection were: Festuca rubra/ovina aggregates, Agrostis capillaris, Galium saxatile, Potentilla erecta, Luzula campestris, Danthonia spp, Deschampsia flexuosa, Nardus stricta, Polygala spp., Calluna vulgaris, Carex pilulifera, Campanula rotundifolia, Rhytidiadelphus squarrous. Five randomly located 2 × 2 m quadrats were surveyed within a 1 ha area. Areas within the grassland that belonged to other plant communities or were strongly affected by animals, tracks and paths, or were in the rain shadows of trees or hedges were avoided. Within each quadrat, all vascular plants and bryophytes were identified to a species level and their cover was estimated using the Domin scale (see Table 2). Cover estimates were made by a total of four different surveyors so the Domin scale was used to minimise error between surveyors. A description of the site was made and data collected on latitude, longitude, aspect, slope, vegetation height (visual estimate of mean height across the site), and soil depth (to bedrock). Management type was recorded and management intensity was estimated based on a visual estimate of vegetation height and the presence of animals. Topsoil samples were taken from the top 10 cm below the litter layer. Samples were taken from two opposing corners of the quadrat, bulked to one sample per quadrat. Ten centimeter depth subsoil samples were taken at a depth of 20–30 cm (or as deep as possible if the soil depth was < 30 cm) from the center of the quadrat using a 5 cm diameter soil auger. Above-ground plant tissue samples were collected from within the vicinity of the quadrats for three species Agrostis capillaris L. (bent grass), Galium saxatile L. (lady’s bedstraw) and the moss Rhytidiadelphus squarrosus (Hedw.) Warnst. These species were selected because they represent the most common and abundant grass, forb and bryophyte in the community. Where values are not provided in the data tables the species was not present on the site. Plant tissue samples were washed in deionized water and gently dried with paper towels within 24 hours of collection. Samples were then stored for up to one week before they were dried in the laboratory.

3. Research Methods

Laboratory: Soil samples were air dried, roots and stones removed and remaining soil ground to <2 mm using a pestle and mortar. For total carbon (C) and N analysis, soils were ground to a fine powder using a ball mill. Plant samples were oven dried for three days at 55 ºC and then ground to < 2 mm using a ball mill or mechanical grinder.

Nitrate, ammonium, dissolved calcium (Ca), aluminium (Al), iron (Fe), magnesium (Mg), manganese (Mn) and Zinc (Zn) concentrations were analyzed using two different methods. Samples collected in 2002 and 2003 were leached with 1 M KCl and the resulting nitrate and ammonium analyzed using an ion chromatograph. Other amples were shaken with 0.4 M NaCl and analyzed using an auto-analyzer. For all samples metal concentrations were determined using an ICP-MS or ICP-OES. An Olsen extraction was used to estimate plant-available P (MAFF, 1986). Absorbance was determined using a colorimeter at a wavelength of 880nm. Total C and N content of the soil and plant material was analyzed using a CN elemental analyzer. All analysis was conducted on dry soil as it was not possible to perform extractions immediately on return to the laboratory (Robertson et al. 1999). Plant tissue phosphorus (P) concentration was determined using a dry ashing extraction method (Chapman and Pratt, 1985; Ryan et al., 2001) followed by a Barton colour complex (MAFF, 1986). Absorbance was determined using a colorimeter at a wavelength of 410 nm. Soil pH was determined using a pH probe in a 1:5 slurry of soil and deionized water.

Instrumentation: Ball mill, mechanical plant grinder, ion chromatograph (Dionex D100 with Ion Pac CS16 column for cations and a IonPac AS9-HC column for anions), colorimetric auto analyzer (Skalar SA-40), ICP-MS (Agilent 7500a), ICP-OES (Thermo Iris Intrepid II), CN elemental analyzer (Interscience CE Instruments CHN; LECO CNS-2000; HEKATECH GmbH EURO EA), colorimeter (Heios Thermo Spectropic colorimeter), pH meter.

Taxonomy and systematics: Taxonomy follows Flora Europaea (http://rbg-web2.rbge.org.uk/FE/fe.html)

Permit history: Permission from landowners and local conservation organisations were obtained prior to visiting all sites.

Legal / organizational requirements: N/A

4. Project personnel: All co-authors plus field assistants.

CLASS III. DATA SET STATUS AND ACCESSIBILITY

A. Status

Latest update: July 2009

Latest Archive date: July 2009

Metadata status: The metadata are complete and up to date.

Data verification: All data have been cross checked with raw data.  Laboratory analysis was conducted in several different laboratories with samples exchanged to ensure consistency.  Ten samples for each analysis were exchanged between laboratories and errors of 10% were deemed acceptable. If errors were more than 10% all samples from the laboratory showing an error were reanalyzed.

B. Accessibility

Storage location and medium: The data are available from the Ecological Society of America’s data archives.

Contact person: Carly Stevens ([email protected])

Copyright restrictions: None.

Proprietary restrictions: None, although we would like to hear how the data are being used (e.g., for what research questions or teaching exercises). Additional data and archived samples are available for some sites for collaborative projects. N deposition data is not provided here but full details can be found in Stevens et al. (2010).

Costs: None.

CLASS IV. DATA STRUCTURAL DESCRIPTORS

ENVIRONMENTAL DATA

A. Data Set File

Identity: environmentaldata.csv

Size: 30 KB.

Format and storage mode: ASCII text, comma separated. No compression scheme was used.

Header information: The first row of the file contains the variable names below.

B. Variable information

TABLE 1. Variable information for the file environmentaldata.csv for 153 sites.

Missing value codes: Missing values are left blank.

SPECIES DATA

1. Identity: speciesdata.csv

2. Size: 323 KB

3. Format and storage mode: ASCII text, comma separated. No compression scheme was used.

4. Header information: The first row of the file contains the species names with cover given in Domin values.

B. Variable information:

TABLE 2. Variable information for the file speciesdata.csv for each of the five quadrats for 153 sites (n = 765).

Missing value codes: Missing values are left blank.

LITERATURE CITED

Chapman, H. D. and P. F. Pratt. 1985. Methods for Analysis of Soils, Plants and Waters. Agricultural Sciences Publications, California, USA.

Duprè, C., C. J. Stevens, T. Ranke, A. Bleeker, C. Peppler-Lisbach, D. J. G. Gowing, N. B. Dise, E. Dorland, R. Bobbink, and M. Diekmann. 2010. Changes in species richness and composition in European acidic grasslands over the past 70 years: the contribution of cumulative atmospheric nitrogen deposition. Global Change Biology 16:344–357.

Fraser, I., and C. J. Stevens. 2008. Nitrogen deposition and loss of biological diversity: Agricultural land retirement as a policy response. Land Use Policy 25:455–463.

Kleinebecker, T., N. Holzel, and A. Vogel. 2008. South Patagonian ombrotrophic bog vegetation reflects biogeochemical gradients at the landscape level. Journal of Vegetation Science 19:151–160.

MAFF. 1986. The analysis of Agricultural Materials. Third Edition. Her Majesty's Stationary Office, London, UK.

Manel, S., S. T. Buckton, and S. J. Ormerod. 2000. Testing large-scale hypotheses using surveys: The effects of land use on the habitats, invertibrates and burds of Himalayan rivers. Journal of Applied Ecology 37:756–770.

MARS. 2009. European Commission Joint Research Centre. http://mars.jrc.it/

Maskell, L. C., S. M. Smart, J. M. Bullock, K. Thompson, and C. J. Stevens. 2010. Nitrogen Deposition causes widespread species loss in British Habitats. Global Change Biology 16:671–679.

Robertson, G. P., D. C. Coleman, C. S. Blesoe, and P. Sollins. 1999. Standard Soil Methods for Long-Term Ecological Research. Oxford University Press, Oxford, UK.

Ryan, J., G. Estefan, and A. Rashid. 2001. Soil and Plant Analysis Laboratory Manual. Second Edition. ICARDA, Aleppo, Syria.

Schwickerath, M. 1944. Das Hohe Venn und seine Randgebiete. Pflanzensoziologie 6:1–278.

Stevens, C. J. 2004. Ecosystem properties of acid grasslands along a gradient of Nitrogen deposition. PhD, The Open University.

Stevens, C. J., N. B. Dise, and D. J. Gowing. 2009. Regional trends in soil acidification and metal mobilisation related to acid deposition. Environmental Pollution 157:313–319.

Stevens, C. J., N. B. Dise, D. J. Gowing, and J. O. Mountford. 2006. Loss of forb diversity in relation to nitrogen deposition in the UK: regional trends and potential controls. Global Change Biology 12:1823–1833.

Stevens, C. J., L. C. Maskell, S. M. Smart, S. J. M. Caporn, N. B. Dise, and D. J. Gowing. 2009. Identifying indicators of atmospheric nitrogen deposition impacts in acid grasslands. Biological Conservation 142:2069–2075.

Stevens, C. J., C. Duprè, E. Dorland, C. Gaudnik, D. J. Gowing, A. Bleeker, M. Diekmann, D. Alard, R. Bobbink, D. Fowler, E. Corcket, J. O. Mountford, V. Vandvik, P. A. Aarrestad, J. F. Muller, and N. B. Dise. In press. The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe. Environmental Pollution.

Stevens, C. J., C. Duprè, E. Dorland, C. Gaudnik, D. J. G. Gowing, A. Bleeker, M. Diekmann, D. Alard, R. Bobbink, D. Fowler, E. Corcket, J. O. Mountford, V. Vandvik, P. A. Aarrestad, S. Muller, and N. B. Dise. 2010. Nitrogen deposition threatens species richness of grasslands across Europe. Environmental Pollution 158:2940–2945.

Stevens, C. J., C. Dupre, C. Gaudnik, E. Dorland, N. B. Dise, D. J. Gowing, A. Bleeker, D. Alard, R. Bobbink, D. Fowler, E. Corcket, V. Vandvik, J. O. Mountford, P. A. Aarrestad, S. Muller, and M. Diekmann. In press. Changes in species composition of European acid grasslands observed along a gradient of nitrogen deposition. Journal of Vegetation Science.