Skip to main content

Advertisement

Log in

Ground floor vegetation assessment within the intensive (Level II) monitoring of forest ecosystems in Germany: chances and challenges

  • Original Paper
  • Published:
European Journal of Forest Research Aims and scope Submit manuscript

Abstract

As a part of the ‘Intensive Forest Monitoring Programme’ of ICP Forests, ground floor vegetation has been surveyed along with parameters of other relevant components of the forest ecosystems and their environment at 80 permanent plots all over Germany. Its floristic composition and their changes can therefore be linked to a wide variety of potentially influencing factors, scrutinising recent hypotheses on floristic changes, mainly soil eutrophication and acidification due to air pollutants. Results of a broad-scaled feasibility study are presented and critically discussed with regard to future in-depth evaluations. After an overview on the most abundant species, the syntaxonomic allocation of the plots is given. An ordination reveals a gradient from nutrient and base rich soils to poor acidic soils. Floristic dynamics are mainly aligned with the main axis, but conclusions about the medium-term development cannot be stated yet. Ordination and subsequent statistics are recommended to open up a wide field for explorative investigations. Indicator values for soil acidity and nutrient supply corroborate the main floristic gradient. Based on an empirical species–area relationship (SAR), species numbers for a common plot size of 400 m2 were calculated. Basic relationships among different diversity measures and between diversity measures and basic stand and site-related parameters were elaborated. Recommendations focus on enhancements of the assessment of ground floor vegetation within the context of the Level II monitoring like annual sampling or harmonisation of the plot sizes.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

References

  • Augustin S, Wolff B (2003) Konzept und Machbarkeitsstudie für die Integrierende Auswertung von Daten des Forstlichen Umweltmonitorings. BFH-Nachrichten 41(2):12–14

    Google Scholar 

  • AG Forsteinrichtung/AK Standortskartierung (1996) Forstliche Standortsaufnahme. 5. Aufl IHW Verlag, Eching, 352S

  • BMELF (Bundesministerium für Ernährung Landwirtschaft und Forsten, Hg) (1997) Dauerbeobachtungsflächen zur Umweltkontrolle im Wald Level II: Methodenleitfaden. Bonn, pp 126

  • Braun-Blanquet J (1964) Pflanzensoziologie. Grundzüge der Vegetationskunde. 3. Aufl, Springer, Berlin Wien New York, 865 S

  • Brunet J, Tyler G (2000) Interannual variability in abundance of field layer species in a Swedish deciduous wood. Flora 195:97–103

    Google Scholar 

  • Camaret S, Bourjot L, Dobremez J-F (coord.) (2004) Suivi de la composition floristique des placettes du réseau (1994/95-2000) et élaboration d’un programme d’assurance qualité intensif. Office National des Forêts, Fontainebleau, 86pp

  • Connell JH (1978) Diversity in tropical rain forests and coral reefs. Science 199:1302–1310

    Article  PubMed  Google Scholar 

  • De Vries W, Reinds GJ, Deelstra, HD, Klap JM, Vel EM (1998) Intensive monitoring of forest condition in Europe: Technical Report 1998. UN/ECE EC, Brussels, Geneva, 193pp

  • De Vries W, Reinds GJ, van der Salm C, Draaijers GPJ, Bleeker A, Erisman JW, Auée J, Gundersen P, Kristensen HL, van Dobben H, de Zwart D, Derome J, Voogd JCH, Vel EM (2001) Intensive monitoring of forest condition in Europe: Technical Report 2001. UN/ECE EC, Brussels, Geneva, pp 177

  • De Vries W, Reinds GJ, Posch M, Sanz MJ, Krause GHM, Calatayud V, Renaud JP, Dupouey JL, Sterba H, Vel EM, Dobbertin M, Gundersen P, Voogd JCH (2003a) Intensive monitoring of forest condition in Europe: Technical Report 2003. UN/ECE EC, Brussels, Geneva, pp 161

  • De Vries W, Vel EM, Reinds GJ, Deelstra H, Klap JM, Leeters EEJM, Hendriks CMA, Kerkvoorden M, Landmann G, Herkendell J, Haußmann T, Erisman JW (2003b) Intensive monitoring of forest ecosystems in Europe. 1. Objectives, set-up and evaluation strategy. For Ecol Manage 174:77–95

    Article  Google Scholar 

  • Diekmann M (1995) Use and improvement of Ellenberg’s indicator values in deciduous forests of the Boreo-nemoral zone in Sweden. Ecography 18:178–189

    Article  Google Scholar 

  • Diekmann M (2003) Species indicator values as an important tool in applied plant ecology—a review. Basic Appl Ecol 4:493–506

    Article  Google Scholar 

  • Diekmann M, Dupré C (1997) Acidification and eutrophication of deciduous forests in northwestern Germany demonstrated by indicator species analysis. J Veg Sci 8:855–864

    Article  Google Scholar 

  • Diekmann M, Falkengren-Grerup U (1998) A new species index for vascular plants: development of functional indices based on mineralization rates of various forms of soil nitrogen. J Ecol 86:269–283

    Article  CAS  Google Scholar 

  • Diggle PJ, Liang K-Y, Zeger SL (1994) Analysis of longitudinal data. Clarendon Press, Oxford, pp 253

    Google Scholar 

  • Dolnik C (2003) Artenzahl-Areal-Beziehung von Wald- und Offenlandgesellschaften. Mitt Arb-gem Geobotanik Schleswig-Holstein u Hamburg 62, pp 183

  • Dumortier M, Butaye J, Jacquemyn H, Van Camp N, Lust N, Hermy M (2002) Predicting vascular plant species richness of fragmented forests in agricultural landscapes in central Belgium. For Ecol Manage 158:85–102

    Article  Google Scholar 

  • Düll R (1992) Zeigerwerte von Laub- und Lebermoosen. Scripta Geobotanica 18:175–214

    Google Scholar 

  • Duvigneaud P, Kestemont P, Timperman J, Moniquet J-D (1977) La hêtraie ardennaise à Festuca altissima à Mirwart: Biomasse et productivité primaire. In: Duvigneaud P, Kestemont P (eds) SCOPE. Traveaux de la section belge du Programme Biologique International. Bembloux, Paris, pp 107–176

    Google Scholar 

  • Ellenberg H (1992) Zeigerwerte der Gefäßpflanzen ohne Rubus. Scr Geobot 18:9–166

    Google Scholar 

  • Ellenberg H (1996) Vegetation Mitteleuropas mit den Alpen. 5. Auflg., Ulmer, Stuttgart, S1059

  • Ellenberg H, Mayer R, Schauermann J (1986) Ökosystemforschung—Ergebnisse des Sollingprojekts. Ulmer, Stuttgart, S507

  • EP GrVeg (Expert Penal on Ground Vegetation Assessment, Aamlid D et al) (2002) Assessment of Ground Vegetation. In: UNECE (ed) Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests, Part VIII, Hamburg, 19pp

  • Ertsen ACD, Alkemade JRM, Wassen MJ (1998) Calibrating Ellenberg indicator values for moisture, acidity, nutrient availability and salinity in the Netherlands. Plant Ecol 135:113–124

    Article  Google Scholar 

  • Ewald J (2000) The influence of coniferous canopies on understorey vegetation and soils in mountain forests of the northern Calcareous Alps. Appl Veg Sci 3:123–134

    Article  Google Scholar 

  • Ewald J (2002) Multiple controls of understorey plant richness in mountain forests of the Bavarian Alps. Phytocoenologia 32:85–100

    Article  Google Scholar 

  • Ewald J (2003) The sensitivity of Ellenberg indicator values to the completeness of vegetation relevés. Basic Appl Ecol 4:507–513

    Article  Google Scholar 

  • Feoli E, Zuccarello V (1988) Syntaxonomy: a source of useful sets for environmental analysis? Coenoses 3:141–147

    Google Scholar 

  • Feoli E, Zuccarello V (1994) Naiveté of fuzzy systems spaces in vegetation dynamics? Coenoses 9:25–32

    Google Scholar 

  • Ferretti M (2000) An introduction to the integrated and combined (I&C) evaluation system designed for the intensive monitoring of forest ecosystems in Italy. Annali Istituto Sperimentale Selvicoltura (Arezzo) 30:7–16

    Google Scholar 

  • Ferretti M, Nibbi R (2000) Procedures to check availability, quality and reliability of data collected at the CONECOFOR permanent monitoring plots. Annali Istituto Sperimentale Selvicoltura (Arezzo) 30:43–58

    Google Scholar 

  • Ferretti M, Chiarucci A (2003) Design concepts adopted in long-term forest monitoring programs in Europe—problems for the future? Sci Total Environ 310:171–178

    Article  PubMed  CAS  Google Scholar 

  • Fischer H, Bens O, Hüttl RF (2002) Veränderungen von Humusform, -vorrat und -verteilung im Zuge von Waldumbau-Maßnahmen im Nordostdeutschen Tiefland. Forstw Cbl 121:322–334

    Article  CAS  Google Scholar 

  • Fischer HS, Bemmerlein FA (1989) An outline for data analysis in phytosociology: past and present. Vegetatio 81:17–28

    Article  Google Scholar 

  • Frey W, Frahm J-P, Fischer E, Lobin W (1995) Die Moos- und Farnpflanzen Europas (Kleine Kryptogamenflora, Band IV, 6. Aufl.). G. Fischer, Stuttgart Jena New York, pp 426

  • Grime JP (1979) Plant strategies and vegetation processes. Wiley, New York, NY

    Google Scholar 

  • Hakes W (1994) On the predictive power of numerical and Braun-Blanquet classification: an example from beechwoods. J Veg Sci 5:153–160

    Article  Google Scholar 

  • Haußmann T, Lux W (1997) Dauerbeobachtungsflächen zur Umweltkontrolle im Wald: Level II. BMELF, Bonn, pp 148

    Google Scholar 

  • Hill MO, Roy DB, Mountford JO, Bunce RGH (2000) Extending Elleberg’s indicator values to a new area: an algorithmic approach. J Appl Ecol 37:3–15

    Article  Google Scholar 

  • Hobohm C, Hennekens SM, Schaminée JHJ (2003) Zur Artenvielfalt der Pflanzengesellschaften in den Niederlanden. Tuexenia 23:51–56

    Google Scholar 

  • Hodgson JG, Wilson PJ, Hunt R, Grime JP, Thompson K (1999) Allocating C-S-R functional types—a soft approach to a hard subject. Oikos 85:282–296

    Article  Google Scholar 

  • Hofmann G (1997) Mitteleuropäische Wald- und Forst-Ökosystemtypen in Wort und Bild. AFZ/Der Wald Sonderheft, 85pp

  • Jensch D (2004) Der Einfluss von Störungen auf Waldbodenvegetation. Diss Bot 386, pp 388

  • Keller W (1995) Bonität als Abgrenzungskriterium von Waldgesellschaften. Inf bl Forsch bereich Landsch WSL 25:1–3

    Google Scholar 

  • Kennedy KA, Addison PA (1987) Some considerations for the use of visual estimates of plant cover in biomonitoring. J Ecol 75:151–157

    Article  Google Scholar 

  • Kowarik I (1987) Kritische Anmerkungen zum theoretischen Konzept der potentiellen natürlichen Vegetation mit Anregungen zu einer zeitgemäßen Modifikation. Tuexenia 7:75–98

    Google Scholar 

  • Kowarik I, Seidling W (1989) Zeigerwertberechnungen nach Ellenberg—zu Problemen und Einschränkungen einer sinnvollen Methode. Landschaft und Stadt 21:132–143

    Google Scholar 

  • Kuhn N, Amiet R, Hufschmid N (1987) Veränderungen in der Waldvegetation der Schweiz infolge Nährstoffanreicherung aus der Atmosphäre. Allg Forst- u Jagd-Ztg 158:77–84

    Google Scholar 

  • Leuschner C (1999) Zur Abhängigkeit der Baum- und Krautschicht mitteleuropäischer Waldgesellschaften von der Nährstoffversorgung des Bodens. Ber d Reinh-Tüxen-Ges 11:109–131

    Google Scholar 

  • Liu Q (1995) A model for species diversity monitoring at community level and its applications. Environ Monit Assess 34:271–287

    Article  Google Scholar 

  • Liu Q (1996) Vegetation monitoring in the ICP IM programme: evaluation of data with regard to effects from N and S deposition. Finnish Environ 27:55–79

    Google Scholar 

  • Lorenz M (1995) International co-operative programme on assessment of monitoring of air pollution effects on forests. Water Air Soil Pollut 85:1221–1226

    Article  CAS  Google Scholar 

  • Neumann M, Starlinger F (2001) The significance of different indices for stand structure and diversity in forests. For Ecol Manage 145:91–106

    Article  Google Scholar 

  • Nilhlgård B (1970) Vegetation types of planted spruce forests in Scania, Southern Sweden. Bot Nor 123:311–337

    Google Scholar 

  • Oberdorfer E (1992) Süddeutsche Pflanzengesellschaften, Teil IV: Wälder und Gebüsche, 2nd edn. G. Fischer, Jena Stuttgart New York, pp 282

    Google Scholar 

  • Odum EP (1971) Fundamentals of ecology, 3rd edn. Saunders, Philadelphia, PA, pp 574

    Google Scholar 

  • Økland RH, Eilertsen O (1996) Dynamics of understory vegetation in an old-growth boreal coniferous forest, 1988–1993. J Veg Sci 7:747–762

    Article  Google Scholar 

  • Palmer MW, White PS (1994) Scale dependence and the species–area relationship. Am Nat 144:718–740

    Article  Google Scholar 

  • Patil GP, Taillie C (1982) Diversity as a concept and its measurement. J Am Stat Assoc 77:548–567

    Article  Google Scholar 

  • Peet RK (1974) The measurement of species diversity. Annu Rev Ecol Syst 5:285–307

    Article  Google Scholar 

  • Peintinger M, Bergamini A, Schmid B (2003) Species–area relationships and nestedness of four taxonomic groups in fragmented wetlands. Basic Appl Ecol 4:385–394

    Article  Google Scholar 

  • Petriccione B (2002) Survey and assessment of vegetation in the CONECOFOR permanent plots. J Limnol 61(Suppl 1):19–24

    Google Scholar 

  • Pielou EC (1969) An introduction to mathematical ecology. Wiley, New York, NY

    Google Scholar 

  • Renaud J-P, Dupouey J-L (2002) Data analysis of the first European vegetation survey in Level II plots ground vegetation species composition. UN-ICP Forests, EU, unpublished Report, 30pp + annexes

  • Runge M (1965) Untersuchungen über die Mineralstoff-Nachlieferung an nordwestdeutschen Waldstandorten. Flora 155:353–386

    CAS  Google Scholar 

  • Salemaa M, Korpela L (2000) Vegetation. In: Ukonmaanaho L, Raitio H (eds) Forest condition monitoring in Finland. National Report 1999. Finnish For Res Inst Res Pap 782:47–54

  • SAS Institute Inc (1990) SAS/STAT User’s Guide, Version 6, 4th edn. Cary, MA, pp 1668

    Google Scholar 

  • Schaffers AP, Sýkora KV (2000) Reliability of Ellenberg indicator values for moisture, nitrogen and soil reaction: a comparison with field measurements. J Veg Sci 11:225–244

    Article  Google Scholar 

  • Schmidt M, Ewald J, Fischer A, von Oheimb G, Kriebitzsch W-U, Schmidt W, Ellenberg H (2003) Liste der Waldgefäßpflanzen Deutschlands. Mitt Bundesforschungsanst Forst- u Holzwirtsch (Hamburg) 212, 32 S + Anhang

  • Schmidt P (1995) Übersicht über die natürlichen Waldgesellschaften Deutschlands. Schriftenrh d Sächs Landesanstalt für Forsten 4/95, S95

  • Schmidtlein S, Ewald J (2003) Landscape patterns of indicator plants for soil acidity in the Bavarian Alps. J Biogeogr 30:1493–1503

    Article  Google Scholar 

  • Schönhar S (1952) Untersuchungen über die Korrelation zwischen der floristischen Zusammensetzung der Bodenvegetation und der Bodenacidität sowie anderer chemischer Bodenfaktoren. Mitteilungen des Vereins für forstliche Standortskartierung (Stuttgart) 2:S23

    Google Scholar 

  • Schulze I, Bolte A (2001) Methoden vegetationskundlicher Aufnahmen im Level-II-Programm in Deutschland. In: BMVEL (Hg) Dauerbeobachtung der Waldvegetation im Level II-Programm: Methoden und Auswertung. Bonn, pp 3–47

  • Schulze I, Bolte A, Seidling W, Stetzka K-M, Wellbrock N (2000) Vegetationskundliche Aufnahmen im Level II-Programm: Methoden, Auswertungen, erste Ergebnisse. Forstarchiv 71:76–83

    Google Scholar 

  • Schütz M, Krüsi BO, Achermann G, Grämiger H (1998) Zeitreihenanalyse in der Vegetationskunde: Analyse und Interpretation von Einzelflächen am Beispiel von Daten aus dem Schweizerischen Nationalpark. Bot Helv 108:1–20

    Google Scholar 

  • Seidling W (1990) Räumliche und zeitliche Differenzierungen der Krautschicht bodensaurer Kiefern-Traubeneichenwälder in Berlin (West). Ber Forschungszentr Waldökosyst, Reihe A, Bd 61, 261pp

  • Seidling W (2001) Auswertungsansätze zu den vegetationskundlichen Erhebungen auf den Dauerbeobachtungsflächen im Level-II-Programm. In: BMVEL (Hg) Dauerbeobachtung der Waldvegetation im Level II-Programm: Methoden und Auswertung. Bonn, pp48–87

  • Seidling W (2003) Ergebnisse und Auswertungspotenziale der Daten zur Bodenvegetation im Level-II-Monitoring. In: BMVEL (Hg) Bericht über den Workshop ‘Integrierende Auswertungen der Daten des Forstlichen Monitorings (Level I/II)’ vom 24–26 Februar 2003 in Bonn-Röttgen, Bonn, pp142–154

  • Seidling W (2005) Outline and examples for integrated evaluations of data from the intensive (Level II) monitoring of forest ecosystems in Germany. Eur J Forest Res (this volume)

  • Seidling W, Rohner M-S (1993) Zusammenhänge zwischen Reaktions-Zeigerwerten und bodenchemischen Parametern am Beispiel von Waldbodenvegetation. Phytocoenologia 23:301–317

    Google Scholar 

  • Seidling W, Lux W, Kürbis H (2002) Das Level-II-Programm—Brücke zwischen Ökosystemforschung und Monitoring im Wald. Beitr Forstwirtsch u Landsch.ökol 36:103–107

    Google Scholar 

  • Shannon CE, Weaver W (1949) The mathematical theory of communication. University of Illinois Press, Urbana, IL, pp 117

    Google Scholar 

  • Shmida A, Wilson MV (1985) Biological determinants of species diversity. J Biogeogr 12:1–20

    Article  Google Scholar 

  • Simpson EH (1949) Measurement of diversity. Nature 163:688

    Article  Google Scholar 

  • ter Braak CJF (1987) The analysis of vegetation–environment relationships by canonical correspondence analysis. Vegetatio 69:69–77

    Article  Google Scholar 

  • ter Braak CJF, Prentice IC (1988) A theory of gradient analysis. Adv Ecol Res 18:271–317

    Article  Google Scholar 

  • ter Braak CJF, Šmilauer P (1998) CANOCO reference manual and user’s guide to CANOCO for WINDOWS. Microcomputer Power, Ithaca, pp 352

    Google Scholar 

  • Thimonier A, Dupouey JL, Timbal J (1992) Floristic changes in the herb layer vegetation of a deciduous forest in the Lorraine plain under the influence of atmospheric deposition. For Ecol Manage 55:149–167

    Article  Google Scholar 

  • Thompson K, Hodgson JG, Grime JP, Rorison IH, Band SR, Spencer RE (1993) Ellenberg numbers revisited. Phytocoenologia 23:277–289

    Google Scholar 

  • Tonteri T (1990) Inter-observer variation in forest vegetation cover assessments. Silva Fennica 24:189–196

    Google Scholar 

  • Tóthmérész B (1998) On the characterization of scale-dependent diversity. Abstracta Botanica 22:149–156

    Google Scholar 

  • Tutin TG, Heywood VH, Burges NA, Moore DM, Valentine DH, Walters SM, Webb DA (1968–1980) Flora Europaea, vol 2–5. Cambridge University Press, Cambridge, MA

  • Tutin TG, Burges NA, Chater AO, Edmondson JR, Heywood VH, Moore DM, Valentine DH, Walters SM, Webb DA (1993) Flora Europaea, vol 1. Cambridge University Press, Cambridge, MA, pp 581

    Google Scholar 

  • van den Brink PJ, ter Braak CJF (1999) Principal response curves: analysis of time-dependent multivariate response of biological communities to stress. Environ Toxicol Chem 18:138–148

    Article  Google Scholar 

  • van der Maarel E, Werger MJA (1978) On the treatment of succession data. Phytocoenosis 7:257–277

    Google Scholar 

  • van Dobben HF, ter Braak CJF, Dirkse GM (1999) Undergrowth as a biomonitor for deposition of nitrogen and acidity in pine forest. For Ecol Manage 114:83–95

    Article  Google Scholar 

  • von Oheimb G (2003) Einfluss forstlicher Nutzung auf die Artenvielfalt und Artenzusammensetzung der Gefäßpflanzen in norddeutschen Laubwäldern. Verlag Dr Kovač, Hamburg, pp 261

    Google Scholar 

  • Wellbrock N, Riek W, Wolff B, Schröder W (2003) Waldschäden. In: Fränzle O, Müller F, Schröder W (eds) Handbuch der Umweltwissenschaften, 9. Erg Lfg 5/03, ecomed, Landsberg, 28pp

  • Wiegleb G (1986) Grenzen und Möglichkeiten der Datenanalyse in der Pflanzenökologie. Tuexenia 6:365–378

    Google Scholar 

  • Wiegleb G, Lehmann A, Hausfeld R (1991) Die Erlenwälder im nordwestlichen Niedersachsen. Methodik der Aufnahme, floristisches Inventar und Gliederung nach strukturellen und floristischen Kriterien. Tuexenia 11:309–343

    Google Scholar 

  • Wildi O (1986) Analyse vegetationskundlicher Daten. Veröff Geobot Inst ETH Stfg Rübel 90, pp 226

  • Wildi O (1988) Linear trend in multi-species time series. Vegetatio 77:51–56

    Article  Google Scholar 

  • Wildi O, Keller W, Kuhn N, Krüsi BO, Schütz M, Wohlgemuth T (1996) Revision der Waldgesellschaften der Schweiz: Die Analyse einer nicht-systematischen Datenbasis. Landschaftsentwicklung und Umweltforschung 104:37–48

    Google Scholar 

  • Williamson MH (1981) Island populations. Oxford University Press, Oxford

    Google Scholar 

  • Wirth V (1995) Die Flechten Baden-Württembergs, vol 2, 2nd edn. Ulmer, Stuttgart

  • Wittig R, Ballach HJ, Brandt CJ (1985) Increase of number of acid indicators in the herb layer of the Millet grass-beech forest of the Westphalian Bight. Angew Bot 59:219–232

    Google Scholar 

  • Wolff B (2002) Daten von gestern für Fragen von heute und Entscheidungen morgen? Beitr Forstwirtsch u Landsch.ökol 36:97–102

    Google Scholar 

  • Zonneveld IS (1994) Vicinism and mass effect. J Veg Sci 5:441–444

    Article  Google Scholar 

Download references

Acknowledgements

This article is based on studies performed in the project ‘Conception and Feasibility Study for Integrated Evaluations of Data from the Environmental Monitoring of Forests (IFOM)’ granted by the German Federal Ministry for Education and Science. Barbara Wolff (Eberswalde), Goddert von Oheimb (Lüneburg) and two anonymous reviewers are acknowledged for their valuable comments on the earlier versions, Wolfgang Lux and Helgard Vaqué (both Eberswalde) for their support around the data pool and Gregor Stolley (Kiel) for his valuable hints.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Walter Seidling.

Additional information

Communicated by Rainer Matyssek

Rights and permissions

Reprints and permissions

About this article

Cite this article

Seidling, W. Ground floor vegetation assessment within the intensive (Level II) monitoring of forest ecosystems in Germany: chances and challenges. Eur J Forest Res 124, 301–312 (2005). https://doi.org/10.1007/s10342-005-0087-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10342-005-0087-1

Keywords

Navigation