Semi-dry grasslands along a climatic gradient across Central Europe

Vegetation classification with validation

Eszter Illyés, Milan Chytrý, Z. Botta-Dukát, Ute Jandt, Iveta Škodová, Monika Janišová, Wolfgang Willner, Ondřej Hájek

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Question: What is the variation in species composition of Central European semi-dry grasslands? Can we apply a training-and-test validation approach for identifying phytosociological associations which are floristically well defined in a broad geographic comparison; can we separate them from earlier described associations with only a local validity? Location: A 1200 km long transect running along a gradient of increasing continentality from central Germany via Czech Republic, Slovakia, NE Austria, Hungary to NW Romania. Methods: Relevés with > 25% cover of Brachypodium pinnatum and/or Bromus erectus were geographically selected from a larger database. They were randomly split into two data sets, TRAINING and TEST, each with 422 relevés. Cluster analysis was performed for each data set on scores from significant principal coordinates. Different partitions of the TRAINING data set were validated on the TEST data set, using a new method based on the comparison of % frequencies of species occurrence in clusters. Clusters were characterized by statistically defined groups of diagnostic species and values of climatic variables. Results: Species composition changed along the NW-SE gradient and valid clusters were geographically well separated. Optimal partition level was at 11 clusters, six being valid: two clusters Germany and the Czech Republic corresponded to the Bromion erecti; two clusters from the Czech Republic and Hungary to the Cirsio-Brachypodion, and two clusters were transitional between these two alliances. Conclusion: The training-and-test validation method used in this paper proved to be efficient for discriminating between robust clusters, which are appropriate candidates for inclusion in the national or regional syntaxonomic overviews, and weak clusters, which are specific to the particular classification of the given data set.

Original languageEnglish
Pages (from-to)835-846
Number of pages12
JournalJournal of Vegetation Science
Volume18
Issue number6
DOIs
Publication statusPublished - Dec 2007

Fingerprint

vegetation classification
Central European region
Czech Republic
grasslands
grassland
taxonomy
Hungary
vegetation
Brachypodium pinnatum
Bromus erectus
Germany
species diversity
Romania
Slovakia
Austria
cluster analysis
methodology
testing
species occurrence
transect

Keywords

  • Austria
  • Bromion
  • Cirsio-Brachypodion
  • Czech Republic
  • Germany
  • Hungary
  • Phytosociology
  • Romania
  • Slovakia
  • Training and test data sets
  • Vegetation database

ASJC Scopus subject areas

  • Forestry
  • Plant Science
  • Ecology

Cite this

Semi-dry grasslands along a climatic gradient across Central Europe : Vegetation classification with validation. / Illyés, Eszter; Chytrý, Milan; Botta-Dukát, Z.; Jandt, Ute; Škodová, Iveta; Janišová, Monika; Willner, Wolfgang; Hájek, Ondřej.

In: Journal of Vegetation Science, Vol. 18, No. 6, 12.2007, p. 835-846.

Research output: Contribution to journalArticle

Illyés, Eszter ; Chytrý, Milan ; Botta-Dukát, Z. ; Jandt, Ute ; Škodová, Iveta ; Janišová, Monika ; Willner, Wolfgang ; Hájek, Ondřej. / Semi-dry grasslands along a climatic gradient across Central Europe : Vegetation classification with validation. In: Journal of Vegetation Science. 2007 ; Vol. 18, No. 6. pp. 835-846.
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