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The influence of data stratification on vegetation classification

The influence of data stratification on vegetation classification. Ilona Kuzelova & Lubomir Tichy Department of Botany Masaryk University in Brno Czech Republic. Databases of phytosociological relevés. + accessibility of information. - attributes and biases of databases.

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The influence of data stratification on vegetation classification

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  1. The influence of data stratification on vegetation classification Ilona Kuzelova & Lubomir Tichy Department of Botany Masaryk University in Brno Czech Republic

  2. Databases of phytosociological relevés + accessibility of information - attributes and biases of databases Vegetation of selected area Vegetation classification Species distribution

  3. Relevés of semi-natural meadow and pasture vegetation in the Czech Republic Poland Germany Slovakia Austria

  4. Unstratified data set Mesic Arrhenatherum meadows Cynosurus pastures Alluvial Alopecurus meadows Wet Cirsium meadows Intermittently wet Molinia meadows 10‘ 6‘

  5. Geographical stratification

  6. Geographical stratification • 1 relevé per square • removes the influence of over-sampling • lower vegetation diversity in the sample

  7. Habitat stratification by associations

  8. Habitat stratification by associations • constant number per habitat • bias commonness or rarity

  9. 121 65 11 537 23 72 7 55 8 23 321 Habitat stratification by numerical classification

  10. 5 5 5 5 5 5 5 5 5 5 5 Habitat stratification by numerical classification

  11. Habitat stratification by ecological indicator values TEMPERATURE ELLENBERG INDICATOR VALUE 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 LIGHT

  12. Habitat stratification by ecological indicator values TEMPERATURE ELLENBERG INDICATOR VALUE 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 LIGHT

  13. Diagnostic species stratification

  14. Diagnostic species stratification • exclusion of relevés without diagnostic species (fragmentary or impoverished communities)

  15. Combination of geographical and other types of stratification (e. g. association + geographical)

  16. Combination of geographical and other types of stratification (e. g. association + geographical) • reflects: • commonness or rarity • vegetation diversity

  17. Classification cluster analysis synoptic table Analysis 10 data sets Comparison of classifications

  18. Geographical stratifications Unstratified data set Habitat stratifications Diagnostic species stratifications PCoA Results

  19. removes the influence of over-sampling • lower vegetation diversity in the sample • equalized number of relevés per habitat • biased commonness or rarity of habitat types exclusion of relevés without diagnostic species (fragmentary or impoverished communities) • reflects: • commonness or rarity • vegetation diversity Conclusions • Vegetation databases have unbalaced structure • Types of stratifications • geographical stratification • habitat stratification • diagnostic species stratification • combination of geographical and other types of stratification • Each stratification shows different behaviour • Selection of appropriate type of stratification for different purposes

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