The influence of data stratification on vegetation classification

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
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Relevés of semi-natural meadow and pasture
vegetation in the Czech Republic
Poland
Germany
Slovakia
Austria
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Unstratified data set
10
6
5
Geographical stratification
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Geographical stratification

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

7
Habitat stratification by associations
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Habitat stratification by associations

• constant number per habitat
• bias commonness or rarity

9
Habitat stratification by numerical
classification
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Habitat stratification by numerical
classification
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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
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Diagnostic species stratification

• exclusion of relevés without diagnostic species
  (fragmentary or impoverished communities)

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

• reflects
• commonness or rarity
• vegetation diversity

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Analysis
10 data sets
Comparison of classifications
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Results
PCoA
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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