Detailed Information on Publication Record
2005
Stratified resampling of phytosociological databases: some strategies for obtaining more representative data sets for classification studies
KNOLLOVÁ, Ilona, Milan CHYTRÝ, Lubomír TICHÝ and Ondřej HÁJEKBasic information
Original name
Stratified resampling of phytosociological databases: some strategies for obtaining more representative data sets for classification studies
Name in Czech
Stratifikovaný výběr dat z fytocenologických databází: některé strategie pro získání reprezentativnějších datových soubor pro klasifikační studie
Authors
KNOLLOVÁ, Ilona (203 Czech Republic, guarantor), Milan CHYTRÝ (203 Czech Republic), Lubomír TICHÝ (203 Czech Republic) and Ondřej HÁJEK (203 Czech Republic)
Edition
Journal of Vegetation Science, Uppsala, Opulus Press, 2005, 110-9233
Other information
Language
English
Type of outcome
Článek v odborném periodiku
Field of Study
10600 1.6 Biological sciences
Country of publisher
Czech Republic
Confidentiality degree
není předmětem státního či obchodního tajemství
References:
RIV identification code
RIV/00216224:14310/05:00012593
Organization unit
Faculty of Science
UT WoS
000232457000014
Keywords in English
Ellenberg indicator values; Geographical stratification; GIS; Habitat stratification; Phytosociological data; Plant community; Relevé; Sampling design; Survey
Tags
Změněno: 16/12/2006 18:44, prof. RNDr. Milan Chytrý, Ph.D.
V originále
Question: The heterogeneous origin of the data in large phytosociological databases may seriously influence the results of their analysis. Therefore we propose some strategies for stratified resampling of such databases, which may improve the representativeness of the data. We also explore the effects of different resampling options on vegetation classification. Methods: We used 6050 plot samples (relevés) of mesic grasslands from the Czech Republic. We stratified this database using (1) geographical stratification in a grid; (2) habitat stratification created by an overlay of digital maps in GIS; (3) habitat stratification with strata defined by traditional phytosociological associations; (4) habitat stratification by numerical classification and (5) habitat stratification by Ellenberg indicator values. Each time we resampled the database, taking equal numbers of relevés per stratum. We then carried out cluster analyses for the resampled data sets and compared the resulting classifications using a newly developed procedure. Results: Random resampling of the initial data set and geographically stratified resampling resulted in similar classifications. By contrast, classifications of the resampled data sets that were based on habitat stratifications (25) differed from each other and from the initial data set. Stratification 2 resulted in classifications that strongly reflected environmental factors with a coarse grain of spatial heterogeneity (e.g. macroclimate), whereas stratification 5 resulted in classifications emphasizing fine-grained factors (e.g. soil nutrient status). Stratification 3 led to the most deviating results, possibly due to the subjective nature of the traditional phytosociological classifications. Conclusions: Stratified resampling may increase the representativeness of phytosociological data sets, but different types of stratification may result in different classifications. No single resampling strategy is optimal or superior: the appropriate stratification method must be selected according to the objectives of specific studies.
In Czech
Testování stratifikovaného výběru dat z fytocenologických databází a některých strategií pro získání reprezentativnějších datových souborů pro klasifikační studie
Links
| GA206/02/0957, research and development project |
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| GA206/05/0020, research and development project |
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| MSM0021622416, plan (intention) |
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