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@article{753051,
author = {Illyés, Eszter and Chytrý, Milan and BottaandDukát, Zoltán and Jandt, Ute and Janišová, Monika and Škodová, Iveta and Willner, Wolfgang and Hájek, Ondřej},
article_location = {Uppsala},
article_number = {6},
keywords = {Austria; Bromion; Cirsio-Brachypodion; Czech Republic; Germany; Hungary; Phytosociology; Romania; Slovakia; Training and test data sets; Vegetation database},
language = {eng},
issn = {1100-9233},
journal = {Journal of Vegetation Science},
title = {Semi-dry grasslands along a climatic gradient across Central Europe: Vegetation classification with validation},
url = {http://www.sci.muni.cz/botany/chytry/Illyes_etal2007_JVS.pdf},
volume = {18},
year = {2007}
}
TY - JOUR
ID - 753051
AU - Illyés, Eszter - Chytrý, Milan - Botta-Dukát, Zoltán - Jandt, Ute - Janišová, Monika - Škodová, Iveta - Willner, Wolfgang - Hájek, Ondřej
PY - 2007
TI - Semi-dry grasslands along a climatic gradient across Central Europe: Vegetation classification with validation
JF - Journal of Vegetation Science
VL - 18
IS - 6
SP - 835-846
EP - 835-846
PB - Opulus Press
SN - 11009233
KW - Austria
KW - Bromion
KW - Cirsio-Brachypodion
KW - Czech Republic
KW - Germany
KW - Hungary
KW - Phytosociology
KW - Romania
KW - Slovakia
KW - Training and test data sets
KW - Vegetation database
UR - http://www.sci.muni.cz/botany/chytry/Illyes_etal2007_JVS.pdf
N2 - 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.
ER -
ILLYÉS, Eszter, Milan CHYTRÝ, Zoltán BOTTA-DUKÁT, Ute JANDT, Monika JANIŠOVÁ, Iveta ŠKODOVÁ, Wolfgang WILLNER and Ondřej HÁJEK. Semi-dry grasslands along a climatic gradient across Central Europe: Vegetation classification with validation. \textit{Journal of Vegetation Science}. Uppsala: Opulus Press, 2007, vol.~18, No~6, p.~835-846. ISSN~1100-9233.
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