Phytosociological data give biased estimates of species
richness

J 2001

Phytosociological data give biased estimates of species richness

CHYTRÝ, Milan

Základní údaje

Originální název

Phytosociological data give biased estimates of species richness

Autoři

CHYTRÝ, Milan (203 Česká republika)

Vydání

Journal of Vegetation Science, Uppsala, Opulus Press, 2001, 110-9233

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10600 1.6 Biological sciences

Stát vydavatele

Švédsko

Utajení

není předmětem státního či obchodního tajemství

Odkazy

URL

Kód RIV

RIV/00216224:14310/01:00004667

Organizační jednotka

Přírodovědecká fakulta

UT WoS

000171440600015

Změněno: 24. 9. 2004 18:33, prof. RNDr. Milan Chytrý, Ph.D.

Anotace

V originále

Large phytosociological datasets of three types of grassland and three types of forest vegetation from the Czech Republic were analysed with a focus on plot size used in phytosociological sampling and on the species-area relationship. The datasets included altogether 12,975 relevés, sampled by different authors in different parts of the country between 1922-1999. It was shown that in the grassland datasets, the relevés sampled before the 1960s tended to have a larger plot size than the relevés made later. No temporal variation in plot sizes used was detected in forest relevés. Species-area curves fitted to the data showed unnatural shapes, with levelling-off or even decrease in plot sizes higher than average. This distortion is explained by the subjective, preferential method of field sampling used in phytosociology. When making relevés in species-poor vegetation, many researchers probably tend to use larger plots in order to obtain species-richer relevés. They seem to do that because a higher number of species gives a higher probability of more diagnostic species being found in the relevé; in the Braun-Blanquet classification system such a relevé can be more easily classified. This behaviour of phytosociologists has at least two consequences: (1) phytosociological databases under-represent species-poor vegetation types or are artificially biased towards higher species richness; (2) the suitability of phytosociological data for species richness estimation is severely limited.

Návaznosti

GA206/99/1523, projekt VaV

Název: Parametrizace fytocenologického systému pomocí velkých souborů dat

Investor: Grantová agentura ČR, Parametrizace fytocenologického systému pomocí velkých souborů dat

MSM 143100010, záměr

Název: Časoprostorová dynamika biodiverzity v ekosystémech střední Evropy.

Investor: Ministerstvo školství, mládeže a tělovýchovy ČR, Časoprostorová dynamika biodiverzity v ekosystémech střední Evropy

Citovat

CHYTRÝ, Milan. Phytosociological data give biased estimates of species richness. Journal of Vegetation Science. Uppsala: Opulus Press, 2001, roč. 12, č. 3, s. 439-444. ISSN 110-9233.

@article{376331,
   author = {Chytrý, Milan},
   article_location = {Uppsala},
   article_number = {3},
   language = {eng},
   issn = {110-9233},
   journal = {Journal of Vegetation Science},
   title = {Phytosociological data give biased estimates of species richness},
   url = {http://www.sci.muni.cz/botany/chytry/JVS2001.pdf},
   volume = {12},
   year = {2001}
}

TY  - JOUR
ID  - 376331
AU  - Chytrý, Milan
PY  - 2001
TI  - Phytosociological data give biased estimates of species richness
JF  - Journal of Vegetation Science
VL  - 12
IS  - 3
SP  - 439
EP  - 439
PB  - Opulus Press
SN  - 1109233
UR  - http://www.sci.muni.cz/botany/chytry/JVS2001.pdf
N2  - Large phytosociological datasets of three types of grassland and three types of forest vegetation from the Czech Republic were analysed with a focus on plot size used in phytosociological sampling and on the species-area relationship. The datasets included altogether 12,975 relevés, sampled by different authors in different parts of the country between 1922-1999. It was shown that in the grassland datasets, the relevés sampled before the 1960s tended to have a larger plot size than the relevés made later. No temporal variation in plot sizes used was detected in forest relevés. Species-area curves fitted to the data showed unnatural shapes, with levelling-off or even decrease in plot sizes higher than average. This distortion is explained by the subjective, preferential method of field sampling used in phytosociology. When making relevés in species-poor vegetation, many researchers probably tend to use larger plots in order to obtain species-richer relevés. They seem to do that because a higher number of species gives a higher probability of more diagnostic species being found in the relevé; in the Braun-Blanquet classification system such a relevé can be more easily classified. This behaviour of phytosociologists has at least two consequences: (1) phytosociological databases under-represent species-poor vegetation types or are artificially biased towards higher species richness; (2) the suitability of phytosociological data for species richness estimation is severely limited.
ER  -

CHYTRÝ, Milan. Phytosociological data give biased estimates of species richness. \textit{Journal of Vegetation Science}. Uppsala: Opulus Press, 2001, roč.~12, č.~3, s.~439-444. ISSN~110-9233.

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