J 2011

Bias in vegetation databases? A comparison of stratified-random and preferential sampling

MICHALCOVÁ, Dana, Milan CHYTRÝ, Samuel LVONČÍK and Ondřej HÁJEK

Basic information

Original name

Bias in vegetation databases? A comparison of stratified-random and preferential sampling

Name in Czech

Chyby ve vegetačních databázích? Srovnání stratifikovaného náhodného a preferenčního sběr dat

Authors

MICHALCOVÁ, Dana (203 Czech Republic, guarantor, belonging to the institution), Milan CHYTRÝ (203 Czech Republic, belonging to the institution), Samuel LVONČÍK (203 Czech Republic) and Ondřej HÁJEK (203 Czech Republic, belonging to the institution)

Edition

Journal of Vegetation Science, Wiley-Blackwell, 2011, 1100-9233

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10600 1.6 Biological sciences

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 2.770

RIV identification code

RIV/00216224:14310/11:00049712

Organization unit

Faculty of Science

UT WoS

000287926500009

Keywords in English

Alpha diversity; Beta diversity; Endangered species; Invasive species; Neophytes; Ordination; Parameter estimation; Relevé; Sample-based rarefaction; Species number; Stratification; Subjectivity

Tags

International impact, Reviewed
Změněno: 3/1/2012 10:57, prof. RNDr. Milan Chytrý, Ph.D.

Abstract

V originále

Aim: Vegetation plots collected since the early 20th century and stored in large vegetation databases are an important source of ecological information. These databases are used for analyses of vegetation diversity and estimation of vegetation parameters, however such analyses can be biased due to preferential sampling of the original data. In contrast, modern vegetation survey increasingly uses stratified-random instead of preferential sampling. To explore how these two sampling schemes affect vegetation analyses, we compare parameters of vegetation diversity based on preferentially sampled plots from a large vegetation database with those based on stratified-random sampling. Location: Moravian Karst and Silesia, Czech Republic. Methods: We compared two parallel analyses of forest vegetation, one based on preferentially sampled plots taken from a national vegetation database and the other on plots sampled in the field according to a stratified-random design. We repeated this comparison for two different regions in the Czech Republic. We focussed on vegetation properties commonly analysed using data from large vegetation databases, including alpha (within-plot) diversity, cover and participation of different species groups, such as endangered and alien species within plots, total species richness of data sets, beta diversity and ordination patterns. Results: The preferentially sampled data sets obtained from the database contained more endangered species and had higher beta diversity, whereas estimates of alpha diversity and representation of alien species were not consistently different between preferentially and stratified-randomly sampled data sets. In ordinations, plots from the preferential samples tended to be more common at margins of plot scatters. Conclusions: Vegetation data stored in large databases are influenced by researcher subjectivity in plot positioning, but we demonstrated that not all of their properties necessarily differ from data sets obtained by stratified-random sampling. This indicates the value of vegetation databases for use in biodiversity studies; however, some analyses based on these databases are clearly biased and their results must be interpreted with caution.

Links

GA206/09/0329, research and development project
Name: Vegetace České republiky: dokončení národního přehledu rostlinných společenstev
Investor: Czech Science Foundation, Vegetation of the Czech Republic: completion of the national survey of plant communities
GD526/09/H025, research and development project
Name: Evolučně-ekologická analýza společenstev a populací
Investor: Czech Science Foundation, Evolutionary ecological analysis of communities and populations
MSM0021622416, plan (intention)
Name: Diverzita biotických společenstev a populací: kauzální analýza variability v prostoru a čase
Investor: Ministry of Education, Youth and Sports of the CR, Diversity of Biotic Communities and Populations: Causal Analysis of variation in space and time