Effects of plot size on the ordination of vegetation samples

OTÝPKOVÁ, Zdenka a Milan CHYTRÝ. Effects of plot size on the ordination of vegetation samples. Journal of Vegetation Science. Uppsala: Opulus Press, 2006, roč. 17, č. 4, s. 465-472. ISSN 110-9233.

Základní údaje

• Originální název: Effects of plot size on the ordination of vegetation samples
• Název česky: Vliv velikosti plochy na ordinaci vegetačních snímků
• Autoři: OTÝPKOVÁ, Zdenka (203 Česká republika) a Milan CHYTRÝ (203 Česká republika, garant).
• Vydání: Journal of Vegetation Science, Uppsala, Opulus Press, 2006, 110-9233.

Další údaje

• Originální jazyk: angličtina
• Typ výsledku: Článek v odborném periodiku
• Obor: 10600 1.6 Biological sciences
• Stát vydavatele: Švédsko
• Utajení: není předmětem státního či obchodního tajemství
• WWW: URL
• Kód RIV: RIV/00216224:14310/06:00016145
• Organizační jednotka: Přírodovědecká fakulta
• UT WoS: 000241092700007
• Klíčová slova anglicky: Beta-diversity; Cover-abundance data; Data set heterogeneity; Detrended Correspondence Analysis; Plant community; Presence/absence data; Principal Components Analysis
• Štítky: beta-diversity, Cover-abundance data, Data set heterogeneity, detrended correspondence analysis, Plant community, Presence/absence data, Principal Components Analysis
• Příznaky: Mezinárodní význam, Recenzováno

Anotace

Questions: Do ordination patterns differ when based on vegetation samples recorded in plots of different size? If so, how large is the effect of plot size relative to the effects of data set heterogeneity and of using presence/absence or cover-abundance data? Can we combine plots of different size in a single ordination? Methods: Two homogeneous and two heterogeneous data sets were sampled in Czech forests and grasslands. Coverabundances of plant species were recorded in series of five or six nested quadrats of increasing size (forest 49-961 m2; grassland 1-49 m2). Separate ordinations were computed for plots of each size for each data set, using either species presences/absences or cover-abundances recorded on an ordinal scale. Ordination patterns were compared with Procrustean analysis. Also, ordinations of data sets jointly containing plots of different size were calculated; effects of plot size were evaluated using a Monte Carlo test in constrained ordination. Results: The results were consistent between forest and grassland data sets. In homogeneous data sets, the effect of presence/ absence vs. cover-abundance was similar to, or larger than, the effect of plot size; for presence/absence data the differences between ordinations of differently sized plots were smaller than for cover-abundance data. In heterogeneous data sets, the effect of plot size was larger than the effect of presenceabsence vs. cover-abundance. The plots of smaller size (< 100 m2 in forests, < 4 m2 in grasslands) yielded the most deviating ordination patterns. Joint ordinations of differently sized plots mostly did not yield patterns that would be artifacts of different plot size, except for plots from the homogeneous data sets that differed in size by a factor of four or higher. Conclusions: Variation in plot size does influence ordination patterns. Smaller plots tend to produce less stable ordination patterns, especially in data sets with low beta-diversity and species cover-abundances. Data sets containing samples from plots of different sizes can be used for ordination if they represent vegetation with large beta-diversity. However, if data sets are homogeneous, i.e. with low beta-diversity, the differences in plot sizes should not be very large, in order to avoid the danger of plot size differences distorting the real vegetation differentiation in ordination patterns.

Anotace česky

Questions: Do ordination patterns differ when based on vegetation samples recorded in plots of different size? If so, how large is the effect of plot size relative to the effects of data set heterogeneity and of using presence/absence or cover-abundance data? Can we combine plots of different size in a single ordination? Methods: Two homogeneous and two heterogeneous data sets were sampled in Czech forests and grasslands. Coverabundances of plant species were recorded in series of five or six nested quadrats of increasing size (forest 49-961 m2; grassland 1-49 m2). Separate ordinations were computed for plots of each size for each data set, using either species presences/absences or cover-abundances recorded on an ordinal scale. Ordination patterns were compared with Procrustean analysis. Also, ordinations of data sets jointly containing plots of different size were calculated; effects of plot size were evaluated using a Monte Carlo test in constrained ordination. Results: The results were consistent between forest and grassland data sets. In homogeneous data sets, the effect of presence/ absence vs. cover-abundance was similar to, or larger than, the effect of plot size; for presence/absence data the differences between ordinations of differently sized plots were smaller than for cover-abundance data. In heterogeneous data sets, the effect of plot size was larger than the effect of presenceabsence vs. cover-abundance. The plots of smaller size (< 100 m2 in forests, < 4 m2 in grasslands) yielded the most deviating ordination patterns. Joint ordinations of differently sized plots mostly did not yield patterns that would be artifacts of different plot size, except for plots from the homogeneous data sets that differed in size by a factor of four or higher. Conclusions: Variation in plot size does influence ordination patterns. Smaller plots tend to produce less stable ordination patterns, especially in data sets with low beta-diversity and species cover-abundances. Data sets containing samples from plots of different sizes can be used for ordination if they represent vegetation with large beta-diversity. However, if data sets are homogeneous, i.e. with low beta-diversity, the differences in plot sizes should not be very large, in order to avoid the danger of plot size differences distorting the real vegetation differentiation in ordination patterns.

Návaznosti

• GA206/05/0020, projekt VaV: Název: Vegetace České republiky: formalizovaná typizace, monografie a expertní systém

Investor: Grantová agentura ČR, Vegetace České republiky: formalizovaná typizace, monografie a expertní systém

• MSM0021622416, záměr: Název: Diverzita biotických společenstev a populací: kauzální analýza variability v prostoru a čase

Investor: Ministerstvo školství, mládeže a tělovýchovy ČR, Diverzita biotických společenstev: kauzální analýza variability v prostoru a čase