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Present-day vegetation helps quantifying past land cover in selected regions of the Czech Republic.

Abraham V, Oušková V, Kuneš P - PLoS ONE (2014)

Bottom Line: Decreasing the site radius has a similar effect as increasing the wind speed parameter.Increasing the background radius does not affect the estimates significantly.However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic; Department of Botany, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.

ABSTRACT
The REVEALS model is a tool for recalculating pollen data into vegetation abundances on a regional scale. We explored the general effect of selected parameters by performing simulations and ascertained the best model setting for the Czech Republic using the shallowest samples from 120 fossil sites and data on actual regional vegetation (60 km radius). Vegetation proportions of 17 taxa were obtained by combining the CORINE Land Cover map with forest inventories, agricultural statistics and habitat mapping data. Our simulation shows that changing the site radius for all taxa substantially affects REVEALS estimates of taxa with heavy or light pollen grains. Decreasing the site radius has a similar effect as increasing the wind speed parameter. However, adjusting the site radius to 1 m for local taxa only (even taxa with light pollen) yields lower, more correct estimates despite their high pollen signal. Increasing the background radius does not affect the estimates significantly. Our comparison of estimates with actual vegetation in seven regions shows that the most accurate relative pollen productivity estimates (PPEs) come from Central Europe and Southern Sweden. The initial simulation and pollen data yielded unrealistic estimates for Abies under the default setting of the wind speed parameter (3 m/s). We therefore propose the setting of 4 m/s, which corresponds to the spring average in most regions of the Czech Republic studied. Ad hoc adjustment of PPEs with this setting improves the match 3-4-fold. We consider these values (apart from four exceptions) to be appropriate, because they are within the ranges of standard errors, so they are related to original PPEs. Setting a 1 m radius for local taxa (Alnus, Salix, Poaceae) significantly improves the match between estimates and actual vegetation. However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain.

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Related in: MedlinePlus

Map of the Czech Republic with pollen sites (yellow crosses) and assigned regions (red circles).Northern Bohemia [49]–[53], Northeastern Bohemia [49], [54]–[63], Polabí [64]–[67], Southern Bohemia [68]–[73], Southern Moravia [74]–[79], Bohemian-Moravian Highland [80]–[85], Šumava Mts. [86]–[88]. Yellow lines and arrows show the allocation of sites to regions in cases when sites are situated in two overlapping regions.
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pone-0100117-g001: Map of the Czech Republic with pollen sites (yellow crosses) and assigned regions (red circles).Northern Bohemia [49]–[53], Northeastern Bohemia [49], [54]–[63], Polabí [64]–[67], Southern Bohemia [68]–[73], Southern Moravia [74]–[79], Bohemian-Moravian Highland [80]–[85], Šumava Mts. [86]–[88]. Yellow lines and arrows show the allocation of sites to regions in cases when sites are situated in two overlapping regions.

Mentions: We used the shallowest sample from every core in the Czech Quaternary Pollen Database (PALYCZ, accessed 01.07.2013). However, these samples were not collected in the same year as the vegetation data (see Table S1), but within the last 40 years, and not all of them have exactly 0 cm depth. Still, we assume that they are the closest representation of recent pollen deposition. Centroids of regional circles were placed visually around the spatial clusters of the sites. When two regions overlapped, certain sites fell into both of them at the same time. In these cases, the region was assigned according to the environmental conditions surrounding the core (vegetation, altitude, climate, etc.) (Figure 1). The pollen sum of selected taxa was limited to 100 pollen grains per sample, but only seven sites had less than 200 grains per sample; the average pollen sum of all 120 sites is 542 grains per sample (Table S1). Names of genera, except Pinus, used to denote selected pollen types refer to all species within the given genera. The name Pinus refers only to species belonging to the subgenus Pinus (diploxylon pines). Plantago lanceolata is the only pollen taxon defined at the species level. Poaceae encompass all wild grasses, and Cerealia comprise the genera Triticum, Hordeum and Avena; if distinguished, pollen of Secale and Zea was excluded.


Present-day vegetation helps quantifying past land cover in selected regions of the Czech Republic.

Abraham V, Oušková V, Kuneš P - PLoS ONE (2014)

Map of the Czech Republic with pollen sites (yellow crosses) and assigned regions (red circles).Northern Bohemia [49]–[53], Northeastern Bohemia [49], [54]–[63], Polabí [64]–[67], Southern Bohemia [68]–[73], Southern Moravia [74]–[79], Bohemian-Moravian Highland [80]–[85], Šumava Mts. [86]–[88]. Yellow lines and arrows show the allocation of sites to regions in cases when sites are situated in two overlapping regions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061133&req=5

pone-0100117-g001: Map of the Czech Republic with pollen sites (yellow crosses) and assigned regions (red circles).Northern Bohemia [49]–[53], Northeastern Bohemia [49], [54]–[63], Polabí [64]–[67], Southern Bohemia [68]–[73], Southern Moravia [74]–[79], Bohemian-Moravian Highland [80]–[85], Šumava Mts. [86]–[88]. Yellow lines and arrows show the allocation of sites to regions in cases when sites are situated in two overlapping regions.
Mentions: We used the shallowest sample from every core in the Czech Quaternary Pollen Database (PALYCZ, accessed 01.07.2013). However, these samples were not collected in the same year as the vegetation data (see Table S1), but within the last 40 years, and not all of them have exactly 0 cm depth. Still, we assume that they are the closest representation of recent pollen deposition. Centroids of regional circles were placed visually around the spatial clusters of the sites. When two regions overlapped, certain sites fell into both of them at the same time. In these cases, the region was assigned according to the environmental conditions surrounding the core (vegetation, altitude, climate, etc.) (Figure 1). The pollen sum of selected taxa was limited to 100 pollen grains per sample, but only seven sites had less than 200 grains per sample; the average pollen sum of all 120 sites is 542 grains per sample (Table S1). Names of genera, except Pinus, used to denote selected pollen types refer to all species within the given genera. The name Pinus refers only to species belonging to the subgenus Pinus (diploxylon pines). Plantago lanceolata is the only pollen taxon defined at the species level. Poaceae encompass all wild grasses, and Cerealia comprise the genera Triticum, Hordeum and Avena; if distinguished, pollen of Secale and Zea was excluded.

Bottom Line: Decreasing the site radius has a similar effect as increasing the wind speed parameter.Increasing the background radius does not affect the estimates significantly.However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain.

View Article: PubMed Central - PubMed

Affiliation: Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic; Department of Botany, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.

ABSTRACT
The REVEALS model is a tool for recalculating pollen data into vegetation abundances on a regional scale. We explored the general effect of selected parameters by performing simulations and ascertained the best model setting for the Czech Republic using the shallowest samples from 120 fossil sites and data on actual regional vegetation (60 km radius). Vegetation proportions of 17 taxa were obtained by combining the CORINE Land Cover map with forest inventories, agricultural statistics and habitat mapping data. Our simulation shows that changing the site radius for all taxa substantially affects REVEALS estimates of taxa with heavy or light pollen grains. Decreasing the site radius has a similar effect as increasing the wind speed parameter. However, adjusting the site radius to 1 m for local taxa only (even taxa with light pollen) yields lower, more correct estimates despite their high pollen signal. Increasing the background radius does not affect the estimates significantly. Our comparison of estimates with actual vegetation in seven regions shows that the most accurate relative pollen productivity estimates (PPEs) come from Central Europe and Southern Sweden. The initial simulation and pollen data yielded unrealistic estimates for Abies under the default setting of the wind speed parameter (3 m/s). We therefore propose the setting of 4 m/s, which corresponds to the spring average in most regions of the Czech Republic studied. Ad hoc adjustment of PPEs with this setting improves the match 3-4-fold. We consider these values (apart from four exceptions) to be appropriate, because they are within the ranges of standard errors, so they are related to original PPEs. Setting a 1 m radius for local taxa (Alnus, Salix, Poaceae) significantly improves the match between estimates and actual vegetation. However, further adjustments to PPEs exceed the ranges of original values, so their relevance is uncertain.

Show MeSH
Related in: MedlinePlus