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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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Histograms of sizes of sedimentation basins in different regions.The number of sites included is indicated at top right.
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pone-0100117-g002: Histograms of sizes of sedimentation basins in different regions.The number of sites included is indicated at top right.

Mentions: REVEALS estimates were calculated by the REVEALS.v4.2.2.Tallinn.wks.exe binary (Sugita unpublished) and by a script written in R [37] (Text S1). Unlike our script, the original programme calculates standard errors, but offers only limited parameter settings. These default settings together with our initial parameters include: Prentice’s [38] model as the dispersal function using bi = 75 vg/u, the fall speed of pollen (vg) extracted from previously published works [39]–[41] and wind speed (u = 3 m/s). The radius of the sedimentation basin (R) was set to the size of the peatbog, a parameter extracted from the Czech Quaternary Palynological Database (Figure 2, Table S1). The maximum range of the regional vegetation Zmax was set 60 km.


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

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

Histograms of sizes of sedimentation basins in different regions.The number of sites included is indicated at top right.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0100117-g002: Histograms of sizes of sedimentation basins in different regions.The number of sites included is indicated at top right.
Mentions: REVEALS estimates were calculated by the REVEALS.v4.2.2.Tallinn.wks.exe binary (Sugita unpublished) and by a script written in R [37] (Text S1). Unlike our script, the original programme calculates standard errors, but offers only limited parameter settings. These default settings together with our initial parameters include: Prentice’s [38] model as the dispersal function using bi = 75 vg/u, the fall speed of pollen (vg) extracted from previously published works [39]–[41] and wind speed (u = 3 m/s). The radius of the sedimentation basin (R) was set to the size of the peatbog, a parameter extracted from the Czech Quaternary Palynological Database (Figure 2, Table S1). The maximum range of the regional vegetation Zmax was set 60 km.

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