Suo - Mires and peat vol. 41 no. 2 | 1990
Esimerkki pseudolajien runsauskynnysten muuntelun vaikutuksesta TWINSPAN-Iuokittelussa.
English title: The effect of pseudospecies cut level settings on the results of TWINSPAN classification.
Avainsanat:
drained peatlands;
mire classification;
vegetation;
mire site type;
multivariate analysis
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TWINSPAN classifications of the same drained mire vegetation data using four different pseudospecies cut level scales were compared. The material consisted of 96 sample plots located on drained spruce and pine mires in eastern Finland. The pseudospecies cut level scales were the octave scale (0, 0.5, 1, 2, 4, 8, 16, 32 and 64%), a coarse scale (0, 5, 10, 20 and 50%), TWINSPAN default settings (0, 2, 5, 10 and 20%), and presence/absence. The classificatons were quite similar at the first division but they differed markedly from each other at the final third division showing that the choice of cut levels has an important effect on TWIN-SPAN results. The sample plots in one TWINSPAN cluster defined with set of cut levels were allocated to several clusters defined with other cut level settings. The presence/absence setting resulted in a classification which was the most different from the classification made using the default settings. The TWINSPAN classifications performed using the default and octave scale settings corresponded the best with the field classification of the plots and were ecologically the most interpretable.
Keywords: Drained peatlands, mire classification, mire site type, multivariate analysis, vegetation
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Hotanen,
The Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, SF-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
Tuhka-ajoitusmenetelmän ja sammalvuosikasvainajoituksen vertailu rahkamättäissä.
English title: A comparison of ash dating and moss-increment dating in Sphagnum hummocks.
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A comparison of two methods for dating recent ombrotrophic peat hummocks was made at three mires. For depths approximately below 10 cm, acid insoluble ash dating gave greater ages than moss-increment dating; for depths above 10 cm, the methods showed more similar ages. The moss-increment dates were assumed to be generally correct since there was a good correlation between several independent dating results and moss-increment ages at one of the study sites. Despite the declining accuracy of moss-increment dating with depth, it should be the method chosen for dating recent peat in areas where the assumption of constant acid insoluble ash deposition is invalid. Increment dating is practically useful only in the moss hummocks, except for when the moss stems have been compressed into a horizontal position.
Keywords: Dating, mineral dust, peatlands, Sphagnum, surface peats
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Eustis,
Department of Ecology and Evolutionary Biology, University of Connecticut, P.O. Box U-42, Storrs, CT 06268, USA
Sähköposti:
ei.tietoa@nn.oo
- Tolonen, Sähköposti: ei.tietoa@nn.oo
Turvesaannon arviointi suotyypin ja turpeen syvyyden perusteella.
English title: Estimation of peat yield of different peat deposit types.
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Preliminary regression models are produced for the estimation of dry peat yield (tons) per unit area (hectare) for different types of peat deposits with different peat thickness. The models are based on 6 500 peat samples obtained for bulk density measurements from 245 vertical peat profiles (70 virgin and drained peadands) in Finland. In general, the increase in the peat yield does not take place in 1:1 relationship with depth because average bulk density tends to decrease with peat deposit thickness. Fairly reliable estimates of the peat yield using depth and mire site type were obtained. R2 values for the eight models representing eight different groups of "mire site types" ranged from 86.0 to 95.3%.
Keywords: Bulk density, mire site types, peat deposits, peat resources
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Tolonen,
Department of Biology, University ofJoensuu, P.O. Box 111,SF-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Ijäs, Sähköposti: ei.tietoa@nn.oo
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