Artikkelit jotka sisältää sanan 'GNMDS'
Kasvillisuuden sukkessio ja monimuotoisuus Teuravuoman koeojitusalueella Pohjois-Suomessa.
English title: Vegetation succession and diversity on Teuravuoma experimental drainage area in northern Finland.
Avainsanat:
fen;
aapa mire;
compositional gradients;
FUPGMA classification;
GNMDS ordination;
peatland vegetation
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This case study deals with the effects of forest drainage on six mire site types represented by 33 permanent sample plots within a Finnish aapa mire complex located in north boreal vegetation zone. We analysed the main compositional gradients, the abundances of plant species and the diversity of vegetation. The vegetation descriptions were made about at the time of drainage in 1933 and after that in 1943, 1950 and 1994. The forest drainage emphasized the importance of spruce mire and hummock-level bog influences (mire margin and mire expanse effects respectively) in controlling the structure of plant communities. The change of plant community was greatest on fertile mire site types, also spruce mire influence promoted the secondary succession. As expected, the shallow-rooted and/or demanding flark-level vascular plants and (eutrophic) fen mosses had not been able to adapt to the ground water level drawdown. At first, after drainage, species number, Shannon's H' and Simpson's D increased: many mire species of hummock and intermediate level microsites had increased while also pioneer and forest species had colonized the plots. By 1994, however, as the mire species were decreasing these measures had turned to decline except on the (most) infertile site types. Pielou's J' and the evenness based on D reacted vaguely, decreasing a little, though, from 1933 to 1994. Thus, in such cases the dominance in the vegetation had increased. The beta-diversity describing here the differences between plant communities (or site types) decreased along with the hydrological conditions becoming more uniform after drainage.
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Hotanen,
The Finnish Forest Research Institute, Joensuu Research Station, P.O.Box 68, FIN-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Nousiainen, Sähköposti: ei.tietoa@nn.oo
- Paalamo, Sähköposti: ei.tietoa@nn.oo
Kasvillisuus ja C02-tase käytöstä vapautuneella turvetuotantoalueella Kihniön Aitonevalla.
English title: Vegetation and CO2 balance in an abandoned harvested peatland in Aitoneva, southern Finland.
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The vegetation and CO2 balance (difference between C02 fixation rate and respiration rate) in an abandoned harvested peatland in Aitoneva, Kihnio (62° 12'N, 23° 18'E) were studied during the summer of 1994. The daytime CO2 fluxes from sample plots representing different kinds of vegetation were measured using two different static chamber techniques. To investigate the compositional variation of vegetation and its relationship with CO2 balance, data on the vegetation of the sample plots was analysed by global non-metric multidimensional scaling (GNMDS). A total number of 20 plant species was observed on the sample plots. The dominant plant species was Eriophorum vaginatum L. The main variation in GNMDS were connected with colonization stage (total cover of vegetation). The C02 fixation rate varied between -56 and 1869 mg m-2 h-1 and the respiration rate varied between 34 and 1168 mg CO2 m-2 h-1. The CO2 fixation and respiration rate increased with increasing total vegetation cover. The highest respiration and the highest CO2 fixation rates were found in sample plots dominated by mature Eriophorum vaginatum tussocks. Those sample plots were the only ones having positive CO2 balance. Regression analysis indicated that the respiration rate depended on soil temperature. Variation in the water table had no influence on the respiration or the C02 fixation rate.
Key words: CO2 balance, Eriophorum vaginatum, GNMDS, harvested peatland, plant colonization
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Tuittila,
Department of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland
Sähköposti:
ei.tietoa@nn.oo
- Komulainen, Sähköposti: ei.tietoa@nn.oo
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