Artikkelit kirjoittajalta Jouko Silvola
A mobile automatic gas chromatograph system to measure C02, CH4 and N2O fluxes from soil in the field.
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A caravan has been converted into a mobile laboratory for measuring fluxes of C02, CH4 and N2O from the soil in the field. The caravan is equipped with a gas chromatograph fitted with TC-, FI- and EC-detectors, and a PC controlled data logger. The gas collecting chambers can be used up to 50 m from the caravan. The closing and opening of the chambers, as well as the flows of sample gases from chambers to the gas chromatograph, is pneumatically regulated. Simultaneous recordings of temperature, light intensity and the depth of water table are made. The system has been used for two months in 1992, and some preliminary results are presented.
Keywords: Automated measuring, carbon dioxide, methane, nitrous oxide, peatland
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Silvola,
Department of Biology, University of Joensuu, P.O. Box III, FIN-80I0I Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Martikainen, Sähköposti: ei.tietoa@nn.oo
- Nykänen, Sähköposti: ei.tietoa@nn.oo
The effect of plant roots on C02 release from peat soil.
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The contribution of roots to the release of C02 from peat has been examined in both field and laboratory experiments. In the field experiment, columns of peat were isolated from the surrounding peat and the green parts of the plants were continually removed in order to exhaust the living roots contained within the column. The isolated columns released c. 10-20% less C02 than the reference spots where only the growth of the green parts was restrained. C02 production in isolated columns was thereby reduced mostly in mire site types with largest dwarf shrub root biomass. In the greenhouse experiment, C02 release was c. 36% greater from containers containing willow (Salix phylicifolia) roots than from bare peat reference containers.
Keywords: Carbon allocation, decomposition, soil respiration
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Silvola,
Department of Biology, University of Joensuu, P.O. Box 111, FIN-80J0/ Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Jukka, Sähköposti: ei.tietoa@nn.oo
- Ahlholm, Sähköposti: ei.tietoa@nn.oo
The effect of changing water table on methane fluxes at two Finnish mire sites.
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Methane fluxes were measured using a static chamber technique on a minerotrophic fen and an ombrotrophic peat bog site located on the Lak-kasuo mire complex in central Finland. Both sites consisted of a virgin area and an area drained in 1961 by ditching. The measurements in 1991 were made biweekly from spring thaw to winter freezing. During this period, the mean CH4 emission from the virgin minerotrophic site and virgin ombrotrophic site was 98 mg m-2 d-1 and 40 mg m-2 d-1 , respectively. The mean emission of CH4 from the drained ombrotrophic site was 18 mg m-2 d-1. The drained minerotrophic site consumed methane during most of the measuring period, the average uptake was 0.13 mg m-2 d-1. Draining had lowered the average water table by 4 cm at the ombrotrophic site and by 20 cm at minerotrophic site. The possible reasons for the different development of the water table and methane fluxes at ombrotrophic and minerotrophic sites after draining are discussed.
Keywords: Drainage, methane flux, methane oxidation, nutrient status, peat soil
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Martikainen,
Department of Environmental Microbiology, National Public Health Institute, P.O. Box 95, FIN-70701 Kuopio, Finland
Sähköposti:
ei.tietoa@nn.oo
- Nykänen, Sähköposti: ei.tietoa@nn.oo
- Crill, Sähköposti: ei.tietoa@nn.oo
- Silvola, Sähköposti: ei.tietoa@nn.oo
Differences in response of two Sphagnum species to elevated CO2 and nitrogen input.
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Cushions of Sphagnum fuscum and S. angustifolium were grown in the laboratory in four different C02 concentrations (350, 700, 1 000, and 2 000 ppm) and N deposition levels (0, 10, 30, and 100 kg ha-1 a-1). The same N deposition levels were also applied in the field. C02 concentration increased both the shoot density and dry mass of S. fuscum but decreased the length increment. There was no net effect on production. For S. angustifolium, shoot density did not alter with elevated C02 con-centration but the C02 induced increment in dry mass and length caused increased production. S. angustifolium suffered from nutrient deficiency on the 0 kg N ha-1a-1 treatment and S. fuscum had difficulties to survive at the heaviest N load. No clear trends in length increment or cover was noticed in the field study during the first year.
Keywords: Bryophyte ecology, climate change, peatlands, production
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Jauhiainen,
University of Joensuu, Department of Biology, P.O. Box 111, FIN-80I0I Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Vasander, Sähköposti: ei.tietoa@nn.oo
- Silvola, Sähköposti: ei.tietoa@nn.oo
Ojituksen ja lannoituksen vaikutus turpeen hiilen vapautumiseen ja ravinteiden mineralisoitumiseen.
English title: Effect of drainage and fertilization on carbon output and nutrient mineralization of peat.
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Carbon dioxide production increased to 2-3 fold from the peat of an oligotrophic sedge pine mire (VSR) after draining had lowered the water table to a depth c, 0.5 m. At two other sites, a mesotrophic sedge pine mire (RhSR) and a spruce swamp (MK), both the fall in the groundwater table and the increase in C02 production were smaller. At the VSR site, the fast-dissolving PK fertilizer and urea each caused a rapid increase while the slow-dissolving PK fertilizer a slow increase in soil respiration. The greatest, steady increase was achieved by treatment with wood ash. At RhSR and MK sites, the use of fertilizers generally led to a decline in soil respiration for 1-2 years, after which the initial level was normally regained. According to a simulation of the C02 production after drainage, the annual decomposition of peat was calculated to be c. 1 000 g (organic matter) m-2 in the VSR site. On the basis of this decomposition rate, the annual amount of nitrogen mineralizated was estimated to be c. 100 kg ha-1 and that of phosphorus c. 5 kg ha-1. Peat contains only a small amount of potassium, and the decomposition of old peat layers increases the amount of soluble potassium in peat very little.
Keywords: Carbon balance, drainage, fertilization, nutrient mineralization, peat decomposition
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Silvola,
Department of Biology, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
Rahkasuon kasvusta kaasunvaihtomittausten perusteella.
English title: Growth of Sphagnum fuscum bog on the basis of gas exchange measurements.
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The CO2-exchange of the Sphagnum fuscum — Empetrum nigrum community of a South Finnish raised bog was studied in the laboratory at different combinations of irradiance and temperature conditions during one growing season. The CO2-exchange of the community was divided into three components, namely those due to Empetrum nigrum, Sphagnum fuscum and peat, respectively. In the conditions used the maximum net CO2 exchange of Empetrum nigrum was c. 200 and that of Sphagnum fuscum c. 250 mg CO2 m-1 h-1. The total respiration in peat increased exponentially from 50 to 350 mg CO2 m-2 h-1 with increasing temperature from 5 to 30°C.
On the basis of the laboratory measurements and of the data on actual field temperatures and irradiation the budget of organic matter for the community was simulated. The net production of 74 for Empetrum and 243 g (dw) m-2 for Sphagnum was predicted for six months period (May 1—Oct 31). The amount of peat decomposed was 233 (g (dw) m-2. The net result for the whole community was 84 g (dw) m-2. The average peat accumulation of the bog in question is c. 40 g (dw) m-2 yr-1. The difference depends most probably on the respiration in winter and on the decomposition of peat deeper than 17 cm, which were not included in simulation.
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Silvola,
Sähköposti:
ei.tietoa@nn.oo
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