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  • 1
    Electronic Resource
    Electronic Resource
    Methane dynamics of a restored cut-away peatland (2000)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 6 (2000), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We measured a cut-away peatland's CH4 dynamics using the static chamber technique one year before and two years after restoration (rewetting). The CH4 emissions were related to variation in vegetation and abiotic factors using multiple linear regression. A statistical model for CH4 flux with cottongrass cover (Eriophorum vaginatum L.), soil temperature, water level, and effective temperature sum index as driving variables explained most (r2 = 0.81) of the temporal and spatial variability in the fluxes. In addition to the direct increasing effect of raised water level on CH4 emissions, rewetting also promoted an increase of cottongrass cover which consequently increased carbon flux (substrate availability) into the system. The seasonal CH4 dynamics in tussocks followed seasonal CO2 dynamics till mid August but in late autumn CH4 emissions increased while CO2 influxes decreased. The reconstructed seasonal CH4 exchange was clearly higher following the rewetting, although it was still lower than emissions from pristine mires in the same area. However, our simulation for closed cottongrass vegetation showed that CH4 emissions from restored peatlands may remain at a lower level for a longer period of time even after sites have become fully vegetated and colonized by mire plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2000.00341.x
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  • 2
    Electronic Resource
    Electronic Resource
    Reconstruction of the carbon balance for microsites in a boreal oligotrophic pine fen, Finland (1997)
    Springer
    Oecologia 110 (1997), S. 423-431 
    Details
    ISSN: 1432-1939
    Keywords: Key words Peatland ecosystem ; Microsite ; Carbon accumulation ; CH4 ; Climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Carbon dioxide (CO2) exchange was studied at flark (minerotrophic hollow), lawn and hummock microsites in an oligotrophic boreal pine fen. Statistical response functions were constructed for the microsites in order to reconstruct the annual CO2 exchange balance from climate data. Carbon accumulation was estimated from the annual net CO2 exchange, methane (CH4) emissions and leaching of carbon. Due to high water tables in the year 1993, the average carbon accumulation at the flark, Eriophorum lawn, Carex lawn and hummock microsites was high, 2.91, 6.08, 2.83 and 2.66 mol C m–2, respectively, and for the whole peatland it was 5.66 mol m–2 year–1. During the maximum primary production period in midsummer, hummocks with low water tables emitted less methane than predicted from the average net ecosystem exchange (NEE), while the Carex lawns emitted slightly more. CH4 release during that period corresponded to 16% of the contemporary NEE. Annual C accumulation rate did not correlate with annual CH4 release in the microsites studied, but the total community CO2 release seemed to be related to CH4 emissions in the wet microsites, again excluding the hummocks. The dependence of CO2 exchange dynamics on weather events suggests that daily balances in C accumulation are labile and can change from net carbon uptake to net release, primarily in high hummocks on fens under warmer, drier climatic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050177
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  • 3
    Electronic Resource
    Electronic Resource
    Seasonal variation in CH4 emissions and production and oxidation potentials at microsites on an oligotrophic pine fen (1997)
    Springer
    Oecologia 110 (1997), S. 414-422 
    Details
    ISSN: 1432-1939
    Keywords: Key words Methane ; Microsites ; Production ; Oxidation ; Oligotrophic fen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Temporal and spatial variation in CH4 emissions was studied at hummock, Eriophorum lawn, flark and Carex lawn microsites in an oligotrophic pine fen over the growing season using a static chamber method, and CH4 production and oxidation potentials in peat profiles from hummock and flark were determined in laboratory incubation experiments. Emissions were lowest in the hummocks, and decreased with increasing hummock height, while in the lawns and flarks they increased with increasing sedge cover. Statistical response functions with water table and peat temperature as independent variables were calculated in order to reconstruct seasonal CH4 emissions by reference to the time series for peat temperature and water table specific to each microsite type. Mean CH4 emissions in the whole area in the snow-free period of 1993, weighted in terms of the proportions of the microsites, were 1.7 mol CH4 m–2. Potential CH4 production and oxidation rates were very low in the hummocks rising above the groundwater table, but were relatively similar when expressed per dry weight of peat both in the hummocks and flarks below the water table. The CH4 production potential increased in autumn at both microsites and CH4 oxidation potential seemed to decrease. The decrease in temperature in autumn certainly reduced in situ decomposition processes, possibly leaving unused substrates in the peat, which would explain the increase in CH4 production potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050176
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of a lowered water table on nitrous oxide fluxes from northern peatlands (1993)
    [s.l.] : Nature Publishing Group
    Nature 366 (1993), S. 51-53 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The sites examined in eastern (site 1, 62° 51' N and 30° 53' E) and central Finland (sites 2, 3, 4 and 5 which are a part of the Lakkasuo mire complex, 61° 47' N and 24° 18' E) differed in their nutrient status and vegetation (Table 1), and represent both ombrotrophic and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/366051a0
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  • 5
    Electronic Resource
    Electronic Resource
    The contribution of plant roots to CO2 fluxes from organic soils (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 126-131 
    Details
    ISSN: 1432-0789
    Keywords: Key words Organic soil ; Root-derived respiration ; Soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The CO2 released in soil respiration is formed from organic matter which differs in age and stability, ranging from soluble root exudates to more persistent plant remains. The contribution of roots, a relatively fast component of soil cycling, was studied in three experiments. (1) Willows were grown in a greenhouse and CO2 fluxes from the substrate soil (milled peat) and from control peat were measured. (2) CO2 fluxes from various peatland sites were measured at control points and points where the roots were severed from the plants. (3) CO2 fluxes in cultivated grassland established on peatland were measured in grassy subsites and in subsites where the growth of grass was prevented by regular tilling. The root-derived respiration followed the typical annual phenology of the vegetation, being at its maximum in the middle and late summer. All the experiments gave similar results, root-derived respiration accounting for 35–45% of total soil respiration in the middle and late summer at sites with an abundant vegetation. The root-derived respiration from the virgin peatland sites correlated well with the tree biomass, and also partly with the understorey vegetation, but in the drained sites the root effect was greater, even in the presence of less understorey vegetation than at virgin subsites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336052
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  • 6
    Electronic Resource
    Electronic Resource
    Fluxes of nitrous oxide from boreal peatlands as affected by peatland type, water table level and nitrification capacity (1996)
    Springer
    Biogeochemistry 35 (1996), S. 401-418 
    Details
    ISSN: 1573-515X
    Keywords: nitrifiers ; nitrification potential ; nitrous oxide ; peatland ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Peat soils with high nitrogen content are potential sources of nitrous oxide (N2O). Fluxes of nitrous oxide were measuredin situ on nine virgin and ten drained peatlands of different hydrology and nutrient status. Numbers of nitrifying bacteria were estimated in different layers of the peat profiles with a most-probable-number technique. Nitrification potentials were determined in soil slurries of pH 4 and 6 from the profiles of six peat soils. Many virgin peatlands showed low N2O uptake. Lowering of the water table generally increased the average fluxes of N2O from the soils, although more in minerotrophic (nutrient rich) than in ombrotrophic (nutrient poor) sites. Ammonium oxidizing bacteria were found on only two sites but nitrite oxidizers were detected in almost all peat profiles. More nitrite oxidizers were found in drained than in virgin peat profiles. Nitrification was enhanced after lowering of the water table in minerotrophic peat but not in ombrotrophic peat. The N2O fluxes correlated positively with the numbers of nitrite oxidizers, nitrification potential, N, P and Ca content and pH of the soil and negatively with the level of water table (expressed as negative values) and K content of the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183033
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  • 7
    Electronic Resource
    Electronic Resource
    Winter CO2 CH4 and N2O fluxes on some natural and drained boreal peatlands (1999)
    Springer
    Biogeochemistry 44 (1999), S. 163-186 
    Details
    ISSN: 1573-515X
    Keywords: carbon dioxide ; gas gradients ; methane ; nitrous oxide ; peatland ; winter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract CO2 and CH4 fluxes during the winter were measured at natural and drained bog and fen sites in eastern Finland using both the closed chamber method and calculations of gas diffusion along a concentration gradient through the snowpack. The snow diffusion results were compared with those obtained by chamber, but the winter flux estimates were derived from chamber data only. CH4 emissions from a poor bog were lower than those from an oligotrophic fen, while both CO2 and CH4 fluxes were higher in the Carex rostrata-occupied marginal (lagg) area of the fen than in the slightly less fertile centre. Average estimated winter CO2-C losses from virgin and drained forested peatlands were 41 and 68 g CO2-C m- 2, respectively, accounting for 23 and 21% of the annual total CO2 release from the peat. The mean release of CH4-C was 1.0 g in natural bogs and 3.4 g m-2 in fens, giving rise to winter emissions averaging to 22% of the annual emission from the bogs and 10% of that from the fens. These wintertime carbon gas losses in Finnish natural peatlands were even greater than reported average long-term annual C accumulation values (less than 25 g C m-2). The narrow range of 10–30% of the proportion of winter CO2 and CH4 emissions from annual emissions found in Finnish peatlands suggest that a wider generalization in the boreal zone is possible. Drained forested bogs emitted 0.3 g CH4-C m-2 on the average, while the effectively drained fens consumed an average of 0.01 g CH4-C m- 2. Reason for the low CH4 efflux or net oxidation in drained peatlands probably lies in low substrate supply and thus low CH4 production in the anoxic deep peat layers. N2O release from a fertilized grassland site in November–May was 0.7 g N2O m-2, accounting for 38% of the total annual emission, while a forested bog released none and two efficiently drained forested fens 0.09 (28% of annual release) and 0.04 g N2O m- 2 (27%) during the winter, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006074606204
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  • 8
    Electronic Resource
    Electronic Resource
    Winter CO2, CH4 and N2O fluxes on some natural and drained boreal peatlands (1999)
    Springer
    Biogeochemistry 44 (1999), S. 163-186 
    Details
    ISSN: 1573-515X
    Keywords: carbon dioxide ; gas gradients ; methane ; nitrous oxide ; peatland ; winter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract CO2 and CH4 fluxes during the winter were measured at natural and drained bog and fen sites in eastern Finland using both the closed chamber method and calculations of gas diffusion along a concentration gradient through the snowpack. The snow diffusion results were compared with those obtained by chamber, but the winter flux estimates were derived from chamber data only. CH4 emissions from a poor bog were lower than those from an oligotrophic fen, while both CO2 and CH4 fluxes were higher in theCarex rostrata- occupied marginal (lagg) area of the fen than in the slightly less fertile centre. Average estimated winter CO2-C losses from virgin and drained forested peatlands were 41 and 68 g CO2-C m−2, respectively, accounting for 23 and 21% of the annual total CO2 release from the peat. The mean release of CH4-C was 1.0 g in natural bogs and 3.4 g m−2 in fens, giving rise to winter emissions averaging to 22% of the annual emission from the bogs and 10% of that from the fens. These wintertime carbon gas losses in Finnish natural peatlands were even greater than reported average long-term annual C accumulation values (less than 25g C m−2). The narrow range of 10–30% of the proportion of winter CO2 and CH4 emissions from annual emissions found in Finnish peatlands suggest that a wider generalization in the boreal zone is possible. Drained forested bogs emitted 0.3 g CH4-C m−2 on the average, while the effectively drained fens consumed an average of 0.01 g CH4-C m−2. Reason for the low CH4. efflux or net oxidation in drained peatlands probably lies in low substrate supply and thus low CH4 production in the anoxic deep peat layers. N2O release from a fertilized grassland site in November–May was 0.7 g N2O m−2, accounting for 38% of the total annual emission, while a forested bog released none and two efficiently drained forested fens 0.09 (28% of annual release) and 0.04 g N2O m−2 (27%) during the winter, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00992977
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  • 9
    Electronic Resource
    Electronic Resource
    Change in fluxes of carbon dioxide, methane and nitrous oxide due to forest drainage of mire sites of different trophy (1995)
    Springer
    Plant and soil 168-169 (1995), S. 571-577 
    Details
    ISSN: 1573-5036
    Keywords: carbon dioxide ; drainage ; methane ; nitrous oxide ; peatlands ; vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Northern peatlands accumulate atmospheric CO2 thus counteracting climate warming. However, CH4 which is more efficient as a greenhouse gas than CO2, is produced in the anaerobic decomposition processes in peat. When peatlands are taken for forestry their water table is lowered by ditching. We studied long-term effects of lowered water table on the development of vegetation and the annual emissions of CO2, CH4 and N2O in an ombrotrophic bog and in a minerotrophic fen in Finland. Reclamation of the peat sites for forestry had changed the composition and coverage of the field and ground layer species, and increased highly the growth of tree stand at the drained fen. In general, drainage increased the annual CO2 emissions but the emissions were also affected by the natural fluctuations of water table. In contrast to CO2, drainage had decreased the emissions of CH4, the drained fen even consumed atmospheric CH4. CO2 and CH4 emissions were higher in the virgin fen than in the virgin bog. There were no N2O emissions from neither type of virgin sites. Drainage had, however, highly increased the N2O emissions from the fen. The results suggest that post-drainage changes in gas fluxes depend on the trophy of the original mires.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029370
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