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  • 1
    Electronic Resource
    Electronic Resource
    Distribution of assimilated carbon in the system Phragmites australis-waterlogged peat soil after carbon-14 pulse labelling (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 1-7 
    Details
    ISSN: 1432-0789
    Keywords: Key words Phragmites australis ; Anaerobic fen¶soil ; Carbon turnover ; Rhizodeposition ; Root respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Short-term (3–6 days) and long-term (27 days) laboratory experiments were carried out to determine the distribution of assimilated C in the system Phragmites australis (common reed)-waterlogged fen soil after 14C pulse labelling. The investigated system of fen plants and anaerobic organic soil showed different patterns of assimilated 14C distribution when compared to systems with cultivated plants and aerobic mineral soil. Between 90% and 95% of the 14C in the system was found in the reed plants. A maximum of 2% of the assimilated plant 14C was released from the fen soil as CO2 and about 5–9% remained in the soil. The 14C remaining in the waterlogged fen soil of the reed plant had the same amount as that of a cultivated plant in mineral soil, despite lower 14C-release (i.e. rhizodeposition and root respiration) from reed roots. Assuming that root respiration of fen plants is low, this indicates that microbial C turnover in waterlogged fen soil is much slower than in mineral soil. The estimated quantity of the assimilated C remaining in the soil was of an ecologically relevant order of magnitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000204
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of increased CO2 and N on CH4 efflux from a boreal mire: a growth chamber experiment (1999)
    Springer
    Oecologia 119 (1999), S. 349-356 
    Details
    ISSN: 1432-1939
    Keywords: Key words Atmospheric change ; CO2 and NH4NO3 fertilisation ; CH4 ; Shoot density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Increases in the supply of atmospheric CO2 and N are expected to alter the carbon cycle, including CH4 emissions, in boreal peatlands. These effects were studied in a glasshouse experiment with peat monoliths cored from an oligotrophic pine fen. The cores with living plants were kept in 720 ppmv and 360 ppmv CO2 atmospheres for about 6 months under imitated natural temperature cycle. Fertilisation with NH4NO3 (3 g m−2 for 25 weeks) was applied to 18 of the 36 monoliths. The rate of CH4 flux was non-linearly dependent on the number of Eriophorum vaginatum shoots growing in the monoliths, probably due to the gas transport properties of the aerenchyma. The average CH4 efflux rate, standardised by the number of shoots, was increased by a maximum of 10–20% in response to the raised CO2 level. In the raised-NH4NO3 treatment, the increase in CH4 release was lower. The effect of combined CO2+NH4NO3 on CH4 release was negligible and even lower than in the single treatments. Both potential CH4 production and oxidation rates at 5, 15 and 25°C were higher near the surface than at the bottom of the core. As expected, the rates clearly depended on the incubation temperature, but the different treatments did not cause any consistent differences in either CH4 production or oxidation. The determination of potential CH4 production and oxidation in the laboratory is evidently too crude a method of differentiating substrate-induced differences in CH4 production and oxidation in vivo. These results indicate that an increase in atmospheric CO2 or N supply alone, at least in the short term, slightly enhances CH4 effluxes from boreal peatlands; but together their effect may even be restrictive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050795
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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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    Paper (German National Licenses)
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