Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Exchange of trace gases between soils and the atmosphere in Scots pine forest ecosystems of the northeastern German lowlands
    ( 2002)
    Butterbach-Bahl, K.
    ;
    Breuer, L.
    ;
    Gasche, R.
    ;
    Willibald, G.
    ;
    Papen, H.
  • Publication
  • Publication
    Improved method for detection of methanotrophic bacteria in forest soils by PCR
    ( 2001)
    Steinkamp, R.
    ;
    Zimmer, W.
    ;
    Papen, H.
    A primer set was designed for the specific detection of methanotrophic bacteria in forest soils by PCR. The primer sequences were derived from highly conservative regions of the pmoA gene, encoding the alpha -subunit of the particulate methane monooxygenase present in all methanotrophs. In control experiments with genomic DNA from a collection of different type I, II, and X methanotrophs, it could be demonstrated that the new primers were specific for members of the genera Methylosinus, Methylocystis Methylomonas, Methylobacter, and Methylococcus. To test the suitability of the new primers for the detection of particulate methane monooxygenase (pMMO) containing methanotrophs in environmental samples we used DNA extracts from an acid spruce forest soil. For simple and rapid purification of the DNA extracts, the samples were separated by electrophoresis on a low-melting-point agarose gel. This allowed us to efficiently separate the DNA from coextracted humic acids. The DNA from the melted agarose gel was ready for use in PCR reactions. In PCR reactions with DNA from the Ah soil layer, products of the correct size were amplified by PCR by use of the new primers. By sequencing of cloned PCR products, it could be confirmed that the PCR products represented partial sequences with strong similarity to the pmoA gene. The sequence was most related to the pmoA sequence of a type II methanotroph strain isolated from the Ah layer of the investigated soils.
  • Publication
    Competition of spruce trees for substrates of microbial N2O-production and -emission in a forest ecosystem
    ( 2001)
    Rennenberg, H.
    ;
    Stoermer, H.
    ;
    Weber, P.
    ;
    Daum, M.
    ;
    Papen, H.
    Uptake of ammonium and nitrate by the roots of spruce trees at a N-limited control site and a site subjected to ammonium sulphate fertilisation with 150 kg N ha(-1) in one dose were determined shortly after and two years subsequent to the treatment. The changes in the rates of nitrogen uptake by the roots were compared with changes in microbial nitrogen conversion that are connected with the production of N2O in, and the emission of these atmospheric trace gases from soils by nitrification and denitrification. Uptake of ammonium and nitrate by the roots of the N-limited trees were low and initially were strongly enhanced by fertiliser application. This increase was mainly due to an increase in ammonium and nitrate available to the roots in. the soil-water. Two years subsequent to the fertiliser application, ammonium and nitrate contents of the soil-water were still enhanced compared to the untreated control site, but uptake of ammonium and nitrate by the spruce roots was completely shut down. At the N-limited control site competition between root uptake of inorganic N and its microbial conversion was largely in favour of root uptake by the spruce trees. The rates of nitrification and denitrification of inorganic N were minute under these conditions and appreciable N2O emission was not observed. Application of ammonium sulphate transiently enhanced both root uptake and microbial N conversion, and was connected with increased emission of N2O. In the long term, ammonium sulphate application completely inhibited ammonium and nitrate uptake by the trees, irrespective of enhanced concentrations of ammonium and nitrate in the soil-water. As a consequence, considerable amounts of inorganic N were still available for microbial conversion 2 years after fertiliser application. At this time nitrification rates were still high at the fertilised site, but the nitrate produced was not further converted by denitrification. It is assumed that nitrate produced by nitrification is subjected to microbial immobilisation. Under these conditions N2O emission from the control site and the fertilised site were low and did not differ significantly.
  • Publication
    N2O and CH4-fluxes from soils of a N-limited and N-fertilized spruce forest ecosystem of the temperate zone
    ( 2001)
    Papen, H.
    ;
    Daum, M.
    ;
    Steinkamp, R.
    ;
    Butterbach-Bahl, K.
    Based on a 3-year data set from measurements of N2O fluxes from soil of a N-limited spruce forest ecosystem it could be demonstrated for the first time that such soils can function as a sink rather than a source for atmospheric N2O. The results suggest that N2O uptake from the atmosphere into the soil is catalyzed by soil denitrifiers which are able to use N2O from the atmosphere instead of nitrate as an electron acceptor for denitrification due to severe limitations of nitrate in the soil. This interpretation is in accordance with the finding that net nitrate production via nitrification was zero or only marginal in the soil of the unfertilized site. On the other hand, the results strongly indicate that atmospheric N-input - simulated in this experiment by ammonium sulfate application (150 kg N ha(-1)) to the forest soil - can lead to a change of the function of the soil of a N-limited forest ecosystem from a sink to a net source of atmospheric N2O. This change was most likely due to stimulation of N2O production via nitrification and denitrification after N-fertilization. N-fertilization lead to a partial inhibition of atmospheric CH4 oxidation. However, this inhibition lasted only short term after N-fertilization and even changed at the end of the observation period to a weak stimulation of CH4 uptake activity at the N-fertilized site when soil ammonium concentrations at this site had decreased to values which were only slightly higher as compared to the unfertilized site. This indicates that at the unfertilized site atmospheric methane oxidizers were N-limited for growth.
  • Publication
    N2O emission from tropical forest soils of Australia
    ( 2000)
    Breuer, L.
    ;
    Papen, H.
    ;
    Butterbach-Bahl, K.
    Three different tropical rain forest sites (Kauri Creek, Lake Eacham, and Massey Creek) on the Atherton Tablelands, Queensland, Australia, were investigated for the magnitude of N2O emission from soils during different seasons, that is, wet season, dry season, and transition periods. Highest mean N2O emission rates were observed for soils derived from granite at the Kauri Creek site with 74.5 + 25.2 µg N2O-N m high -2 h high -1, whereas for soils derived from Metamorphics (Lake Eacham site) mean N2O emission rates were much lower (13.1 + 1.1 µg N2O-N m high -2 h high -1). For the Massey Creek site, with soils derived from Rhyolite, a mean annual N2O emission rate of 46.2 + 1.1 µg N2O-N m high -2 h high -1 was calculated. The mean annual N2O emission rate calculated for all three sites over the entire observation period was 39.0 µg N2O-N m high -2 h high -1 and thus at the high end of reports from tropical rain forest soils. N2O emission rates showed at all sites pronounced temporal as well as spatial variability. The magnitude of N2O emissions was strongly linked to rainfall events; that is, N2O emissions strongly increased approximately 6-8 hours after precipitation. Correlation analysis confirmed the strong dependency of N2O emissions on changes in soil moisture, whereas changes in soil temperature did not mediate considerable changes in N2O fluxes. Spatial variability of N2O fluxes on a site scale could be explained best by differences in water-filled pore space, CO2 emission, and C/N ratio of the soil. On the basis of all published N2O flux rates from tropical rain forest soils we recalculated the contribution of such forests to the global atmospheric N2O budget and come up with a figure of 3.55 Tg N2O-N yr high -1, which is approximately 50 % higher than reported by others.
  • Publication
    A process-oriented model of N2O and NO emissions from forest soils. 1. Model development
    ( 2000)
    Li, C.S.
    ;
    Aber, J.
    ;
    Stange, F.
    ;
    Butterbach-Bahl, K.
    ;
    Papen, H.
  • Publication
    Impact of changes in temperature and precipitation on N2O and NO emissions from forest soils
    ( 2000)
    Butterbach-Bahl, K.
    ;
    Stange, F.
    ;
    Papen, H.
    ;
    Grell, G.
    ;
    Li, C.
  • Publication
    Evaluating annual nitrous oxide fluxes at the ecosystem scale
    ( 2000)
    Groffman, P.M.
    ;
    Brumme, R.
    ;
    Butterbach-Bahl, K.
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    Dobbie, K.
    ;
    Mosier, A.R.
    ;
    Ojima, D.S.
    ;
    Papen, H.
    ;
    Parton, W.J.
    ;
    Smith, K.A.
    ;
    Wagner-Riddle, C.
    Evaluation of N2O flux has been one of the most problematic topics in environmental biogeochemistry over the last 10 - 15 years. Early ideas that we should be able to use the large body of existing research on terrestrial N cycling to predict patterns of N2O flux at the ecosystem scale have been hard to prove due to extreme temporal and spatial variability in flux. The vast majority of the N2O flux measurement and modeling activity that has taken place has been process level and field scale, i. e., measurement, analysis and modeling of hourly and daily fluxes with chambers deployed in field plots. It has been very difficult to establish strong predictive relationships between these hourly and daily fluxes and field-scale parameters such as temperature, soil moisture, and soil inorganic N concentrations. In this study, we addressed the question of whether we can increase our predictive understanding of N2O fluxes by examining relationships between flux and environmental parameters at larger spatial and temporal scales, i. e., to explore relationships between annual rather than hourly or daily fluxes and ecosystem-scale variables such as plant community and soil type and annual climate rather than field-scale variables such as soil moisture and temperature. We addressed this question by examining existing data on annual fluxes from temperate forest, cropland, and rangeland ecosystems, analyzing both multiyear data sets from individual sites as well as cross-site comparison of single annual flux values from multiple sites. Results suggest that there are indeed coherent patterns in annual N2O flux at the ecosystem scale in forest, cropland, and rangeland ecosystems but that these patterns vary by region and only emerge with continuous (at least daily) flux measurements over multiple years. An ecosystem approach to evaluating N2O fluxes will be useful for regional and global modeling and for computation of national N2O flux inventories for regulatory purposes but only if measurement programs are comprehensive and continuous.