Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Antioxidative Systems in Spruce Clones Grown at High Altitudes
    ( 1999)
    Polle, A.
    ;
    Rennenberg, H.
    ;
    Scholz, F.
    Antioxidative systems were studied in current-year needles of 15 different clones of four-year-old spruce trees (Picea abies (L.) Karst.) grown at three altitudes (800 m, 1150 m and 1750 m above sea level) and compared with those in mature spruce trees after life-time growth at these sites. In both mature spruce trees and clones antioxidative systems increased and chlorophyll decreased with increasing elevation. In general, the increase in antioxidative systems was less pronounced and chlorophyll reductions were higher in clones than in mature spruce trees. Ozone-tolerant clones did not display higher antioxidant contents and superoxide dismutase or guaiacol peroxidase activities than ozone sensitive clones. The maintenance of enhanced chlorophyll b contents in tolerant clones with increasing elevation suggests that stress compensation was associated with other factors than the antioxidants analysed.
  • Publication
    Impact of rice cultivars on CH4 emission from rice paddy fields
    ( 1997)
    Butterbach-Bahl, K.
    ;
    Rennenberg, H.
    ;
    Papen, H.
  • Publication
    Role of methane and nitrous oxide in climate change
    ( 1995)
    Rennenberg, H.
    ;
    Wassmann, R.
    ;
    Papen, H.
    ;
    Seiler, W.
  • Publication
    Methane emissions from rained rice fields
    ( 1995)
    Wassmann, R.
    ;
    Neue, H.U.
    ;
    Lantin, R.S.
    ;
    Javellana, M.J.
    ;
    Diego, R.
    ;
    Lignes, V.E.
    ;
    Hoffmann, H.
    ;
    Papen, H.
    ;
    Rennenberg, H.
    This experiment encompassed three treatments with varying water regimes representing irrigated rice with assured flooding and two types of rainfed rice a ffected by droughts. Methane emission was recorded by an automatic closed chamber system facilitating continuous measurements over the entire dry and wet season of 1994. The methane emission rates in the dry season were generally higher than in the wet season; the seasonal patterns of methane emission in the individual treatments showed a high degree of similarity in both seasons. Mid-tillering drainage prompted a pronounced decrease in methane emission rates which was attributed to the influx of oxygen into the soil. Low methane fluxes prevailed even after the field was reflooded. In the other treatments, which were kept flooded during tillering stage, methane emission rates stayed relatively constant. Drainage at 14 days before harvest prompted a short-term increase of methane emission rate which was attributed to a degassing of soi l entrapped methane. In the field that was flooded throughout the growing season, the process of harvesting was also associated with the short-term release of large amounts of methane. The results of this experiment demonstrate that 1) rainfed rice has a lower emission potential than irrigated rice, 2) the impact of droughts on methane emission depends on the actual growing stage the drought occurs, 3) methane emission from rainfed rice will increase with advances gained in water supply, and 4) temporary drainage can be an effective measure to reduce methane emission from rice.
  • Publication
  • Publication
    Emissionen von N2O, NO und NO2 aus Böden zweier Fichtenstandorte im Schwarzwald
    ( 1992)
    Papen, H.
    ;
    Hermann, H.
    ;
    Dörsch, P.
    ;
    Rennenberg, H.
    While dial variations in N2O, NO, and NO2 emissions from soils of measuring sites in Villingen (V) and Schluchsee (S) could not be observed with certainty, seasonal changes were observed. N-emissions in May were significantly higher than in September 91. Volatile N-losses were primarily in the form of N2O, less in the forms of NO and NO2. Soils at both sites were net reductions for NO2. An effect of liming on N-emissions was not yet detected. The additional application of (NH4) 2SO4 to Villingen sites resulted in September in enhanced N-gains compared to the control site. Autotrophic NH4+-oxidizers could not be found at any site. At a few sites autotrophic NO2-oxidizers were detected. Heterotrophic nitrifiers represented a significant part of the total bacterial population. From inhibitory studies on intact soil cores it is concluded that besides denitrification other microbial processes, some of which have not been identified at present, are involved in the N-trace gas emissions observed.
  • Publication
    Konzept der Forschungsarbeiten am Schwerpunktstandort Kalkalpen
    ( 1989)
    Rennenberg, H.
    High concentrations of photooxidants transported above inversion layers are thought to be responsible for the non-biotic damage to the forests of the Northern Alps. At present this hypothesis is supported (1) by investigations on the atmospheric gas mixing ratio of atmospheric pollutants, (2) the characteristics of the injury to the trees observed with increasing altitude, (3) the changes in the atmospheric gas-mixing ratio of ozone with increasing altitude, and (4) the analysis of the detoxification capacity of spruce needles for toxic oxygen species. The impact of the observed local acidification of the soil as a factor of injury to the trees can presently not be evaluated.
  • Publication