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  • 1
    Electronic Resource
    Electronic Resource
    Physiological, stomatal and ultrastructural ozone responses in birch (Betula pendula Roth.) are modified by water stress (1998)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The physiological, stomatal and ultrastructural responses to ozone and drought of ozone-sensitive and more ozone-tolerant birch (Betula pendula Roth.) clones were studied singly and in combination, in a high-stress chamber experiment and in a low-stress open-field experiment. In the chamber experiment, well watered (WW), moderately watered (MW) or drought-stressed (DS) saplings were exposed for 36 d to 0 or 130 nmol mol∠1 ozone. In the open-field experiment, well watered or drought-stressed saplings were grown for one growing season in ambient air or exposed to 1·8 × ambient ozone. Drought stress reduced growth rate, stomatal conductance, stomatal density and the proportion of starch and thylakoids in chloroplasts, but stimulated net photosynthesis, Rubisco and chlorophyll quantity at the end of the growing season, and increased the size and density of plastoglobuli. Ozone fumigations caused more variable, clone- and exposure-dependent responses in growth, decreased stomatal conductance and net photosynthesis, an increased number of stomata, visible and ultrastructural chloroplast injuries, and enhanced autumn yellowing of the leaves. Ozone-induced changes in plastoglobuli, starch and thylakoids resembled drought responses. The two experiments revealed that, depending on the experimental conditions and the variable, the response to drought and ozone stress can be independent, additive or interactive. Drought protected the plants from ozone injuries under high-stress conditions in the chamber experiment. In the low-stress, open-field experiment, however, enhanced ozone damage was observed in birch saplings grown under restricted water supply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00303.x
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  • 2
    Electronic Resource
    Electronic Resource
    Ambient ultraviolet radiation in the Arctic reduces root biomass and alters microbial community composition but has no effects on microbial biomass (2005)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 11 (2005), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We assessed the effects of ambient solar ultraviolet (UV) radiation on below-ground parameters in an arctic heath in north-eastern Greenland. We hypothesized that the current UV fluxes would reduce root biomass and mycorrhizal colonization and that these changes would lead to lower soil microbial biomass and altered microbial community composition. These hypotheses were tested on cored soil samples from a UV reduction experiment with three filter treatments (Mylar, 60% UV-B reduction; Lexan, up to 90% UV-B reduction+UV-A reduction; UV transparent Teflon, filter control) and an open control treatment in two study sites after 3 years' manipulation. Reduction of both UV-A and UV-B radiation caused over 30% increase in the root biomass of Vaccinium uliginosum, which was the dominant plant species. UV reduction had contrasting effects on ericoid mycorrhizal colonization of V. uliginosum roots in the two sites, while it had no clear effects on fungal (ergosterol) or microbial biomass (measured both with fumigation–extraction and quantitative lipid biomarker analysis) in soil. However, principal component analysis of lipid biomarkers (phospholipid and glycolipid fatty acid profiles) showed that microbial community composition was altered by UV reduction. Although the UV responses were slight considering the large dose difference between the treatments (from near-ambient to up to 90% UV-B reduction), we cannot rule out the possibility that the recovery of ozone layer would change the below-ground functioning of arctic ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.00933.x
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  • 3
    Electronic Resource
    Electronic Resource
    Uptake of Sr-85 in joints damaged by rheumatoid arthritis (1968)
    Springer
    Calcified tissue international 2 (1968), S. 35-35 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02065217
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The influence of elevated CO2 and O3 concentrations on Scots pine needles: changes in starch and secondary metabolites over three exposure years (1998)
    Springer
    Oecologia 114 (1998), S. 455-460 
    Details
    ISSN: 1432-1939
    Keywords: Key wordsPinus sylvestris ; Carbon dioxide ; Ozone ; Starch ; Secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Scots pine (Pinus sylvestris L.) trees, aged about 20 years old, growing on a natural pine heath were exposed to two concentrations of CO2 (ambient CO2 and double-ambient CO2) and two O3 regimes (ambient O3 and double-ambient O3) and their combination in open-top chambers during growing seasons 1994, 1995 and 1996. Concentrations of foliar starch and secondary compounds are reported in this paper. Starch concentrations remained unaffected by elevated CO2 and/or O3 concentrations during the first 2 study years. But in the autumn of the last study year, a significantly higher concentration of starch was found in current-year needles of trees exposed to elevated CO2 compared with ambient air. There were large differences in concentrations of starch and secondary compounds between individual trees. Elevated concentrations of CO2 and/or O3 did not have any significant effects on the concentrations of foliar total monoterpenes, total resin acids or total phenolics. Significantly higher concentrations of monoterpenes and resin acids and mostly lower concentrations of starch were found in trees growing without chambers than in those growing in open-top chambers, while there were no differences in concentrations of total phenolics between trees growing without or in chambers. The results suggest that elevated concentrations of CO2 might increase foliar starch concentrations in Scots pine, while secondary metabolites remain unaffected. Realistically elevated O3 concentrations do not have clear effects on carbon allocation to starch and secondary compounds even after 3 exposure years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050469
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of ozone on birch (Betula pendula Roth.) clones (1995)
    Springer
    Water, air & soil pollution 85 (1995), S. 1331-1336 
    Details
    ISSN: 1573-2932
    Keywords: Betula pendula ; clones ; ozone ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Saplings of five birch clones (Betula pendula Roth.) were exposed to ozone doses 1.2–1.7 × higher than the ambient under field conditions during growing seasons 1991–1993. The clones were also fumigated with 40 ppb – 150 ppb ozone in three chamber experiments.The effects of nitrogen supply on ozone responses were studied using field fumigation system and three levels of nitrogen supply (low, medium, high). The ozone-sensitivity was clone-spesific. Even low ozone exposure decreased the biomass production of the most sensitive clone, whereas the most tolerant clone showed unaffected growth rate. In all clones, ozone fumigation accelerated autumn senescence of leaves, increased ultrastructural injuries, especially in chloroplasts, and increased diffusion resistance and stomatal density of leaves. Ozone-induced changes in the tissue and fine structure of leaves were interpreted as enhanced senescence. The plants receiving high nitrogen supply were more resistant to ozone than the plants under lower nitrogen availability. Significant interactions between ozone and nitrogen supply were found in growth and leaf anatomical parameters. The ozone sensitivity and the growth rate of birch clones seem to be related to biochemical and ultrastructural changes of chloroplasts, as reduced growth rate of the most sensitive clone was accompanied by lower contents of Rubisco small subunit and chlorophyll, and lower net photosynthesis. Fast enlarging and young mature leaves without acclimation were more sensitive to ozone fumigation than the leaves emerging under ozone stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00477166
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