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  • 1
    Electronic Resource
    Electronic Resource
    Solar UV-B decreases decomposition in herbaceous plant litter in Tierra del Fuego, Argentina: potential role of an altered decomposer community (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Tierra del Fuego, Argentina (55°S), receives increased solar ultraviolet-B radiation (UV-B) as a result of Antarctic stratospheric ozone depletion. We conducted a field study to examine direct and indirect effects of solar UV-B radiation on decomposition of Gunnera magellanica, a native perennial herb, and on the native community of decomposer organisms. In general, indirect effects of UV-B mostly occur due to changes in the chemical composition of litter, whereas direct effects during decomposition result from changes in decomposer organisms and/or differences in the photochemical breakdown of litter. We designed a full-factorial experiment using senescent leaves that had received either near-ambient or attenuated UV-B during growth. The leaves were distributed in litterbags and allowed to decompose under near-ambient or reduced solar UV-B during the growing season. We evaluated initial litter quality, mass loss, and nutrient release of decomposing litter, and microbial colonization of both initial litter and decomposed litter. We found that litter that decomposed under near-ambient UV-B had significantly less mass loss than litter that decomposed under reduced UV-B. The UV-B conditions received by plants during growth, which did not affect mass loss and nutrient composition of litter, affected fungal species composition but in different ways throughout the decomposition period. Before the decomposition trial, Beauveria bassiana and Penicillium frequentans were higher under reduced UV-B, whereas Cladosporium herbarum and pigmented bacteria were more common under the near-ambient compared to the reduced UV-B treatment. After the decomposition period, leaves that had grown under reduced UV-B showed higher frequency of Penicillium thomii and lower frequency of Trichoderma polysporum than leaves that had grown under near-ambient conditions. The UV-B condition received during decomposition also affected fungal colonization, with Penicillium chrysogenum being more frequent in leaves that had decomposed under reduced UV-B, while the other species were not affected. Our results demonstrate that, in this ecosystem, the effects of UV-B radiation on decomposition apparently occurred mostly through changes in the fungal community, while changes in photochemical breakdown appeared to be less important.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00667.x
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  • 2
    Electronic Resource
    Electronic Resource
    Direct and indirect effects of solar ultraviolet-B radiation on long-term decomposition (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: As a result of stratospheric ozone depletion, more solar ultraviolet-B radiation (UV-B, 280–315 nm) is reaching the Earth's surface. Enhanced levels of UV-B may, in turn, alter ecosystem processes such as decomposition. Solar UV-B radiation could affect decomposition both indirectly, by changes in the chemical composition of leaves during growth, or directly by photochemical breakdown of litter and through changes in decomposer communities exposed to sunlight. In this experiment, we studied indirect and direct effects of solar UV-B radiation on decomposition of barley (Hordeum vulgare). We used barley straw and leaf litter grown under reduced UV-B (20% of ambient UV-B) or under near-ambient UV-B (90% of ambient UV-B) in Buenos Aires, Argentina, and decomposed the litter under reduced or near-ambient solar UV-B for 29 months in Tierra del Fuego, Argentina.We found that the UV-B treatment applied during growth decreased the decay rate. On the other hand, there was a marginally significant direct effect of elevated UV-B during the early stages of decomposition, suggesting increased mass loss. The effect of UV-B during growth on decomposition was likely the result of changes in plant litter chemical composition. Near-ambient UV-B received during plant growth decreased the concentrations of nitrogen, soluble carbohydrates, and N/P ratio, and increased the concentrations of phosphorus, cellulose, UV-B-absorbing compounds, and lignin/N ratio. Thus, solar UV-B radiation affects the decomposition of barley litter directly and indirectly, and indirect effects are persistent for the whole decomposition period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.1027.x
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    Paper (German National Licenses)
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