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  • 1995-1999  (16)
  • 1
    Electronic Resource
    Electronic Resource
    Hydrology, water availability and tundra ecosystem function in a changing climate: the need for a closer integration of ideas? (1999)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Hydrologists and ecologists studying tundra ecosystems have worked largely independently, with little cross-fertilization between disciplines. Their disciplines are, however, inextricably linked by a need to understand the dynamics and significance of the common substance water, in its liquid, solid and gaseous state within tundra environments. The impacts of predicted long-term changes in climate have particularly important consequences for the functioning of tundra systems and there is a pressing need to initiate studies that integrate hydrological and ecological methodologies and concepts. Our paper attempts to summarize existing information on the role of water within tundra ecosystems, to emphasize the fundamental links between the biotic and the physico/chemical environments and to suggest how a closer integration of ideas might be achieved. Given the breadth of the subject matter the paper is intended to be illustrative rather than comprehensive. The paper examines the physical impacts of water in its various states on the tundra environment, emphasizing in particular the causes of spatial variation in water availability to living organisms. The significance of water is discussed for a range of organism groups, including plants, invertebrates and microorganisms and its pivotal role in ecosystem function and disturbance stressed. The need to develop integrated hydological/ecological models for tundra systems on different spatial scales is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00229.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    LIFE ON THE EDGE:Insect Ecology in Arctic Environments (1998)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Entomology 43 (1998), S. 85-106 
    Details
    ISSN: 0066-4170
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The restricted Arctic insect fauna is usually explained by a lack of recolonization since the last glacial period, inadequate supply of suitable resources, or insufficient adaptation to such a harsh environment. These hypotheses and others that attempt to explain the latitudinal gradient of species distributions and abundance are reviewed. Arctic habitats available to insects are strongly heterogeneous, requiring a similarly diverse array of adaptive responses, characteristic of those species that have colonized and survived in such a stressful climate. Important adaptations in morphology (size, wings), behavior (activity patterns, thermoregulation), life cycles, and ecophysiology (cold hardiness, anaerobiosis, desiccation resistance) are discussed. The current focus of global climate change research on polar regions is identifed, particularly the opportunity to study fundamental ecological processes and spatial dynamics in the relatively simple Arctic ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ento.43.1.85
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature change and complex dynamics (1997)
    Springer
    Oecologia 112 (1997), S. 543-550 
    Details
    ISSN: 1432-1939
    Keywords: Key words Nonlinear dynamics ; Time series analysis ; Models ; Aphids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Density-dependent factors, such as population growth rate and migration, influence dynamic behaviour in ecological models. Temperature, an abiotic and density-independent factor, is also an important determinant of insect population growth. We investigated the endogenous dynamics of a density-dependent response-surface model that included temperature, based on time series for two aphid species. We investigated the effects of temperature and random noise on the model dynamics. In most cases, an increase in temperature resulted in a higher predicted equilibrium density; it could induce complex dynamics. Noise at the level of the natural variation in temperature resulted in extinctions in some models. Our results from these models indicate that aphid populations might become more abundant, and less stable in some circumstances, if there is climate warming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050343
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of experimental temperature elevation on high-arctic soil microarthropod populations (1996)
    Springer
    Polar biology 16 (1996), S. 147-153 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An experiment was conducted to measure the effects of summer warming on the total population densities of soil-dwelling microarthropods in the high Arctic and to compare these results with those from natural between-year and between-site variations. Small polythene tents were used to elevate summer temperatures over 3 years on polar semi-desert and tundra heath in West Spitsbergen, Svalbard, Norway. Soil cores were taken at regular intervals from tented and untented (control) plots and heat extracted for mites (Acarina: Oribatida) and springtails (Collembola). Species present were similar at both sites, but at the start of the experiment total springtail populations were greater at the polar semi-desert whilst oribatid mite densities were equal at both sites. No significant effect of temperature elevation on oribatid mite populations emerged, even after 3 years. By contrast, springtail numbers were significantly lower on tented versus control plots at the polar semi-desert at the end of year 3, but not so at the tundra heath. Collembola numbers declined at both sites during the warm dry midsummers of 1992/1993 and this was most marked at the better drained polar semi-desert site. Over the equivalent period total oribatid mite populations, while relatively more stable, increased significantly at the polar semi-desert as a result of an increase in the number of juveniles. Results are interpreted in the context of the ecophysiological adaptations of oribatid mites and springtails to soil temperature and moisture. The resulting survival characteristics are considered in relation to the temperature and moisture characteristics of the two sites. The experiment demonstrated that year to year variation in climate, interacting with physical differences between sites, produced an equal or greater effect on microarthropod numbers at any one site than the 8–10% increase in “heat availability” (day degrees above zero) resulting from the summer tent treatment. The limitations of the use of tents to elevate soil temperatures are discussed. Comparisons are made with microarthropod population data from other polar and alpine sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050039
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  • 5
    Electronic Resource
    Electronic Resource
    Factors limiting the distribution of Acyrthosiphon svalbardicum (Hemiptera: Aphididae) on Spitsbergen (1995)
    Springer
    Polar biology 15 (1995), S. 375-380 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of the high arctic aphid Acyrthosiphon svalbardicum was found to have a distinct limit in the Kongsfjorden area of Spitsbergen; the probability of site occupancy increased with distance from the fjord mouth and decreased with distance from the shore. Superimposed on this general distribution pattern, sites that cleared of snow early in the polar summer were more likely to be occupied by aphids. The phenology of the aphid was significantly affected by small changes in microclimate over distances of a few metres. The aphid only occurs in the warmer parts of the region, but laboratory cultures were successfully reared on plant material collected from colder regions that the aphid does not presently occupy. These observations suggest that the local distribution of A. svalbardicum is determined by summer thermal conditions. On a smaller scale, within patches where the aphids occurred, densities were higher on flowers and flowering shoots than on non-flowering shoots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238489
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  • 6
    Electronic Resource
    Electronic Resource
    Life-cycle and morph production in the Arctic aphid Acyrthosiphon brevicorne (1996)
    Springer
    Polar biology 16 (1996), S. 293-300 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The life-cycle of the sub-Arctic, Dryas-feeding aphid, Acyrthosiphon brevicorne, is described and shown to be intermediate between that of the high-Arctic aphid (Acyrthosiphon svalbardicum) and typical holocyclic, monoecious, temperate species. The fundatrix of A. brevicorne can give rise directly to both sexual morphs, a necessary adaptation to the short Arctic summer. Production of males is predetermined; some males are produced by all-viviparous mothers, but at lower frequencies in the birth sequences of the fundatrix than in subsequent generations. By contrast, the production of oviparae is controlled, at least in part, by photoperiod.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050056
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of experimental temperature elevation on high-arctic soil microarthropod populations (1996)
    Springer
    Polar biology 16 (1996), S. 147-153 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experiment was conducted to measure the effects of summer warming on the total population densities of soil-dwelling microarthropods in the high Arctic and to compare these results with those from natural between-year and between-site variations. Small polythene tents were used to elevate summer temperatures over 3 years on polar semi-desert and tundra heath in West Spitsbergen, Svalbard, Norway. Soil cores were taken at regular intervals from tented and untented (control) plots and heat extracted for mites (Acarina: Oribatida) and springtails (Collembola). Species present were similar at both sites, but at the start of the experiment total springtail populations were greater at the polar semi-desert whilst oribatid mite densities were equal at both sites. No significant effect of temperature elevation on oribatid mite populations emerged, even after 3 years. By contrast, springtail numbers were significantly lower on tented versus control plots at the polar semi-desert at the end of year 3, but not so at the tundra heath. Collembola numbers declined at both sites during the warm dry midsummers of 1992/1993 and this was most marked at the better drained polar semi-desert site. Over the equivalent period total oribatid mite populations, while relatively more stable, increased significantly at the polar semi-desert as a result of an increase in the number of juveniles. Results are interpreted in the context of the ecophysiological adaptations of oribatid mites and springtails to soil temperature and moisture. The resulting survival characteristics are considered in relation to the temperature and moisture characteristics of the two sites. The experiment demonstrated that year to year variation in climate, interacting with physical differences between sites, produced an equal or greater effect on microarthropod numbers at any one site than the 8–10% increase in “heat availability” (day degrees above zero) resulting from the summer tent treatment. The limitations of the use of tents to elevate soil temperatures are discussed. Comparisons are made with microarthropod population data from other polar and alpine sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02390435
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  • 8
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    Global Change and Arctic Ecosystems: Conclusions and Predictions from Experiments with Terrestrial Invertebrates on Spitsbergen (1998)
    Taylor & Francis
    Details
    Publication Date: 1998-08-01
    Print ISSN: 0004-0851
    Topics: Geography , Geosciences
    Published by Taylor & Francis
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  • 9
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    Thermal Environments of Arctic Soil Organisms during Winter (1995)
    Taylor & Francis
    Details
    Publication Date: 1995-11-01
    Print ISSN: 0004-0851
    Topics: Geography , Geosciences
    Published by Taylor & Francis
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  • 10
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    Life-cycle and morph production in the Arctic aphid Acyrthosiphon brevicorne (1996)
    Springer
    Details
    Publication Date: 1996-04-04
    Print ISSN: 0722-4060
    Electronic ISSN: 1432-2056
    Topics: Biology
    Published by Springer
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