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  • Canadian Science Publishing  (3)
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Verlag/Herausgeber
  • Canadian Science Publishing  (3)
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  • 1
    Online-Ressource
    Online-Ressource
    Canadian Science Publishing ; 1998
    In:  Canadian Journal of Forest Research Vol. 28, No. 5 ( 1998-05-01), p. 774-787
    In: Canadian Journal of Forest Research, Canadian Science Publishing, Vol. 28, No. 5 ( 1998-05-01), p. 774-787
    Kurzfassung: High-resolution analysis of macroscopic charcoal in sediment cores from Little Lake was used to reconstruct the fire history of the last 9000 years. Variations in sediment magnetism were examined to detect changes in allochthonous sedimentation associated with past fire occurrence. Fire intervals from ca. 9000 to 6850 calendar years BP averaged 110 ± 20 years, when the climate was warmer and drier than today and xerophytic vegetation dominated. From ca. 6850 to 2750 calendar years BP the mean fire interval lengthened to 160 ± 20 years in conjunction with the onset of cool humid conditions. Fire-sensitive species, such as Thuja plicata Donn ex D. Don, Tsuga heterophylla (Raf.) Sarg., and Picea sitchensis (Bong.) Carr., increased in abundance. At ca. 4000 calendar years BP, increases in allochthonous sedimentation increased the delivery of secondary charcoal to the site. From ca. 2750 calendar years BP to present, the mean fire interval increased to 230 ± 30 years as cool humid conditions and mesophytic taxa prevailed. The Little Lake record suggests that fire frequency has varied continuously on millennial time scales as a result of climate change and the present-day fire regime has been present for no more than 1000 years.
    Materialart: Online-Ressource
    ISSN: 0045-5067 , 1208-6037
    Sprache: Englisch
    Verlag: Canadian Science Publishing
    Publikationsdatum: 1998
    ZDB Id: 1473096-0
    SSG: 23
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Canadian Science Publishing ; 1992
    In:  Canadian Journal of Forest Research Vol. 22, No. 11 ( 1992-11-01), p. 1727-1738
    In: Canadian Journal of Forest Research, Canadian Science Publishing, Vol. 22, No. 11 ( 1992-11-01), p. 1727-1738
    Kurzfassung: During the 21st century, global climate change is expected to become a significant force redefining global biospheric boundaries and vegetation dynamics. In the northern hardwood–boreal forest transition forests, it should, at the least, control reproductive success and failure among unmanaged mixed forest stands. One means by which to predict future responses by the mixed forests is to examine the way in which they have responded to climate changes in the past. We used proxy climate data derived from Holocene (past 10 000 years) pollen records in the western Upper Peninsula of Michigan to drive forest gap models, in an effort to define regional prehistoric vegetation dynamics on differing soils. The gap models mimic forest reproduction and growth as a successional process and, hence, are appropriate for defining long-term tree and stand dynamics. The modeled period included a mid-postglacial period that was warmer than today's climate. Model failures, made apparent from the exercise, were corrected and the simulations were repeated until the model behaved credibly. Then, the same gap model was used to simulate potential future vegetation dynamics, driven by projections of a future climate that was controlled by greenhouse gases. This provided us with the same "measure" of vegetation in the past, present, and future, generating a continuously comparable record of change and stability in forest composition and density. The resulting projections of vegetation response to climate change appear to be affected more by the rate than by the magnitude of climate change.
    Materialart: Online-Ressource
    ISSN: 0045-5067 , 1208-6037
    Sprache: Englisch
    Verlag: Canadian Science Publishing
    Publikationsdatum: 1992
    ZDB Id: 1473096-0
    SSG: 23
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Online-Ressource
    Online-Ressource
    Canadian Science Publishing ; 2004
    In:  Canadian Journal of Forest Research Vol. 34, No. 10 ( 2004-10-01), p. 2110-2121
    In: Canadian Journal of Forest Research, Canadian Science Publishing, Vol. 34, No. 10 ( 2004-10-01), p. 2110-2121
    Kurzfassung: Fire-history reconstructions are based on tree-ring records that span the last few centuries and charcoal data from lake-sediment cores that extend back several thousand years. The two approaches have unique strengths and weaknesses in their ability to depict past fire events and fire regimes, and most comparisons of these datasets in western conifer forests have focused on sites characterized by high-severity crown fires. Tree-ring and charcoal data spanning the last 300 years in four watersheds in the montane forests of the Klamath Mountains provided an opportunity to compare the records in a fire regime of frequent low- to moderate-severity surface events. The charcoal data were obtained from small lakes, and tree-ring records were derived from fire-scar chronologies at multiple sites within each watershed. The comparison indicates that the tree-ring records detected individual fires not evident in the lake-sediment profiles, whereas the charcoal data disclosed variations in fuel loading and general levels of burning at broader spatial scales. Regional burning in the late 19th and early 20th centuries was evident in the lake-sediment records, and both datasets registered a decline in fire activity in the late 20th century. Thus, the two types of data provide complementary as well as supplementary information on past fire conditions.
    Materialart: Online-Ressource
    ISSN: 0045-5067 , 1208-6037
    Sprache: Englisch
    Verlag: Canadian Science Publishing
    Publikationsdatum: 2004
    ZDB Id: 1473096-0
    SSG: 23
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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