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  • 1. Cairns, David M.
    et al.
    Lafon, Charles W.
    Mouton, Michelle F.
    Stuteville, Rachel L.
    Young, Amanda B.
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Comparing two methods for ageing trees with suppressed, diffuse-porous rings (Betula pubescens ssp. czerepanovii)2012Ingår i: Dendrochronologia, ISSN 1125-7865, E-ISSN 1612-0051, Vol. 30, nr 4, s. 252-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The annual growth rings of diffuse porous species such as mountain birch are often difficult to distinguish when samples are collected from trees that grow at treeline or in other harsh environments. In this study we document the differences in seedling and sapling ring counts obtained from two methods of analysis: a traditional analysis based on reflected light and low-power microscopy and one based on transmitted light with higher power magnification that uses thin-sections of the samples. Rings are easier to resolve using the more labor-intensive transmitted light method. Small rings are often missed when using the reflected light method, resulting in an underestimation of tree age. The dates estimated by the standard method agreed with those determined using the thin-sectioning method in 9.6% of the cases. Most commonly, the standard method gave a younger age than did thin-sectioning (72.4% of the trees). In only 18.03% of the cases did the standard method result in a greater age than did thin-sectioning. The reflected light method produced age estimations that were on average 1.37 years younger than those determined using the transmitted light method. The difference between the two methods was positively correlated with age and negatively correlated with mean ring-width. Age-class histograms based on the two methods show little difference at coarser aggregation levels (decades and pentads), but annualized age-class histograms have less agreement between the two methods. Therefore, we suggest using the more labor-intensive thin-sectioning method when annualized age counts are necessary in suppressed seedlings and saplings, for example, comparing tree establishment with annual climate conditions at treeline.

  • 2.
    Thomas, Wieloch
    et al.
    German Research Centre for Geosciences - GFZ, Section 5.2 Climate Dynamics and Landscape Evolution, Potsdam Dendro Laboratory, Telegrafenberg, Potsdam, Germany.
    Helle, G.
    Heinrich, I.
    Voigt, M.
    Schyma, P.
    A novel device for batch-wise isolation of a-cellulose from small-amount wholewood samples2011Ingår i: Dendrochronologia, ISSN 1125-7865, E-ISSN 1612-0051, Vol. 29, nr 2, s. 115-117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel device for the chemical isolation of α-cellulose from wholewood material of tree rings was designed by the Potsdam Dendro Laboratory. It allows the simultaneous treatment of up to several hundred micro samples. Key features are the batch-wise exchange of the chemical solutions, the reusability of all major parts and the easy and unambiguous labelling of each individual sample. Compared to classical methods labour intensity and running costs are significantly reduced.

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