Mayne Diana H.

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Mayne
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Diana H.
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  • Article
    Fire history of a giant African baobab evinced by radiocarbon dating
    (Dept. of Geosciences, University of Arizona, 2010-08) Patrut, Adrian ; Mayne, Diana H. ; von Reden, Karl F. ; Lowy, Daniel A. ; Van Pelt, Robert ; McNichol, Ann P. ; Roberts, Mark L. ; Margineanu, Dragos
    The article reports the first radiocarbon dating of a live African baobab (Adansonia digitata L.), by investigating wood samples collected from 2 inner cavities of the very large 2-stemmed Platland tree of South Africa. Some 16 segments extracted from determined positions of the samples, which correspond to a depth of up to 15–20 cm in the wood, were processed and analyzed by accelerator mass spectrometry (AMS). Calibrated ages of segments are not correlated with their positions in the stems of the tree. Dating results indicate that the segments originate from new growth layers, with a thickness of several centimeters, which cover the original old wood. Four new growth layers were dated before the reference year AD 1950 and 2 layers were dated post-AD 1950, in the post-bomb period. Formation of these layers was triggered by major damage inside the cavities. Fire episodes are the only possible explanation for such successive major wounds over large areas or over the entire area of the inner cavities of the Platland tree, able to trigger regrowth.
  • Article
    Age and growth rate dynamics of an old African baobab determined by radiocarbon dating
    (Dept. of Geosciences, University of Arizona, 2010-08) Patrut, Adrian ; Mayne, Diana H. ; von Reden, Karl F. ; Lowy, Daniel A. ; Venter, Sarah ; McNichol, Ann P. ; Roberts, Mark L. ; Margineanu, Dragos
    In 2008, a large African baobab (Adansonia digitata L.) from Makulu Makete, South Africa, split vertically into 2 sections, revealing a large enclosed cavity. Several wood samples collected from the cavity were processed and radiocarbon dated by accelerator mass spectrometry (AMS) for determining the age and growth rate dynamics of the tree. The 14C date of the oldest sample was found to be of 1016 ± 22 BP, which corresponds to a calibrated age of 1000 ± 15 yr. Thus, the Makulu Makete tree, which eventually collapsed to the ground and died, becomes the second oldest African baobab dated accurately to at least 1000 yr. The conventional growth rate of the trunk, estimated by the radial increase, declined gradually over its life cycle. However, the growth rate expressed more adequately by the cross-sectional area increase and by the volume increase accelerated up to the age of 650 yr and remained almost constant over the past 450 yr.
  • Preprint
    Comparative AMS radiocarbon dating of pretreated versus non-pretreated tropical wood samples
    ( 2009-10) Patrut, Adrian ; von Reden, Karl F. ; Lowy, Daniel A. ; Mayne, Diana H. ; Elder, Kathryn L. ; Roberts, Mark L. ; McNichol, Ann P.
    Several wood samples collected from Dorslandboom, a large African baobab (Adansonia digitata L.) from Namibia, were investigated by AMS radiocarbon dating subsequent to pretreatment and, alternatively, without pretreatment. The comparative statistical evaluation of results showed that there were no significant differences between fraction modern values and radiocarbon dates of the samples analyzed after pretreatment and without pretreatment, respectively. The radiocarbon date of the oldest sample was 993 ± 20 BP. Dating results also revealed that Dorslandboom is a multi-generation tree, with several stems showing different ages.