An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides)

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    Abstract

    Duncan, R.P. (1989). An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides). New Zealand Natural Sciences 16: 31-37. Twelve kahikatea (Dacrycarpus dacrydioides) discs were used to assess the likely errors associated with estimating tree age from growth ring counts in increment cores. Two major sources of error were examined: (1) Failure of the increment core to pass through the tree's chronological centre. A geometric model is developed for estimating the distance to the chronological centre in cores where the arcs of the inner rings are visible. The mean percentage error from 84 cores that passed within 50 mm of the chronological centre was ± 35% corresponding to a mean absolute error of ± 21 years. The majority of this error is due to growth rate differences between the missing radius and the measured part of the core. (2) Missing rings. The average age underestimate from 48 cores due to missing rings was 13%. A significant correlation between radius length and age under estimate (r = 0.81) suggests that sampling along the longest radii will reduce this error. The average age underestimate due to missing rings from cores located along the longest radii of the twelve samples was 3%.
    Original languageEnglish
    Pages (from-to)31-37
    Number of pages7
    JournalNew Zealand Natural Sciences
    Volume16
    Publication statusPublished - 1989

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    Dacrycarpus
    tree age
    Natural Science Disciplines
    Growth
    growth rings
    New Zealand
    Research Design
    sampling

    Cite this

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    title = "An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides)",
    abstract = "Duncan, R.P. (1989). An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides). New Zealand Natural Sciences 16: 31-37. Twelve kahikatea (Dacrycarpus dacrydioides) discs were used to assess the likely errors associated with estimating tree age from growth ring counts in increment cores. Two major sources of error were examined: (1) Failure of the increment core to pass through the tree's chronological centre. A geometric model is developed for estimating the distance to the chronological centre in cores where the arcs of the inner rings are visible. The mean percentage error from 84 cores that passed within 50 mm of the chronological centre was ± 35{\%} corresponding to a mean absolute error of ± 21 years. The majority of this error is due to growth rate differences between the missing radius and the measured part of the core. (2) Missing rings. The average age underestimate from 48 cores due to missing rings was 13{\%}. A significant correlation between radius length and age under estimate (r = 0.81) suggests that sampling along the longest radii will reduce this error. The average age underestimate due to missing rings from cores located along the longest radii of the twelve samples was 3{\%}.",
    author = "R.P. Duncan",
    note = "cited By 238",
    year = "1989",
    language = "English",
    volume = "16",
    pages = "31--37",
    journal = "New Zealand Natural Sciences",
    issn = "0113-7492",
    publisher = "University of Canterbury",

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    T1 - An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides)

    AU - Duncan, R.P.

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    PY - 1989

    Y1 - 1989

    N2 - Duncan, R.P. (1989). An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides). New Zealand Natural Sciences 16: 31-37. Twelve kahikatea (Dacrycarpus dacrydioides) discs were used to assess the likely errors associated with estimating tree age from growth ring counts in increment cores. Two major sources of error were examined: (1) Failure of the increment core to pass through the tree's chronological centre. A geometric model is developed for estimating the distance to the chronological centre in cores where the arcs of the inner rings are visible. The mean percentage error from 84 cores that passed within 50 mm of the chronological centre was ± 35% corresponding to a mean absolute error of ± 21 years. The majority of this error is due to growth rate differences between the missing radius and the measured part of the core. (2) Missing rings. The average age underestimate from 48 cores due to missing rings was 13%. A significant correlation between radius length and age under estimate (r = 0.81) suggests that sampling along the longest radii will reduce this error. The average age underestimate due to missing rings from cores located along the longest radii of the twelve samples was 3%.

    AB - Duncan, R.P. (1989). An evaluation of errors in tree age estimates based on increment cores in kahikatea (Dacrycarpus dacrydioides). New Zealand Natural Sciences 16: 31-37. Twelve kahikatea (Dacrycarpus dacrydioides) discs were used to assess the likely errors associated with estimating tree age from growth ring counts in increment cores. Two major sources of error were examined: (1) Failure of the increment core to pass through the tree's chronological centre. A geometric model is developed for estimating the distance to the chronological centre in cores where the arcs of the inner rings are visible. The mean percentage error from 84 cores that passed within 50 mm of the chronological centre was ± 35% corresponding to a mean absolute error of ± 21 years. The majority of this error is due to growth rate differences between the missing radius and the measured part of the core. (2) Missing rings. The average age underestimate from 48 cores due to missing rings was 13%. A significant correlation between radius length and age under estimate (r = 0.81) suggests that sampling along the longest radii will reduce this error. The average age underestimate due to missing rings from cores located along the longest radii of the twelve samples was 3%.

    M3 - Article

    VL - 16

    SP - 31

    EP - 37

    JO - New Zealand Natural Sciences

    JF - New Zealand Natural Sciences

    SN - 0113-7492

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