Disturbances prevent stem size-density distributions in natural forests from following scaling relationships

D.A. Coomes, R.P. Duncan, R.B. Allen, J. Truscott

    Research output: Contribution to journalArticle

    141 Citations (Scopus)

    Abstract

    Enquist and Niklas propose that trees in natural forests have invariant size-density distributions (SDDs) that scale as a -2 power of stem diameter, although early studies described such distributions using negative exponential functions. Using New Zealand and 'global' data sets, we demonstrate that neither type of function accurately describes the SDD over the entire diameter range. Instead, scaling functions provide the best fit to smaller stems, while negative exponential functions provide the best fit to larger stems. We argue that these patterns are consistent with competition shaping the small-stem phase and exogenous disturbance shaping the large-stem phase. Mortality rates, estimated from repeat measurements on 1546 New Zealand plots, fell precipitously with stem size until 18 cm but remained constant after that, consistent with our arguments. Even in the small-stem phase, where SDDs were best described by scaling functions, the scaling exponents were not invariantly -2, but differed significantly from this value in both the 'global' and New Zealand data sets, and varied through time in the New Zealand data set.
    Original languageUndefined
    Pages (from-to)980-989
    Number of pages10
    JournalEcology Letters
    Volume6
    Issue number11
    DOIs
    Publication statusPublished - 2003

    Cite this

    @article{40227c5052674b90bc1e584ffbab545c,
    title = "Disturbances prevent stem size-density distributions in natural forests from following scaling relationships",
    abstract = "Enquist and Niklas propose that trees in natural forests have invariant size-density distributions (SDDs) that scale as a -2 power of stem diameter, although early studies described such distributions using negative exponential functions. Using New Zealand and 'global' data sets, we demonstrate that neither type of function accurately describes the SDD over the entire diameter range. Instead, scaling functions provide the best fit to smaller stems, while negative exponential functions provide the best fit to larger stems. We argue that these patterns are consistent with competition shaping the small-stem phase and exogenous disturbance shaping the large-stem phase. Mortality rates, estimated from repeat measurements on 1546 New Zealand plots, fell precipitously with stem size until 18 cm but remained constant after that, consistent with our arguments. Even in the small-stem phase, where SDDs were best described by scaling functions, the scaling exponents were not invariantly -2, but differed significantly from this value in both the 'global' and New Zealand data sets, and varied through time in the New Zealand data set.",
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    Disturbances prevent stem size-density distributions in natural forests from following scaling relationships. / Coomes, D.A.; Duncan, R.P.; Allen, R.B.; Truscott, J.

    In: Ecology Letters, Vol. 6, No. 11, 2003, p. 980-989.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Disturbances prevent stem size-density distributions in natural forests from following scaling relationships

    AU - Coomes, D.A.

    AU - Duncan, R.P.

    AU - Allen, R.B.

    AU - Truscott, J.

    N1 - cited By 114

    PY - 2003

    Y1 - 2003

    N2 - Enquist and Niklas propose that trees in natural forests have invariant size-density distributions (SDDs) that scale as a -2 power of stem diameter, although early studies described such distributions using negative exponential functions. Using New Zealand and 'global' data sets, we demonstrate that neither type of function accurately describes the SDD over the entire diameter range. Instead, scaling functions provide the best fit to smaller stems, while negative exponential functions provide the best fit to larger stems. We argue that these patterns are consistent with competition shaping the small-stem phase and exogenous disturbance shaping the large-stem phase. Mortality rates, estimated from repeat measurements on 1546 New Zealand plots, fell precipitously with stem size until 18 cm but remained constant after that, consistent with our arguments. Even in the small-stem phase, where SDDs were best described by scaling functions, the scaling exponents were not invariantly -2, but differed significantly from this value in both the 'global' and New Zealand data sets, and varied through time in the New Zealand data set.

    AB - Enquist and Niklas propose that trees in natural forests have invariant size-density distributions (SDDs) that scale as a -2 power of stem diameter, although early studies described such distributions using negative exponential functions. Using New Zealand and 'global' data sets, we demonstrate that neither type of function accurately describes the SDD over the entire diameter range. Instead, scaling functions provide the best fit to smaller stems, while negative exponential functions provide the best fit to larger stems. We argue that these patterns are consistent with competition shaping the small-stem phase and exogenous disturbance shaping the large-stem phase. Mortality rates, estimated from repeat measurements on 1546 New Zealand plots, fell precipitously with stem size until 18 cm but remained constant after that, consistent with our arguments. Even in the small-stem phase, where SDDs were best described by scaling functions, the scaling exponents were not invariantly -2, but differed significantly from this value in both the 'global' and New Zealand data sets, and varied through time in the New Zealand data set.

    U2 - 10.1046/j.1461-0248.2003.00520.x

    DO - 10.1046/j.1461-0248.2003.00520.x

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    EP - 989

    JO - Ecology Letters

    JF - Ecology Letters

    SN - 1461-023X

    IS - 11

    ER -