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Managing the matrix: decadal responses of eucalypt-dominated savanna to ambient fire regimes

Journal Article


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Abstract


  • Much of our understanding of the response of savanna systems to fire

    disturbance relies on observations derived from manipulative fire plot studies. Equivocal

    findings from both recent Australian and African savanna fire plot assessments have

    significant implications for informing conservation management and reliable estimation of

    biomass stocks and dynamics. Influential northern Australian replicated fire plot studies

    include the 24-year plot-scale Munmarlary and the five-year catchment-scale Kapalga, mesic

    savanna (.1000 mm/yr of rainfall) experiments in present-day Kakadu National Park. At

    Munmarlary, under low-to-moderate-intensity fire treatments, woody vegetation dominated

    by mature eucalypts was found to be structurally stable. At Kapalga, substantial declines in

    woody biomass were observed under more intense fire treatments, and modeling assessments

    implicate early-season fires as having adverse effects on longer-term tree recruitment. Given

    these contrasting perspectives, here we take advantage of a landscape-scale fire response

    monitoring program established on three major northern Australian conservation reserves

    (Kakadu, Litchfield, and Nitmiluk National Parks). Using statistical modeling we assess the

    decadal effects of ambient fire regime parameters (fire frequency, severity, seasonality, time

    since fire) on 32 vegetation structure components and abundance of 21 tree and 16 grass

    species from 122 monitoring plots. Over the study period the mean annual frequency of

    burning of plots was 0.53, comprising mostly early-dry-season, low-severity fires. Structural

    and species responses were variable but often substantial, notably resulting in stem

    recruitment and declines in juveniles, but only weakly explained by fire regime and habitat

    variables. Modeling of these observations under three realistic scenarios (increased fire severity

    under projected worsening climate change; modest and significant reductions in fire frequency

    to meet conservation criteria) indicates that all scenarios have positive and negative structural

    implications. Effecting significant regional fire regime change (e.g., reduction in frequency and

    size of severe fires) is demonstrably feasible, but it incurs risks and potentially some

    undesirable structural consequences. Given recent Australian and African experience, the

    generality and application of landscape-scale implications derived from manipulative fire

    assessments (including variable grazing and browsing regimes) in savanna require more critical

    assessment

Authors


  •   Russell-Smith, Jeremy (external author)
  •   Price, Owen F.
  •   Murphy, Brett P. (external author)

Publication Date


  • 2010

Citation


  • Russell-Smith, J., Price, O. F. & Murphy, B. P. (2010). Managing the matrix: decadal responses of eucalypt-dominated savanna to ambient fire regimes. Ecological Applications, 20 (6), 1615-1632.

Scopus Eid


  • 2-s2.0-77956432008

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=8538&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5195

Number Of Pages


  • 17

Start Page


  • 1615

End Page


  • 1632

Volume


  • 20

Issue


  • 6

Place Of Publication


  • http://www.esajournals.org/loi/ecap

Abstract


  • Much of our understanding of the response of savanna systems to fire

    disturbance relies on observations derived from manipulative fire plot studies. Equivocal

    findings from both recent Australian and African savanna fire plot assessments have

    significant implications for informing conservation management and reliable estimation of

    biomass stocks and dynamics. Influential northern Australian replicated fire plot studies

    include the 24-year plot-scale Munmarlary and the five-year catchment-scale Kapalga, mesic

    savanna (.1000 mm/yr of rainfall) experiments in present-day Kakadu National Park. At

    Munmarlary, under low-to-moderate-intensity fire treatments, woody vegetation dominated

    by mature eucalypts was found to be structurally stable. At Kapalga, substantial declines in

    woody biomass were observed under more intense fire treatments, and modeling assessments

    implicate early-season fires as having adverse effects on longer-term tree recruitment. Given

    these contrasting perspectives, here we take advantage of a landscape-scale fire response

    monitoring program established on three major northern Australian conservation reserves

    (Kakadu, Litchfield, and Nitmiluk National Parks). Using statistical modeling we assess the

    decadal effects of ambient fire regime parameters (fire frequency, severity, seasonality, time

    since fire) on 32 vegetation structure components and abundance of 21 tree and 16 grass

    species from 122 monitoring plots. Over the study period the mean annual frequency of

    burning of plots was 0.53, comprising mostly early-dry-season, low-severity fires. Structural

    and species responses were variable but often substantial, notably resulting in stem

    recruitment and declines in juveniles, but only weakly explained by fire regime and habitat

    variables. Modeling of these observations under three realistic scenarios (increased fire severity

    under projected worsening climate change; modest and significant reductions in fire frequency

    to meet conservation criteria) indicates that all scenarios have positive and negative structural

    implications. Effecting significant regional fire regime change (e.g., reduction in frequency and

    size of severe fires) is demonstrably feasible, but it incurs risks and potentially some

    undesirable structural consequences. Given recent Australian and African experience, the

    generality and application of landscape-scale implications derived from manipulative fire

    assessments (including variable grazing and browsing regimes) in savanna require more critical

    assessment

Authors


  •   Russell-Smith, Jeremy (external author)
  •   Price, Owen F.
  •   Murphy, Brett P. (external author)

Publication Date


  • 2010

Citation


  • Russell-Smith, J., Price, O. F. & Murphy, B. P. (2010). Managing the matrix: decadal responses of eucalypt-dominated savanna to ambient fire regimes. Ecological Applications, 20 (6), 1615-1632.

Scopus Eid


  • 2-s2.0-77956432008

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=8538&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5195

Number Of Pages


  • 17

Start Page


  • 1615

End Page


  • 1632

Volume


  • 20

Issue


  • 6

Place Of Publication


  • http://www.esajournals.org/loi/ecap