Simplifying the savanna

the trajectory of fire-sensitive vegetation mosaics in northern Australia

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Aim: Fire is a key agent in savanna systems, yet the capacity to predict fine-grained population phenomena under variable fire regime conditions at landscape scales is a daunting challenge. Given mounting evidence for significant impacts of fire on vulnerable biodiversity elements in north Australian savannas over recent decades, we assess: (1) the trajectory of fire-sensitive vegetation elements within a particularly biodiverse savanna mosaic based on long-term monitoring and spatial modelling; (2) the broader implications for northern Australia; and (3) the applicability of the methodological approach to other fire-prone settings.

     

    Location: Arnhem Plateau, northern Australia.

     

    Methods: We apply data from long-term vegetation monitoring plots included within Kakadu National Park to derive statistical models describing the responses of structure and floristic attributes to 15 years of ambient (non-experimental) fire regime treatments. For a broader 28,000 km2 region, we apply significant models to spatial assessment of the effects of modern fire regimes (1995–2009) on diagnostic closed forest, savanna and shrubland heath attributes.

     

    Results: Significant models included the effects of severe fires on large stems of the closed forest dominant Allosyncarpia ternata, stem densities of the widespread savanna coniferous obligate seeder Callitris intratropica, and fire frequency and related fire interval parameters on numbers of obligate seeder taxa characteristic of shrubland heaths. No significant relationships were observed between fire regime and eucalypt and non-eucalypt adult tree components of savanna. Spatial application of significant models illustrates that more than half of the regional closed forest perimeters, savanna and shrubland habitats experienced deleterious fire regimes over the study period, except in very dissected terrain.

     

    Main conclusions: While north Australia’s relatively unmodified mesic savannas may appear structurally intact and healthy, this study provides compelling evidence that fire-sensitive vegetation elements embedded within the savanna mosaic are in decline under present-day fire regimes. These observations have broader implications for analogous savanna mosaics across northern Australia, and support complementary findings of the contributory role of fire regimes in the demise of small mammal fauna. The methodological approach has application in other fire-prone settings, but is reliant on significant long-term infrastructure resourcing.

    Original languageEnglish
    Pages (from-to)1303-1317
    Number of pages15
    JournalJournal of Biogeography
    Volume39
    Issue number7
    DOIs
    Publication statusPublished - Jul 2012

    Fingerprint

    savanna
    trajectories
    savannas
    trajectory
    vegetation
    fire regime
    shrublands
    shrubland
    mosaic
    stems
    stem
    statistical models
    small mammals
    infrastructure
    national parks
    plateaus
    fauna
    small mammal
    biodiversity
    monitoring

    Cite this

    @article{5b2b0fb2a24f4900a60f1a035e03535f,
    title = "Simplifying the savanna: the trajectory of fire-sensitive vegetation mosaics in northern Australia",
    abstract = "Aim: Fire is a key agent in savanna systems, yet the capacity to predict fine-grained population phenomena under variable fire regime conditions at landscape scales is a daunting challenge. Given mounting evidence for significant impacts of fire on vulnerable biodiversity elements in north Australian savannas over recent decades, we assess: (1) the trajectory of fire-sensitive vegetation elements within a particularly biodiverse savanna mosaic based on long-term monitoring and spatial modelling; (2) the broader implications for northern Australia; and (3) the applicability of the methodological approach to other fire-prone settings.   Location: Arnhem Plateau, northern Australia.   Methods: We apply data from long-term vegetation monitoring plots included within Kakadu National Park to derive statistical models describing the responses of structure and floristic attributes to 15 years of ambient (non-experimental) fire regime treatments. For a broader 28,000 km2 region, we apply significant models to spatial assessment of the effects of modern fire regimes (1995–2009) on diagnostic closed forest, savanna and shrubland heath attributes.   Results: Significant models included the effects of severe fires on large stems of the closed forest dominant Allosyncarpia ternata, stem densities of the widespread savanna coniferous obligate seeder Callitris intratropica, and fire frequency and related fire interval parameters on numbers of obligate seeder taxa characteristic of shrubland heaths. No significant relationships were observed between fire regime and eucalypt and non-eucalypt adult tree components of savanna. Spatial application of significant models illustrates that more than half of the regional closed forest perimeters, savanna and shrubland habitats experienced deleterious fire regimes over the study period, except in very dissected terrain.   Main conclusions: While north Australia’s relatively unmodified mesic savannas may appear structurally intact and healthy, this study provides compelling evidence that fire-sensitive vegetation elements embedded within the savanna mosaic are in decline under present-day fire regimes. These observations have broader implications for analogous savanna mosaics across northern Australia, and support complementary findings of the contributory role of fire regimes in the demise of small mammal fauna. The methodological approach has application in other fire-prone settings, but is reliant on significant long-term infrastructure resourcing.",
    keywords = "coniferous forest, fire history, floristics, Landsat, long-term change, satellite imagery, savanna, small mammal, Arnhem Plateau, Australia, Kakadu National Park, Northern Territory, Allosyncarpia ternata, Callitris intratropica, Mammalia",
    author = "Jeremy Russell-Smith and Edwards, {Andrew Craig} and Owen Price",
    year = "2012",
    month = "7",
    doi = "10.1111/j.1365-2699.2012.02679.x",
    language = "English",
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    journal = "Journal of Biogeography",
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    }

    Simplifying the savanna : the trajectory of fire-sensitive vegetation mosaics in northern Australia. / Russell-Smith, Jeremy; Edwards, Andrew Craig; Price, Owen.

    In: Journal of Biogeography, Vol. 39, No. 7, 07.2012, p. 1303-1317.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Simplifying the savanna

    T2 - the trajectory of fire-sensitive vegetation mosaics in northern Australia

    AU - Russell-Smith, Jeremy

    AU - Edwards, Andrew Craig

    AU - Price, Owen

    PY - 2012/7

    Y1 - 2012/7

    N2 - Aim: Fire is a key agent in savanna systems, yet the capacity to predict fine-grained population phenomena under variable fire regime conditions at landscape scales is a daunting challenge. Given mounting evidence for significant impacts of fire on vulnerable biodiversity elements in north Australian savannas over recent decades, we assess: (1) the trajectory of fire-sensitive vegetation elements within a particularly biodiverse savanna mosaic based on long-term monitoring and spatial modelling; (2) the broader implications for northern Australia; and (3) the applicability of the methodological approach to other fire-prone settings.   Location: Arnhem Plateau, northern Australia.   Methods: We apply data from long-term vegetation monitoring plots included within Kakadu National Park to derive statistical models describing the responses of structure and floristic attributes to 15 years of ambient (non-experimental) fire regime treatments. For a broader 28,000 km2 region, we apply significant models to spatial assessment of the effects of modern fire regimes (1995–2009) on diagnostic closed forest, savanna and shrubland heath attributes.   Results: Significant models included the effects of severe fires on large stems of the closed forest dominant Allosyncarpia ternata, stem densities of the widespread savanna coniferous obligate seeder Callitris intratropica, and fire frequency and related fire interval parameters on numbers of obligate seeder taxa characteristic of shrubland heaths. No significant relationships were observed between fire regime and eucalypt and non-eucalypt adult tree components of savanna. Spatial application of significant models illustrates that more than half of the regional closed forest perimeters, savanna and shrubland habitats experienced deleterious fire regimes over the study period, except in very dissected terrain.   Main conclusions: While north Australia’s relatively unmodified mesic savannas may appear structurally intact and healthy, this study provides compelling evidence that fire-sensitive vegetation elements embedded within the savanna mosaic are in decline under present-day fire regimes. These observations have broader implications for analogous savanna mosaics across northern Australia, and support complementary findings of the contributory role of fire regimes in the demise of small mammal fauna. The methodological approach has application in other fire-prone settings, but is reliant on significant long-term infrastructure resourcing.

    AB - Aim: Fire is a key agent in savanna systems, yet the capacity to predict fine-grained population phenomena under variable fire regime conditions at landscape scales is a daunting challenge. Given mounting evidence for significant impacts of fire on vulnerable biodiversity elements in north Australian savannas over recent decades, we assess: (1) the trajectory of fire-sensitive vegetation elements within a particularly biodiverse savanna mosaic based on long-term monitoring and spatial modelling; (2) the broader implications for northern Australia; and (3) the applicability of the methodological approach to other fire-prone settings.   Location: Arnhem Plateau, northern Australia.   Methods: We apply data from long-term vegetation monitoring plots included within Kakadu National Park to derive statistical models describing the responses of structure and floristic attributes to 15 years of ambient (non-experimental) fire regime treatments. For a broader 28,000 km2 region, we apply significant models to spatial assessment of the effects of modern fire regimes (1995–2009) on diagnostic closed forest, savanna and shrubland heath attributes.   Results: Significant models included the effects of severe fires on large stems of the closed forest dominant Allosyncarpia ternata, stem densities of the widespread savanna coniferous obligate seeder Callitris intratropica, and fire frequency and related fire interval parameters on numbers of obligate seeder taxa characteristic of shrubland heaths. No significant relationships were observed between fire regime and eucalypt and non-eucalypt adult tree components of savanna. Spatial application of significant models illustrates that more than half of the regional closed forest perimeters, savanna and shrubland habitats experienced deleterious fire regimes over the study period, except in very dissected terrain.   Main conclusions: While north Australia’s relatively unmodified mesic savannas may appear structurally intact and healthy, this study provides compelling evidence that fire-sensitive vegetation elements embedded within the savanna mosaic are in decline under present-day fire regimes. These observations have broader implications for analogous savanna mosaics across northern Australia, and support complementary findings of the contributory role of fire regimes in the demise of small mammal fauna. The methodological approach has application in other fire-prone settings, but is reliant on significant long-term infrastructure resourcing.

    KW - coniferous forest

    KW - fire history

    KW - floristics

    KW - Landsat

    KW - long-term change

    KW - satellite imagery

    KW - savanna

    KW - small mammal

    KW - Arnhem Plateau

    KW - Australia

    KW - Kakadu National Park

    KW - Northern Territory

    KW - Allosyncarpia ternata

    KW - Callitris intratropica

    KW - Mammalia

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    U2 - 10.1111/j.1365-2699.2012.02679.x

    DO - 10.1111/j.1365-2699.2012.02679.x

    M3 - Article

    VL - 39

    SP - 1303

    EP - 1317

    JO - Journal of Biogeography

    JF - Journal of Biogeography

    SN - 0305-0270

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    ER -