Retreating Melaleuca swamp forests in Kakadu National Park

Evidence of synergistic effects of climate change and past feral buffalo impacts

David Bowman, Lynda Prior, Siobhan De Little

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Melaleuca swamp forests form a fringe around seasonally inundated freshwater flood plains of Kakadu National Park (KNP). Previous studies based on the analysis of aerial photography reported an increase in woody plant cover on these flood plains, apparently associated with changed fire regimes, increased rainfall and possibly increased atmospheric CO2. In opposition to this woody vegetation encroachment past high densities of feral buffalo in the 1960 to mid 1980s changed the hydrology of the KNP flood plains, allowing increased penetration of saltwater causing extensive death of Melaleuca forests. Climate change has increased sea levels and there is concern that this will threaten the freshwater ecosystems of KNP. We hypothesized that Melaleuca forests that were previously impacted by high densities of feral buffalo have continued to decline because of salinization driven by sea level rise. We examined this hypothesis by overlaying georeferenced aerial photography taken in 1964, 1984 and 2004 in a geographic information environment, and then constructing generalized linear fixed effects and mixed effects models to rank the statistical strength of different drivers of Melaleuca forest contraction. We found that there has been a 5% overall contraction of Melaleuca forests over the last 50 years on our study sites, although the amount of contraction varied both geographically and temporally. The amount of Melaleuca forest contraction was greatest during the 1984-2004 interval, when buffalo densities were low. Contraction was greatest on the Melaleuca forest edges, at low-lying sites, and where high densities of buffalo were apparent in 1964. These results suggest the enduring legacy effect of past buffalo damage will amplify the effects of sea level rise on the flood plains of KNP. � 2010 The Authors. Journal compilation � 2010 Ecological Society of Australia.
    Original languageEnglish
    Pages (from-to)898-905
    Number of pages8
    JournalAustral Ecology
    Volume35
    Publication statusPublished - 2010

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    Melaleuca
    swamp forest
    swamps
    contraction
    buffaloes
    national parks
    national park
    climate change
    floodplains
    aerial photography
    sea level
    forest edge
    freshwater ecosystem
    salinization
    woody plant
    fire regime
    hydrology
    spatial data
    penetration
    effect

    Cite this

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    title = "Retreating Melaleuca swamp forests in Kakadu National Park: Evidence of synergistic effects of climate change and past feral buffalo impacts",
    abstract = "Melaleuca swamp forests form a fringe around seasonally inundated freshwater flood plains of Kakadu National Park (KNP). Previous studies based on the analysis of aerial photography reported an increase in woody plant cover on these flood plains, apparently associated with changed fire regimes, increased rainfall and possibly increased atmospheric CO2. In opposition to this woody vegetation encroachment past high densities of feral buffalo in the 1960 to mid 1980s changed the hydrology of the KNP flood plains, allowing increased penetration of saltwater causing extensive death of Melaleuca forests. Climate change has increased sea levels and there is concern that this will threaten the freshwater ecosystems of KNP. We hypothesized that Melaleuca forests that were previously impacted by high densities of feral buffalo have continued to decline because of salinization driven by sea level rise. We examined this hypothesis by overlaying georeferenced aerial photography taken in 1964, 1984 and 2004 in a geographic information environment, and then constructing generalized linear fixed effects and mixed effects models to rank the statistical strength of different drivers of Melaleuca forest contraction. We found that there has been a 5{\%} overall contraction of Melaleuca forests over the last 50 years on our study sites, although the amount of contraction varied both geographically and temporally. The amount of Melaleuca forest contraction was greatest during the 1984-2004 interval, when buffalo densities were low. Contraction was greatest on the Melaleuca forest edges, at low-lying sites, and where high densities of buffalo were apparent in 1964. These results suggest the enduring legacy effect of past buffalo damage will amplify the effects of sea level rise on the flood plains of KNP. � 2010 The Authors. Journal compilation � 2010 Ecological Society of Australia.",
    keywords = "aerial photograph, climate change, environmental degradation, floodplain, forest fire, landscape change, population density, ruminant, salinization, sea level change, swamp, woody plant, Australia, Kakadu National Park, Northern Territory, Animalia, Melaleuca",
    author = "David Bowman and Lynda Prior and {De Little}, Siobhan",
    year = "2010",
    language = "English",
    volume = "35",
    pages = "898--905",
    journal = "Australian Journal of Ecology",
    issn = "1442-9985",
    publisher = "Blackwell Publishing",

    }

    Retreating Melaleuca swamp forests in Kakadu National Park : Evidence of synergistic effects of climate change and past feral buffalo impacts. / Bowman, David; Prior, Lynda; De Little, Siobhan.

    In: Austral Ecology, Vol. 35, 2010, p. 898-905.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Retreating Melaleuca swamp forests in Kakadu National Park

    T2 - Evidence of synergistic effects of climate change and past feral buffalo impacts

    AU - Bowman, David

    AU - Prior, Lynda

    AU - De Little, Siobhan

    PY - 2010

    Y1 - 2010

    N2 - Melaleuca swamp forests form a fringe around seasonally inundated freshwater flood plains of Kakadu National Park (KNP). Previous studies based on the analysis of aerial photography reported an increase in woody plant cover on these flood plains, apparently associated with changed fire regimes, increased rainfall and possibly increased atmospheric CO2. In opposition to this woody vegetation encroachment past high densities of feral buffalo in the 1960 to mid 1980s changed the hydrology of the KNP flood plains, allowing increased penetration of saltwater causing extensive death of Melaleuca forests. Climate change has increased sea levels and there is concern that this will threaten the freshwater ecosystems of KNP. We hypothesized that Melaleuca forests that were previously impacted by high densities of feral buffalo have continued to decline because of salinization driven by sea level rise. We examined this hypothesis by overlaying georeferenced aerial photography taken in 1964, 1984 and 2004 in a geographic information environment, and then constructing generalized linear fixed effects and mixed effects models to rank the statistical strength of different drivers of Melaleuca forest contraction. We found that there has been a 5% overall contraction of Melaleuca forests over the last 50 years on our study sites, although the amount of contraction varied both geographically and temporally. The amount of Melaleuca forest contraction was greatest during the 1984-2004 interval, when buffalo densities were low. Contraction was greatest on the Melaleuca forest edges, at low-lying sites, and where high densities of buffalo were apparent in 1964. These results suggest the enduring legacy effect of past buffalo damage will amplify the effects of sea level rise on the flood plains of KNP. � 2010 The Authors. Journal compilation � 2010 Ecological Society of Australia.

    AB - Melaleuca swamp forests form a fringe around seasonally inundated freshwater flood plains of Kakadu National Park (KNP). Previous studies based on the analysis of aerial photography reported an increase in woody plant cover on these flood plains, apparently associated with changed fire regimes, increased rainfall and possibly increased atmospheric CO2. In opposition to this woody vegetation encroachment past high densities of feral buffalo in the 1960 to mid 1980s changed the hydrology of the KNP flood plains, allowing increased penetration of saltwater causing extensive death of Melaleuca forests. Climate change has increased sea levels and there is concern that this will threaten the freshwater ecosystems of KNP. We hypothesized that Melaleuca forests that were previously impacted by high densities of feral buffalo have continued to decline because of salinization driven by sea level rise. We examined this hypothesis by overlaying georeferenced aerial photography taken in 1964, 1984 and 2004 in a geographic information environment, and then constructing generalized linear fixed effects and mixed effects models to rank the statistical strength of different drivers of Melaleuca forest contraction. We found that there has been a 5% overall contraction of Melaleuca forests over the last 50 years on our study sites, although the amount of contraction varied both geographically and temporally. The amount of Melaleuca forest contraction was greatest during the 1984-2004 interval, when buffalo densities were low. Contraction was greatest on the Melaleuca forest edges, at low-lying sites, and where high densities of buffalo were apparent in 1964. These results suggest the enduring legacy effect of past buffalo damage will amplify the effects of sea level rise on the flood plains of KNP. � 2010 The Authors. Journal compilation � 2010 Ecological Society of Australia.

    KW - aerial photograph

    KW - climate change

    KW - environmental degradation

    KW - floodplain

    KW - forest fire

    KW - landscape change

    KW - population density

    KW - ruminant

    KW - salinization

    KW - sea level change

    KW - swamp

    KW - woody plant

    KW - Australia

    KW - Kakadu National Park

    KW - Northern Territory

    KW - Animalia

    KW - Melaleuca

    M3 - Article

    VL - 35

    SP - 898

    EP - 905

    JO - Australian Journal of Ecology

    JF - Australian Journal of Ecology

    SN - 1442-9985

    ER -