Changes over 46 years in plant community structure in a cleared brigalow (Acacia harpophylla) forest

Robert W. Johnson, William J. McDonald, Roderick J. Fensham, Clive A. McAlpine, Michael J. Lawes

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Plant succession theory underpins the development of strategies for the conservation and regeneration of native communities. Current theory has been based largely on space-for-time rather than long-term monitoring data, which have known limitations. There is general consensus that more site-specific studies are needed to corroborate existing hypotheses. The target vegetation is a brigalow (Acacia harpophylla, Mimosaceae) forest in one of Australia's most endangered ecosystems, which was cleared and burnt in 1963. Forty quadrats were placed systematically within each of six 20 m × 20 m permanent plots. Presence, density and per cent canopy cover data were recorded for each species at 18 times over 46 years. Brigalow dominated the original vegetation, assumed dominance soon after clearing through massive root suckering and remained dominant throughout the study. It achieved maximum density within two years when severe intraspecific competition led to self-thinning. After approximately 30 years, vacant niches appeared. Woody understorey species were slow to recolonise. Species richness and other diversity indices increased rapidly to a maximum after 2–4 years, declined until the 30th year when they again increased. This was the pattern of the species-rich herbaceous layer; woody species showed a steady monotonic increase. The ‘hump-shaped’ relationship between cover (biomass) and species richness was confirmed. This example fits the inhibition model for which few examples have been described. While the long-term successional pattern is slightly confounded by climatic variability preceding sample surveys, this space-for-time study not only supports a bimodal pattern of diversity over time but also indicates that the relative species richness of the herbaceous and woody layers may explain the extreme variability reported in the literature.

    Original languageEnglish
    Pages (from-to)644-656
    Number of pages13
    JournalAustral Ecology
    Volume41
    Issue number6
    DOIs
    Publication statusPublished - 1 Sep 2016

    Fingerprint

    Acacia harpophylla
    plant community
    plant communities
    community structure
    species diversity
    species richness
    suckering
    development theory
    vegetation
    ecological succession
    intraspecific competition
    self thinning
    thinning (plants)
    Fabaceae
    understory
    niches
    diversity index
    canopy
    niche
    regeneration

    Cite this

    Johnson, R. W., McDonald, W. J., Fensham, R. J., McAlpine, C. A., & Lawes, M. J. (2016). Changes over 46 years in plant community structure in a cleared brigalow (Acacia harpophylla) forest. Austral Ecology, 41(6), 644-656. https://doi.org/10.1111/aec.12354
    Johnson, Robert W. ; McDonald, William J. ; Fensham, Roderick J. ; McAlpine, Clive A. ; Lawes, Michael J. / Changes over 46 years in plant community structure in a cleared brigalow (Acacia harpophylla) forest. In: Austral Ecology. 2016 ; Vol. 41, No. 6. pp. 644-656.
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    abstract = "Plant succession theory underpins the development of strategies for the conservation and regeneration of native communities. Current theory has been based largely on space-for-time rather than long-term monitoring data, which have known limitations. There is general consensus that more site-specific studies are needed to corroborate existing hypotheses. The target vegetation is a brigalow (Acacia harpophylla, Mimosaceae) forest in one of Australia's most endangered ecosystems, which was cleared and burnt in 1963. Forty quadrats were placed systematically within each of six 20 m × 20 m permanent plots. Presence, density and per cent canopy cover data were recorded for each species at 18 times over 46 years. Brigalow dominated the original vegetation, assumed dominance soon after clearing through massive root suckering and remained dominant throughout the study. It achieved maximum density within two years when severe intraspecific competition led to self-thinning. After approximately 30 years, vacant niches appeared. Woody understorey species were slow to recolonise. Species richness and other diversity indices increased rapidly to a maximum after 2–4 years, declined until the 30th year when they again increased. This was the pattern of the species-rich herbaceous layer; woody species showed a steady monotonic increase. The ‘hump-shaped’ relationship between cover (biomass) and species richness was confirmed. This example fits the inhibition model for which few examples have been described. While the long-term successional pattern is slightly confounded by climatic variability preceding sample surveys, this space-for-time study not only supports a bimodal pattern of diversity over time but also indicates that the relative species richness of the herbaceous and woody layers may explain the extreme variability reported in the literature.",
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    Johnson, RW, McDonald, WJ, Fensham, RJ, McAlpine, CA & Lawes, MJ 2016, 'Changes over 46 years in plant community structure in a cleared brigalow (Acacia harpophylla) forest', Austral Ecology, vol. 41, no. 6, pp. 644-656. https://doi.org/10.1111/aec.12354

    Changes over 46 years in plant community structure in a cleared brigalow (Acacia harpophylla) forest. / Johnson, Robert W.; McDonald, William J.; Fensham, Roderick J.; McAlpine, Clive A.; Lawes, Michael J.

    In: Austral Ecology, Vol. 41, No. 6, 01.09.2016, p. 644-656.

    Research output: Contribution to journalArticleResearchpeer-review

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