Soil production in heath and forest, Blue Mountains, Australia

Influence of lithology and palaeoclimate

Marshall Wilkinson, John Chappell, Geoff Humphreys, Keith Fifield, Bart Smith, Paul Hesse

    Research output: Contribution to journalArticle

    67 Citations (Scopus)

    Abstract

    Recent determinations of soil production from in situ cosmogenic nuclides indicate that production decreases exponentially with soil depth. This contrasts with a long-held assumption that maximum soil production occurs under a soil cover of finite depth. Sites in the Blue Mountains, Australia, show a sharp decrease of soil depth where vegetation changes from forested plateau surfaces to heath-covered spurs, and bands of bare rock in the heath suggest that soil production depends on presence of a finite depth of soil. The substrate varies from hard ferruginized sandstone to soft saprolite. In situ 10Be determinations indicate that apparent rates of erosion and soil production are greater under the relatively thin heath soil than under the thicker forest soil but, in contrast to other studies, these sites do not show significant depth-dependence of apparent soil production. The pattern reflects both hardness variation in the rock substrate and the effect of Late Quaternary climatic change. Optically stimulated luminescence (OSL) dating indicates that soil ≤30 cm depth is of Holocene age whereas the deeper soil is substantially older. The age-break coincides with a stone line interpreted as a former surface lag deposit. Assuming that pre-Holocene soil depths were 30 cm less than today, recalculated soil production tends to decrease with increasing depth. Soil production at this site requires soil cover but bare rock patches and vegetation comprise a shifting mosaic. In the long term, average rates of erosion and soil production decrease with increasing soil depth.

    Original languageEnglish
    Pages (from-to)923-934
    Number of pages12
    JournalEarth Surface Processes and Landforms
    Volume30
    Issue number8
    DOIs
    Publication statusPublished - Aug 2005

    Bibliographical note

    An erratum for this article exists and can be found in Earth Surface Processes and Landforms, vol. 30, issue 13, pp. 1683-1685. DOI: 10.1002/esp.1311

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