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| Titel |
A first attempt to reproduce basaltic soil chronosequences using a process-based soil profile model: implications for our understanding of soil evolution |
| VerfasserIn |
M. Johnson, M. Gloor, J. Lloyd |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068246
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| Zusammenfassung |
| Soils are complex systems which hold a wealth of information on both current and past
conditions and many biogeochemical processes. The ability to model soil forming processes
and predict soil properties will enable us to quantify such conditions and contribute to our
understanding of long-term biogeochemical cycles, particularly the carbon cycle and plant
nutrient cycles. However, attempts to confront such soil model predictions with data are rare,
although increasingly more data from chronosquence studies is becoming available for such a
purpose. Here we present initial results of an attempt to reproduce soil properties with a
process-based soil evolution model similar to the model of Kirkby (1985, J. Soil Science).
We specifically focus on the basaltic soils in both Hawaii and north Queensland,
Australia. These soils are formed on a series of volcanic lava flows which provide
sequences of different aged soils all with a relatively uniform parent material. These
soil chronosequences provide a snapshot of a soil profile during different stages of
development. Steep rainfall gradients in these regions also provide a system which
allows us to test the model’s ability to reproduce soil properties under differing
climates.
The mechanistic, soil evolution model presented here includes the major processes of soil
formation such as i) mineral weathering, ii) percolation of rainfall through the soil, iii)
leaching of solutes out of the soil profile iv) surface erosion and v) vegetation and
biotic interactions. The model consists of a vertical profile and assumes simple
geometry with a constantly sloping surface. The timescales of interest are on the order
of tens to hundreds of thousand years. The specific properties the model predicts
are, soil depth, the proportion of original elemental oxides remaining in each soil
layer, pH of the soil solution, organic carbon distribution and CO2 production and
concentration.
The presentation will focus on a brief introduction of the model, followed by a description of
novel methods using tracers such as optically stimulated luminescence (OSL) dates and
meteoric 10Be to evaluate the modelled processes of bioturbation and surface erosion. We
will also discuss comparisons of modelled properties with observations and conclude with
implications on our understanding of soil evolution. |
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