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The Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH, UK l.dawson{at}macaulay.ac.uk
Resistant compounds associated with vegetation have potential for understanding and uniquely describing soil. Although much of the forensic identification of soils has focused on the mineral component, this study illustrates how the origin of the organic component can be a useful tool in soil identification. The epicuticular wax of most plants containts mixtures of hydrocarbons (mainly n-alkanes) and plant species differences are persistent. Evidence from three separate studies is compiled to show the validity of this approach. In the first example, on upland grassland vegetation, the n-alkane pattern of the soil at one site reflected that of the overlying grass, whereas at another site, it reflected that of the previous vegetation, heather. In the second study, n-alkane analysis data indicated the presence of heather in a buried horizon, matching independent evidence from pollen identification. The third study was one covering the whole of Scotland, using an unbiased grid-sampling strategy. Results show that the patterns in the soil n-alkane profiles reflected the overlying vegetation. Where this was not the case, the profiles matched previously grown vegetation. Such biomarker information, derived from plant wax signatures, coupled with soil spatial information, has potential in the unique identification of soils.
