super(13)C/ super(12)C ratios of soil organic matter as indicators of vegetation changes in the Congo

The super(13)C/ super(12)C ratios were determined for the organic matter of all horizons of a podzol profile and of the A sub(1) horizons of some ferrallitic soils, in some grass shoots and in a fossil root fragment from the B sub(2h) horizon of the podzol. The ratios in the lower horizons match those of organic matter in the A sub(1) horizons of soils under forest and that of the fossil root fragment in the B sub(2h) horizon. The ratios thus demonstrate that the humus enrichment of the B sub(2h) horizon of the podzol occurred while it was under forest vegetation and that the present grass vegetation did not take part in the podzolization process.