The effects of soil horizons and faunal excrement on bacterial distribution in an upland grassland soil

There were no differences in bacterial density between areas dominated by excrement from earthworms and excrement from enchytraeids, although densities in both areas were significantly increased by liming. Variability in bacterial density at spatial scales of less than 1 mm was linked to the occurrence of excrement. Bacterial densities within areas of both types of excrement were significantly greater than those in the surrounding soil. However, the frequency distribution of the ratios of density in excrement to that in the soil was bimodal, with a majority of occurrences having a ratio near 1 and only some 20-30% having a much larger ratio. These variations can probably be explained by variations in the age of the excrement and its suitability as a substrate.