SOME POPULATION SIZES AND EFFECTS OF THE ENCHYTRAEIDAE (OLIGOCHAETA) ON SOIL STRUCTURE IN A SELECTION OF SCOTTISH SOILS

This paper is a summary of the results obtained from an investigation of the occurrence of Enchytraeidae in several Scottish soils. Population counts from two sites, one consisting of a rotation of eight crops each grown on plots at four different pH levels and the other consisting of a mixed pine and larch forest, show the highest numbers of enchytraeids at low soil pH levels. Soil thin sections from five sites show that at low pH the main effects of enchytraeids on soil structure are (1) the production of a large number of small granules (faecal pellets) which later fuse to form a soil matrix, and (2) their deposition in channels, other pores and old roots. At higher pH levels enchytraeids consume earthworm aggregates and replace them with their small faecal pellets and they form new pores due to their burrowing activities.