Faunal micromorphological features in moder humus of some Western Canadian soils

Abstract

Examination of soils extending from the Arctic and Alpine to the Boreal Forest and Prairie regions of Canada showed faunal fecal material to be a significant component of all organic-rich surface layers. In particular, Collembola and Enchytraeidae appeared to play a major role in the development of microstructures within the moder humus forms. The composition of pellets within the thin mull-like moder immediately below the moder layer reflected the indiscriminate feeding habits of Enchytraeids. Fecal material of Tipulid larvae were found throughout the upper layer of moder as well as within partially decomposed leaf litter. Diptera larvae deposited small fecal pellets widely within the moder often extending to an underlying mull-like moder layer. Casts of mull-like material produced by endogeic earthworms in the moder humus were observed as individual units in the Boreal Forest-Tundra region and as a thin welded layer in the Boreal Forest-Prairie region. Fecal pellets of Diplopoda were also present in moder humus from the Boreal Forest and Prairie regions. Oribatid mites produced very distinctive fecal pellets within cavities of partially decomposed plant tissue in all humus profiles. Although morphological similarities often made it difficult to differentiate between excrement produced by different fauna, the possibility of differences in contribution to the organic cycle and plant nutrition must be recognized.