Composition of the soil fauna in forested and grassy plots at Delhi, Ontario

Abstract

There were several differences between invertebrate fauna collected from 15 cm deep cores taken from previously cultivated soil (now in grass) and fauna of a similar Fox loamy sand series in a nearby woodlot at Delhi, Ontario (42°51′ N, 80°30′W). Soil invertebrate populations in the grassy field were less dense (931 × 103 vs. 1853 × 103 animals/m2) and less diverse, had less than half of the biomass (1.2 vs. 2.9 g dry wt./m2), and exhibited little significant decrease in invertebrate densities with increasing soil depth compared with woodlot soil cores; woodlot soils exhibited significant decreases in invertebrate densities with increasing soil depth. The litter layer (LFH) of the woodlot provided the highest invertebrate densities and biomasses of any soil horizon tested over the 5-month sampling period. Percent abundances at both sites for most taxa were relatively similar; nematodes, protozoans, and mites were most abundant and earthworms, least abundant. The category "other arthropods" (including hexapods, myriapods, and araneids) was the largest contributor at both sites when taxa were ranked according to biomass. Earthworms were virtually nonexistent in the grassy field and were represented by only two species, Dendrobaena octaedra (Savigny) (which was dominant in both abundance and biomass) and Aporrectodea tuberculata (Eisen), in woodlot soil. Woodlot faunal densities and biomasses for most taxa were similar to comparable Eurasian sites of similar climate and vegetation.