The Ecology of Earthworms in Cattle-Grazed Machair in Tiree, Argyll

Abstract

In a discussion of the distribution of the Lumbricidae in the shell-sand-peat complex of the Hebrides (1957a), and later in a detailed description of the distribution on a dune-machair (mature maritime grassland) transition in Tiree, Argyll (1957b), Boyd has drawn attention to the effects of naturally deposited bullock droppings on the species complex. These effects are now more thoroughly investigated in an area in the island of Tiree, Argyll, where the ground is flat, grazed only by cattle, and where the soil, vegetation and drainage are highly uniform. By selecting such a uniform type of habitat it was hoped to eliminate other large-scale ecological variation, and outline clearly the effect of the dung. Evans & Guild (1947, 1948b) discussed the seasonal abundance of some British earthworms including two species present in the population now under examination, and (1948a) the reproductive cycle of several species including two present here, relating all to temperature and moisture content of the soil. The seasonal abundance and reproductive cycles of the machair population in Tiree are examined here and comparisons drawn with the findings of Evans & Guild.