Distribution of introduced earthworms in the norhtern jarrah forest of Western Australia

Abstract

Five species of introduced earthworm were recorded in the northern jarrah forest of Western Australia during 1980-83. These are Aporrectodea trapezoides (Duges), A. caliginosa (Savigny), Eisenia fetida (Savigny), Octolasion cyaneum (Savigny) (all Lumbricidae) and Microscolex dubius (Fletcher) (Megascolecidae). A. trapezoides was recorded most frequently. These introduced species occur within the forest only where there has been major disturbance, especially where forest has been replaced by pasture, orchards or settlement. They have not been recorded in forest that has been logged or in plantations of exotic trees. Introduced species of earthworm were frequently found in association with indigenous species. Most individuals of A. trapezoides kept in jarrah forest soil in the laboratory lost weight over 30 days, in contrast to an indigenous species of earthworm. How and when earthworm species were introduced is discussed in terms of the early European history of the jarrah forest.