The colonization of a habitat by earthworms primarily de-
pends upon food and water supply. Accordingly, there is
considerable variation in the number of earthworms per
square metre:
Low-input pasture400–500 earthworms
Fertilized meadow200–300 earthworms
Hardwood forest150–250 earthworms
Low-input arable field120–250 earthworms
Poor grassland30–40 earthworms
Spruce forest10–15 earthworms