Ecology

Abstract

To estimate earthworm populations, some method of determining the number of worms in small sample areas is necessary. Most of the early studies involved digging up soil samples and sorting these by hand (Stockli, 1928), and indeed many workers still use this method, except that they take cores or quadrats of soil of exact dimensions to enable accurate population estimates to be made. Workers who have estimated populations by handsorting include Bretscher (1896), Bornebusch (1930), Ford (1935), Hopp (1947), Reynoldson (1955), Low (1955), Svendsen (1955), Wilcke (1955), Barley (1959), Van Rhee and Nathans (1961), El-Duweini and Ghabbour (1965). Zicsi (1962) compared the efficiency of samples of sizes 0.06, 0.25, 0.5 and 1.0 m², taken with a square sampling tool, for estimating populations of earthworms by handsorting. He concluded that sixteen sample units of an area of 1/16 m² taken to a depth of 20 cm gave an adequate estimation of a population of medium-sized species. For larger worms and deeper samples, a larger area of deeper sample was required.