THE DISTRIBUTION OF LUMBRICID EARTHWORM COMMUNITIES IN RELATION TO FLATWORMS - A COMPARISON BETWEEN NEW-ZEALAND AND EUROPE

Earthworms play a very important role in the soil, helping to redistri bute soil organic materials, enhance the availability of soil nutrient s, increase soil drainage and improve root penetration. In contrast, f latworms do not actively burrow into the soil and ale not known to hav e any beneficial effects on the soil. Indeed flatworms, such as Artiop osthia triangulata, are known to be obligate predators of beneficial e arthworms. Flatworms apparently have little impact on lumbricids in Ne w Zealand, but in some areas of the United Kingdom they are reported t o cause reduction of earthworm populations. Although difficult to quan tify, this loss of earthworms could have a major impact on the product ive capability of the soil. Concern has risen in Europe about the demi se of earthworm populations consequential on the introduction of A. tr iangulata to Northern Ireland in 1963 and its subsequent spread. Three other lumbricid consuming flatworm species, presumed to be Australasi an in origin, have also been found in the United Kingdom. They have si milar characteristics to A. triangulata, and may also have a deleterio us effect on earthworm populations. Consequently, some European countr ies have introduced measures to slow the introduction and spread of A, triangulata. This paper compares New Zealand and northern Europe in r elation to the geographical distribution and community structure of ea rthworms and flatworms. By comparing the prevalent earthworm ecotypes that are found (i.e. epigeic, endogeic and anecic species), the potent ial susceptibility of European populations of individual earthworm spe cies to flatworm predation is evaluated.