The distribution of lumbricid earthworm communities in relation to flatworms: a comparison between New Zealand and Europe

摘要

Earthworms play a very important role in the soil, helping to redistribute soil organic materials, enhance the availability of soil nutrients, increase soil drainage and improve root penetration. In contrast, flatworms do not actively burrow into the soil and are not known to have any beneficial effects on the soil. Indeed flatworms, such as Artioposthia triangulata, are known to be obligate predators of beneficial earthworms. Flatworms apparently have little impact on lumbricids in New Zealand, but in some areas of the United Kingdom they are reported to cause reduction of earthworm populations. Although difficult to quantify, this loss of earthworms could have a major impact on the productive capability of the soil. Concern has risen in Europe about the demise of earthworm populations consequential on the introduction of A. triangulata to Northern Ireland in 1963 and its subsequent spread. Three other lumbricid consuming flatworm species, presumed to be Australasian in origin, have also been found in the United Kingdom. They have similar characteristics to A. triangulata, and may also have a deleterious effect on earthworm populations. Consequently, some European countries,have introduced measures to slow the introduction and spread of A. triangulata. This paper compares New Zealand and northern Europe in relation to the geographical distribution and community structure of earthworms and flatworms. By comparing the prevalent earthworm ecotypes that are found (i.e. epigeic, endogeic and anecic species), the potential susceptibility of European populations of individual earthworm species to flatworm predation is evaluated.