RELATIONSHIPS BETWEEN PLANTS COMMON IN AC ID SOIL SWAMPY MEADOWS AND THE ABUNDANCE OF LYMNAEA-TRUNCATULA MULLER, SNAIL HOST OF FASCIOLA-HEPATICA LINNAEUS

Phytosociological and malacological investigations were carried out ov er June-July in 84 swampy meadows on acid soil, located in the departm ent of Haute-Vienne (France) in order to determine possible relationsh ips between the most frequent plants and the density of the snail Lymn aea truncatula. Plants present in at least 60 % of stations are hygrop hilous (Cardamine pratensis, Juncus acutiflorus, Juncus effusus, Lotus uliginosus, Myosotis scorpioides, Ranunculus flammula) or mesophilous (Anthoxanthum odoratum, Holcus lanatus). The density of L. truncatula in these meadows was studied in relation to the abundance of the most frequent three plants (Juncus acutiflorus, Juncus effusus, Lotus ulig inosus) and no significant relationship was found between the two para meters. Snail density was significantly lower when the calcium content in water was under 5 mg/l. it was also independent from plant coverin g or meadow maintenance (species of ruminants which grazed vegetation, meadow-resting). In the swampy meadows on acid soil, hygrophilous pla nts are only indicative and cannot be related to the density of L. tru ncatula.