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English summary: Land-snails in rich fens in the province of Västmanlands län (C. Sweden), with comments on the species and recommendations of conservation measures for the investigated objects At the request of the local nature conservation unit of the province of Västmanlands län, 18 fen objects were investigated for land molluscs 2007-2008. The location of all investigated sites is presented in Figur 1. The rich fens in the province of Västmanland can, according to the land mollusc fauna, mainly be classified as intermediary rich fens or transition fens to the extreme rich type. Pronounced extreme rich calcareous fens (often with springs) are rare, and only four of the investigated objects can be classified as such. Several of the fens are mosaics, with different types of transitions. More closed parts, which have to be classified as marsh forests, are often closely connected to the open fens. The most characteristic species for the intermediate rich fens is Vertigo lilljeborgi, which occurred in almost all the investigated sites. It is often accompanied by other, less demanding hygrophiles, such as Euconulus praticola and Deroceras laeve. In four of the richer fens the fastidious, rare and red-listed Vertigo geyeri was found – it can be considered a very characteristic species for the richest type of calcareous fen habitats. These records confirm the occurrence of the species in the province of Västmanlands län. Only one older, geographically bad defined record was previously known – and the species was considered extinct. In one site V. geyeri co-existed with the likewise rare and red-listed Perforatella bidentata – a species, which is known from a few sites in the area, mostly of more closed character (marsh forests). A few of the sites have a more eutrophic character and harbours Vertigo antivertigo, which is rare in the central and northern parts of Västmanland. The rich fens in the province of Västmanlands län are exclusively of the ‘woodland type’, dominating in Central and Northern Sweden. In this area, forest felling and connected drainage undertakings, have been the major causes of destroyed fen habitats, and hence the disappearance of V. geyeri. A few decades ago, before drainage in woodlands was forbidden by law, this led to a large extent of destruction of valuable marsh forests and fen habitats in Central and Northern Sweden (cf. results from the neighbouring provinces of Gästriklands and Uppsala län). Conservation measures are proposed for each object, and it is considered as especially important that the four sites harbouring V. geyeri are kept in such a way that their character, as open fens are preserved – to secure the survival of the species. På uppdrag av Länsstyrelsen i Västmanlands län har ett antal rikkärrsobjekt inventerats med avseende på landmolluskfaunan. I inventeringarna har ingått: Undersökning av landmolluskfaunan på 15 utvalda objekt (18 lokaler, i vissa större objekt har mer än en punkt inventerats). Objekten finns redovisade i avsnitt 6 nedan och deras läge framgår av kartan (Figur 1). Objekten har utvalts av länsstyrelsen enligt kriterierna: Befintliga naturreservat, blivande naturreservat, källkärr, extremrikkärr, rikkärr där skötselinsatser är tänkbara, rikkärr som tidigare inventerats och/eller finns omnämnda i en rapport om landmolluskfaunan i Västmanlands län (Waldén 2001). Inventeringarnas syfte har varit: Att ge aktuell information om landmolluskfaunans sammansättning i västmanländska rikkärr och eventuell förekomst av rödlistade och/eller sällsynta arter. Att med särskild hänsyn till landmolluskfaunan, och särskilt förekomsten av rödlistade och/eller sällsynta landmollusker, ge skötselrekommendationer för de undersökta objekten. Fältarbete, rekognoscering och provtagning, liksom bestämningsarbete, sammanställning och rapportskrivning har genomförts av 1:e museiintendent Ted von Proschwitz. Kontaktpersoner på Länsstyrelsen har varit Karin Wiklund, Åsa Hedin och Markus Rehnberg. Det tidsödande arbetet med extraktionen av snäckorna ur de insamlade sållproven har genomförts av museiintendent Elisabeth Hagström, museiintendent Birgitta Hansson och museiassistent Annika Westring. Snäckillustrationerna har ritats av Ann-Marie Kihlberg och Barbara Landelius. Texten har språkgranskats av museiintendent Elisabeth Hagström. Vid sammanställningen av material ur markfaunadatabasen och andra kringdata har även museiintendent Torsten Nordander medverkat. Samtliga vid Göteborgs Naturhistoriska Museum Regionala inventeringsrapporter import från MDP 2015-05 |
