Field meeting - The Forest of Dean 11-12 October 2008 | The Conchological Society of Great Britain and Ireland

Authors

David Long

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This meeting aimed at examining Forestry Commission sites in the middle and towards the east side of the Forest of Dean for the presence of the old woodland fungus eater, the Slender Slug, Malacolimax tenellus [Figures 2 slug and Fig 7 attendees]. This species was recorded from near Symonds Yat in 1920 by Charles Oldham, but was not refound in the Forest and Wye Valley until 1989. Since then there have been scattered records spread over the area from the north end of the Forest to near Blakeney.

Three of the 8 sites were selected as having pre 2007 records; the others were chosen as appearing to be potential sites for the slug. Each site was searched for 30 to 60 minutes.

Sites were all on generally acid Carboniferous rocks and were in mixed deciduous woodland, or wood pasture, managed to be dominated by Oak or Beech, with varying amounts of fallen timber.

Comments on assemblages, a listing of species found and of acknowledgements, including the names of attendees is below.

Sites in order of visit were:

Foxes Bridge (SO630124) on 11 October [Fig 4] Oak dominated wood pasture. Previously unexamined for this species; one M. tenellus found by Keith Alexander under a log. Foxes Bridge Bog was not examined; there is a past record for Vertigo substriata from the Bog.
Cannop Ponds (SO 610105) on 11 October. Slightly damp mixed deciduous woodland with a glade. M. tenellus not found; but site looks likely.
Sallowvallets (SO611134), on 11 October. Slightly damp area of Oak etc bordering conifers. Previous records for this area 1989, 1990 1994, and on a pre-meeting site check on 24 September 2008. One M. tenellus found by Keith Alexander under a willow log.
Sallowvallets, Middle Ridge area (SO610135) on 11 October. Open Oak wood with cycle tracks. M. tenellus not found. Site selected as final visit before attending the excellent Ostrich Inn at Newland.
Wench Ford (SO654077) on 12 October. Mixed deciduous woodland, with a stream (the Blackpool Brook) and parking cum picnic area. Previous record 1989. One M. tenellus found by John Fleming in leaf litter by a dead Beech log.
Bullocks Beech (SO658098) on 12 October [Fig 6]. Beech wood with rides and little understorey. One M. tenellus found by John Fleming under a log, and one in similar habitat found by Rosemary Hill, another found in leaf litter by John Fleming and Peter Long
Soudley Ponds (SO662116) on 12 October. Oak and Beech wood with Luzula. M. tenellus not found.
Near “The Rookery” (SO663166) on 12 October. 1990 record for Rookery Plantations, Plump Hill. Area of Beech with nearby trackside hedge and diggings. M. tenellus not refound in fading light.

Although 37 species were found during the two days, mollusc assemblages were not highly diverse, with slugs and “Glass snails,” Zonitidae, conspicuous in leaf litter and under logs. The Zonitdae included the calcifuge Zonitoides excavatus, at 5 sites. The finds are listed by site below. Along with M. tenellus at its 4 sites the fauna included Limax cinereoniger another old woodland species (4 sites). Arion flagellus was found at 6 sites. The commonest helicid was the “Brown snail”, Zenobiella subrufescens which is associated with old woods but can live in adjoining low green herbage and small trees, including on this trip, Holly, Clematis, Bracken, and grasses. Trochulus striolatus was found at 3 sites which was unexpected, in one case associated with trackside vegetation.

It was noticeable that damper sites, such as near the Blackpool Bridge at Wench Ford, the stream in Sallowvallets and Deschampsia grass tussocks at Bullocks Beech appeared richer in species that the drier bare areas of leaf litter and fallen wood.

Acknowledgements: With many thanks to Denise Baker for arranging Forestry Commission permission for this event, to Rosemary Hill, Ron Boyce, David Haigh, Keith Alexander, John Fleming, and Peter Long for attending and providing most of the finds on the day, and to David Haigh for accompanying me on most of the preliminary site checks. Ron Boyce and Rosemary Hill provided photographs

Figure 1: Pale form of Arion flagellus found at Foxes Bridge (Ron Boyce)

Figure 2: Malacolimax tenellus with a nematode at Foxes Bridge(Ron Boyce)

Figure 3: Limax cinereoniger"juvenile" at Cannop Ponds (Ron Boyce)

Figure 4: Woodland scene at Foxes Bridge (Rosemary Hill)

Figure 5: Ron Boyce, and Peter and David Long at Foxes Bridge (Rosemary Hill)

Figure 6: The site at Bullocks Beech (David Long)

Figure 7: Attendees on 12 October, Ron Boyce, Rosemary Hill, Peter Long, David Haigh, John Fleming (David Long)