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© 2017, INRA and Springer-Verlag France SAS, part of Springer Nature. Key message: Mature exotic Sitka spruce (Picea sitchensis; Bong. Carriere)-dominated stands, particularly trees of greater circumference, result in greater numbers ofGeomalacus maculosus(Allman) captures than adjacent clear-felled stands and adjacent peatland with Before-After-Control-Impact-Paired analysis indicating lower catches ofG. maculosuspost-felling. Context: The discovery of EU-protected Geomalacus maculosus in commercial plantations requires an understanding of the implications of forestry practices for the species within the context of sustainable forest management. Aims: 1.Compare Geomalacus maculosus captures across mature exotic Sitka spruce-dominated stands, previously clear-felled stands and adjacent peatland habitats.2.Assess the suitability, for forest managers, of population estimate models for G. maculosus.3.Assess the implications of felling by comparing relative abundances of G. maculosus directly before and after clear-felling at a mature exotic Sitka spruce-dominated stand. Methods: Geomalacus maculosus catches were compared at four sites across two to three mature (43–45 years old) conifer stands per site, one clear-felled stand per site, and one adjacent peatland per site using refuge traps and hand searching. Capture-mark-recapture studies were undertaken to estimate population sizes. A BACIP (Before-After-Control-Impact-Paired) analysis was undertaken in one forest stand at one forest site to determine impacts of a clear-felling event. Results: Mean catches of Geomalacus maculosus adults in the mature forest stands were over 10 and 11 times greater than mean catches on peatland and clear-fell stands, respectively. The Schnabel model for estimating population size was most suited for mature forest stands but could not be utilised for the other habitats. BACIP analysis showed a significant impact of clear-felling with a 95% reduction in mean G. maculosus catches after a clear-felling event where none of the individuals marked prior to felling were recaptured compared to 21% recapture rates at the control site. Greater tree circumference in mature conifer stands correlated with greater catches. Conclusion: Guidelines are needed to ensure the protection of Geomalacus maculosus in commercial forestry. Interventions could include patch/tall stump retention at final felling and/or translocation of the protected species.

Geomalacus maculosus is a slug species protected under EU law with a distribution limited to the west of Ireland and north-west Iberia. The species, originally thought to be limited within Ireland to deciduous woodland and peatland, has been found in a number of commercial conifer plantations since 2010. While forest managers are now required to incorporate the protection of the species where it is present, no clear species monitoring protocols are currently available. This study examines the efficacy of De Sangosse refuge traps across three habitats frequently associated with commercial forest plantations in Ireland and compares them with hand searching, a commonly used method for slug monitoring. Catch data during different seasons and under different weather conditions are also presented. Results indicate that autumn is the optimal time for sampling G. maculosus but avoiding extremes of hot or cold weather. While refuge traps placed at 1.5 m on trees in mature conifer plantations and directly on exposed rock in blanket peatlands result in significantly greater catches, hand searching is the most successful approach for clear-fell areas. Hand searches in clear-fell preceded by rain are likely to result in greater numbers caught. The results of this study form, for the first time, the basis for G. maculosus monitoring guidelines for forestry managers. © 2016, The Ecological Society of Japan

The impact of selected entomopathogenic nematodes and Phasmarhabditis hermaphrodita on the European-Union-protected slug Geomalacus maculosus and the sympatric Lehmannia marginata was investigated. There was no significant difference in mortality between slugs treated with nematodes and their controls. The presence of P. hermaphrodita in two G. maculosus cadavers may be the result of necromenic behaviour. This study constitutes the first record of P. californica in Europe.