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Depletion of Ca from forest soils due to acidic deposition has had potentially pervasive effects on forest communities, but these impacts remain largely unknown. Because snails, salamanders, and plants play essential roles in the Ca cycle of northern hardwood forests, we hypothesized that their community diversity, abundance, and structure would vary with differences in biotic Ca availability. To test this hypothesis, we sampled 12 upland hardwood forests representing a soil Ca gradient in the Adirondack Mountains, New York (USA), where chronic deposition has resulted in acidified soils but where areas of well-buffered soils remain Ca rich due to parent materials. Along the gradient of increasing soil [Ca 2+ ], we observed increasing trends in snail community richness and abundance, live biomass of redback salamanders (Plethodon cinereus (Green, 1818)), and canopy tree basal area. Salamander communities were dominated by mountain dusky salamanders (Desmognathus ochrophaeus Cope, 1859) at Ca-poor sites and changed continuously along the Ca gradient to become dominated by redback salamanders at the Ca-rich sites. Several known calciphilic species of snails and plants were found only at the highest-Ca sites. Our results indicated that Ca availability, which is shaped by geology and acidic deposition inputs, influences northern hardwood forest ecosystems at multiple trophic levels, although the underlying mechanisms require further study.Résumé : L'épuisement du Ca dans les sols forestiers à cause des dépôts acides a eu des répercussions potentiellement gé-néralisées sur les communautés forestières mais ces impacts demeurent largement inconnus. Étant donné que les escargots, les salamandres et les plantes jouent un rôle essentiel dans le cycle du Ca des forêts feuillues nordiques, nous avons émis l'hypothèse que la diversité, l'abondance et la structure de leurs communautés varieraient en fonction de la disponibilité du Ca. Pour tester cette hypothèse, nous avons échantillonné 12 forêts feuillues en milieu sec dans les monts Adirondacks, dans l'État de New York aux États-Unis d'Amérique, où des dépôts chroniques ont acidifié les sols mais où il y a encore des endroits où les sols ont un pouvoir tampon élevé et demeurent riches en Ca à cause du matériau originel. À mesure que la concentration de Ca 2+ augmentait le long du gradient, nous avons observé des tendances à la hausse de l'abondance et de la richesse des communautés d'escargots, de la biomasse vivante de salamandres rayées (Plethodon cinereus (Green, 1818)) et de la surface terrière des arbres qui forment la canopée. Les communautés de salamandres étaient dominées par la salamandre sombre des montagnes (Desmognathus ochrophaeus Cope, 1859) dans les stations pauvres en Ca et changeaient progressivement le long du gradient de Ca pour devenir dominées par la salamandre rayée dans les stations riches en Ca. Plusieurs espèces calcicoles connues d'escargots et de plantes ont été observées seulement dans les stations les plus riches en Ca. Nos résultats indiquent qu...

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The Appalachian Mountains of North America hold a unique diversity of land snails, including those within the family Polygyridae genus Triodopsis. West Virginia has ten or more representatives of the genus (Hubricht, 1985), displaying variations upon the conchological theme of a depressed heliciform shape with a reflected peristome bearing three lamellae. However, it remains unclear whether all of the recognized variants on this theme represent species as commonly defined. In the case of the Triodopsis juxtidens (Pilsbry, 1894) subgroup as defined by Emberton (1988)—T. juxtidens, T. discoidea (Pilsbry, 1904), T. neglecta (Pilsbry, 1899), and T. pendula Hubricht, 1952—no penial morphology or allozyme differences are known (Emberton, 1988). Conversely, mitochondrial DNA analysis that included five T. juxtidens specimens suggests this putative species is not monophyletic (Perez et al., 2014). Rampant variation in shell morphology among Triodopsis species creates further taxonomic and identification challenges. Without additional supporting evidence for species-level differences, such as anatomical and genetic analyses, a conservative taxonomic approach is to recognize regionally distinct forms as subspecies. A unique form from the upper Bluestone River watershed is described here as Triodopsis juxtidens robinae subsp. nov.