Changes in faunal and vegetation communities along a soil calcium gradient in northern hardwood forests

Abstract

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...

Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

“…Unlike grasslands, where elevated N has often led to light limitations and subsequent competitive exclusion (13), plant growth in the herbaceous layers of forest understories is typically primarily light-limited (14) regardless of the extent of N inputs. Moreover, soil chemistry can be heterogeneous, influencing the potential of soil acidification by nitrogen deposition (15). In most arid ecosystems, moisture may be more important than nutrients in controlling plant growth during the growing season (16,17).…”

Regional growth decline of sugar maple (Acer saccharum) and its potential causes

“…Sugar maple (Acer saccharum Marsh) is arguably the most ecologically and economically important species in the northern hardwood forests of eastern North America. Ecologically, sugar maple provides nutrient-rich litter to forest soils (Long et al 2009, Lucash et al 2012, promotes N mineralization and reduces leaching of nitrate into groundwater (Lovett et al 2004), and shapes the diversity of plant and animal communities (Beier et al 2012a). Economically, the tree provides the raw materials for a profitable maple syrup industry, provides dura-ble hardwood for furniture and flooring, and offers aesthetically pleasing fall foliage (Millers et al 1989).…”

Can the eastern red‐backed salamander (Plethodon cinereus) persist in an acidified landscape?

“…To these data we added observations from 96 additional P. cinereus in the Adirondack Mountains based on 2009 surveys by Beier et al. (). The lowest P. cinereus abundance was one individual at site 28014 in the Adirondacks and the maximum was 33 individuals at VTEQ02 in the Green Mountains (Fig.…”

“…We also incorporated data from previous surveys by Beier et al. () in June 2009 at 12 sites in the Adirondack Mountains which involved the same search effort.…”

“…Previous research has shown that P. cinereus is sensitive to acidic soils and avoid substrates with a pH below 3.8 (Wyman and Hawksley‐Lescault , Wyman , Wyman and Jancola , Sugalski and Claussen ) and are found in greater abundances in forests with higher soil pH and base cation availability (Beier et al. ). Laboratory experiments have shown that P. cinereus exposed to acid substrates between pH 3–4 have reduced growth rates, while substrate pH < 3 caused increased sodium efflux rates and acute mortality (Wyman and Hawksley‐Lescault ).…”