Given the vital importance of calcium (Ca) for organisms, the depletion of Ca from forest soils due to chronic acidic deposition (‘acid rain’) has likely had pervasive effects on the diversity, abundance and structure of forest communities, but these impacts remain largely unresolved. To investigate these effects across a landscape variably influenced by acidic deposition, we sampled land snail, amphibian, and plant communities along a broad gradient in soil Ca concentration in upland northern hardwood forests of the Adirondack Mountains, New York.
Results/Conclusions

We found strong evidence for community responses of land snails and salamanders to a complex of factors including soil Ca, NO₃ and SO₄ deposition, elevation and plant community traits. With increasing soil Ca, we observed positive linear or log-linear responses of snail abundance, snail family richness, and live biomass of red-backed salamanders (Plethodon cinereus). Several snail and plant taxa were only found at 2-3 highest Ca sites, suggesting that such highly-buffered soils may support neorefugia despite chronic acid rain inputs. Our findings warrant further study to better understand how Ca availability may contribute to forest ecosystem resilience by maintaining the diversity and productivity of multiple biotic communities.