Response of earthworm abundance, diversity, survival, and growth to soil pH and calcium availability

Acidic deposition has decreased soil pH and calcium availability in areas with low buffering capacity, such as the Adirondack Region of New York (Adirondacks). Crushed limestone (lime) additions may be used to restore calcium, increase pH, and ameliorate the negative effects of acidic deposition. We studied earthworms at limed and un-limed forested watersheds in the Adirondacks and Madison County, New York, where soils are well-buffered by limestone bedrock. We additionally studied growth and survival of two exotic taxa (Eisenia foetida and Amynthas sp.) in limed and un-limed Adirondack and Madison County soils in microcosms. Earthworms were more abundant and diverse in Madison County (16.2 individuals m^-2; 9 spp) than at Adirondack sites (1.1 m^-2; 1 sp). Amynthas tended to grow better in limed treatments (F_{1, 10} = 4.769; P = 0.054), and survival was highest in Madison County soils (F_{1, 32} = 24.568; P < 0.001) and in limed treatments (F_{1, 32} = 18.576; P < 0.001). Survival of Amynthas was very low in un-limed Adirondack soils. Eisenia grew best in Madison soils (F_{1, 23} = 5.181; P = 0.032) and limed treatments (F_{1, 23} = 53.149; P < 0.001), and survival was high in all treatments. This study supports the notion that acidic soils tend to be associated with lower density and diversity of earthworms in forests, though species differ in sensitivity to acidic conditions. Sensitivity of Amynthas, which is a new immigrant to upstate New York, may limit the ultimate geographic extent of its North American invasion.