Identifying potential keystone species from field data - an example from temporary ponds

Identifying keystone species is essential for understanding community dynam ics and preserving species richness. However, few studies have used quantit ative, a priori methods to identify potential keystone species. Species kno wn tu act as keystones in North Carolina (NC) temporary ponds (Notophthalmu s viridescens ns, eastern newt, and Siren intermedia, lesser siren) were te sted to see whether they played the same role in similar habitats in South Carolina (SC). Newts and sirens had no effect on anuran species richness in SC. Instead, another salamander (Ambystoma talpoideum, mole salamander) ab sent from the NC ponds was identified as a strong keystone in SC. It functi oned independently of environmental factors and the densities of other pred ators. Larval dragonflies (Tramea carolina, Carolina saddlebag) were identi fied as weak, context-dependent keystones in SC, supporting anuran richness in isolated ponds with very low pH. The results suggest that the identity of keystone species varies, even in similar habitats within a physiographic region.