Range Edge Red Spruce in New-Jersey, USA - Bog Versus Upland Population-Structure and Climate Responses

Red spruce (Picea rubens Sarg.) was investigated at its lower elevational range limit in northwestern New Jersey, USA, where small disjunct populations of scattered young trees occur in bogs and on adjacent rocky upland slopes. The bog habitat, unusual for the species elsewhere in its range, supported slower tree growth but more robust populations, with older trees, more cone production, more trees of canopy status, and higher seedling densities. Surrounding upland slopes supported short-lived, increasingly drought-sensitive populations with somewhat higher incidence of nonlethal adelgid galls and old leader damage.