Dependence of Great Basin Bristlecone Pine on Clark's Nutcracker For Regeneration at High Elevations

Abstract

Great Basin bristlecone pine, Pinus longaeva D.K. Bailey, has small, winged seeds typical of wind-dispersed conifers. It is characteristically found on rigorous sites at high elevations. On such sites it regenerates far more frequently from seed caches of Clark's nutcracker, Nucifraga columbiana Wilson, than from wind-dispersed seeds. On mild low-elevation sites where it rarely occurs, however, bristlecone pine establishes predominantly from wind-dispersed seed. Thus, most populations of bristlecone pine are maintained by nutcrackers on sites to which the species is only partially adapted, but which it can tolerate.