Dendrochronology of bristlecone pine; a progress report.

Abstract

Dendrochronological studies of bristlecone pine, Pinus longaeva, in the White Mountains of California have resulted in the establishment of a continuous tree-ring sequence back to 6700 B.C., a total of 8681 years. Recent collections at a site in the White Pine Range, east-central Nevada, have provided excellent material for a chronology back to 3240 B.C., a total of 5221 years. This site will ultimately provide the second longest continuous record of isotopic and paleoclimatic variation at the lower, rainfall dependent range of the bristlecone pine. The project has provided dendrochronologically dated samples for an interlaboratory calibration of the radiocarbon time scale, and continues to do so as material for selected time periods becomes available. From this standpoint of paleoclimatic research the long tree-ring series from California and Nevada provide a unique data set for investigating Holocene-modern climatic variation. The primary climatic signal that can be isolated in each series is annual moisture variability. Current efforts are directed at calibration of the tree-ring series with instrumented climatic series. Climatic reconstructions can be attempted if the statistical models that are developed survive verification testing.