Interpreting and Refining the Climate Signal in Millennial-Length 5-Needle Pine Chronologies

Investigator: Kurt Kipfmueller

In the western US, long-lived 5-needle pines (Pinus flexilis, P.albicaulis, P. balforianus, P. aristata, and P. longeava) have great potential to provide multi-millennial length records of past climate. These pines are widely distributed, grow at or near tree line, and in conjunction with their length of record, may provide better spatiotemporal estimates of temperature and moisture. However, the relationship between growth and climate in these species is often complex and difficult to interpret. This indicates the need for a systematic, widespread survey of all available 5-needle pine chronologies to disentangle the climate/growth response, and to identify individual chronologies containing regionally-representative and temporally-robust climatic information.

The goal of this project is to employ a range of strategies to investigate the nature of the climate signal in these trees and the best ways to isolate and extract the proxy climate information. Our study will be based on the 78 existing 5-needle pine chronologies archived in the International Tree-Ring Data Bank, and a number of new chronologies currently being processed. Investigations will include spatial analyses, wavelet decomposition, process modeling, and comparisons of these chronologies with those known to have a robust climate signal. If possible, we will produce a set of reconstructions that best highlights the most robust climate signals in these data, with quantified uncertainties of the estimated values. Our results will guide future work, both in terms of the use these 5-needle pine chronologies as proxies for climate data and for targeting new collections.

Collaborators: Connie Woodhouse, Peter Brown, Stephen Gray, Lisa Graumlich, Malcolm Hughes, Greg Pederson, and Matthew Salzer.