Dendroclimatic Interpretration of Latewood Width of Conifers

1. Dendroclimatic Interpretration of Latewood Width of Conifers Kiyomi Morino, Dave Meko, and Chris Baisan Laboratory of Tree-Ring Research, The University of Arizona 6th International Conference on Dendrochronology, Quebec City, Quebec, Canada, 22-27 August, 2002 n INTRODUCTION Latewood width of conifers in the American Southwest has long been recognized as a useful proxy for summer rainfall. We are trying to refine analysis methods to use this proxy to extend information on the variability of the North American Monsoon System (NAMS). Because southeastern Arizona is situated toward the northern edge of the NAMS, the summer precipitation there is sensitive to shifts in the governing atmospheric circulation features. Fortunately, conifer species with desirable earlywood-latewood properties are common in this region. We have focused on Douglas-fir (Pseudotsuga menziesii) because of its typically sharp earlywood-latewood transition. Graph illustating statistical Link between EWW and LWW Tree photo Psme lower elevation Photos illustrating LWW features For last few years of some FLR cores: 1)sharp transition w no false 2) False ring 3) Gradual transition 4) Mssg EW? Earlywood/latewood transition is sharpest at low elevation sites for many trees we have studied in this region. Winter soil moisture is more likely to be completely exhausted before the start of summer rains at these sites than at higher elevations. Caption: importance of Age-statified sampling Caption, incl list of pcp anomalies For last few years at sr expt stn. Also transition marked AFTER start of Denser wood Plot showing rltn Of adj LWW index To n-day-mean Pcp in SE AZ Caption Graph showing age trend of EWW and LWW for Sample core Text describing Collection strategy In SE az: Monsoon Spatial variability Requires dense sampling Tsp showing weak Between station Agreement in Summer pcp anomalies ACKNOWLEDGEMENTS Research was funded by NOAA Paleoclimatology Program, Award NA86GP0454. Xing Gao dated and measured many of the ring-width series. NOTES Cores were photographed with a Spot Insight digital camera hooked up to a binocular microscope with a photo tube. The camera is described on the Diagnostics Instruments web page: http://www.diaginc.com/home.htm caption Caption: importance of Age-statified sampling