Dendroclimatic Interpretration of Latewood Width of ConifersKiyomi Morino, Dave Meko, and Chris Baisan

Laboratory of Tree-Ring Research, The University of Arizona

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.

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.

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ACKNOWLEDGEMENTSResearch was funded by NOAA Paleoclimatology Program, Award NA86GP0454.

Xing Gao dated and measured many of the ring-width series.

NOTESCores 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

6th International Conference on Dendrochronology, Quebec City, Quebec, Canada, 22-27 August, 2002

Tree photoPsme lower

elevation

Text describingCollection strategyIn SE az: MonsoonSpatial variability

Requires densesampling

Tsp showing weakBetween stationAgreement in Summer pcp

anomalies

Caption, incl list of pcp anomaliesFor last few years at sr expt stn.

Also transition marked AFTER start of Denser wood

Photos illustrating LWW featuresFor last few years of some FLR cores:1)sharp transition w no false2) False ring3) Gradual transition4) Mssg EW?

caption

Graph showing age trend ofEWW and LWW for

Sample core

Caption: importance ofAge-statified sampling

Graph illustating statisticalLink between EWW and

LWW

Caption: importance ofAge-statified sampling

Plot showing rltnOf adj LWW index

To n-day-meanPcp in SE AZ

Caption