Temporal Stability and Dendroclimatology in Silver Fir and Red Spruce By Kevin T. SMITH 1) , Katarina ČUFAR 2) & Tom LEVANIČ 2) K e y w o r d s : Dendrochronology, climate change. Summary SMITH K.T., ČUFAR K. & LEVANIČ T. 1999. Temporal stability and dendroclimatology in silver fir and red spruce. - Phyton (Horn, Austria) 39 (3): (xxx) - (xxx). Dendroclimatology uses precisely dated tree-ring series and climate measurements to reconstruct climate for periods prior to instrumented records. Dendroclimatology requires a predictable, relationship between growth and climate. Tree-ring series from silver fir in Slovenia and red spruce in the northeastern US were calibrated to monthly climate variables for two periods, corresponding approximately to the first and second halves of the 20th Century. Bootstrapped response function analysis indicated that growth during the two periods was associated with markedly different variables of monthly mean temperature and monthly total precipitation. These findings suggest caution in dendroclimatic reconstruction and are interpretable as indications that the relationship of tree growth to climate may have changed during the 20th Century. Introduction Dendroclimatology reconstructs past climate patterns through mathematical models that relate precisely dated tree-ring records to climate measurements (FRITTS 1976). The mathematical relationship is then extrapolated to tree-ring series formed prior to climate measurement. Such dendroclimatological reconstructions depend on a predictable linkage of growth to climate. Recent research questioned the stability of the dendroclimatic relationship for trees at high elevations and far-northern latitudes across the northern hemisphere (BRIFFA & al. 1998). In this research we examine the temporal stability of the dendroclimatic 1) US Forest Service, P.O. Box 640, Durham, New Hampshire, 03824, USA. Fax: +1 603- 868-7604, e-mail: kts@hopper.unh.edu 2) Biotechnical Faculty, University of Ljubljana, Rozna dolina c. VIII/34, 1001 Ljubljana, P.O.Box 95, Slovenia. Fax: +386 (0) 61 123-50-35. Phyton (Austria) Special issue: "Plant Physiology" Vol. 39 Fasc. 3 (117)-(122) 30. 11. 1999