Note

Measurements of maximum and minimum density as well as earlywood and latewood thickness are measured on Swiss alpine trees using the x-ray densitometry facilities at the Eidgenössische Anstalt für das forstliche Versuchswesen, Birmensdorf, Switzerland. Methods for assuring accurate estimates of absolute density are described. The characteristics of each type of ring measurement are discussed, and their relationships to monthly temperature and precipitation data are analysed by means of Gleichläufigkeit percentages and response function techniques. The temperature during the growing season is directly correlated with the various parameters, especially with maximum density, but temperature at other times during the year and precipitation also have some influence. Four transfer functions were obtained between the treering data and temperature at four meteorological stations from July through September. Maximum density was the single tree-ring characteristic most highly related to climatic data, but a calibration using all four tree-ring variables for the growth year concurrent with climate and for the year following the occurrence of climate gave the most reliable result. In the latter case, 70.6% of the temperature variance was calibrated, and 62.4% of the variance was verified using independent climatic data from the same climatic stations. Excellent climatic reconstructions are obtained using the four tree-ring parameters derived from the densitometric measurements.