Evaluation of the effects of climatic and nonclimatic factors on the radial growth of Yezo spruce (Picea jezoensis Carr) by dendrochronological methods

Abstract

The responses to climatic and nonclimatic factors of Yezo spruce (Picea jezoensis Carr) trees growing in a natural forest in Tomakomai, Hokkaido were analyzed by dendrochronological methods. The effects of climatic factors were examined by response function analysis. More than 70 % of the variance of ring-width and maximum-density indices was explained by climatic data from 1924 to 1965. The effect of nonclimatic factors on radial growth from 1966 to 1990 was analyzed by comparing actual indices with the estimated indices of ring width and maximum density calculated from the climatic data. Actual ring-width indices were lower than the estimated indices every year from 1969 to 1977. Actual maximum-density indices were lower than the estimated indices every year from 1971 to 1974. These results indicate that some nonclimatic factors might have affected both ring width and maximum density in the 1970s.