Pärn, H. 2009. Temporal History of Relationships between Scots Pine (Pinus sylvestris L.) Growth and Mean Monthly Temperatures.  Baltic Forestry 15 (1): 48-57

The study on the temporal variation in relationships between the radial growth of Scots pine (Pinus sylvestris L.) stands and mean monthly temperatures was performed using the radial growth parameters of three pine stands in Estonia and one stand in Russia. Stands were of different age and have different site conditions. The variability of the growth - temperature relationships was studied by computing and comparing the correlation coefficients between radial growth and mean monthly temperatures from January to August for 30-year, 60-year and 100-year moving periods with a step of one year. The variability, expressed by variances in the time series of the correlation coefficients, is large and decreases significantly with the lengthening of the moving period. The analysis revealed pronounced trends in the correlation coefficients in all stands. The trends were ascending when average monthly temperatures of winter and summer months were used and predominantly descending in spring months. The values of the overall average correlation coefficients decrease, not depending on the stand age, with the lengthening of the periods. Although most relationships between periodical correlation coefficients and mean monthly temperatures of the same periods were statistically significant, the best correlations were generally obtained if average monthly temperatures of periods beginning 15–25(30) years ago were used.

Key words: Tree rings, Scots pine, temperature, variability, trends