DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu
| ŠUMARSKI LIST 7-8/2022 str. 51 <-- 51 --> PDF |
greater than 3.5. The calculated tBP ranged from 3.8 (between Site 4 and Site 5) to 6.8 (between Site 1 and Site 4) and GLK from 0.553 (between Site 4 and Site 5) to 0.705 (between Site 1 and Site 3). Coefficients GLK between sites of Austrian pine trees were also statistically significant and tBP values greater than 3.5. The calculated tBP ranged from 7.0 (between Site 4 and Site 5) to 10.9 (between Site 2 and Site 3) and GLK ranged from 0.645 (between Site 2 and Site 3) to 0.986 (between Site 2 and Site 4). The determined coefficients were higher than the coefficients calculated for Scots pine trees (Table 4). These results obtained both for Scots pine and Austrian pine trees showed that there was a high similarity and a significant harmonisation between the obtained chronologies at different sites. This indicated that these chronologies were suitable to develop a regional chronology for Scots pine and a regional chronology for Austrian pine in Zavidovići-Teslić area. According to Wigley et al. (1984), a year with a minimum of 5 series of tree rings was taken as the first year of chronology. A 145-year-long regional chronology of Scots pine was obtained. The first year of the chronology was 1870 and the last 2014 (Figure 4). The average value of the tree-ring width index was 1.006, the standard deviation of the tree-ring width was 0.122, the asymmetry coefficient -0.028, and the flattening coefficient 4.967. The mean sensitivity was 0.134. In order to evaluate the quality and reliability of the obtained chronology for the analysis of the influence of climatic parameters on the formation of tree rings, the values of the EPS (Expressed Population Signal) coefficient were calculated and analysed. This parameter ranged from 0.861 to 0.952 in the period in which the influence of climatic parameters was analysed (from 1952 to 2014). The total length of the obtained regional chronology of Austrian pine was 180 years. The first year of the chronology was 1835 and the last 2014 (Figure 4). The average value of the tree ring-width index was 1.001, the standard deviation of the tree-ring width was 0.117, the asymmetry coefficient 0.099, and the flattening coefficient 3.255. The mean sensitivity was 0.136. The EPS coefficient values ranged from 0.947 to 0.956 in the period in which the climate impact was analysed. The analysis of the relationship between the obtained chronologies of Scots and Austrian pine, i.e. t-value (tBP = 8.5) and the coefficient of agreement (GLK = 0.7330; p = 0.00) revealed a very good agreement between the obtained chronologies. It meant that a significant impact of climatic conditions on tree radial growth could be expected. In order to determine the influence of climatic parameters on radial growth or formation of tree rings, we further conducted a correlation analysis of the relationship between the tree-ring index and the sum of precipitation and temperature in certain characteristic periods of the year: September and October of the previous year (so), period from November of the previous year to March of the current year (ndJFM), April and May (AM), June, July, and August (JJA), September and October (SO) and growing season (GS). The growing season at the study sites lasts from April to October. Both tree species experienced a negative effect of temperature on the formation of tree rings in the study periods, except in the period from November of the previous year to March of the current year, i.e. in the winter months, when higher temperatures positively affected radial growth. According to the correlation coefficient for Scots pine trees, the dependence of the radial growth index on temperature was statistically significant for the period from June to August. Besides the same period, Austrian pine showed statistically significant dependence for September and October of the previous year and the growing season. The influence of winter temperatures was also statistically significant in Scots pine (Figure 5). In contrast to temperature, a positive effect of precipitation was found (Figure 6). In both tree species, the correlation between the tree-ring width index and precipitation was statistically significant for the following periods: September |