DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 7-8/2018 str. 32 <-- 32 --> PDF |
of the study (Schweingruber et al., 1990). In our case, thresholds of Py ≥ 1 for positive and ≤ –1 for negative pointer year was selected. The pointer year was considered when an extremely narrow or wide tree-ring was detected in at least 40 % of trees per site (Cropper, 1979; Douda et al., 2009). Results Rezultati Basic biometric characteristics of the investigated stands are presented in Table 1. Stands are 28-47 years old, considerably uniform of small diameter and height differentiation. The chronologies are calculated based on 24 series (Table 2). Mean tree diameter of the basin is 27.6 cm, with a standard deviation of 3.6 cm and mean tree height is 17.0 m with a standard deviation of 2.1 m. Mean tree-ring width is 3.1 mm. In terms of production possibilities, maximal ring width 14.0 mm recorded on the plot P5 is interesting. On this plot the highest average tree-ring width 4.1 ± 1.8 mm has also been found. Obvious it is the most productive plot. Due to the impact of the size of individuals on assessment of their incremental possibilities comparison of BAIav values appear more appropriate. According to comparison of all eight PRPs, the growth trend along the altitudinal gradient is clearly visible and confirmed by the statistical testing (Figure 2). The results of one-way analysis of variance confirm a statistically significant effect of the altitude on the dynamic of the diameter increment. The highest value of BAIav is observed in the individuals located at an altitude of 605 m. (P5), whereas the lowest BAIav value is observed at an altitude of 685 m. (P2). After recalculating of BAIav per hectare values for the model stand and to stand volume increment the same trend is maintained (Table 1). Again, a significant culmination at an altitude of 605 m (P5) is evident. Average volume increment of all grey alder stands is 4.59 ± 1.26 m3ha-1y-1. Basic characteristics of raw tree-ring series from the investigated plots are summarised in Table 2. It is worth mentioning, that the most productive plot P5 shows at the same time the lowest value of mean series sensitivity (MSs) and the highest values of Gleichläufigkeit (G). These facts present generally low variability in the tree ring widths and simultaneously a common trend in the growth. It means that grey alder finds here its ecological optimum. Values of between-tree correlation (RBT) and expressed population signals (EPS) are generally high and confirm rather good agreement between individual series at all sites and relatively low influence of non-climatic factors. The correlation of raw chronology with temperature in a current year is significantly negative. It is caused by fast decreasing growth trend and generally increasing temperatures. Decreasing raw chronology and gradually increasing April |