The objective of this B. Sc. thesis was the dynamics of radial growth of Black Pine (Pinus nigra Arnold) in the Karst region based on the developmental phase of the stand, the intensity of silvicultural treatment (thinning), and the influence of climatic factors. The research utilized 100 increment cores collected from seven study plots in the Sežana Forest Management Area, encompassing managed and unmanaged stands in the thicket (letvenjak), polewood (drogovnjak), and high forest (debeljak) stages. Tree-ring widths (1897 to 2022) were measured using the ATRICS system and CooRecorder/CDendro software. Data were statistically analyzed using the T-test for independent samples and Pearson's correlation analysis, while growth was modeled using the Richard-Chapman growth function. Results showed that radial growth in managed stands was statistically significantly greater in the high forest (mean difference 0.523 mm) and polewood stages, confirming the positive impact of thinning. Conversely, in the thicket stage, unmanaged stands exhibited statistically significantly greater widths (mean difference 0.827 mm). The hypothesis that radial increment decreases with tree age was confirmed, with management effectively slowing this decline and maintaining a higher Mean Annual Increment (MAI). Climate analysis found no statistically significant connection between mean annual air temperature and increment (r = 0.16 managed, r = 0.03 unmanaged). However, a moderately positive, statistically significant correlation was identified with annual precipitation (r = 0.42 managed, r = 0.39 unmanaged). We conclude that the reduction in Black Pine growth is due to a combination of natural age-related decline and climate stress, where precipitation is a more critical factor than average temperature.
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