In this thesis, we used stable carbon isotopes in silver fir (Abies alba Mill.) tree rings to investigate the species response to environmental changes at a lowland, non-carbonate site in Grmače near Litija. From six isotopic samples, we extracted homogeneous wood powder from each tree ring. The carbon isotopic composition of the samples was determined using the Thermal Conversion / Elemental Analysis – Isotope Ratio Mass Spectrometry. The results are expressed as δ-values (‰). We then compared these measurements with meteorological data from the Ljubljana Bežigrad station for the period 1948–2023. During the period of increased environmental stress (1960–1995), the fir treesshowed reduced radial growth and less negative δ¹³C values, which can be associated with sulfur dioxide pollution. After 2000, δ¹³C values continuously decreased, indicating the influence of climate change. The chronologies of the samples showed strong alignment, particularly in the years 2003, 2017, and 2022. Statistical
analysis revealed very strong correlations between the stable isotope ratios in the rings and average monthly temperature data, with the highest correlation observed for the month of June. This confirmed the temperature sensitivity of fir growth in June on a regional scale. No statistically significant correlation was found between the isotope ratios and precipitation, likely due to sufficient water availability at the study site. The
results highlight a specific response of the studied site, suggesting that further research incorporating additional environmental parameters would be valuable to better understand the impact of climate change on plant growth.
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