In this undergraduate thesis, we used dendrochronological analysis of silver fir to determine its response to changing climatic conditions on the Bohor Mountain. We took cores from 20 selected trees. We measured the tree-ring width of the cores using the tool ATRICS. For the analysis, we entered the tree-ring widths into RStudio, where we performed the analysis using the dplR, treeclim and pointRes software libraries. We compared the measured data with climatological data from KNMI Climate explorer (Climate explorer …, b. l.). We performed static and sliding correlation analysis with a window of 25 years. We compared 3 parameters between 1955 and 2018: monthly precipitation, average monthly temperature and maximum monthly temperature. Our results showed a positive static correlation between growth and precipitation in July, average temperatures in February and September and maximum temperatures in February. Based on sliding correlations, we found that precipitation in July of the current year always had a positive impact, but in the last quarter of the 20th century, the positive impact of precipitation increased from June to August, both in the current and previous year. We also found with sliding correlation analysis that in recent decades, maximum and average temperatures from June to August have a significantly more negative correlation than in the past. We performed a descriptive analysis of pointer years. We determined 8 pointer years: 3 positive (1974, 1997, 2008), 5 negative (1957, 1976, 1993, 2003, 2013). We managed to confirm the sensitivity of fir to summer temperatures, that it responds to dry years with a lower growth rate and that elevated temperatures have a negative impact on its growth rate. We confirmed the increase in the impact of precipitation on fir growth, but further research would be needed to confirm our findings.
|
