## 2 Materials and Methods
### Tree-Ring Sampling and Measurements  
For our research, we chose 20 typical junipers from every stand. We chose the healthy, undamaged junipers of I-II Kraft [31] classes with the average diameter and height for the given stand. The choice of the sample junipers was determined by the scope of growth conditions, exposition of the slope, and representation of Lithuanian natural climatic regions. The chosen junipers widely represented the whole scope of the above-listed conditions.  
In the initial phase of our research, we took the annual ring samples with the increment borer at breast height (1.3 m). The primary analysis showed that due to the often missing (sometimes more than 10 per sample) or double annual rings, it was impossible to synchronize the increment data; thus, these samples could not be used for future analysis. That made us choose another way of research: the sample junipers were cut, and the stem discs were taken from their root collar and at the heights of 0.5 and 1.3 m. This method let us synchronize the annual rings and determine if the annual rings were forming in the bottom part of the stem despite unfavorable conditions [32]. The cutting of junipers for the scientific aims was officially allowed by the local forest management and environmental authorities. In total, we sampled 480 stem discs from 160 junipers; however, the discs (63) from 21 junipers were later excluded from the further analysis due to the non-synchronic rings.  
The stem discs were dried for a month at room temperature, and then polished with a belt sander. After such preparation, the stem discs were measured using the MBS-9 microscope, with an accuracy of 0.05 mm. Due to the eccentricity of the juniper stem discs, the annual rings were measured in all 4 cardinal directions (N, E, S, W). For the further analysis, we used the average increment for every stem slice.  
As the comparison of the mean annual increment can only be conducted using synchronous tree rings, the data from all the stem discs of every sampled juniper were synchronized between themselves using the following formula, applied in the MS Excel software (Office 365):  
\[P_{r}=\frac{n^{+}}{n-1} \tag{1}\]  
where \(P_{r}\) is the similarity rate, \(n^{+}\) is the number of concurrent rings, and \(n\) is the total number of compared tree rings.  
Regarding the recommendations for other coniferous species, tree-ring dynamics with similarity rates lower than 0.5 were considered non-synchronic, those between 0.51 and 0.6--weakly synchronic, between 0.61 and 0.7--moderately synchronic, between 0.71 and 0.8--highly synchronic, and those higher than 0.8--very synchronic [33]. Junipers with the non-synchronic chronologies were excluded from the further analysis.  
The rings of the remaining samples were cross-dated using the software Tsap-Win professional 4.89, which determines the cross-dating index (cdi). For our research, the threshold cdi value was \(>\)20 at \(\alpha\) = 0.001 [34]. During the procedure, the missing or double rings were determined.  
For every juniper, we determined the pattern of radial increment using the method of the 5-year moving average with the 1-year step, based on the relatively small age of the junipers, previously made similarity analysis, and the methods used for other coniferous species [35].  
For the evaluation of the climate effect on the radial increment of junipers, we used the long-term data on temperatures and precipitation from the meteorological stations situated close to the research objects (Table 2). Regarding the measured junipers' age, we used the data for the period from 1893 to 2011.  
We used the data for the hydrologic year (from September to August) because this is the period affecting the formation of the annual rings [36]. The data consisted of monthly temperature and precipitation averages. For this analysis, we used the increment data, standardized using the TSAP-Win software. The detrending procedure was applied to the chronology of all samples. After that, the indexation procedure was applied.