## 3 Results
### Pine Tree Growth Index: Relationship with Climate Variables  
Correlations Between the Growth Index and Climate Variables  
In this paragraph, we compare two periods of tree growth: (1) from the warming-driven summer temperature increase (ca. 1985, Figure 2a) to the beginning of soil drought decrease (2009), and (2) since soil and air drought decrease (2010) until 2024 y (Figure 2c). Red and green bars indicated those periods in Figure 4.  
May-June air temperatures negatively influenced tree GI during both analyzed periods. However, during the period of growth increase (2010-2023), the influence of temperature became insignificant in July-August (Figure 5a). Maximal values of the GI dependence on precipitation shifted from May (in 1985-2009) to June (2010-2024), which referred to the precipitation maximum shift to earlier dates (Figure 6).  
The precipitation pattern changed during the time interval 2010-2023 compared to 1985-2009. The maximum precipitation shifted to early dates, i.e., precipitation increased in April-July and decreased in August-September. Precipitation during the cold period (October-February) did not change (Figure 6).  
The dependence of the GI on the soil moisture (indicated by Palmer's scPDSI) significantly differed between the analyzed periods. Earlier (1985-2009), the GI was correlated with soil moisture throughout the growth period (with maximal values in May), whereas later (2010-2024) correlations with April-June soil moisture decreased due to both precipitation increase and precipitation shift to the earlier dates (Figures 5c and 6).  
The GI correlations with air drought (indicated by SPEI) were similar for both analyzed time intervals (Figure 5d). It is worth noting that the pine GI is sensitive to the soil moisture stored in the previous year (August-September) (Figure 7). Thus, \"conserved\" moisture stimulates tree growth by smoothing \"seasonal drought\" in the spring. It is notable that trees were more sensitive to stored water during low precipitation periods compared to increased ones (Figure 7a,b).  
Figure 4: The tree-ring chronology of pine trees at all sites. The maximum GI values in 2019 exceeded their historical values by 1.4 times. The red and green lines indicate mean GI values for the years 1985-2009 (0.83 \(\pm\) 0.11) and 2010–2023 (1.35 \(\pm\) 0.20), respectively. “Green” and “red” periods are used in further dendroclimatic analysis. The gray bars indicate a confidence level of \(p\) ¡ 0.05.  
Thus, the increase in air temperature as such does not limit but rather promotes the growth of pines in combination with a sufficient moisture supply. This phenomenon has been most pronounced during recent years (2010-2023), when warming has been synchronized with precipitation increase and soil and air drought decrease.  
Figure 5: [PERSON]’s correlations of GI with temperature (**a**), precipitation (**b**), scPDSI (**c**), and SPEI (**d**). The red and green lines indicate \(p\)-levels for 1985–2009 and 2010–2023, respectively. Dashed and solid lines corresponded to \(p<0.1\) and \(p<0.05\).  
Figure 6: The difference (delta) between precipitations in 2010–2023 and 1985–2009. The maximum precipitation shifted to early dates, i.e., precipitation increased in April–July and decreased in August–September. Precipitation during the cold period (October–February) did not change.