## 4 Discussion  
Climate warming at the southern edge of the Scots pine range did not lead to a chronic decrease in the GI, which is the predictor of tree decline and mortality [36]. Moreover, since the warming restart, the pine growth index has surpassed its historical values. Maximal GI values occurred from 2010 to 2023, i.e., during the period of decreased soil and air drought (Figure 3). The pine tree growth index strongly correlates with the GPP and NPP in pine stands (\(r\) = 0.82) (Figure 8). Moreover, increasing trends of GPP and NPP are observed in the majority (80%-90%) of surrounding bush-steppe communities (Figures 9 and 10). Therefore, warming itself does not suppress tree growth and vegetation productivity. On the contrary, an increase in air temperature stimulates growth when combined with increased moisture supply. That phenomenon has been observed during the past decade, when increased precipitation has entailed soil and air drought decrease. In addition, the shift of precipitation maximum towards the beginning of the growth season reduced seasonal spring drought. Alongside GPP/NPP, positive EVI trends have prevailed in pine stands and surrounding vegetation communities. An EVI increase has been observed in 23% of the area, with decreases in less than 1% (\(p\) < 0.05) (Figure 11). Thereby, gross and net primary productivity increase, together with elevating EVI index values, indicate the \"greening\" of the Scots pine habitat and forest-steppe communities. According to climatic models, precipitation in the pine habitat is expected to increase to ca. 560-570 mm by 2100 (scenarios SSP4.5, SSP7.0, and SSP8.5). In addition, air temperatures are expected to rise by +2.7 \({}^{\circ}\)C (SSP4.5), +3.6 \({}^{\circ}\)C (SSP7.0), and +4.4\({}^{\circ}\)C (SSP8.5) [38,39]. Climate arity, as it is known, is estimated as the difference between precipitation and potential evapotranspiration (PET). We found that elevated temperatures will lead to an increase in PET of 505, 539, and 594 mm by 2100 (according to SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, correspondingly). Presently, the mean annual precipitation and PET were 369 and 533 mm, i.e., the \"precipitation deficit\" was about 44%. According to all scenarios, that deficit will be between \(-\)5% and +5%, i.e., there is expected to be zero deficit of precipitation by the end of the 21 st century. Thus, the results obtained for the period of warming restart support the predicted improvement in the Scots pine habitat in its southern range. Meanwhile, warming leads to an increase in extreme weather events, including periodic severe droughs and severe wildfires that threaten pine forest viability [39]. Scots pine, a pyrolytic species, can survive multiple surface fires and live for hundreds of years (Figures 14a and A1). The studied relict pine forests successfully survived wildfires throughout the Holocene period. A sufficient number of mother-trees, a positive GI, and viable and numerous seedlings in the burns indicate Scots pine resilience to observed warming. However, unprecedented warming is accompanied by an unprecedented increase in burning rate. Thus, since the warming restart, the fire-return interval has been shortened to 3 \(\pm\) 2 years, which leads to severe damage to pine seedlings and afforestation. That impairs pine forest preservation under the current fire regime. Meanwhile, it has been reported that the burning rate in some parts of Siberian taiga has decreased during the past decade due to an increase in precipitation [21]. That also might occur in the southern Scots pine habitat. In general, fire regimes, in combination with moisture supply, are major determinants of the southern pine forest preservation. Firefighting is a key factor in pine survival. It is worth noting that during the period of intense fire suppression (1950s-1980s), the FRI in pine stands reached its historical maximum (about 30 y). Presently, a high burning rate, combined with poor fire-suppression management, is a serious threat to the preservation of relict pine forests.