## 3 Results
### Fire Dynamics  
The fire-return intervals (FRI) since 1985, reconstructed based on satellite data and based on burn marks on trees (1835-1996), are shown in Figures 13 and 14. After the warming restart, the frequency of fires reached its maximum in the first decade of the 21 st century, with a consequent decrease. This \"fire lag\" can be attributed to the elimination of \"fuel load\" (i.e., on-ground woody debris) by previous fires. As fuels have accumulated, fires have occurred again in recent years (Figure 13).  
Figure 11: **(a)** Positive EVI trends were observed in pine forests (1–3) and in the surrounding bush–steppe (\(p<0.05\)). Positive and negative trends were observed in 23% and 1% of the area, respectively. **(b)** The difference (delta) between EVI values during (2001–2009) and (2010–2024). The positive and negative delta occurred in 22% and <1% of the area, respectively. Trends were estimated using the Theil–Sen algorithm [28]. Differences were estimated using the Mann–Whitney U-test. Period: 2001–2024. Elevations > 1000 m a.s.l. are indicated by gray. Annual EVI data were extracted from the MODIS MOD13Q1 product [29].  
Figure 12: The growth index (GI) of pine trees regressions vs GPP and NPP (mean values for all sites).  
The burning-rate increase led to a reduction in FRI. Thus, FRI at the Ulug-Hady site decreased to 5 \(\pm\) 1 years, i.e., by more than two-fold compared to its historical value (1835-1996; 12 \(\pm\) 5 years; \(p\) < 0.02). The longest FRI (ca. 28 y) coincided with the period of effective fire suppression (1983-1981, Figure 14b). The FRI for the total area of all sites was 3 \(\pm\) 2 years. Please note that due to forest fragmentation, fire might not spread over  
Figure 14: (**a**) Scots pine stump with multiple burns, and (**b**) the GI chronology with fire dates. (**c**) The pine GI before (negative values) and after (positive values) the fire (date of fire marked by “0” and arrow). (**d**) The fire-return intervals dynamics (based on the dendrochronology and Landsat data). The presented data referred to a fragment of the Ulug-Hady forest.  
Figure 13: The dynamics of burned areas caused by “single” and “multiple” (i.e., repeated) fires. The frequency of fires was maximal in the first decade of the 21 st century, followed by saturation. Data were obtained for all sites.  
the entire area. Similar FRI (2-3 years) was reported for relict pine forests in other parts of the southern pine range, and the East Trans-Baikal region [16]. In the West Trans-Baikal region, the FRI range is 4-45 years [18]. It is worth noting that an increase in the burning rate led to a significant decrease in the pine area in the Balgazyn forestry, specifically from about 20,000 ha in the 1980s to 5900 ha at the beginning of the 2000s [15]. A similar decrease in pine forests was reported in the Trans-Baikal region, where fires eliminated pines over about 16,000 ha, or 2/3 of their former area. Moreover, follow-on surface fires burned post-fire pine regeneration. In the northern part of the pine range (northern Siberia), a reduction in FRI was also reported [37]. Alongside pine, larch (_Larix sibrica_) forests in the Trans-Baikal region were partly transformed into shrub and steppe communities due to repeated fires [21].