# Siberian Pine and Larch Response to Warming-Drying Climate in the Southern Boundary of Their Range
## 5 Conclusions  
The warming restart stimulated an increased growth of Siberian pine and larch in areas with sufficient precipitation (high elevations and treeline ecotone), whereas warming negatively influenced both species' growth at low elevations. However, the species' responses to warming are different. Thus, the Siberian pine's sensitivity to moisture variables strongly increased. In addition, the growth dependence on temperature switched from positive to negative. Larch growth experienced less significant changes. Larch is migrating in both uphill and downhill directions, while Siberian pine is migrating uphill only. Increasing early spring temperatures decreased both species' growth, although larch is more predisposed to that because it may \"flash needles\" while the water supply is still blocked in the frozen soil. Since the warming restart, the growth of both species (especially Siberian pine) became sensitive to soil water that was stored in the previous year. That water smooths the moisture stress at the beginning of the growing season. Siberian pine gradually decreased its proportion in the mixewood (minus 12%), whereas areas of larch and birch strongly increased (plus 150% and 100%, respectively). Forest loss occurred at low elevations (c. <1300 m), whereas forest gain occurred at high (>2000 m) elevations. The upper boundary of forests and shrubs shifted uphill (+30 and +10 m, respectively). The annual upslope migration rates of the closed forests and shrubs are estimated at 0.8 and 0.3 m/yr, respectively. Notably, winter winds suppressed the growth of both larch and Siberian pine trees in the treeline and at high elevations.  
In the warming-drying climate, the retraction of Siberian pine (as well as other moisture-sensitive conifers, i.e., _Abies sibirica_ and _Picea obovata_) in the southern low elevations should be inevitable due to their narrow ecological niches. Consequently, afforestation must not be based on the planting of Siberian pine but on planting drought-tolerant larch species.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/f15061054/s1](https://www.mdpi.com/article/10.3390/f15061054/s1)]([https://www.mdpi.com/article/10.3390/f15061054/s1](https://www.mdpi.com/article/10.3390/f15061054/s1)), Figure S1: A May-September air temperature strong increase since c. 1997 (arrow) observed occurred throughout Northern Hemisphere.  
Conceptualization, I.A.P. and V.I.K.; methodology, V.I.K. and I.A.P.; validation, V.I.K., A.S.G., S.T.I. and I.A.P.; formal analysis, S.T.I., I.A.P. and A.S.G.; investigation, V.I.K.; S.T.I. and I.A.P.; resources, S.T.I., A.S.S., A.S.G. and S.O.O.; data curation, S.T.I., I.A.P. and A.S.G.; writing--original draft preparation, V.I.K. and I.A.P.; visualization, S.T.I., I.A.P., A.S.G. and A.S.S.; supervision, V.I.K. and I.A.P.; project administration, V.I.K.; funding acquisition, V.I.K. and S.O.O. All authors have read and agreed to the published version of the manuscript.  
The research was funded by the Tomsk State University Development Program (\"Priority-2030\") and Russian Science Foundation (project No. 23-14-20015).  
The data presented in this study are openly available: climate data in [[https://cds.climate.copernicus.eu/cdsapp](https://cds.climate.copernicus.eu/cdsapp)]([https://cds.climate.copernicus.eu/cdsapp](https://cds.climate.copernicus.eu/cdsapp)) (accessed on 15 September 2023); SPEI in [[https://spei.csic.es/map/maps.html](https://spei.csic.es/map/maps.html)]([https://spei.csic.es/map/maps.html](https://spei.csic.es/map/maps.html)) (accessed on 15 September 2023).  
The authors declare no conflicts of interest.