Reaction of coniferous trees in the Kuznetsk Alatau alpine forest-tundra ecotone to climate change

In recent decades there has been an increase in the radial growth of Larix sibirica Ledeb., Pinus sibirica Du Tour, and Abies sibirica in the Kuznetsk Alatau alpine forest-tundra ecotone. Larch growth correlates positively with summer temperatures; cedar and fir growth is determined by temperature, precipitation, and sunshine duration. It is shown that the current growth of maturing larch trees is about 55% higher than that of a similar age group observed 200 years ago. The rate of larch advancement along the height gradient is estimated at 1 m/10 years. A periodical limitation of the radial growth in fir by winter and summer temperatures is found; the strongest correlation is revealed with summer temperatures (r = 0.9). The growth rate of all conifers correlates highly with the concentration of CO₂ in the atmosphere (r = 0.42–0.84). Increased winter temperatures induce the transformation of the elfin forms in larch and cedar (the early 1970s) and later fir (the early 1980s) into vertical forms.