Climate warming disturbances periodicity of Siberian stone pine seed production (Pinus sibirica Du Tour)

Abstract

Siberian stone pine is one of the main edificator plants of taiga forests of Western Siberia. Sustainable functioning of forest ecosystems depends on its successful cone crops, as its seeds are the basis for the diet of many forest animals. A cone crop in this species is characterized by pronounced interannual variability, manifested in the formation of high seed yields once in 3-4 years. However, in the last 20 years, high yields have been rare, replaced by years with average and low yields. To establish the reasons for these changes, the dynamics of seeding in the period from 1990 to 2023 and weather conditions in spring in the pollination year during the same period were analyzed. It was found that the number of mature cones in the crown largely depended on spring weather in the year of pollination and was negatively correlated with the sum of active temperatures above +5°C accumulated before the late spring frost. If frost occurred at SAT above 300°C, the following year’s crop was minimized. Analysis of weather conditions showed that, on average, there is a tendency to shift the dates of the last frosts to later dates, and even a short-term decrease in temperature to -1 °C leads to complete death of the future crop of cones. Despite the growth of heat availability in the spring period due to active temperature increase in April, the expected shift of frosts to earlier dates is not observed in the south of Western Siberia. For Siberian stone pine, such situation is fraught with strengthening of negative trend in seeding dynamics. It is supposed that at further climate warming the beginning of spring development of reproductive structures will occur at earlier dates, so reproductive structures will be more damaged by late spring frosts, since the latter remain within the same time frames.