Temperature as a Key Factor in Cone Initiation of Pinus sibirica: Evidence from a 28-Year Study in Western Siberia

Siberian stone pine (Pinus sibirica Du Tour) is a long-lived gymnosperm species that dominates the taiga forests, where its successful seeding ensures a balance between forest ecosystems and the sustenance in them of diverse wildlife. Seed cone production is erratic, with exceptionally large cone crops (or mast seeding) occurring once every 3–4 years. As such, it is important to study the factors that cause this periodicity at all successive stages of crop formation, including cone initiation. Since there are very few studies on how external factors influence cone initiation, in this work, the authors focused on weather as one of these factors. The authors considered initiated cones over a 28-year period in mature Siberian stone pine trees in the southern part of Western Siberia under the influence of temperature and precipitation during the time when cone initiation is possible (for three decades from July 20 to August 20). Seed cone initiation was observed to correlate with temperature only during the first decade of August, while precipitation had no noticeable effect over the studied period. In years with high cone initiation levels, the mean temperature during the first decade of August dropped by approximately 2°C below the long‑term average for this period. On the contrary, cone initiation is limited when the temperature during the first decade of August is roughly one SD higher than the long-term average temperature for that period. The authors hypothesized that hypersensitivity of initiated cones to temperature is timed only to the start of floral induction, when the morphogenesis program inside the bud “switches” from lateral shoot initiation to cone initiation. The authors concluded that for more cones to be initiated, a short-term, at least 4–5-day, cooling to +17.5°C should occur in the first decade of August. Just during this period, short-term weather anomalies can reduce the cone number. Cite this article as: Velisevich, S., Goroshkevich, S., & Popov, A. (2026). Temperature as a key factor in cone initiation of Pinus sibirica: evidence from a 28-year study in Western Siberia. Forestist, 76, 0146, doi: 10.5152/forestist.2026.25146.