Ecological variability of seed production quality of Siberian stone pine (Pinus sibirica Du Tour) along the latitudinal gradient in the West Siberian Plain

Abstract

The range of Siberian stone pine (Pinus sibirica Du Tour) in the flat part of Western Siberia occupies a wide strip from the forest-steppe zone in the south to the Arctic Circle in the north, therefore, the ecological amplitude of its growth covers conditions with different heat and moisture conditions. Optimal for this species is the moderately cold and humid climate of the middle taiga. In the north of the area, growth and reproduction are limited by a cold and short growing season, in the south of the area, by insufficient soil moisture. The relevance of studying the quality of sexual reproduction in the north and south of the area is due to the observed climatic changes, since the quality of the seeds determines the potential for adaptation and advancement of the species to new frontiers. This work analyzes the ecological variability of crop quality in three populations: (1) the border of the northern taiga subzone with the forest-tundra, (2) the middle taiga subzone, (3) the border of the southern taiga subzone with the forest-steppe. Analysis of the 22-year dynamics of the formation and maturation of cones on female shoots showed that in the southern population, with good quality of cones and seeds and a high average long-term level of cone formation, there is a tendency to reduce their maturation. The number of years with high seed production has decreased. In the northern population, the quality of cones was worse due to a decrease in the proportion of fertile scales, developed and filled seeds. The seeds had a normal weight but a short embryo. The frequency of high seed production is once every ten years. With a lower average number of initiated and matured cones on the shoot, their inter-annual dynamics demonstrates a steady upward trend.