Pollination phenology of Juniperus excelsa M. Bieb. in the conditions of the Mountainous Crimea

Abstract

The studies were carried out in natural populations of Juniperus excelsa M. Bieb. in the Mountainous Crimea. Using forest taxation methods, 15 trial areas were laid within the Main Ridge of the Crimean Mountains. On each trial area there were 10 model trees allocated to conduct phenological observations of the pollen regime of the J. excelsa forest plantations. As a result of the conducted research, it was found that in 2024 there was a significant change in the timing of the beginning of pollen release of J. excelsa. The geographical differentiation of pollen dispersion has been revealed, in the central part of the distribution of J. excelsa on the southern macroslope of the Main Ridge of the Crimean Mountains at Cape Martyan, Cape Sarych and Mount Koshka, the earliest pollen flight was noted. The early onset of pollen release and unstable weather in late winter – early spring 2024 contributed to a noticeable increase in the duration of the J. excelsa pollen flight period. In the marginal territories of the eastern part of the J. excelsa range, the pollen release phase was observed 2 weeks later. It is shown that the phenological development of the male reproductive sphere in the eastern part of the J. excelsa plantings is adapted to low temperatures. This determines the specifics of the pollen regime of the eastern part of the plantations, reduces the possibility of exchanging genetic information with the central and western areas and can contribute to the development of populations resistant to low temperatures. The pollen regime of J. excelsa depends on orographic conditions. With an increase in the height of the growing area above sea level, the beginning of pollen release occurs later, its duration increases.