Ontogenesis, ontogenetic structure and assessment of the state of Melilotus albus (Fabaceae) cenopopulations in Central Yakutia

Melilotus albus Medic. (Fabaceae) – annual/biennial plant with elongated shoots. In Central Yakutia, in the ontogeny of M. albus, 6 ontogenetic states have been identified: se – seeds, p – seedlings, j – juvenile, im – immature, v – virginal, g – generative. M. albus is renewed only by seed. M. albus is a species alien to Yakutia, where it was introduced at the beginning of the 20th century, and is found in the central and southern parts of the republic. All studied cenopopulations are normal and incomplete. The M. albus density is mainly affected by the humidity of the habitat. In moist areas, plants of M. albus quickly gain weight and suppress the growth and reproduction of other species. With low anthropogenic load, heavy precipitation in June causes rapid germination of honey clover, and by mid-summer – the development of groups of immature individuals. The predominance of the generative individuals in ontogenetic spectra can be observed in the absence or under low anthropogenic load and sufficient moisture (near water bodies, during irrigation). High anthropogenic load (grazing, mowing) increases the proportion of virginal individuals. With sufficient moisture under the forest canopy, the proportion of the juvenile individuals increases. M. albus displays itself as a flexible species – drought-resistant, shade-tolerant, resistant to soil compaction and trampling, as well as mechanical damage. Due to the accumulation of coumarins in the generative phase of development, adult M. albus are not consumed by horses, but suffer mechanical damage. Therefore, horse grazing is not a limiting factor for the development of M. albus. The total score assessment of M. albus cenopopulations showed that the habitat moisture and the absence of anthropogenic load are the main success factors for growth and development of the species. Regular annual mowing of M. albus causes a decrease in individual biometric indicators even with sufficient moisture in the habitat.