Aspects of the methodology of plant populations research (by means of the example of rare species)
Authors: Kyyak Volodymyr , Malynovskyі Andriy 
Published: December 2020

In this work basic concepts and problematic issues of modern population ecology of plants are considered. Quite different views on many aspects of terminology and research methodology one can observed in the scientific literature. Basic terms such as: «vitality», «age structure», «ontogenetic structure», «self-renewal», «strategy», «regeneration niche», «buffering», population size establishment, etc can be interpreted differently, which causes significant discrepancies in research methodology, and thus are reflected in the interpretation of results. The population is considered as an indivisible and unique set of individuals of one species, which is characterized by self-reproduction while maintaining its main properties. The statemen concerning the population as a unit of biodiversity accountability is justified. The study of strategy, intra-population diversity, viability and mechanisms of self-recovery has shown that the existence of populations for a long time is ensured by a certain structure. The structure of the population is a set of quantitative and qualitative components of its organization at the individual and group level, which characterize the structure and ensure the functioning of the population as a whole system. At the same time, establishing which structural elements play a leading role in the changed environmental conditions continues to be an urgent task for species of different life forms in the variety of conditions of their habitats. The example of isolated populations of rare species shows the most typical stages of structure change due to pessimization of living conditions: simplification of spatial structure, aging or pseudo-rejuvenation, reduction of vitality of individuals and population loci, reduction of self-sufficiency and reproduction, simplification and reduction of ontogenesis of individuals, predominance of death rate over birth rate, reduction of area, number and density, cessation of formation of generative individuals, cessation of undergrowth replenishment, reduction of vegetative reproduction, loss of population viability. An integral characteristic that reflects the current state of the population based on the most important individual and group parameters of structure, growth, development and reproduction is the vitality of the population. Intrapopulation structural components - population loci of reproduction - are of the greatest importance in preserving the viability of populations and ensuring the prospects of their existence in the event of adverse changes in the environment. Among population structures, the highest dynamic endurance and stability of functioning for a long time under different conditions of natural and anthropogenically altered environment were found in metapopulations. Understanding of the processes taking place on the verge of existence of the population during its emergence, and especially during the period of its loss of viability and extinction, is extremely important. However, there are still not so many researches aimed at revealing the patterns of behavior of populations during these most vulnerable periods of their long life cycle.