ONTOGENETIC AND POPULATION ANALYSIS OF IVA XANTHIIFOLIA NUTT. IN AGROCENOSES OF THE RIGHT-BANK FOREST-STEPPE OF UKRAINE

The article presents the results of a detailed ontogenetic and population analysis of the adventive species Iva xanthiifolia Nutt., which is widely distributed in the agrocenoses of field crops in the Right-Bank Forest-Steppe of Ukraine.The research was conducted on the territory of private farms in the Odesa and Vinnytsia regions, characterized by intensive farming practices.The adventive species was identified as a model species due to its high segetal potential, confirmed by high indicators of abundance, projective cover, and frequency of occurrence in the studied agrocenoses.Analysis of the age structure revealed that I. xanthiifolia populations are characterized by a high density of individuals and the formation of complete right-sided spectra of ontogenetic states.This indicates the presence of all age groups, including reproductive and senescent individuals, ensuring the population's stability and effective reproduction in anthropogenically transformed landscapes.The analysis of ontogenetic spectra based on the indices of age (Uranov) and efficiency (Zhivotovsky) showed that all studied populations belong to mature, young, and transitional types.This is typical for anthropophytes and indicates active recovery processes.A steady trend toward the transition of populations from mature or transitional types to the young type was established during the 2017 -2024 period in most agrocenoses (sunflower, winter barley, winter wheat, sugar beet).In sunflower crops (Farm "BON"), a transition from the transitional stage (Δ/ ω 0.35/0.53;2013-2016) to the young stage (Δ/ω 0.31/0.44;2017-2024) was recorded.In winter wheat crops (Farm "Zorya Podillya"), a transition from the mature type (Δ/ω 0.34/0.65) to the young type (Δ/ω 0.28/0.49)was observed.Such dynamics are likely determined by a complex of anthropogenic factors, including changes in agrotechnologies (herbicide application, soil tillage, crop rotation), climatic changes (weather conditions), and competitive interactions.The identified dynamics of the ontogenetic structure confirm the high competitiveness and ability of I. xanthiifolia for effective self-maintenance of its numbers.The results obtained are of fundamental importance for understanding the bioecology of invasive species and serve as a scientific basis for developing effective integrated control systems for the spread of marsh elder, aimed at minimizing its negative impact on the productivity of agricultural crops under conditions of intensive farming in Ukraine.