Abiotic and biotic factors influencing the colonization of woody plants by mistletoe

Abstract

Aims. The aim of the study is to analyze the natural factors that determine the extent of the spread of white mistletoe (Viscum album subsp. album) in different regions of Ukraine, as well as to clarify their role in the formation of expansive processes in tree plantations. Methods. The study is based on a summary of literature data and our own visual observations of the condition of trees and shrubs. Particular attention was paid to urban phytocenoses, where mistletoe expansion was most widespread. The climatic conditions, morphological and chemical properties of host trees, as well as the role of various bird species in seed dispersal were considered.
Results and discussion. It has been established that the leading abiotic factor in the spread of mistletoe is climate warming, which expands its range and increases the number of potential hosts. Biotic factors are related to the characteristics of woody plants and avifauna. The success of seed attachment depends not only on the thickness of the bark, but also on its chemical composition, in particular the content of polyphenolic substances. Birds play a significant role in spreading mistletoe. Their large numbers, supported by anthropogenic factors (landfills, easily accessible food sources), contribute to the rapid spread of mistletoe in urban agglomerations. There is also a pattern of increasing infestation of trees with age. At the same time, the level of resistance of individual tree species to mistletoe colonization is not always clear and varies significantly depending on local conditions in the region. Conclusions. The expansion of white mistletoe in Ukraine is a complex ecological phenomenon caused by the interaction of abiotic and biotic factors. The most important of these is climate warming, which ensures the expansion of the range and increased aggressiveness of the semi-parasite. The morphological and chemical characteristics of host trees determine the specifics of local colonization processes. The significant participation of synanthropic bird species in the spread of mistletoe in cities indicates a close relationship between natural and anthropogenic factors. The growth in the number of mistletoe poses a threat to the stability of plantings (primarily urban) and requires further scientific study and the development of effective measures to control and combat this phenomenon.