Peculiarities of the formation of phytocoenotic ranges of vegetatively propagated herbs and shrubs in forest plant groups of the Ukrainian Polissia
Peculiarities of the formation of phytocoenotic ranges of vegetatively propagated herbs and shrubs in forest plant groups of the Ukrainian Polissia

Summary/Abstract: Forest ecosystems are characterized by a vast biological diversity, comprising millions of plants, animals, fungi, and microorganisms, which interact and form complex food chains and interdependencies. Forest ecosystems contain several strata, from the litter vegetation and shrubs to the tree tops, each supporting an array of life forms and performing specific functions. The upper tier of forest provides the protection from the sun, thus controlling the microclimate at the lower levels, influencing the temperatire and soil humidity. Forests play a crucial role in the global biogeochemical cycles, such as carbon and water cycles. Trees consume carbon dioxide emissions from the atmosphere and produce oxygen through phosynthesis, mitigating the climate change. Water circulates through forest ecosystems, evaporates from the leaf surface, condenses in the clouds, and returns back to Earth as precipitation. Forest ecosystems continuously change subject to both natural and anthropogenic factors. Forests provide a variety of ecosystemic services, ranging from regulation of climate and preservation of soils to filtration of water and support of biodiversity. They also serve as living places for numerous vulnerable and endemic species, thus performing the role of natural reservoirs of genetic resources. Therefore, forest ecosystems are extremely ecologically valuable, and their preservation is crucial to a balanced functioning of the planet. Our studies were conducted in the forest ecosystems of the Desna-Stara Huta National Nature Park, located in the Ukrainian Polissia. The materials and methods of the study included systematic collection of data on the frequency of occurrence of vegetatively propagated herbs and shrubs in forest ecosystems of the Ukrainian Polissia. For the data analysis, we used statistical methods. In the studied group of plants, the largest phytocoenotic ranges, which included 7– 9 types of phytocoenoses, were observed for Vaccinium myrtillus and Maianthemum bifolium. Narrow phytocoenotic ranges, which included only 3-4 phytocoenoses, were noted for Calluna vulgaris and Aegopodium podagraria. The narrowing of phytocoenotic ranges of the forest herbs and shrubs was found attributable to the populations spreading farther away from their hytocoenotic optima. As the stress factors increased, the species and populations underwent the following transformations: decline in the level of productive process, with decrease in the size of phytomass of individuals – diminution of plant size; their reproductive potential; reduced population density; changes in the age composition of populations, where the share of plants of older ages increased, while the share of pre-generative plants declined; changes in the vital structure of populations that reflected their diversity by vital condition, shifting from prospering to depressing. In total, those processes act as a limiting mechanism of expansion of the plants’ phytocoenotic ranges. The comparative analysis of the yielded results revealed that the species individuality of phytocoenotic ranges of forest herbaceous and shrub plants of the Ukrainian Polissia is characterized by two main parameters: the width of phytocoenotic range and the abundance distribution in the phytocoenoses within their phytocoenotic range.

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