Dimensional features of Thymus serpyllum L. Emend. Mill. and Thymus x polessicus Klokov (Lamiaceae) in the conditions of different phytocenoses in the Shostka geobotanical district, Sumy region

Introduction . As a part of the different phytocenoses, Thymus serpyllum L. Emend. Mill. та Thymus x polessicus Klokov undergoes significant anthropogenic effects and requires detailed study and development of measures for the reservation and reproduction of its populations. The issues of changing the morphometric parameters, depending on the forest site type and the stand density, remain not well studied. The study of dimensional features Th. serpyllum та Th. polessicus allows to interfere purposefully in the processes of growth and development of plants, to use more fully the natural properties of plants, to preserve and reproduce the population and increase its productivity. In this article analyzed the dimensional features Th. serpyllum and Th. polessicus plants in different  phytocenoses in Shostka geobotanical district of Sumy region. Purpose . To estimate dimensional features of Thymus serpyllum L. Emend. Mill. та Thymus x polessicus Klokov (Lamiaceae) and to their main morphometric features in different  phytocenoses in Shostka geobotanical district of Sumy region. Methods. To determine the dimensional parameters of plants of the researched species, we made a morphometric analysis. For this purpose, a number of static metric and static alometric parameters were evaluated in the studied cenopopulations. Based on the generally accepted approaches of morphometric analysis such parameters from the number of static metric parameters were determined, in particular, the height of the main shoot (H), the diameter of the main shoot (D), the number of leaves (NL), and the buds (B), the total weight of the plant (W), of all leaves (WL) and of one leaf (W1L), total weight of generative organs (Wg) and total area of leaf surface(A). From static alometric parameters we estimated leaf area ratio (LAR=A/W), leaf weight ratio (LWR=WL/W), heartwood ratio (HWR=H/W), height diameter ratio (HDR=H/D), absolute diameter ratio (ADR=A/D); specific leaf area (SLA=A/WL) and reproductive effort: (RE1=(Wg / W) x 100%, RE2=(Wg / A) x 100%). Results . As a conclusion, we can say that, рlants of Th. serpyllum and Th. polessicus show a rather diverse nature of changes in the magnitude of morphological parameters relative to the group in which they grow. Formation of plants Th. serpyllum in the group , is characterized by the smallest static metric and alometric parameters indicating the proximity of places to ecological-cenotic stress conditions. Conversely, the presence in Th. polessicus of large-sized individuals, which are also distinguished by the highest values of a number, static metric and alometric parameters, indicates the proximity of this location to the ecological-cenotic optimum. Originality . On the basis of the obtained quantitative and qualitative characteristics of the cenopopulations of the researched species, we are able to distinguish more  fo estimate the resource potential of Th. serpyllum and Th. polessicus and to propose scientifically grounded approaches for the rational use of available stocks of valuable medicinal raw materials in the research district. Conclusions. The results of our analysis show that the realization of morphological variability (variation of values of plant morphoparameters within one population) and morphological plasticity (change of average values of morphoparameters at the "transition" from population to population) are an integral component of the complex of processes that provide and transform of populations of Th. Serpyllum and Th. polessicus in the territory of Shostka geobotanical district, Sumy region .