Tetiana Iusypiva, Galyna Miasoid, The Impact of Industrial Pollution with Toxic Gases on Stem Histological Parameters of Woody Plant Undergrowth under Conditions of the Southern Industrial Zone of the City of Dnipro, Ukraine, Volume 59, International Letters of Natural Sciences (Volume 59)
    The paper examines the influence of industrial emissions of sulphur (IV) and nitrogen (IV) oxides on stem histological parameters of the autochthonous woody plant species undergrowth of <i>Acer platanoides</i> L. and <i>Fraxinus excelsior</i> L., which are natural forest edificators in the steppe zone of Ukraine. It shows that stem anatomical characteristics undergo quantitative changes in the annual undergrowth shoots of the two tree species under anthropogenic burden, with the most significant changes in the area of heavy pollution. Results indicate the decrease of such stem parameters as stem and stele diameters, wood radius and primary cortex thickness under high concentrations of SO<sub>2</sub> and NO<sub>2</sub> in seedlings of both species. However, this parameter drops in <i>A. platanoides</i> stems by reducing the collenchyme width, whereas it reduces in <i>F. excelsior</i> stems due to cork thickness loss. Another difference in the response of <i>A. platanoides</i> to the influence of phytotoxic pollutants compared to <i>F. excelsior</i> is the depletion of conducting elements of its phloem, which results in thinning the stem secondary cortex. The research findings prove high vulnerability of <i>A. platanoides</i> undergrowth to the chronic SO<sub>2</sub> and NO<sub>2 </sub>exposure. Therefore, this woody species is suggested to be used as a test object in monitoring research on plants of virginal group in the technogenic areas contaminated with sulphur (IV) and nitrogen (IV) oxides.
    Planting, Stem Histological Indices, Toxic Gases, Woody Plant Undergrowth