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

Abstract

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 ofAcer platanoidesL. andFraxinus excelsiorL., 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 SO2and NO2in seedlings of both species. However, this parameter drops inA. platanoidesstems by reducing the collenchyme width, whereas it reduces inF. excelsiorstems due to cork thickness loss. Another difference in the response ofA. platanoidesto the influence of phytotoxic pollutants compared toF. excelsioris the depletion of conducting elements of its phloem, which results in thinning the stem secondary cortex. The research findings prove high vulnerability ofA. platanoidesundergrowth to the chronic SO2and NO2exposure. 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.