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 of Acer platanoides L. and Fraxinus excelsior 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 SO2 and NO2 in seedlings of both species. However, this parameter drops in A. platanoides stems by reducing the collenchyme width, whereas it reduces in F. excelsior stems due to cork thickness loss. Another difference in the response of A. platanoides to the influence of phytotoxic pollutants compared to F. excelsior is the depletion of conducting elements of its phloem, which results in thinning the stem secondary cortex. The research findings prove high vulnerability of A. platanoides undergrowth to the chronic SO2 and NO2 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.

The Impact of Industrial Pollution on the Stem Anatomical Characteristics of Woody Plant Undergrowth in the City of Dnipro, Ukraine

“…In our previous paper, we examined the impact of toxic gases on the anatomical characteristics of woody plant undergrowth stems in absolute values [22]. However, to analyse the changes in the shares of histological elements of undergrowth stems of woody plant species in anthropogenic areas, we need to know the indices of anatomical parameters in relative values, i.e.…”

“…The impact of industrial pollution on ratio of the primary cortex share to the central cylinder share of woody plant undergrowth stems Our research indicates that chronic effect of toxic gases of SO 2 and NO 2 does not affect the share of the primary cortex and the central cylinder in the total annual stems volume in the undergrowth shoots of the both studied species (differences between reference and test samples are insignificant at p <0.05) (Table 1). Thus, although the thickness of both parts of the stem undergoes quantitative changes when exposed to the influence of industrial emissions of sulfur (IV) and nitrogen (IV) oxides [22], the same ratio between the shares of these parts of the stem is inherent in plants in the relatively clean zone. A. Lugovskyy (1992) came to a similar conclusion, demonstrating that qualitative structural features of the stem and the shares of components in it are independent of the plant nature and extent of contamination in the plants of Pinus sylvestris L. and Quercus robur L. at different age stages.…”

“…In view of the above mentioned, the purpose of our work is to identify changes in the shares of histological elements in the undergrowth stems of Acer platanoides L. and Fraxinus excelsior L. under the chronic pollution by SO 2 and NO 2 in conditions of the southern industrial zone of Dnipro (Ukraine). This work is a continuation of the study on the anatomical structure of the undergrowth stems of Norway maple and European ash when exposed to the pollution of industrial toxic gases [22].…”