Influence of multicomponent contamination on the content of photosynthetic pigments in the leaves of woody plants commonly planted for greening of cities

Abstract

Woody plants, as an important element of optimization of the urban environment, respond negatively to the ever-increasing technogenic pressure in cities. Therefore, it is necessary to assess their vital status, the most sensitive indicator of which being the content of plastid pigments. In this article we analyze the effects of multicomponent contamination on quantitative fluctuation of the level of photosynthetic pigments in the leaves of woody plants and identify sensitive species for the purpose of phytoindication in order to assess the state the environment is currently in. For the purposes of our research we chose the most widespread tree species in the city of Dnipro (Steppe zone of Ukraine), growing in the area of intensive industrial pollution and high levels of emissions by vehicles. We determined the content of photosynthetic pigments (chlorophylls a and b, a + b, carotenoids) in the leaves of woody plants during different months of the growing season (June, July, August) and afterwards this data was used to compare the given parameters against the values taken from trees in the control area. The sum of chlorophyll levels a + b for the majority of plants was decreasing compared to the control. A more significant decrease in the content given by the sum of the a and b chlorophyll levels is observed in the assimilation organs of Aesculus hippocastanum L., Pinus pallasiana (D. Don) and Picea abies (L.) H. The most significant changes in the content of pigments in the leaves of plants under study were detected at the end of the growing season (in August). The content of green pigments in the leaves of Robinia pseudoacacia L., Platanus orientalis L. remains virtually unchanged. Under the influence of multicomponent contamination, the amount of pigments in the case of chlorophyll a in the majority of woody plant species decreases more rapidly compared to the control than in the case of chlorophyll b. The most noticeable drop in the content of chlorophyll a occurs in the leaves of Betula pendula Roth, Ae. hippocastanum, P. pallasiana, Acer platanoides L. and Tilia cordata Mill. The needles of P. abies and Picea pungens Engelm. 'Glauca’ on the contrary suffer from a significant reduction in the concentration of chlorophyll b. The species most resistant to multicomponent contamination in terms of changes in the content of chlorophyll in the leaf blade are R. pseudoacacia, P. orientalis. The concentration of carotenoids in the leaves of plants such as B. pendula, Ae. hippocastanum, A. platanoides, T. cordata, P. abies is lower than that of species growing in the relatively clean zone. The concentration of pigments in Populus alba L., P. pungens 'Glauca’ was higher during all of the months elapsed since the beginning of our study, whereas Ulmus laevis Pall., P. orientalis and R. pseudoacacia – had their concentrations reach an all time high in the second half of the growing season. Therefore, the peculiarities of quantitative fluctuation of photosynthetic pigments in plants, which are characterized by the variable resistance ability against the effects of technogenic multicomponent contamination, have been identified.

Ecological and biological features of the development of introduced species of the genus Abies Mill

“…The increased anthropogenic impact on the biosphere has led not only to global environmental perturbations and decrease in the level of environment comfort, but also has created conditions that are dangerous for human health [1][2][3][4][5]. Against this background, the role of landscape architecture is increasing as one of the main directions of creating a harmonious human environment.…”

“…Against this background, the role of landscape architecture is increasing as one of the main directions of creating a harmonious human environment. Natural and artificial green plantings, including urban and suburban forests, parks and other green areas of various functional purposes, directly related to both the aesthetic properties of the living environment and the ecological ones, perform primarily environmental functions and are of vital importance for human [2][3][4][5][6][7][8].…”

“…Plants have a beneficial effect on the microclimate, moisturize and enrich the air with oxygen, reduce noise, serve as a natural filter that absorbs dust, and improve the radiation regime. By adsorbing a significant amount of toxic components, including heavy metals, from the air and neutralizing them in the tissues, and releasing phytoncides, they contribute to maintaining a healthy gas balance in the atmosphere [2,[4][5][6][9][10][11][12][13][14][15]. However, when working on the creation of landscaping objects, it should be taken into account that woody plants differ significantly from each other in terms of stability in urban environment.…”

“…Green plantings are leveled by unfavorable factors of natural and man-made origin, are exposed to chemical, physical, biological and complex pollution. The high degree of influence of urbanized territories negative factors often leads to vegetation weakening, damage by diseases and pests, loss of their biological stability, decrease in decorative properties, premature aging and trees drying [5,8,13,[17][18][19][20].…”