Assessment of adaptive capacity of native and adventive species of trees and shrubs in Dnipro region

Abstract

Nowadays, deterioration and loss of ecological functions of urban tree and shrub plantations take place in Europe and, in particular, in Ukraine; it was noted that their number is insufficient to counteract the negative impact of global climate change and protect the population against industrial pollution effects. The issue of resistance of native and adventitious tree species used in the plantations of industrial cities remains relevant; it necessitates the assessment of physiological and biochemical aspects of their adaptation to extreme environmental factors, such as moisture limit in the steppe zone, periodic dangerously low winter temperatures and anthropo-technogenic load (in large urban agglomerations). In order to optimize the assortment of tree species of large megalopolises of the steppe zone of Ukraine and determine their potential resistance to anthropogenic pressures the study was conducted in conditionally clean forest biogeocenoses of the Samara River levee zone and in artificial plantations on the territories located in the coastal zone of the Dnipro River within 1500 m from the Prydneprovskaya thermal electric station (PTES, Dnipro city). It well known that the TPP is the source of atmospheric air pollution by such heavy metals as lead and cadmium. A study of the activity of antioxidant protection enzymes in leaves of native and adventive tree species showed that in the zone of Prydneprovskaya TES impact there was an increase of guaiacol peroxidase activity in Acer platanoides, Ulmus minor, Morus alba; benzidine peroxidase in Acer negundo, Ulmus laevis, Acer platanoides; catalase in A. platanoides, A. negundo, U. laevis, Ulmus pumila and Robinia pseudoasasia. High peroxidase activity, which is complemented by higher catalase activity, indicates the relative resistance of these species to atropo-technogenic pressures supported by antioxidant defense mechanisms. Total chlorophyll content (Chla + Chlb) in leaves of native species Ulmus laevis, Acer platanoides and adventive Morus alba decreased in the zone of TPP impact in relation to conditionally clean areas. The ratio of chlorophyll a to chlorophyll b in contaminated areas significantly increased in leaves of native species Ulmus laevis, Ulmus minor, Acer platanoides compared with control. The invasive species Acer negundo, Morus alba, Ulmus pumila had no significant changes in this indicator. In invasive species such as Ulmus pumila, Acer negundo there was an increase in leaf mass, which may indicate adaptation of these species to anthropogenically altered growth conditions.