Ecophysiological adaptations of Pinus nigra Arn., Gesculus hippocastanum L. and Platanus acerifolia (Ait.) Willd. species in urban environments with different sources of pollution

Urbana staništa su pod snažnim antropogenim uticajem i karakteriše ih intenzivno zagađenje vazduha, vode i zemljišta materijama poreklom iz različitih stacionarnih i mobilnih izvora. Specifična vrsta polutanata u ovim sredinama su metali koji se zbog svoje toksičnosti i biološke nerazgradivosti akumuliraju u zemljištu. Istraživanja u okviru ove disertacije su obavljena u urbanim parkovima u Pančevu, Smederevu, Obrenovcu i Beogradu koji su izloženi zagađivanju hemijskim elementima uključujući toksične metale poreklom iz različitih izvora. Obuhvatala su analize biljaka, kao i zemljišta na kojima rastu. Za ekofiziološka istraživanja odabrane su tri drvenaste vrste biljaka koje se dugi niz godina uspešno gaje na urbanim staništima: Pinus nigra Arn., Aesculus hippocastanum L. i Platanus acerifolia (Ait.) Willd. Osnovni cilj doktorske disertacije je bio definisanje faktora limitirajućih za razvoj biljaka, kao i ispitivanje njihovih ekofizioloških karakteristika i adaptivnog odgovora. Posebna pažnja je posvećena problemu zagađivanja metalima i metaloidima, njihovoj mobilnosti i dostupnosti biljkama, kao i njihovom uticaju na fiziološke procese u bilјkama (efikasnost fotosinteze i sadržaj fotosintetičkih pigmenata). Ispitivanja fizičko-hemijskih karakteristika zemljišta su pokazala da urbana zemljišta karakteriše visok udeo frakcije peska, nizak sadržaj higroskopne vlage, organskog ugljenika i azota, alkalna reakcija, ali i povoljan odnos C/N za mineralizaciju organske materije i oslobađanje minerala esencijalnih za biljke. Navedeni limitirajući faktori (toksičan sadržaj B, Cr, Ni i Pb izmerenih u zemljištu urbanih parkova) u sinergističkom delovanju sa visokim temperaturama i malom količinom padavina u značajnom delu ispitivane vegetacijske sezone su uticali na funkcionisanje ispitivanih vrsta biljaka na urbanim staništima. Analiza sadržaja hemijskih elemenata u četinama i listovima je pokazala da postoje razlike u sadržaju elemenata između vrsta, ali i da su ispitivane vrste izložene toksičnim koncentracijama B i Sr i istovremenom deficitu esencijalnih elemenata Cu, Mn i Zn. Generalno, kod P. nigra, A. hippocastanum i P. acerifolia postoje razlike u fotosintetičkoj efikasnosti, sadržaju pigmenata i u morfološkim oštećenjima listova. Uprkos navedenom, sve ispitivane vrste, pre svega listopadne A. hippocastanum i P. acerifolia su pokazale visok potencijal za toleranciju stresa zagađivanja toksičnim metalima i metaloidima, što ih čini pogodnim za sadnju u urbanim parkovima i industrijskim zonama, pa kao takve predstavlјaju značajan resurs za dalјa istraživanja.Urban habitats are under strong anthropogenic influence and are often characterized by intense air, water and soil pollution originating from various stationary and mobile sources. The specific type of pollutants in these habitats are metals that due to their toxic, persistent and nonbiodegradable properties accumulate in the soil. Research was conducted in urban parks in Pančevo, Smederevo, Obrenovac and Belgrade that are exposed to pollution by chemical elements, including toxic metals originating from various sources. Research included plant and soil analyses. For ecophysiological research, three woody plant species that have been successfully grown in urban areas were selected: Pinus nigra Arn., Aesculus hippocastanum L. i Platanus acerifolia (Ait.) Willd. The central aim and subject of this doctoral dissertation was to define the factors that limit the functioning of plants, and to determine their ecophysiological characteristics and adaptive responses. Special attention was paid to the problem of pollution by toxic metals and metalloids, their mobility and availability to plants, as well as their impact on physiological processes in plants (photosynthesis efficiency and photosynthetic pigment content). Analyses of the physical and chemical properties of the soils showed that urban soils are characterized by high proportion of a sand fraction, a low content of hygroscopic moisture, organic carbon and nitrogen and an alkaline reaction, but also a favorable C/N ratio for mineralization of organic matter and release of essential minerals for plants. The limiting factors (toxic levels of B, Cr, Ni and Pb measured in soils from urban parks) in synergy with high temperatures and low precipitation during a significant part of the vegetation season, influenced the functioning of the examined plant species in urban habitats. Analysis of the chemical element contents in pine needles and leaves revealed species differences, and also that the examined species were exposed to toxic concentrations of B and Sr and, at the same time, deficits of the essential elements, Cu, Mn and Zn. Generally, in P. nigra, A. hippocastanum and P. acerifolia, differences in photosynthetic efficiency, pigment contents and in morphological symptoms of injury were observed. In spite of the above, all the investigated species, first of all A. hippocastanum and P. acerifolia, exhibited a high potential for tolerance to stress pollution by toxic metals and metalloids, which makes them suitable for planting in urban parks and industrial zones. These species represent a significant resource for further research.