Physiological-biochemical adaptation of the Siberian larch Larix sibirica Ledeb. to urban environments
2018
L. V. Afanas’eva
The aim of this study was to investigate the change of pigment complex and biochemical parameters of the Siberian larch Larix sibirica Ledeb. needles in the various functional zones of Ulan-Ude city (Republic of Buryatia, Russia). Using a scanning electron microscope with an energy dispersive X-ray spectroscopy (EDS), the size, distribution and chemical composition of individual particles were examined on the surface of needle discs of the Siberian larch. The majority of particles (40–50 % of the needle surface) were observed on the needle from traffic zone of city. In the residential part of the city, in urban parks and squares, the particles occupied 20–30 % of the needle surface. Single particles were found on the needle from background part. Chemical composition indicated that the most particles were soot and dust with minor constituents such as Si, S, Fe, Al, Cu, Zn, W, Ti, Ca, Сl, Cr, Ni. Much higher concentration trace metals exceeding background levels in 1.4–7.7 times were found in needle from traffic zone. Accumulation of pollutant elements in needles leads to activation of antioxidant protection. The amount of photosynthetic pigments in needles increases by 1.5–2.2 times compared with background values, mainly due to chlorophyll b and carotenoids. Ratio of сhl. a / chl. b, and also chlorophylls to carotenoids decreases by 13–26 %. Proline content increases 1.6–7.5 times, ascorbic acid – 1.2–1.3 times, catechin and proanthocyanidins – 3.0–4.8 times. The highest concentrations of these compounds were found in the traffic zone of the city.
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