Leaf shape as a bioindicative indicator of violations of the stability of betula pendula Roth development in the gradient of road pollution (on the example of Vladikavkaz, RSO-Alania)

Sarkisyants Laura Hovhannesovna, Bikbaeva Larisa Vladimirovna, Tsutsieva Anna Leonidovna

The regularities of morphogenesis of Betula pendula leaf plates in cenopopulations with varying degrees of technogenic transformation determined by the level of automobile load (AH) are investigated. The established nonspecific nature of the reaction of this type of bioindicator to technogenic stress [Zhuikova T.V., Popova A.S., Meling E.V., 2021], as well as the fact that road pollution is one of the main ones for it, [Guskov et al., 2000; Zakharov et al., 2000; Samecka-Cymerman et al., 2009] determine the relevance of research on the mechanisms of disruption of the stability of the development of the hanging birch in the territory of the RSO-Alania. To assess the phenotypic response of Betula pendula, the leaves of plants of different biotopes were examined by methods of geometric morphometry (GM) after digitization procedures and placement of reference marks reflecting the location of anatomical structures, using programs of the TPS series developed by J. Rolf: tpsUtil32 and tpsDig232. The obtained landmark coordinate matrices were subjected to statistical processing using methods of multidimensional statistics. In the method of the main components, the main directions of the variability of the shape of the leaf of different biotopes are determined, related to the indicators of its width, the shape of the tip, as well as the position of the landmarks characterizing the places of departure of the lateral veins of the first order. Based on the results of canonical analysis, 3 groups of plants with similar patterns of formation were identified: with an egg-shaped organ (СЗI-ПIII), a diamond-shaped shape and a pointed tip (ИIV и СЗIII), intermediate between the first two (ИIII, ПII). For an average sample of trees growing near highways with AHIV, a decrease in the width of the organ was noted in comparison with the group with AHI with the formation of a diamond-shaped pointed shape. High indicators of the quality of discrimination, identified primarily for cenopopulations with AHI and AHIV, indicate a high predictive ability of geometric morphometry methods, which makes it possible to recommend their inclusion in the protocols of phytomonitoring studies on the territory of the RSO-A.

Keywords:geometric morphometry, Betula pendula Roth, leaf plate shape, automotive load classes, Procrustean coordinates, methods of multidimensional statistics, permutation test, cross-validation test.