ECOLOGICAL AND XYLOTOMIC ANALYSIS OF WOODY FLOWERING PLANTS FROM VARIOUS PHYTOCENOSES AT THE EASTERN REGIONS OF THE NORTH CAUCASUS
Authors:   Botanical Institute of the Russian Academy of Sciences named after V.L. Komarov, CHAVCHAVADZE Eugenia , UMAROV Mukhadi ,   Institute named after X. I. Ibragimov of the Russian Academy of Sciences, SIZONENKO Olga ,   Botanical Institute of the Russian Academy of Sciences named after V.L. Komarov, VOLKOVA Svetlana ,   Botanical Institute of the Russian Academy of Sciences named after V.L. Komarov
Published: February 2022

Deep study of plant adaptations at different levels of their organization, from cellular to cenotic, is one of the fundamental problems of ecological botany. Its important aspect is the study of the structural responses of different tissue types on the change of environmental factors, including highly fluctuating conditions of the mountains. A significant role in the ability of plants to acqure a particular natural environment belongs to the organization of wood – a complex tissue performing water-conducting, mechanical and storage functions. An essential aspect of ecological anatomy is the detection of a complex of structural features characterizing the originality of the secondary xylem (wood) in representatives of arboriflora of the North Caucasus. The aim of our study was to perform comparative ecological and xylotomic analysis of the water-conducting tissues of woody flowering plants of various phytocenoses in eastern regions of the North Caucasus and the identification of the basic xylotomic character facilitating the growth of these species in the humid and arid habitats. Materials and methods of research. Samples of wood for xylotomic analysis are taken from the collections of the Botanical Museum and Herbarium of Komarov Botanical Institute (RAS, St. Petersburg), CI RAS Laboratory (Grozny), and also collected from several phytocenoses of the successive mountain belts, including foothill lowlands, during expeditions in the territory of the Chechen Republic. In total, we have examined 72 species of 51 genus from 28 families of woody flowering plants belonging to various biomorphs – tree, shrub,semifrutex, liana. Microslides and their descriptions are made by conventional methods (Yatsenko-Khmelevsky, 1954; Metcalfe, Clark, 1983), using the terminology proposed by the International Association of wood anatomists – IAWA (Wheeleretal., 1989). The method of xylotomyc characteristics’ code is used in the analysis of wood structure (Umarov and others 2007). Results. Ecological and xylotomic analysis of the waterconducting tissues of woody xerophytes of Tersko-Kumskaya lowland and Itumkalinskyintermontane depression showed their sufficiently high specialization. The structural and functional wood features of such plants increase environmental capabilities, allowing plants to reserve and economically consume water and settle in conditions of sharp shortage of moisture, high temperatures, strong drying winds and soil poverty. As it was shown by the analysis of mesophilic species of mountain forest from the river Fortanga gorge, among arily advanced characters are present along with primitive. This indicates a distinct manifestation of heterobathmia, which is typical for plants of the 1st and 2nd layers. The ratio of feature set of different levels of specialization may vary depending on the life form of the plant and its position in the forest cenosis. In comparison with the above-mentioned phytocenoses, the hydrosystem of plants of subalpine and Alpine biotopes (Andian ridge slopes, Harami pass) is characterized by a large number of primitive features. The structure of the water-conducting tissue of their species has common features and some differences, determined mainly by their life forms (in the Alpine zone – mostly tiny creeping shrubs). Conclusion. It is shown that complex of structural features of the water-conducting system in xerophytes is more specialized than that onr of mesophytes. This greatly expands their ecological amplitude, allowing them to acclimate in the areas characterized by high temperatures, sharp shortage of moisture and soil poverty. The existence of plants with less specialized hydrosystem is possible in the humid habitats of mountain zones, with a more favorable regime of water and soil resources.