Analysis of phytolith composition of the main plant steppe ecosystems of Western Siberia

In this paper, we attempted to establish a set of species-specificity phytolith forms of plants in different taxonomic groups of steppe phytocenosis in the south of Western Siberia under the International Code for Phytoliths Nomenclature 1.0. We sampled plant material of dominant species at the site of the steppe ridges in the south of Novosibirsk region (south of Western Siberia, Russia). The basic families are Asteraceae, Poaceae, Rosaceae, Cyperaceae, Fabaceae, Lamiaceae, Scrophulariaceae, Brassicaceae, Caryophyllaceae, Plumbaginaceae and Iridaceae. We carried out a comparative and quantitative characterization of phytolith content. Phytoliths were extracted from plants by dry ashing. We divided forms of each species into diagnostic, dominant and background. Diagnostic forms account for 30% or more of the total number of morphological types in the sample and are the most important. Background forms are contributed less than 10%, their indicator role is small. We found four types of phytoliths assemblage with the help of the factor analysis of plant phytoliths: 1) phytoliths assemblage of steppe phytocoenosis; 2) assemblage of dominant morphotypes of phytoliths of monocots and dicotyledonous families (diagnosis classes); 3) assemblage of diagnostic morphological types of phytoliths of family Poaceae; and 4) diagnostic phytolith morphotype (definition of Cyperaceae class and some genera of Poaceae). Phytolith assemblage of Poaceae are of trapeziform polylobate, trapeziform sinuate, trapeziform short cell, еchinate long cell, scrobiculate long cell, rondel, lanceolate, saddle, parallelepipedal and cuneiform forms. Phytoliths assemblage of dicotyledonous are of psilate long cell and globular psilate shape. The complex of diagnostic morphotypes of phytoliths of Poaceae is bilobate, orbicular flat, scrobiculate long cell, parallelepipedal and cuneiform forms. The diagnostic phytoliths morphotype allow determining the genus of monocots. Papillae forms are typical of Cyperaceae. Bilobate and cross forms are typical of Cleistogenes sp. Parallelepipedal and cuneiform forms are typical of Phragmites sp. The results of this study concerning the systematics of phytoliths of steppe communities can be used for paleoecological reconstructions of steppe ecosystems.

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