Composition of the Flora on Tailing Dumps of Chalcopyrite Fields in the Southern Transural Region

Abstract

Centers of the mining industry providing for the needs of nonferrous metallurgy in the southern Urals are located in the southern Transural Region (Bashkortostan, eastern part of Orenburg oblast), and large areas are under tailing dumps of chalcopyrite fields. The tailings consist of small and large fragments of igneous and metamorphic acid rocks and have been dumped for more than 60 years. The pioneer communities on this substrate cannot develop into climax communities and continue to exist as chronically serial communities without obvious changes in their composition. This is due to substrate mobility, its periodic overlaying with fresh portions of overburden rocks, toxicity, weathering, and erosion. Studies on the state of these ecosystems and, primarily, on the processes of self-overgrowing of disturbed lands, are of great importance. The chalcopyrite tailing dumps were studied in the zonal series from the forest‐ steppe to southern steppe. These were the dumps of open-cut mines of the Uchalinskii Mining and Ore-Processing Works (UMOW, Uchaly city), Bashkir Copper‐ Sulfur Works (BCSW, Sibai city), and Gaiskii Mining and Ore-Processing Works (GMOW, Gai city). The characteristics of natural complexes on these dumps are presented in Table 1. In order to survey the flora and vegetation on tailings, 300 geobotanical descriptions were made between 1999 and 2002, in which 330 species of higher vascular plants from 49 families were recorded. Analysis of the lists and taxonomic spectra of the floras showed that the number of species changes in a north‐ south direction in the series 113‐250‐122. The high floristic richness of the BCSW dump is explained by its location within city limits, where the probability of accidental species introduction is higher. Hemicryptophytes, a species of natural (steppe and meadow) plant communities, are the dominant life form on the dumps (about 60%) (Table 2). Therophytes (20‐30%) are second in abundance, which is indicative of the disturbance of vegetation and mobility of substrates. Some increase in the proportion of therophytes in the south is connected with the adaptation of most annual plants to the dry climate of the steppe zone.