Abstract
On the territory of our country, in foreign Europe, in North America, in some regions there are outcrops calcareous rocks. The high endemism and the same of rare plant species concentration are characteristic features of such landscapes. The results of elemental composition primary assessment of aboveground and underground organs of three plant species from calcareous biotopes of Samara region are given. Three species were chosen for studies: obligate calcephite Gypsophila jusepczukii Ikonn., calcephilic Hedysarum grandiflorum Pall. (both included in the Red Book of Samara Region), Reseda lutea L., a ruderal species. For the quantitative analysis of the content of metals in the stems, leaves, flowers, and roots of these plants, the method of spectrometry with inductively coupled plasma was used. It was shown that the effective barrier function of roots in relation to most of the analyzed elements is characteristic of calcephilous (Hedysarum) and calcephytic (Gypsophila) plant species, but not for Reseda lutea. To a certain extent, the stem tissues play a barrier biogeochemical role in Reseda. A general biogeochemical feature of these species, especially pronounced for Reseda, is expressed in increased Se accumulation in aboveground organs.
Highlights
Massive outcrops of calcium-containing rocks in sediments of certain geological epochs are presented on different continents and are localities where special conditions of soil formation develop and specific plant communities – calcareous floras - are formed
High endemism and the same of rare plant species concentration are characteristic features of the Eurasia calcareous outcrops, which is associated with the historical past of the considered ecotopes, the characteristics of the substrate and the locality of habitats that do not promote new taxons to spread and mix themselves with similar forms in other territories [3]
It is known that the ash component accumulation in plants under normal habitat conditions reflects the level of tissues metabolic activity - the leaf mesophyll usually has the highest ash content, the lowest is in wood, which consists mainly of conductive and mechanical tissues without living protoplasts, there are noticeable differences between plant species [7]
Summary
Massive outcrops of calcium-containing rocks in sediments of certain geological epochs are presented on different continents and are localities where special conditions of soil formation develop and specific plant communities – calcareous floras - are formed. In the complex of these conditions, the following are distinguished: absence or weak soils development; substrate mobility; specific microclimate of these habitats; chemical and physical characteristics of chalk as a substrate The combination of such features forms an edaphic specificity of the calcareous outcrops, which is reflected in the life forms composition of plants growing here, adapted to concrete types of habitats. Plants of chalk outcrops are usually distinguished by a rather clearly pronounced xeromorphic structure of aboveground organs with a complex of specific features (pubescence, waxy bloom, smaller leaves, often with a silvery sheen, etc.) These plants have a low competitive ability in relation to common steppe species on chernozems, but within the calcareous outcrops, calcephytes have no competitors. A high proportion of rhizome plants is characteristic of the calciphytic-petrophytic variant of meadow steppes and reflects more mesophytic conditions of their existence [4]
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