Ecological, floristic, physiological, and biochemical characteristics of calciphyte plants of the Zhiguli Mountains
O. A. ROZENTSVET, V. N. NESTEROV, E. S. BOGDANOVA, V. A. ROZENTSVET
Samara Federal Research Center of the Russian Academy of Sciences, Institute of Ecology of the Volga Basin of the Russian Academy of Sciences, Tolyatti, Russia
Keywords: calciphytes, endemics, adaptation, leaf morphology, pigments, lipids, antioxidants
Abstract
We studied the ecological, floristic, physiological, and biochemical characteristics of plants in carbonate substrates of the Zhiguli Mountains, one of Russia’s unique botanical and geographical regions. All species are confined to the cenoses of petrophytic steppes in two different biotopes, but differ in their geographic distribution. Five of them represent Middle and Lower Volga-South Ural species, three are endemic to the Zhiguli Upland, two are Southeast European species, and one each represents the groups of East European-Asian, South European-Central and Central Asian, and European-Asian species. Plants have various life forms: perennial herbs, subshrubs, and shrubs. They are obligate and facultative calciphytes with respect to the soil substrate. The biomass and architecture of leaves, pigment content, membrane complex indicators and elements of antioxidant systems were determined as parameters characterizing the structural and physiological-biochemical properties of calciphytes. We established the differentiation of plant groups depending on the soil substrate (facultative/obligate species), zonal-geographical element, life form for all measured characteristics. To clarify the reasons for the differences, we compared the variability of individual variables across different ecological groups. It has been established that calciphyte plants of the Zhiguli Mountains represented by various taxa and ecological groups, are capable of using complementary adaptation strategies to carbonate substrates. The adaptation of obligate calciphytes to the growing conditions of a given region is achieved through lower leaf density, less susceptibility to oxidative processes, and more effective antioxidant protection. These properties are especially evident in the endemic species of Zhiguli. The greater involvement of phenolic compounds, sugars, and proline in protecting against oxidative stress can be considered as one of the possible reasons why endemics thrive in certain local environments.
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