Influence of Solar Radiation on the Distribution of Halophytes in Plant Communities
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uence of Solar Radiation on the Distribution of Halophytes in Plant Communities P. A. Sharya, *, L. S. Sharayab, and T. M. Lysenkob, c, d aInstitute
of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, 142290 Russia b Institute of the Ecology of the Volga Basin, Russian Academy of Sciences, Tolyatti, 445003 Russia c Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, 197376 Russia d Tobolsk Integrated Research Station, Ural Branch, Russian Academy of Sciences, Tobolsk, 626152 Russia *e-mail: [email protected] Received October 10, 2019; revised December 6, 2019; accepted January 9, 2020
Abstract—A correlation between the proportions of halophyte life forms (LFs) and slope insolation in the saline soils of Samara oblast is analyzed. Perennial grasses (hemicryptophytes) are dominant in plant communities on slightly saline and nonsaline soils. These conditions give them advantages over annual grasses (therophytes) in competing for light and heat. An increase in the degree of salinity of ecotope soils in the plant community leads to a growth in the proportion of therophytes, which successfully compete with hemicryptophytes for light under these conditions. It is shown that hemicryptophytes and therophytes change the pattern of their correlation with the radiation index even within the same study area, depending on soil salinity. Regression models using slope insolation and topographic characteristics as predictors account for over 74% of the variance in the number of LF species. Keywords: saline soils, halophytes, solar radiation, species richness, life forms DOI: 10.1134/S1067413620040104
Halophytes, or salt-loving plants, are plants that can normally develop at a soil salinity of 0.5% (5 g/L) or more; plants that do not have this ability are called glycophytes [1]. The number of halophyte species is 2% of the total number of terrestrial angiosperm species; half of higher plant families contain halophyte species; more than half of the 550 species of the family Chenopodiaceae are halophytes [2]; the families Asteraceae, Poaceae, and Fabaceae also include a large number of halophyte species; however, their number is less than 5% of all species in these families [2]. Halophytes are known to be used in agriculture and industry [3]. Whereas glycophytes can hardly resist soil salinity [4], halophytes accumulate salts in the vacuoles of leaf cells, thereby maintaining the osmotic pressure by 3.2 times higher in the leaves than in the soil [2]. However, the increase in soil salinity by over 6% leads to a reduction of photosynthesis in most halophytes [5, 6]. Therefore, solar radiation can play a particular role for the survival of halophytes in saline soils. The attempt to rank halophytes by their way to reduce the effect of salts has proved to be ineffective [2]. Halophytes belong to different life forms (LFs) [7]; however, this aspect also reveals almost no clear patterns, except that the proportion of annual grasses
(therophytes) slightly increases in sali
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