Novikova N.M., Volkova N.A., Ulanova S.S., Chemidov M.M. Change of Vegetation on Reclaimed Sodic Soils on the Priergeninskaya Plain After 10 Years (Repablic of Kalmykia) // Arid ecosystems. 2020. V. 26. № 3 (84). P. 30-39. | PDF
After 10 years the new observations of natural vegetation restoration were made. As 10 years ago at the same time (end of May) same methods of data collecting on 9 sites at the Arshan-Zelmen scientific station were used. Almost 50 years ago reclamation works that lasted for 20 years were stopped at the scientific station. Comparison of data obtained during field work for two observation periods (2008 and 2018) shows that changes in the salt profile of soils caused by reclamation remain unchanged. All these soils are of the same type of strongly transformed soils – deeply-saline agrozems. In the soil profile, the plowed layer (45 cm) and below lying horizon down to 50-60 cm, free from salts, identified in the 2008 descriptions were preserved in 2018. But in soil samples taken in 2018, the content of salts and, in particular, the chlorine ion increased in most areas under layer 50-60 cm. These changes were not reflected in the vegetation and the formation of plant communities that are typical for the final stages of secondary succession on light-chestnut soils rather than on solonetz continues. The total number of species recorded on geobotanical sites decreased from 70 to 62. From the list of species in 2008 almost half (35 species) fell out, and by 2018, 27 species had been introduced. This occurred mainly in groups of perennial and annual herbage species. Tree and shrub species (Populus album, Quercus robur, Ulmus pumila, Acer tatarica, Cotinus coggygria) continue to shrink and fall out, and only pear (Pyrus communis) and golden currant (Ribes aureum) have regeneration. Despite the decrease of total number of species, the species abundance of communities on all geobotanical sites increased significantly — by 1.5-2.5 times. During last 10 years representative species of zonal communities became widely spread: Artemisia lerchiana, Tanacetum achilleifolium, Poa bulbosa, Stipa lessingiana, Leymus ramosus, Artemisia austriaca. This fact contributed to the flattering of the species composition of plant communities on observation sites and caused an increase of species composition similarity between these communities up to 56-77%, which is significant compared with similarity 37-57% calculated in 2008. Similar changes were detected in the aboveground phytomass: not only the increase (average phytomass in 2008 and 2018 was respectively 734 and 849 C/ha), but also some flattering of the values on different sites. In 2018 in the virgin sodic soils the upper layer of 20 cm remain unsalted, and the above-ground phytomass in 2018 became more than twice higher than in 2008.
Key words: Caspian lowland, sodic (solonetz) soils, reclamation, irrigated afforestation, irrigated arable land, soil salinization-desalinization, species richness, plant communities, stages of succession, aboveground phytomass.