Vegetation Restoration on Reclaimed Soils on the Peri-Yergenian Plain (Republic of Kalmykia)

Abstract

The modern state of vegetation and soils on the Peri-Yergenian plain (northwest Peri-Caspian lowland, the Republic of Kalmykia) have been studied. This area was subjected to deep ameliorative plowing, irrigation, and agroforestry in the 1950–1960s (irrigation ceased in 1971; periodical plowing ceased in 1984). A homogenous soil cover has formed under the conserved tree plantations and on the former irrigated arable lands; however, the morphological and physical and chemical properties of the initial solonetzic soil complex (solonetz and solonetzic light-chestnut soils) have practically been transformed there. The plough layer (0–45 cm) and subsurface layer (50–60 cm) can still be determined there. They are free of salts, and the exchangeable sodium content decreased there. All of these soils belong to one type of deeply saline solonetzic agrozems. The apple orchard died without irrigation 6–7 years after planting. Other trees were only partially preserved in irrigated areas; seed regeneration has been observed only for Elaeagnus angustifolia, Ulmus pumila, and Ribes aureum, and sprouting regeneration has been seen for Pyrus communis. At sites of degraded trees, species of shrubs that were cultivated in the forest belts, as well as local flora, appeared in this area. These communities have greater species richness and larger aboveground phytomass in comparison with the surrounding virgin vegetation. The present species composition and the structure of herbaceous plant communities allow us to conclude that there is a restoration plant succession and that communities typical for virgin chestnut soils with a predominance of Artemisia lerchiana, Tanacetum achilleifolium, and representatives of the family Gramineae (Festuca valesiaca and Stipa lessingiana) have formed. At reclaimed sites without irrigation, the restoration of vegetation leads to the formation of plant communities similar to those observed on virgin solonetz soils.