In arid areas, it is necessary to apply phytomelioration widely to create an organized, stable and ecologically well-maintained forest–agrarian landscape in which agricultural lands can provide diverse and stable products, and to provide optimum ecologyfor the existence of a natural and anthropogenic system. The aim of this work is to select shrub and herbaceous plant species for the restoration of degraded lands in the arid zone of the European part of Russia with the prospect of preserving and increasing the productivity of native biodiversity, and the structure and dynamics of pasture ecosystems. The object of this study is the desert and semi-desert zone in the south-east of the European part of Russia within the Caspian lowland. The productivity of vegetation in the studied zone is largely determined by soil conditions, seasonal weather phenomena and animal grazing. The lowest forage productivity is characterized by the winter period with very strongly beaten white-field-grain pastures on unsalted, weakly- and medium-salted light chestnut soils; very strongly beaten bulbous-bluegrass-white-field pastures on saline deep, medium and strongly saline light chestnut soils; or medium-beaten black-wormwood and bulbous-bluegrass-black-wormwood pastures on small and crusty salt flats. The highest productivity is observed in the spring-summer period on unbroken areas of unsalted, weakly and medium saline light chestnut soils occupied by white-field cereal phytocenoses. The intensity of transpiration of perennial forage grasses growing on sandy loam soils of the dry steppe zone was measured. The analysis of biomorphological features of native forage species resistant to climate change and pasture load, and promising for phytomeliorative reconstruction of degraded pastures include: ecotypes of the genus Artemisia (A. pauciflora, A. Lercheana) and the genus Agropyron (A. cristatum, A. fragile, A. pectinatum), growing on various soils in natural conditions in the south-east of the European part of Russia. It was revealed that the seed productivity of Agropyron varieties varies within 0.5–4.0 c/ha depending on the variety, the method of sowing and climatic conditions of the year. To increase seed productivity, wide-row sowing with row spacing widths of 45 and 70 cm is promising.

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Abstract. The purpose of the research is to substantiate the relationship between the parameter of the greatest growth of plants with a specific rate of grazing of animals on pasture. It is necessary to solve problems with the intensity of animal grazing, and also to establish, according to the data, a statistical relationship between the parameters of the logistic equation that describes the average statistical growth of plants on natural pastures. Research methods. The experiments were carried out at the research sites of the lysimetric complex of the FSC of Agroecology RAS with various soil substrates (Kumskiy sand, Bazhiganskiy sand, chernozem-like sandy loam substrate). Sowing mixtures of multicomponent herbs of the Stavropol selection was performed for further analysis of plant growth and development, taking into account the different season of use. Results. The article presents the equation of the course of growth of the grass stand for the growing season, which proves that even after the removal of part of the phytomass, the plant growth law is preserved according to the principle of the sigmoid curve. The maximum plant height after simulating phytomass etching was recorded on a lysimeter No. 6 and averaged: with phytomass removal of ⅓ – 121 cm, ½ – 97 cm, ⅔ – 61 cm. The smallest average plant height was noted on lysimeter No. 13 – 64 cm. The highest height on this lysimeter was 110 cm with ⅓ removal. The average growth at the end of the growing season of plants for all simulation models was distributed as follows: with the withdrawal of 33 % – 73 %; 50 % – 53 %; 67 % – 31 %. The experiments showed that it is not recommended to remove more than ⅓ of the plant phytomass. The main role is played by the rate of phytomass removal (grazing rate) for the stable restoration of the grass stand of degraded pastures, and it is also necessary to take into account the vegetative period of the plant. Scientific novelty. The relationship between plant growth parameters has been established. It allows you to predict the characteristics of further growth, improve the natural degraded grass stands, establish the sequence of grazing in different areas in accordance with the species composition of plants.