Patterns of growth of Ulmus pumila L. and Fraxinus lanceolata Borkh. in protective forest strips in the irrigated dry-steppe Zavolzhye

The article is devoted to topical studies of the state and growth patterns of the main tree species (62-year-old squat elm and lanceolate ash) used in protective afforestation of the dry-steppe and semi-desert zones of the Russian Federation. The authors presented an analytical review, according to which the improvement of the soil water regime has a positive effect on growth, increasing the resistance of forest strips to diseases (where graphiosis is the main reason constraining the widespread use of elm) and pests. The purpose of the research was to establish the growth patterns of squat elm and lanceolate ash in the protective forest strips of the irrigated dry-steppe Volga region located along the perimeter of the irrigated area. The research was based on the experience on 4 trial sites of forest strips, placed depending on their distance from the irrigation canal, where due to the deterioration of the lining, significant water losses are observed for filtration through the bottom and walls of the canal and affecting the growth and development of tree species. The plantings were studied by forest taxation methods according to OST 56-69-83, the VNIALMI methodology and the textbook of the St. Petersburg Forestry University. Individual taxation indicators were studied according to K.K. Vysotsky, S.S. Pyatnitsky. Experiments have revealed the outstripping growth of elm and ash in forest strips as they approach the irrigation canal. At a distance of 50 and 150 m from the canal, the root-accessible soil moisture reserves, over the long-term study period, amounted to 75-70% of the lowest moisture capacity (HB), respectively 750 and 1300 m - 55-50%, with a wilting humidity value of 48% HB. The decrease in soil moisture is the result of less water intake with filtration losses from the irrigation channel in the form of a headwater. Depending on the distance to the canal, the growth intensity index of elm is lower than that of ash by up to 59.5%, and the productivity of cambial tissue is higher by up to 26.5%. The bonus of elm and ash is ahead by a class or more when approaching the forest strip to the channel. With the improvement of water nutrition, the absence of graphiosis was noted in the elm. The coefficients of determination of the relationship between the height of elm and ash growing in forest strips from the indicators of age, growth intensity, productivity of cambium were 0.96-0.97, which indicates a close relationship. The authors recommend using squat elm and lanceolate ash (as the main species) in protective forest plantations of the dry steppe zone, especially on irrigated lands in the following mixing scheme: Yal-Vp-Vp-Yal - instead of the existing one: Vp-Yal-Vp-Yal-Vp-Yal.

1. Dospekhov B.A. Methodology of field experience (with the basics of statistical processing of research results). 5th ed., supplement and revision. M.: Agropromizdat, 1985. 351 p. (In Russ.)

2. Iozus A.P., Zavyalov A.A., Kryuchkov S.N. Hybridization of elms Ulmus L. in the dry steppe of southeastern Russia. Successes of modern natural science, 2022, no. 7, pp. 14-19. (In Russ.)

3. Makarova N.M., Balakai G.T., Makarov A.V. Increasing the reclamation role of protective forest plantations on agricultural lands of southern Russia. Scientific Journal of the Russian Research Institute of Land Reclamation Problems, 2020, no. 1 (37), pp. 122-139. (In Russ.)

4. Manaenkov A.S., Podgaetskaya P.M., Podgaetskiy M.E. Features of growth of low -order forest strips on chestnut soils. Bulletin of the Moscow University, Ser. 5. Geography, 2022, no. 3. pp. 134-142. (In Russ.)

5. Methodology of system research of forest - agrarian landscapes / Ed. by E.S. Pavlovsky and M.I. Dolgilevich. M.: VASHNIL, 1985. 112 p. (In Russ.)

6. Minaev V.N., Leontiev L.L., Kovyazin V.F. Forest taxation. St. Petersburg: Lan, 2022. (In Russ.)

7. Primakov N.V., Tsaloeva E.G. The state of agroforestry landscapes of Agroalliance LLC of Krasnodar Krai. Successes of modern natural science, 2022, no. 3, pp. 16-21. (In Russ.)

8. Proezdov P.N., Eskov D.V., Mashtakov D.A. Avtonomov A.N., Rozanov A.V. Regularities of the growth of the pedunculate oak (Quercus Robur L., 1753) in the protective zones of the steppe and forest - steppe of the Volga upland. URL: https:www.researchsquare.com/researchers/preprints, published on August 10 2021. DOI: doi.prg/10.21203/rs-773724/vl. (In Russ.)

9. Pyatnitsky S.S., Kovalenko M.P., Lokhmatov N.A. Vegetative forest. M.: Agricultural Publishing House, 1963. 448 p. (In Russ.)

10. Stepanov A.M. Agroforestry of irrigated lands. M.: Agropromizdat, 1987. 207 p. (In Russ.)

11. Strategy for the development of protective afforestation in the Russian Federation until 2025. Volgograd: FSC of agroecology RAS, 2018. 36 p. (In Russ.)

12. Vysotsky K.K. Regularities of the structure of mixed stands. M.: Goslesbumizdat, 1962. 177 p. (In Russ.)