Vegetation transformation as a limiting factor in the existence of rodent populations in open area (using the example of Spermophilus suslicus)

A comparative analysis of the composition and structure of plant communities in two places of the former habitat of Spermophilus suslicus in the Nikolaevsky district of the Ulyanovsk region is provided. Our analysis of the current state of S. suslicus populations in the Volga region has shown that over the past fifty years there has been a critical decline in the numbers of the species, and even its complete disappearance has been noted in some regions. A number of researchers note that dynamic changes in vegetation have certain influence on these processes. Therefore, the goal of our work was a comparative study of the vegetation of biotopes at the time of high numbers of animals against the background of intensive grazing and in the absence of gopher settlements for more than 15–20 years in the absence of grazing. Our studies have shown an increase in the species richness and structural diversity of communities due to the introduction of species from the upland, nemoral and boreal ecological-coenotic groups into their composition. Phytocenoses of steppe meadows with a high participation of Festuca valesiaca, Poa pratensis, Helictotrichon pubescens, and Elytrigia repens after the cessation of grazing are replaced by cenoses of meadow steppes with the dominance of Bromopsis riparia, Poa angustifolia, and Calamagrostis epigeios. There is an increase in the total projective cover of the grass stand (from 40 up to 60– 70%). Forage species that are background ones when the number of animals is high sharply reduce their participation in the grass stand. Changes in the ecological conditions of biotopes are characteristic, namely: modern communities are formed in drier, less nitrogen-rich and “acidic” habitats. The preservation and possible restoration of spotted ground squirrel settlements in the Volga region is possible subject to scientifically based anthropogenic impact, implemented in the form of haymaking and grazing.

1. Abaturov B. D. Microdepressions microrelief of Caspian lowland and mechanisms of its formation. Arid Ecosystems, 2010, vol. 16, no. 5, pp. 31–45 (in Russian).

2. Abrakhina I. B. Influence of land plowing on the number and distribution of ground squirrels in the Ulyanovsk region. In: Vliyanie antropogennoi transformatsii landshafta na naselenie nazemnykh pozvonochnykh zhivotnykh: tezisy Vsesoyuznogo soveshchaniya [Influence of Anthropogenic Transformation of the Landscape on the Population of Terrestrial Vertebrates: Abstracts of the All-Union Meeting]. Moscow, VNII okhrany prirody i zapovednogo dela Gosagroproma SSSR, 1987, pt. 1, pp. 308–310 (in Russian).

3. Artemyev Yu. T. Ecological and Morphological Sketch of Squirrels of the Volga-Kama Region. Thesis Diss. Cand. Sci. (Biol.). Kazan, 1966. 24 p. (in Russian).

4. Assessment and Conservation of Forest Cover Biodiversity in the Reserves of European Russia. Moscow, Nauchnyi mir, 2000. 196 p. (in Russian).

5. Barabash-Nikiforov I. I. Zveri yugo-vostochnoi chasti Chernozemnogo Tsentra [Beasts of the South-Eastern Part of the Black Earth Center]. Voronezh, Voronezhskoe knizhnoe izdatel'stvo, 1957, pp. 219–230 (in Russian).

6. Bogdanov M. N. Birds and mammals of the chernozem zone in the Volga region and valleys of both Middle Volga and Lower Volga (biogeographic materials). Proceedings of the Society of Naturalists in the Imperial Kazan University, 1871, vol. 1, pp. 4–226 (in Russian).

7. Dufrene M., Legendre P. Species assemblages and indicator species: The need for a flexible asymmetrical approach. Ecological Monographs, 1997, vol. 67, no. 3, pp. 345–366. https://doi.org/10.2307/2963459

8. Fedorovich F. F. Animals and birds of the Penza province. Trudy Penzenskogo obshchestva lyubiteley prirody, 1915, iss. 2, pp. 41–76 (in Russian).

9. Hill M. O., Gauch H. G. Detrended correspondence analysis: An improved ordination technique. Vegetatio, 1980, vol. 42, iss. 1–3, pp. 47–58. https://doi.org/10.1007/BF00048870

10. Krylova T. V., Deistfeldt L. A. Patterns of stationary distribution of settlements of the small mountain gopher. Ecologiya, 1987, no. 1, pp. 59–66 (in Russian).

11. Lobkov V. A. Spotted Sousliks of the Northeastern Black Sea Region: Biology and Population Functioning. Odessa, AstroPrint, 1999, pp. 113–120 (in Russian).

12. Lobkov V. A. Ecological reasons for changes in the number and distribution of the speckled ground squirrel Spermophilus suslicus (Guldenstaedt, 1770). Bulletin of Moscow Society of Naturalists. Biological Series, 2006, vol. 111, iss. 5, pp. 59–64 (in Russian).

13. Magerramov S. V., Martsokha K. S., Yakovlev S. A., Mandzhieva V. S., Bondarev V. A., LidzhiGaryaeva G. V., Matrosov A. N., Popov N. V. Modern climate warming impact on the population dynamics of the small ground squirrel (Spermophilus pygmaeus Pallas, 1778) (Rodentia, Mammalia) in the Ilmenno-Prideltovy region of the Caspian lowland. Povolzhskiy Journal of Ecology, 2022, no. 1, pp. 17–33 (in Russian). https://doi.org/10.35885/1684-7318-2022-1-17-33

14. Magerramov Sh. V., Matrosov A. N., Bocharnikova T. A., Grazhdanov A. K., Martsokha K. S., Kuznetsov A. A., Sludsky A. A., Popov N. V. Decrease in the population of the small ground squirrel – Spermophilus pygmaeus Pallas, 1779 (Rodentia, Sciuromorpha, Sciuridae) in the Volga– Ural steppe natural focus of plague. Povolzhskiy Journal of Ecology, 2025, no. 1, pp. 48–63 (in Russian). https://doi.org/10.35885/1684-7318-2025-1-48-63

15. McCune B., Grace J. B. Analysis of Ecological Communities. Gleneden Beach, Oregon, MjM Software Design, 2002. 300 p.

16. McCune B., Mefford M. J. Multivariate Analysis of Ecological Data. Gleneden Beach, Oregon, MjM Software Design, 1999. 237 p.

17. Nedosekin V. Yu., Ushakov M. V. On the state of the speckled ground squirrel in the Lipetsk region. In: Ground Squirrels of Eurasia (Genera Spermophilus, Spermophilopsis): Origin, Taxonomy, Ecology, Behavior, and Species Diversity Conservation: Proceedings of the Russian Scientific Conference. Moscow, KMK, 2005, pp. 65–66 (in Russian).

18. Nitsenko A. A. On the problem of investigation of ecological structure of the vegetational cover. Botanicheskii zhurnal, 1969, vol. 54, no. 7, pp. 1002–1014 (in Russian).

19. Okulova N. M. A burrow of the little souslik as a consortia. Parazitologiya, 2003, vol. 37, iss. 5, pp. 361–380 (in Russian).

20. Oparin M. L., Oparina O. S. Bird and mammal complex transformation of steppe ecosystems under ploughing up (with Saratov steppes as examples). Povolzhskiy Journal of Ecology, 2010, no. 4, pp. 361–373 (in Russian).

21. Persson S. Ecological indicator values as an aid in the interpretation of ordination diagrams. Journal of Ecology, 1981, vol. 69, no. 1, pp. 71–84. https://doi.org/10.2307/225981

22. Pivanova S. V., Shubina Yu. E. Factors affecting the abundance of speckled ground squirrel (Spermophilus suslicus Güldenstaedt, 1770) in natural and anthropogenic landscapes. In: Pest Management and Problems of Biodiversity Conservation: Materials of the Russian ScientificPractical Conference with International Participation. Moscow, A. N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences Publ., 2009, pp. 48–49 (in Russian).

23. Popov V. A. Mlekopitaiushchie Volzhsko-Kamskogo kraya (nasekomoyadnye, rukokrylye, gryzuny) [Mammals of the Volga-Kama Region (Insectivora, Chiroptera, Rodentia)]. Kazan, Kazan Branch of the USSR Academy of Sciences Publ., 1960. 468 p. (in Russian).

24. Rodimtsev A. S. New settlements of spotted souslik (Spermophilus suslicus Güld., 1770) in Tambov region. Tambov University Reports. Series: Natural and Technical Sciences, 2012, vol. 17, iss. 2, pp. 784–785 (in Russian).

25. Sapelnikov S. F., Sapelnikova I. I. Postnatal development of speckled ground squirrel (Spermophilus suslicus Güld, 1770) (Sciuridae, Mammalia) in Captivity. Povolzhskiy Journal of Ecology, 2019, no. 1, pp. 47–60. https://doi.org/10.35885/1684-7318-2019-1-47-60

26. Sapelnikov S. F., Sapelnikova I. I. Retrospective analysis of condition of populations of Spermophilus suslicus Güldenstädt, 1770 in Central Black Earth region and in adjacent territories and possible ways of preserving the species. Field Biologist Journal, 2021, vol. 3, no. 2, pp. 167– 212 (in Russian). https://doi.org/10.52575/2658-3453-2021-3-2-167-212

27. Shilova S. A. Abundance control and conservation of sousliks in Russia (G. spermophilus). Arid Ecosystems, 2011, vol. 17, no. 4, pp. 267–272. https://doi.org/10.1134/S2079096111040147

28. Shilova S. A., Neronov V. V., Shekarova O. N., Savinetskaya L. E. Dynamics of colonies of the speckled ground squirrel (Spermophilus suslicus Guld., 1770) on the northern boundary of the habitat. Biology Bulletin, 2010, vol. 37, no. 5, pp. 532–536. https://doi.org/10.1134/S1062359010050134

29. Smirnov V. E., Khanina L. G., Bobrovsky M. V. Validation of the ecological-coenotical groups of vascular plant species for European Russian forests on the basis of ecological indicator values, vegetation releves and statistical analysis. Bulletin of Moscow Society of Naturalists. Biological Series, 2006, vol. 111, iss. 2, pp. 36–47 (in Russian).

30. Smirnova O. V., ed. Forests of Eastern Europe: Holocene History and Modern Times: in 2 books. Moscow, Nauka, 2004, 1 books. 476 p. (in Russian).

31. Stoyko T. G., Denisov V. P., Gudkov A. S. Speckled ground squirrel as an indicator of anthropogenic impact on steppe communities of the forest-steppe zone. In: Materialy V soveshchaniya po gryzunam [Proceedings of the V Meeting on Rodents]. Moscow, Nauka, 1980, pp. 447–449 (in Russian).

32. Tikhvinsky V. I. Materialy po izucheniyu suslika v Tatrespublike [Materials on the Study of the souslik in the Tatar Republic]. Kazan, Oblastnaya poligrafshkola FZU im. Lunacharskogo, 1931. 11 p. (in Russian).

33. Titov S. V. Current distribution and changes in number of the spotted souslik, Spermophilus suslicus, in the eastern part of its range. Zoologicheskiy zhurnal, 2001, vol. 80, no. 2, pp. 230–235 (in Russian).

34. Titov S. V. Habitat preference in Spermophilus major and S. suslicus in recently developed sympatric zone. Zoologicheskiy zhurnal, 2000, vol. 79, no. 1, pp. 64–72 (in Russian).

35. Titov S. V. Relationships Between the Speckled Ground Squirrel and the Great Ground Squirrel in the Recently Emerged Sympatry Zone. Thesis Diss. Cand. Sci. (Biol.). Moscow, 1999. 24 p. (in Russian).

36. Titov S. V., Kartavov N. A., Leonova N. A., Smirnov D. G., Chernyshova O. V., Kuzmin A. A. Current status of populations of speckled ground squirrels (Spermophilus suslicus Güld.) in Volga region: History and scale of extinction. Russian Journal of Ecosystem Ecology, 2024, vol. 9, no. 3, pp. 1–13 (in Russian). https://doi.org/10.21685/2500-0578-2024-3-1

37. Titov S. V., Kuzmin A. A., Naumov R. V., Ermakov O. A., Zaks S. S., Chernyshova O. V. Dynamics of Habitats and the Current State of Settlements of Terrestrial Squirrels in the Right Bank Regions of the Volga Region. Penza, Penza State University Publ., 2015. 124 p. (in Russian).

38. Tkachenko V. S. Placement of mountain gopher burrows inside isolated habitats. In: Ekologiya i okhrana gornykh vidov mlekopitayushchikh: materialy III Vsesoyuznoj shkoly [Ecology and Protection of Mountain Species of Mammals: Materials of the III All-Union School]. Moscow, Severtsov Institute of Evolutionary Morphology and Ecology of Animals of the USSR Academy of Sciences Publ., 1987, pp. 183–185 (in Russian).

39. Tsyganov D. N. Fitoindikatsiya ekologicheskikh rezhimov v podzone khvoyno-shirokolistvennykh lesov [Phyto-indication of Ecological Regimes in the Subzone of Coniferous-deciduous Forests.]. Moscow, Nauka, 1983. 196 p. (in Russian).

40. Zhigarev I. V., Rumyantsev V. Yu. Modern situation in spotted ground squirrel (Spermophilus suslicus) populations within the forest steppe of European Russiа. Bulletin of Moscow Society of Naturalists. Biological Series, 2024, vol. 129, iss. 6, pp. 3–13 (in Russian). https://doi.org/10.55959/MSU0027-1403-BB-2024-129-6-3-13

41. Zozulin G. M. Historical formations of vegetation of a part of the USSR. Botanicheskii zhurnal, 1973, vol. 58, no. 8, pp. 1081–1092 (in Russian).

42. Zozulin G. M. Relationships between forest and herbaceous vegetation in the Central Black Earth State Reserve. Proceedings of the Central Chernozem State Reserve, 1955, iss. 3, pp. 102– 234 (in Russian).