Additional files [RJEE Vol. 9 (3). 2024 – 2]

• Fig. 1. Map of the Usmansky Bor and Voronezhsky State Nature Reserve
• Fig. 2. Landscape structure of the Voronezhsky Reserve [32, 33]: ЛУ – landscape level. The red square indicates the western section of the second floodplain terrace, which is the study area
• Fig. 3. Scheme of forest ecological types on second floodplain terrace based on the forest inventory data of 1965. Orange colour A₂, red B₂, green C₂D, blue C₂C ecological conditions
• Fig. 4. Forest inventory scheme on the second floodplain terrace of the Voronezh River and floodplain of the Ivnitsa River (based on forest inventory data of 1992). The red colour is patches dominated by Pinus sylvestris, green Populus tremula, grey Quercus robur, purple Alnus incana, blue Betula pendula and B. pubescens, white is glades. The grid is 1 × 0.5 km
• Fig. 5. Aspen-dominated stands (green) in the study area according to 2013 forest inventory data
• Fig 6. Vegetation plots of aspen forest in the first two NMS axes together with vectors of plot characteristics. Green indicates plots in C₂D according to 1965 forest inventory; red plots of 2001 in A₂ and B₂; blue plots of 2013 and 2023 in A₂ and B₂. Lc and Rc lighting and soil acidity (decreasing with increasing values); A % tree crown cover; Sp total number of species in the forest floor; MdSt number of meadow-steppe species. The first two axes of ordination explain 81 % of data variation; stress 0.2
• Fig. 7. Bracken Fern (Pteridium) and mixed herbaceous aspen forest. Plot No. 727, quarter 301, stand 9, 03.08.2001
• Fig. 8. Mixed herbaceous aspen forest with Rubus saxatilis. Plot No. 725, quarter 322, stand 11, 03.08.2001
• Fig. 9. Ecological-coenotic structure of the forest floor of aspen forests described in 2001 in B₂ and A₂ ecological conditions. The X axis is the title of vegetation plots. The Y axis is percentage of species of different ECGs with regard to projective cover. MdSt dry meadow-steppe; MFr wet meadow; Nm nemoral; Br boreal; Pn piny forest; Nt nitrophilous; and Ps psammophilous ECGs
• Fig. 10. Grassy and mixed herbaceous aspen forest; quarter 320, stand 10, 15.08.2013
• Fig. 11. Grassy and mixed herbaceous aspen forest; quarter 320, stand 10, 04.08.2023
• Fig. 12. Grassy and mixed herbaceous aspen forest with decay canopy; quarter 322, stand 11, 18.07.2023
• Fig. 13. Grassy and mixed herbaceous aspen forest with decay canopy; quarter 320, stand 9, 04.08.2023
• Fig. 14. Ecological-coenotic structure of the forest floor of aspen forests described in 2013 (plots 1104, 1102, 1091, 1106) and 2023 (plots 1107, 1092, 1093, 1085) in B₂ and A₂ ecological conditions. The X axis is the title of vegetation plots. The Y axis is percentage of species of different ECGs with regard to projective cover. ECGs are the same as in Fig. 9
• Fig. 15. Grassy glade with Chamaecytisus ruthenicus formed after the decay of a grassy aspen forest in quarter 363, stand 20, 28.07.2023 (plot 724)
• Fig. 16. Ecological-coenotic structure of the forest floor of glades on the tops of sandy hillocks in B₂ and A₂ ecological conditions. The X axis is the title of vegetation plots. The Y axis is percentage of species of different ECGs with regard to projective cover. ECGs are the same as in Fig. 9
• Fig. 17. Mixed herbaceous glade with Prunus fruticosa formed after the decay of aspen stand No. 2 in quarter 384, plot 1089, 28.07.2023
• Fig. 18. Vegetation of aspen stand in 2013 and after stand decay in 2023: а – quarter 320, stand 11, plot 1104, 15.08.2013; б – quarter 320, stand 11, 08.08.2023
• Fig. 19. Vegetation on the site of the decay aspen stand No. 8 in quarter 320, 04.08.2023
• Fig. 20. Large clumps of Quercus robur with closed canopy in the undergrowth (plot 1098) and in the second tree layer (plot 1101): а – quarter 384, stand 6, plot 1101, 17.06.2022; б – quarter 384, stand 6, plot 1098, 28.07.2023
• Fig. 21. Ecological-coenotic structure of the forest floor of glades and under stocked stands on slopes and in depressions in B₂ ecological conditions. The X axis is the title of vegetation plots. The Y axis is percentage of species of different ECGs with regard to projective cover. ECGs are the same as in Fig. 9
• Fig. 22. A clump of Tilia cordata in the place of decayed aspen forest in a depression between grass-green-moss Pinus sylvestris forests. Quarter 322, stand 8, 18.07.2023. A lime trunk up to 15 m high in the centre of the clump. The lime was first recorded in 2001 under aspen canopy as part of low (up to 1.5 m) understorey with projective cover of 3.5 %
• Fig. 23. A stand of Tilia cordata with Quercus robur and a second layer of Acer platanoides. Quarter 258, stand 13, plot 1114, 17.08.2023
• Fig. 24. Decay of aspen stand with the second layer of Acer plataniodes. Quarter 298, stand 23, plot 1115, 11.08.2023
• Fig. 25. Decay of aspen stand with the second layer of Acer plataniodes. Quarter 298, stand 20, plot 1117, 11.08.2023
• Fig. 26. Ecological-coenotic structure of the forest floor of Acer platanoides and Tilia cordata forest stands formed after decay of aspen stands in C₂ ecological conditions The X axis is the title of vegetation plots. The Y axis is percentage of species of different ECGs with regard to projective cover. ECGs are the same as in Fig. 9
• Table П.4 Vegetation relevés of plant communities at different successional stages formed after decay of aspen canopy in B₂ ecological conditions (2013 and 2023 data)