Morphometric variability of Carabidae as an indicator of ecological restoration of revitalized habitats in the European important protected landscape area of the Danube floodplains

Revitalization measures currently represent an important tool in ecological practice for the recovery of disturbed habitats, and their effectiveness is increasingly assessed using bioindicator groups, including ground beetles (Carabidae). Between 2020 and 2023, we conducted research in the European habitat of the Danube Floodplains, where we evaluated the impact of revitalization measures on ground beetle assemblages. The study was carried out at 15 study sites representing eight habitat types. At each site, five pitfall traps were installed in a linear arrangement. In total, 5,292 individuals belonging to 47 species were analyzed, with a mean ellipsoid biovolume of 192 mm 3 per individual. PCA analysis revealed a division of species into two main clusters according to their preference for forest and open habitats, with reference sites without management characterized by a higher proportion of apterous and brachypterous species. In contrast, habitats subjected to restoration measures showed dominance of macropterous species typical of disturbed and dynamic ecosystems. Significant differences in ellipsoid biovolume and all morphometric traits were confirmed among habitats and study years. Habitats with restoration measures exhibited a gradual increase in ellipsoid biovolume and morphometric traits of individuals, indicating improved food availability and more favorable living conditions. Prediction of ellipsoid biovolume development using LSTM models (neural networks) indicated stabilization of Carabidae assemblages in forest habitats after the completion of restoration measures, whereas pronounced fluctuations persisted in open habitats, suggesting the need for a longer time period or more intensive interventions to achieve community stability. The results provide a practical basis for planning and evaluating the effectiveness of restoration and management measures in European habitats of conservation importance, as well as for biodiversity conservation and adaptive landscape management, particularly in optimizing interventions in forest and open ecosystems to achieve long-term stability of Carabidae assemblages.