Assessment of anthropogenic load by the level of fluctuating asymmetry of Betula pendula leaves (using the example of the Don State Technical University training and experimental site)

Background. This study aimed to assess the level of anthropogenic stress on the territory of the Don State Technical University training and experimental site (Rassvet, Rostov Oblast) using the fluctuating asymmetry method of Betula pendula Roth. A comparative analysis of the integral index of fluctuating asymmetry was conducted between zones with different levels of expected impact (“Site 1” and “Site 3”) and a conventional background zone (“Roshcha”). The level of fluctuating asymmetry in the anthropogenic impact groups was significantly higher than in the background zone, and the overall environmental condition of the study area corresponded to the “alarm” category. The most stress-sensitive traits were the length of the second vein and the angle between the veins. The fluctuating asymmetry method has proven its effectiveness for bioindicating complex anthropogenic stress in urban ecosystems.

Purpose. The aim of the study was to quantitatively assess the level of anthropogenic stress on the territory of the Don State Technical University training and experimental site by analyzing the fluctuating asymmetry of the leaves of Betula pendula Roth and identifying the most sensitive morphological features.

Materials and methods. The study focused on Betula pendula Roth growing in anthropogenically altered habitats, with special attention to the fluctuating asymmetry of its leaf morphological traits in the leaf blade of Betula pendula as an indicator of developmental instability. A method for assessing fluctuating asymmetry of the leaf blade was employed. Standard biometric methods were used to measure five leaf blade traits, followed by calculation of the relative asymmetry value for each trait and the integral fluctuating asymmetry index for each leaf. Statistical data processing included descriptive statistics, testing for normality (Shapiro-Wilk test), and homogeneity of variance (Levene’s test). One-way analysis of variance (ANOVA) with Tukey’s post hoc test was used to compare groups.

Results. The integral fluctuating asymmetry index (IIFA) for the combined sample was 0.093, which corresponds to the “alarm” zone according to Zakharov’s scale. Statistical analysis revealed significant differences (p < 0.001) between the conventional background zone “Roshcha” (IIFA = 0.065 ± 0.004) and the impact zones “Site 1” (0.110 ± 0.007) and “Site 3” (0.104 ± 0.006). At the same time, no significant differences were found between the two sites (p = 0.721). Analysis of the contribution of individual traits showed that the “Length of the second vein” (0.152) and “Angle between veins” (0.095) exhibit the greatest sensitivity to anthropogenic stress.

Conclusion. The study demonstrates that fluctuating asymmetry in Betula pendula leaves is an effective tool for diagnosing complex anthropogenic stress. The data indicate an unfavorable environmental situation within the Don State Technical University training and experimental site, where developmental disturbances reach alarming levels. Spatial differentiation of FA values confirms the hypothesis of higher stress in areas immediately adjacent to infrastructure. Identifying the most sensitive morphological features allows for the optimization of bioindication monitoring programs for such urbanized areas.