Structure and Regularities of the Development of Forest Stands with Oak Represents in Mari El Republic

Abstract

Introduction. The value of fluctuating asymmetry of bilateral characteristics of biological objects is considered as an integral assessment of the environmental quality. The peculiarity of this indicator is that when evaluating the environmental quality, the response of living organisms to the environmental conditions is considered, not the types of environmental pollution (soil, water, air, etc.). The research is aimed at assessing the ecological state of populated localities in urban and municipal districts of Mari El Republic with the help of fluctuating asymmetry of bilateral morphological characters of European white birch (Betula pendula). Material and methods. The research was conducted in Mari El Republic in June-August of 2019. Gathering of leaf blades of European white birch was conducted in the localities with the population of not less than 2 thousand people, 472 986 people in total. According to the data of the Federal State Statistic Service, it comprises 69% of Mari El Republic population for January 1, 2017. All administrative divisions of Mari El Republic were under examination (3 urban districts and 14 municipal districts). Leaf blades were gathered and measured according to the methodological recommendations. The results were analyzed using the analysis-of-variance models. The CVR indicator was used as a quantitative assessment of fluctuating asymmetry. Results and discussion. The analysis of variance shows that all localities do not differ (P=0.71) with regard to the indicator of the CVR fluctuating asymmetry, except for Yoshkar-Ola suburbs (Medvedevo, Ruem, Znamenskiy, and Semenovka). The differences between the sampling locations in the settlements were significant (P=0.007). Multiple comparisons of the sampling locations showed differences in the value of fluctuating asymmetry in impact and buffer zones (Scheffe’s test, P=0.008). At that, the value of fluctuating asymmetry was the same in the buffer zone and background territory (Scheffe’s test, P=0.15). Yoshkar-Ola suburbs have much lower CVR indicators. Thus, the sampling locations of birch with the highest values of fluctuating asymmetry (CVR=0.097) are defined not by the geographical position of the settlement in the region but its closeness to industrial and agricultural enterprises or federal and (or) regional motor roads, i.e. sources of pollution. Conclusion. Mari El Republic, on the whole, is characterized by rather low values of fluctuating asymmetry, which is indicative of a high level of stability of biological objects  and, consequently,  no considerable stress. The increased values of fluctuating asymmetry are not driven by the geographical position of the localities in the region but by the presence of large industrial and agricultural enterprises and motor roads. The highest values of fluctuating asymmetry are observed in the impact zones of the localities, where the man-caused load is more significant.