The influence of climatic and hydrological changes on the forest-growing conditions of the river floodplains of the Don basin

The article deals with the problem of floodplain forest degradation in the steppe zone, using the Don basin’s rivers as an example. The floodplains of the Khoper, Buzuluk, Ilovlya, Medveditsa, and Chir rivers were the key objects of the study. Identification of the landscape-hydrogeological conditions of river floodplains was carried out using the profiling method. In total, five transverse landscape profiles were laid in the floodplains of the listed rivers, along which leveling was carried out to build a hypsometric profile and a comprehensive soil and plant description. For the arid zone rivers, ground feeding is an important source of moisture in addition to atmospheric. Therefore, one of the main tasks was to determine the groundwater level using subsurface sounding (georadar). The analysis of the maximum levels of data for spring floods showed a trend of decreasing the height of floods since the late 1990s. Comparison of these data with the hypsometric profile and radar survey data revealed that the provision of complete flooding of floodplains occurs once every 10-20 years. The absence of annual complete flooding of floodplains with water has led to a decrease in the groundwater level to 5-6 m, which is an unfavorable factor for the development of woody vegetation. The climatic and hydrological conditions of the steppe zone considered in the article are unfavorable for the development of woody vegetation since they do not correspond to the conditions of its initial formation. In view of the existing conditions and the identified trends in the reduction of floods and the fall of the groundwater level, it is possible to predict a further reduction and redistribution of the forest cover of the Don basin’s river floodplains.