Effects of River Control and Climate Changes on the Dynamics of the Terrestrial Ecosystems of the Lower Volga Region

Abstract

We continued the complex ecological studies in the Lower Volga Region that we started in 2014 in order to investigate the current state of floodplain terrestrial ecosystems and to describe the tendencies in the transformation of the natural environment and the responses of terrestrial ecosystems to changing climate conditions and the influence of anthropogenic factors. The study was conducted with the original two-step method for the estimation of disorders in terrestrial ecosystems after changes in the water content of studied areas. The first step included the determination of possible changes in the water content based on an analysis of long-term annual changes in climatic and hydrological data. The second step included the estimation of disorders in the ecosystems and landscapes based on various biological parameters. We determined the main factors of changes in the abiotic (hydrological and climatic) components of ecosystems in the Lower Volga Region influencing the transformation of landscapes. We described the main causes of changes in a separate component of terrestrial ecosystems related to the increased water flow rate of the winter low-water period and winter runoff, which contribute to a higher level of gleying throughout the entire soil profile and to the degradation of floodplain ecosystems (along with climatic changes).