Influence of Floods and Pollutants on Development of Plant Abiotic Stress in the Amur River Floodlands

Effects of floods on chemical pollution of floodplain soils and abiotic stress on plants were assessed. The presented research has revealed that hydrological conditions (flooding depth, temperature regime of flood waters and flood duration) affect the survival of plant species. The resulting hydrological regime and high concentrations of pollutants in flood waters cause abiotic stress for floodplain vascular plants. The intensification of riverbed processes reduces the stability of the habitats of meadow complexes, disrupts the ratio of their species composition and affects changes in the structure of the vegetation cover. Consequences of such changes are still poorly understood. The concentration of soluble compounds of heavy metals in soils and their absorption by plant roots has a decisive influence on mechanisms of regulation of enzymes and metabolism of vascular plants. Emerging toxicity effect contributes to the development of abiotic stress on certain types of plant communities (phenomenon chlorosis). Plants affected by heavy metals have shorter root and stem lengths. It is emphasized that concentrations of Fe³⁽²⁾⁺, Zn ²⁽¹⁾⁺ and Cu²⁽¹⁾⁺ in soil solutions identify the specificity of plant responses to abiotic stress. Mechanisms and interrelationships of these events are described. Despite significant progress in understanding of many aspects of floodings as an abiotic stressor no synthesis and analysis of the obtained data have been made so far. This study discusses the toxic effects caused by various heavy metals in plants. This is our first attempt to contribute to such research attempts.