The succession of the plant community on a decontaminated radioactive meadow site

Abstract

Long-term observation of the succession in a plant community is considered a fundamental unit used to investigate the expected consequences of soil contamination by radionuclides and to understand restoration of technogeneously disturbed ecosystems. The development of arboreal willow meadow under remediation of a radioactively contaminated site has been studied for half a century. Succession stages in the formation of the de novo community were noted. Changes in the floristic composition, soil structure as well as radionuclide activity concentrations in topsoil were registered on each step. Technical recultivation of the area including covering radioactive wastes with a mixture of sand and gravel led to lower the radiation levels and was suitable for decontamination during first 5-8 years. This allowed the community to develop with maximal effectiveness on the initial steps. Than the covering layer lost its barrier functions but no adverse effects at dose rates up to 150 μGy/h on completion of the community formation were registered. Radioecological conditions and changes in the plant community development were registered simultaneously on the area studied that makes possible to follow main doseforming radionuclides migration and to determine main steps of the succession. The study results is a practical demonstration that edaphic niches, climatic conditions and сoenotic relationships between plants play a more important role in the evolution of the studied community than the contamination type and radiation exposure levels.