Over 50 Years of Overgrowth of the Ash Dump, The Content of Nitrogen and Phosphorus Changed in Young Soils but it Did Not Change in Plants

Changes in the nitrogen (N) and phosphorus (P) content in the ash substrate and plant leaves during the primary succession of overgrowing ash dumps of different ages were studied. The work was carried out on the young (overgrowth duration 5–8 years) and old (overgrowth duration 53–56 years; two sites – with meadow and forest vegetation) ash dumps of a thermal power plant in the Middle Urals. In the emerging soil and leaves of model plants, the content of N and P was determined on each dump. In young soils, a predictable and explainable successional dynamics of N and P was established: over 53–56 years, the N content increased 2.4–7.1 times, while the P content decreased 1.1–2.1 times. In plant leaves, the content of N and P at different stages of overgrowth was actually constant: 1.6–2.1% of N and 2.2–2.9 mg/g of P. In general, it has been found that in successionally young habitats, and in more advanced ones with developing forest vegetation, against the background of a multiple increase in the N content in the soil, the N content in plants remains low. With a high probability, on both dumps, the availability of nitrogen is a factor limiting the development of plants. This is evidenced by the results of the analysis of N/P ratio values in leaves and comparison of our array of N values in leaves with global averages of N content in the same species. Thus, the results with respect to the successional dynamics of the content of nitrogen and phosphorus in soils and plants of dumps of different ages turned out to be surprisingly little consistent with each other.