Effect of European Black Alder Monocultures on The Characteristics of Reclaimed Mine Soil

The effect of European black alder (Alnus glutinosa L.) on the contents of carbon and nitrogen, exchangeable base cations, and plant available forms of phosphorus in the reclaimed mine soils formed by waste deposition from opencast lignite mines was researched in central Serbia. It was concluded that the greatest part of dead organic residues reaching the soil under European black alder monocultures was liable to rapid decomposition into end products. This was the consequence of a narrow C/N ratio in the European black alder litterfall which amounted on average to 12.77 in the study monocultures. Only a small part of organic residues was transformed into humus. On that account, European black alder monocultures did not have a major impact on the accumulation of organic carbon and total nitrogen in the soil. The content of carbon in the surface layers accounted for 1.55-1.57%, and the content of nitrogen to 0.085-0.132%. Fast mineralisation of organic matter, and thus also of the organic forms of nitrogen, resulted in the surplus of soil nitrates, which were liable to washing through the soil. Nitrate movement resulted in the soil leaching and the movement of base cations, primarily calcium, to the deeper layers of the solum. The total soil phosphorus content was low, and also the level of plant available forms. A significant portion of total phosphorus in the surface layers of the reclaimed mine soils was composed of its organic forms.