Influence of Forest Vegetation on Organic Matter Composition after Restoration of Mining Spoils in the Town of Pernik

Three tree species are studied: coniferous plantation of black pine / Pinus nigra Arn./ and deciduous: birch / Betulla alba L./ and ash / Fraxinus pennsylvanica Marsh/, on the territory of Baikusheva neighborhood in Pernik, near the mine "M. Tolbuhin ”, after performed 45 years ago reclamation. The accumulation of organic matter in the mining spoil and humus composition are analysed. High amounts of org.C are found under all three types of woody plants (tC% = 3.65 ÷ 9.50 in top layers 0-20cm). This is also due to the presence of large amounts of coal carbon particles in the substrate. Humus accumulation is more pronounced under deciduous species and especially under the newly studied species of Fraxinus pennsylvanica Marsh (Humus% = 11.42 ÷ 16.38). But here the process of humification takes place to a lesser extent (~ 10 ÷ 16%). On the contrary, under the coniferous plantation of Pinus nigra Arn. is accumulated less org. C (tC% = 1.34 ÷ 3.65), but the humification processes are going in the highest degree (~ 18 ÷ 32%). However, this is also associated with the formation of the largest amounts of the more mobile parts of the organic matter: fulvic acids (Cf ~ 11% from tC). Among deciduous species under Fraxinus pennsylvanica Marsh, fulvic acids move in the range of the lowest values (4-5% of tC).