Reforestation of Brown Coal Dumps in Bashkortostan: Characteristics of the Soil and the Condition of Birch (Betula pendula Roth) Stands (Results of a 35-year Experiment)

Abstract

In 1980–1984, reforestation of the dumps of the Kumertau brown coal deposit (Republic of Bashkortostan, Russia) was carried out. Birch stands were created on the dumps of overburdened rocks. The authors studied the agrochemical properties of soils, described the state of birch stands and established the patterns of metal accumulation in birch organs 35 years after reforestation. It is established that 35 years after planting birch trees on the dumps, the trees are characterized as `healthy'. The concentration of copper, zinc, lead and cadmium in birch organs changes in the following sequence: root system > bark > shoots > leaves. Soil formation processes are noted in birch stands on dumps. The upper (0–20 cm) soil layer acidity shifted by two units to the acidic side. There is a slight decrease in the content of phosphorus and the exchange forms of calcium and magnesium. Thus, birch is a promising tree species for the reforestation of mining industry dumps.