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)

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 metalaccumulation 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 bytwo 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. Keywords: dumps, reforestation, Betula pendula Roth, metal accumulation, soil formation processe

DIFFERENTIATION ОF TREES IN SANITARY-PROTECTIVE FOREST LANDINGS ОF THE STERLITAMAK INDUSTRIAL CENTER

The paper presents the results of many years of research on the assessment of the relative vital state and accumulation of cadmium in the aboveground and underground organs in healthy and weakened poplar trees of balsamic and birch trees in the conditions of industrial contamination of the Sterlitamak industrial center. It is shown that in the conditions of industrial pollution of the Sterlitamak industrial center, the overwhelming majority of balsamic poplar trees belong to the category of «weakened» and «healthy» birch trees. Under the influence of industrial pollution in the poplar balsamic there is a decrease in the density of the crown and the formation of a large number of dead branches. When studying root systems in healthy and weakened trees under conditions of industrial contamination of the Sterlitamak industrial center, it was found that at a depth of 0–20 cm, the rooting of the soil by the absorbing roots of balsamic and birch poplar roots decreases compared to the control. Also, it is established that in conditions of industrial pollution, the roots of healthy balsamic poplar trees are able to absorb more cadmium from the soil, thereby reducing their transport to terrestrial plant organs

New procedure for the simulation of belowground competition can improve the performance of forest simulation models

The major part of existing models of belowground competition in mixed forest stands is limited in explaining the spatial distribution of roots as a response to competitive pressure from neighbours and heterogeneity of soil properties. We are presenting a new spatially explicit and multi-layered discrete model of belowground competition, RootInt (ROOTs INTake). It describes spatial distribution of belowground biomass and allows simulation of competition between trees for soil nutrients. The tree-specific area of root zone is calculated on the basis of stem diameter, with site-specific modifiers to account for the effect of soil fertility and moisture. The shape of root zone is dependent on the amount of available nitrogen in the current cell, distance between this cell and the stem base, and the mass of roots of other plants. RootInt was incorporated into ecosystem model EFIMOD to refine the existing description of belowground competition in forest stands with multiple cohorts and tree species. The results of simulation showed that bringing more complexity into structure of stand (including initial spatial locations of trees, species composition and age structure, vertical structure of canopy) resulted in higher spatial variation in competition intensity, as well as in higher rates of resource uptake. This indicates that stands with complex canopy structure had high plasticity in their root systems and were adapted to intensive competition for soil resources.201