Vol 71, No 2 (2016)

This paper tracks the annual dynamics of carbon dioxide production (emission and profile concentration) by soils of the arboretum in the Moscow State University Botanical Garden that are planted with Siberian spruce and common pine. The high biological activity of the studied soils is caused by the high content of organic matter, slightly alkaline reaction, and good structure and texture. Differences in CO₂ production by the soils of a spruce and pine forest (1.5–2 times higher in the latter) can be explained by different structures of soil profiles rather than a temperature regime. The seasonal dynamics of CO₂ production are the same for both soils and associated with seasonal changes in climatic parameters. In the cold season, there is noticeable production of carbon dioxide by soils.

The long-term dynamics of humus parameters and bioproductivity of soddy-podzolic soils in an agrocenosis under the conditions of well-pronounced microfeatures of topography and agrotechnical impact of different intensity has been studied. Unfavorable changes in qualitative and quantitative parameters of humus in soils of depressions and their role in the productivity of phytocenoses have been analyzed. The difference between the pronouncement rate of humus degradation and a drop in productivity of phytocenoses in depressions in comparison with elevated areas and its dependence on the kind of agrotechnical impact has been revealed.

A simulation model of the ⁹⁰Sr dynamics in the soil and stand components of deciduous forest ecosystems with a 1-day step was developed; this model was used to conduct numerical experiments to clarify the mechanisms of the ⁹⁰Sr behavior. The algorithm allows one to take into account the effect of meteorological, phenological, and physiological factors on the behavior of the radionuclide and simulate different fallout conditions. The results of simulation can be used in the valuation of deciduous forest products. The model is applicable for studying the redistribution of calcium in the stand of deciduous forest ecosystems.

Accumulation and distribution of ¹³⁷Cs by the root systems of forests in the radioactive contamination zone of Bryansk oblast have been discussed. It has been found that the phytomass and distribution of roots of pine and birch trees along the soil profile in the studied BGCs differ considerably. The specific activity of ¹³⁷Cs in the roots changes depending on their diameter: the lowest specific activity is observed in small fractions of the roots, and the highest one in large fractions. It has been shown that the contribution of roots in the total reserves of ¹³⁷Cs in the soil layer of 0–50 cm of various biogeocenoses is different: the largest contribution is characteristic for birch forests (1.66%) with variation of this parameter in separate soil layers from 1.12 to 3.53%, while the contribution for pine forests is lower (0.97%) with the variation from 0.82 to 7.5%. The contribution of roots to the overall contamination of soils in the studied plant communities increases with depth.