Vol 74, No 2 (2019)

Stand litter of some coniferous and deciduous plantations within the Botanical Garden of Moscow State University is studied. It is established that stand litter of destructive types develops under conditions of deciduous plantations, whereas it is fermentative and humified in coniferous plantations. The total reserves of stand litters range from 500–800 g/m² in deciduous plantations to 1000–5000 g/m² in coniferous plantations. It is shown that small-leaved plantations are characterized by high rates of cycling with a significant decrease in the coniferous ecosystems. It was shown for the first time that the overall decomposition rate of terrestrial litter increases substantially with an increase in the proportion of leaves in the litter, which is confirmed by the theory of “hot points” proposed in the scientific literature.

The content of potassium was determined in the whole soil and in fractions >5, 1–5, and <1 μm in extracts of 1 M NH₄OAc, 2 M HCl, and hot 10% HCl in the (AO)EL horizon of a podzolic soil in the rhizosphere of Norway maple (Acer platanoides L.) and from the bulk soil. It was established that the content of exchangeable potassium is significantly higher in the rhizosphere with a higher amount of organic matter as compared with the bulk soil. Based on the existing gradations of supply of tree cultures with this element, the soil of the rhizosphere refers to the gradation of increased level of supply, and the bulk soil is moderately provided with potassium. In the soil of the maple rhizosphere, as compared with the bulk soil, there is more hardly hydrolysable potassium, which can be explained by the transition of the element to the acid extract from the fine and poorly crystallized mica and illite particles. It is assumed that the increased content of these minerals in the rhizosphere is due the intensification of the processes of illitization and physical disintegration of mica and illite particles occurring in coarser fractions.

The article reports the results from the analysis of content and distribution of petroleum hydrocarbons in the soils of geochemical landscapes in southern Sakhalin. It discusses the main types of soil formed in this region and the parameters determining the migration of petroleum hydrocarbons in the landscapes. It has been shown that the soils of transit-accumulative and accumulative landscapes are characterized by the highest content and the penetration depth of petroleum hydrocarbons into the soil profile. In the event of accidental oil spills, along with lateral migration, a significant role is played by vertical migration of petroleum hydrocarbons to the accumulative landscapes.