Marina Sergeevna Rozanova

Th e features of soils and litters, formed in pine ecosystems of the Moscow region, within the nesting grounds of
gray herons, have been established. It is shown that, in densely located herons’ nesting sites, in comparison with
the control plots, the total trophicity of ecosystems sharply increases, which is manifested in a wide distribution of
species characterized by high demands on the nutrient regime of soils. Th is is confi rmed by the increased content
of water-soluble forms of phosphorus, nitrates, sulfates, potassium, magnesium and calcium in the soils within the
nests of gray herons. On the contrary, the soils in the control plots are characterized by the usual content of the
main components characteristic of the soils of the zone of coniferous-deciduous forests. Taking into account the low
mobility of phosphorus and its probable fi xation in the composition of immobile complexes, it has been suggested
that the increased content of this element in soils under the conditions of the spread of soddy-podzolic soils, if the
role of anthropogenesis is excluded, may serve as an indicator of the former infl uence of ornithogenic ecosystems.

The article presents the results of an 18-month field experiment assessing the impact of 11 mulching substrates used in urban soils on a range of physical, chemical, and biological properties. The following substrates were studied: serpentine, marble, volcanic tuff, foam glass, coconut chips, painted and unpainted pine chips, large and small fractions of larch bark, and large and small fractions of pine bark. The substrates used were shown to have no negative impact on pH, total carbon (Corg) content, or its water-soluble forms (Cws), and no effect of the substrates on soil bulk density. The use of mulching substrates on urban soils contributed to an increase in the biological activity of the soil prokaryotic complex and a decrease in the number of sanitary-indicator and potentially pathogenic bacteria (Escherichia coli) in the soil, which reduces potential risks to the health of the urban population. The most favorable soil properties, based on the totality of the studied parameters, are formed under organic mulching substrates consisting of fine-sized particles, coconut chips and larch bark. An increase in the content of microscopic fungi in the upper horizon of urban soil under a 5-cm-thick mulch layer was detected. This may pose potential risks to human health due to the allergenic and potentially pathogenic properties of some soil micromycetes and requires further research. The obtained results allow us to recommend mulching urban soils with organic substrates not only for decorative purposes but also to enhance biological activity and, consequently, improve the biological condition of soils in anthropogenically transformed conditions.