2015,    N 6 (22)    

ECOLOGY

Sarzhanov D., Vasenev I., Valentini R.

Analysis of spatial variability and temporal dynamics of the greenhouse gases (CO2, СH4, N2O) soil flaxes in conditions of Kursk representative urboecosystems

One of the principal factors of global climate and biota changes are characteristic for XXI century accelerated land-use structure changes with rapid urban areas growth, cardinal changes in the urboecosystems soil cover functioning and greenhouse gases raised emission by them. Environmental risks of the urbanized greenhouse gases increased soil emission are especially sharp in regions with the increased stocks of background soils organic matter. Among such regions in the European territory of Russia, first there are the industrially developed cities at the Central Chernozemic region. In particular, here is Kursk which is characterized by big total area (with diameter until 30 km), the humus-rich forest-steppe chernozems and dark grey forest soils domination, and clear land-use differentiation by the residential, industrial and recreational functional zones. The paper has been based on the results of long-term soil-ecological investigation in the key monitoring sites representative for three functional zones of Kursk city. They are included in the comparative analysis with data of background territories with comparable variants of chernozems and grey forest soils. In frame of 2013-2015 research there are been studied the regional-typological regularities in the diurnal, seasonal and particular annual dynamics of greenhouse gases (CO2, CH4, N2O) soil fluxes. It gives possibility to evaluate their principal ecological factors by human (a functional zone of the city) and bioclimatic (background soil type, soil and air temperature and moisture) nature. In result of the year-round and, during warm season, ten-day monitoring investigation there has been fixed the stably increased CO2 emission by investigated urban soils: in 20-25% higher than by their natural background ones. Seasonal measurement of CH4 fluxes by the investigated urban soils showed their drops in 2-6 times in comparison with local natural controls. All studied soils emitted N2O with maximal efflux in the industrial zone. Soil temperature and extra-moisture were the limiting factors (RTS until 0,92, RWS until -0.61) in daily and seasonal dynamics of greenhouse gases soil fluxes in spring and autumn, whereas soil moisture has a predominant positive effect (RWS until 0.73) in summer. The specific contribution of CH4 and N2O soil fluxes to the general soil greenhouse gases emission in the studied ecosystems is rather small (until first relative percents – negative for СH4 and positive for N2О), but it is much higher, than in their background controls. The integrated assessment of urban greenhouse gases emission has to be done taking into attention the city functional zoning, functional-ecological features of their man-changed and background soils, based on the results of long-term environmental monitoring. The urban soils environmental functions normalizing can be very effective for greenhouse gases regional fluxes stabilization in conditions of the Central Chernozemic region of Russia that in turn is an important factor in prevention of the Global climate and biota changes accelerated in XXI century.

Keywords: ECOLOGY, URBOECOLOGY, GLOBAL CHANGES, GREENHOUSE GASES, URBAN SOILS, CHERNOZEMS, GREY FOREST SOILS, FUNCTIONAL ZONES, ENVIRONMENTAL FACTORS, SOIL FLUXES, SPATIAL VARIABILITY, TEMPORAL DYNAMICS