Microbial communities of buried soils of the Tsaritsyn Defense Line (1718–1720)

Abstract

Microbial communities of recent surface soils and the soils buried beneath the rampart of the Tsaritsyn Defense Line (1718–1720) in the Little Ice Age were studied. The contribution of the time factor to the variability in the number of microorganisms from different trophic groups was shown to be minor (0.2–0.3%), although significant. In the upper horizon of the paleosols reflecting the environmental conditions intrinsic to the period of the rampart construction, the lower (by two times) content of live microbial biomass, the lower metabolic activity of the microbial community, and the more contrasting changes in the microbiological parameters as compared to these characteristics in the recent soils were found for all the elements of the local topography. The stabilities of the microbial communities in the buried and recent soils were almost the same. The ecological–trophic structure of the microbial communities in the buried soils evidences that, the climate of the 18th century in the southern Privolzhskaya Upland was more humid than now. At the same time, temperature conditions of the Little Ice Age did not prevent the development of steppe vegetation and corresponding soil microbial communities in this area. Our data on the morphology and physicochemical properties of the soils confirm the assumption about more humid climatic conditions at the beginning of the 18th century in the studied area.