Subaerial endolithic systems of the current extreme environments on Earth provide exclusive insight into emergence and development of soils in the Precambrian when due to various stresses on the surfaces of hard rocks the cryptic niches inside them were much more plausible habitats for organisms than epilithic ones. Using an actualistic approach we demonstrate that transformation of silicate rocks by endolithic organisms is one of the possible pathways for the beginning of soils on Earth. This process led to the formation of soil-like bodies on rocksin situand contributed to the raise of complexity in subaerial geosystems. Endolithic systems of East Antarctica lack the noise from vascular plants and are among the best available natural models to explore organo-mineral interactions of a very old “phylogenetic age” (cyanobacteria-to-mineral, fungi-to-mineral, lichen-to-mineral). On the basis of our case study from East Antarctica we demonstrate that relatively simple endolithic systems of microbial and/or cryptogamic origin that exist and replicate on Earth over geological time scales employ the principles of organic matter stabilization strikingly similar to those known for modern full-scale soils of various climates.
Monitoring of active layer thawing depth and active layer thickness (ALT), using mechanical pronging and continuous temperature data logging, has been undertaken under the Circumpolar Active Layer Monitoring – South (CALM-S) program at a range of sites across Antarctica. The objective of this study was to summarize key data from sites in different Antarctic regions from 2006 to 2015 to review the state of the active layer in Antarctica and the effectiveness of the CALM-S program. The data from 16 sites involving 8 CALM-S and another 8 boreholes across the Antarctic have been used in the study. Probing for thaw depth, while giving information on local spatial variability, often underestimates the maximum ALT of Antarctic soils compared to that determined using continuous temperature monitoring. The differences are likely to be caused by stones limiting probe penetration and the timing of probing not coinciding with the timing of maximum thaw, which varies between seasons. The information on the active layer depth is still sparse in many regions and the monitoring needs to be extended and continued to provide a better understanding of both spatial and temporal variability in Antarctic soil thermal properties.
An analogous time series of fallow ecosystems (gray soils (Luvic Phaeozems) plowed and fallowed for 2, 7, 20, 60, and more than 120 years) in the broad-leaved forest zone of Orel oblast has been analyzed. Changes in carbon pool and CO2 emission in the course of postagrogenic succession during the vegetation and winter seasons have been estimated. The restoration of ecosystems on Luvic Phaeozems follows regularities revealed in analogous studies of southern taiga Podzols and forest-steppe Chernozems. Analogously to the other studied zonal chronosequences, total annual soil respiration on Luvic Phaeozems reaches the initial level of undisturbed ecosystems simultaneously with the restoration of phytomass reserve, although significantly earlier than the organic carbon reserve in soils is restored. According to regression models, among the zonal fallows in European Russia, including the southern taiga (Podzols), mixed forests (Luvisols), broadleaved forests (Luvic Phaeozems ), forest-steppe (Chernozems) and dry steppe (Calcisol–Solonetz soil complexes), the mean annual soil respiration is maximum in the zone of gray soils and Chernozems. The increase in soil respiration under artificial wetting (Birch effect) on fallows in the broad-leaved forest zone is minimum among the studied zonal chronosequences: 1.1 ± 0.6 (no effect), which corresponds to the optimal hydrothermal conditions in this zone.
Urbanization results to a wide spread of Technosols. Various materials are used for Technosols’ construction with a limited attention to their ecosystem services or disservices. The research focuses on the integral assessment of soil-like materials used for Technosols’ construction in Moscow megalopolis from the ecosystem services’ perspective. Four groups of materials (valley peats, sediments, cultural layers, and commercial manufactured soil mixtures) were assessed based on the indicators, which are integral, informative, and cost-effective. Microbial respiration, C-availability, specific respiration, community level physiological profile, and Shannon’ diversity index in the materials were compared to the natural reference to assess and rank the ecosystem services and disservices. The assessment showed that sediments and low-peat mixtures (≤30% of peat in total volume) had a considerably higher capacity to provide C-sequestration, climate regulation and functional diversity services compared to peats and high-peat mixtures. Urban cultural layers provided ecosystem disservices due to pollution by potentially toxic elements and health risks from the pathogenic fungi. Mixtures comprising from the sediments with minor (≤30%) peat addition would have a high potential to increase C-sequestration and to enrich microbial functional diversity. Their implementation in urban landscaping will reduce management costs and increase sustainability of urban soils and ecosystem.
Urban pedosediments (cultural layers) dating back to the 10th–11th centuries AD and soddypodzolic soils buried under them were studied in two archaeological excavations in Velikii Novgorod. Stages of...