Beschreibung: Soil analyses have been carried out in permafrost environment in Victoria Land, Continental Antarctica, in 9 sites within the network of the sensitive system permafrost-vegetation for the assessment of climate change effects along a latitudinal and geographical transect (77° - 72°S). Within each site the samples have been collected in different ecological and environmental conditions concerning active layer thickness, vegetation type and coverage, substrata, occurrence of glacial and periglacial features. In each site the vertical profile of the ground have been described and the samples collected within the active layer representing all the layers with visible differences regarding texture, structure and color. Organic C and N show specific patterns allowing to discriminate: a) vegetated vs unvegetated sites; b) among the unvegetated sites, ground with and without disturbance processes, mainly represented by frost heave and salt concrections. The barren grounds with frost heave and/or salt efflorescences show highest values of organic C and N. In the vegetated sites, organic C and N show different patterns related to the vegetation type and to their ecological requirements in terms of nutrient regime. The higher values are associated in particular with moss communities and with ground colonized by nitrophytic epilithic lichens. On inundated grounds the content of both organic C and N increases respect to close sites with similar vegetation. On the contrary, bacteria have a wide range of variability (between complete sterile soils to a more than 100K of cells/g soil) with less clear patterns of spatial distribution. In the surficial layers (〈 5cm) in the unvegetated sites the higher bacteria values couple with the higher values of Al and Fe, but not with the organic C and N. In these sites the higher bacteria values are always associated to the more xeric conditions while the only really sterile site is the true inland one (Cape Sastrugi). Although the vegetated sites show more abundant bacteria, the highest values have been found within unvegetated gelifluction terracettes soils. The vertical distribution of the measured parameters show regular patterns, with lower values at the surface, maximum at intermediate depth, and a decrease in the deeper parts of the profile, except for C and N in some sites with a progressive decrease with depth. These depths are consistent with the values of active layer thickness characterizing the different sites. The vertical profile of the bacteria are differentiated between vegetated soils and barren grounds, the former with the higher values in the upper layers, the latter with an opposite pattern. The relatively high values of bacteria in barren grounds and in strongly disturbed soils (as gelifluction terracettes) need further research especially because in literature these Antarctic environments have been considered sterile and therefore not particularly sensitive to the climate change.

Beschreibung: This report is the product of international collaboration of several permafrost researchers working in Svalbard. The report aims to provide an overview of ground thermal conditions and active-layer thickness as they are recorded at five sites during the 2016/2017 hydrological year from 1 September 2016 to 31 August 2017 in Svalbard. We report on this period, as this is when observation variables are available from all sites. This provides the basis for comparison of spatial variations in permafrost thermal conditions and active layer thickness in Svalbard. For earlier summaries of permafrost conditions on Svalbard see Humlum et al. (2003) and Christiansen et al. (2010). The specific objectives of this report are to: (1) introduce the study area and permafrost in Svalbard; (2) describe instrumentation and operation at each of the five sites; (3) characterize the ground thermal regime and present the active-layer thickness from the last 20162017 hydrological year; (4) provide an overall analysis of the ground-thermal observations with a focus on the implications of changing permafrost on other parts of the cryosphere relevant for the SIOS network; (5) ensure access to the reported data through the Global Terrestrial Network on Permafrost (GTN-P) adhering to the SIOS Data policy and (6) point to potential avenues and geographic locations for future permafrost observation needs in Svalbard. This report builds on the IPY 2007-2008 snapshot of the permafrost thermal state and active layer thickness in Svalbard (Christiansen et al., 2010), but now provides ground temperatures from more areas in Svalbard thanks to the international collaboration. The report may serve as a baseline for future regional observation programs and collaborative activities within the SIOS network.

Beschreibung: Soil analyses have been carried out in permafrost environment in Victoria Land, Continental Antarctica, in 9 sites, located along a latitudinal and geographical transect, covering 5 degrees (77° - 72°S). The samples have been collected in correspondence of long term monitoring sites within the network of the sensitive system permafrost-vegetation established for the assessment of climate change effects (Cannone and Guglielmin, 2003). Within each site the samples have been collected in different ecological and environmental conditions concerning active layer thickness, vegetation type and coverage, substrata, occurrence of glacial and periglacial features. In each site the vertical profile of the ground have been described and the samples have been collected within the active layer representing all the layers with visible differences regarding texture, structure and color.Organic C and N show specific patterns allowing to discriminate: a) vegetated vs unvegetated sites; b) among the unvegetated sites, ground with and without disturbance processes, mainly represented by frost heave and salt concrections. The barren grounds with frost heave and/or salt efflorescences show highest values of organic C and N. The highest value of organic C is associated to a buried gley horizon, and is compatible with the low rate of organic matter mineralization associated to the anaerobic environment producing this kind of layers. The vertical distribution of the measured parameters show regular patterns, with lower values at the surface, the maximum value at intermediate depth, and a decrease in the deeper parts of the profile. These depths are consistent with the values of active layer thickness characterizing the different sites.In the vegetated sites, organic C and N show different patterns related to the vegetation type and to their ecological requirements in terms of nutrient regime. The higher values are associated in particular with moss communities and with ground colonized by nitrophytic epilithic lichens. On inundated grounds the content of both organic C and N show an increase respect to sites located in the close nearby and with a similar vegetation occurring. This fact indicates the lower speed of mineralization processes of the organic substances and a tendency to peat production and accumulation. The vertical distribution of both organic C and N show two different patterns: a) the same pattern characterising the unvegetated sites, with the maximum values occurring at intermediate depth; b) a different accumulation rate, with the highest values associated to the more surficial layers and a progressive decrease with depth. The former one is typical of vegetation composed by lichens, indipendently from their growth form. The latter pattern is typical of moss communities developing directly on the ground and indicates that the greatest part of the organic substances is strictly associated to these living organisms. These patterns, as well as those associated to disturbance processes in the unvegetated sites, are highly susceptible of significant variations in response to climate change effects. Therefore, it is essential to include their analysis within the monitoring activities planned for the network of the sensitive system permafrost-vegetation as indicators of functional processes occurring in the physical environment and in the associated ecosystems. Furthermore, it is planed to study CO2 fluxes and the involved microbial community along the transect for understanding the carbon dynamic under changing environmental conditions.

Beschreibung: Antarctica is the last pristine environment on Earth, its biota being adapted to the harsh and extreme polar climate. Until now, soil formation and vegetation development in continental Antarctica were considered very slow due to the extreme conditions of this polar desert. Since the austral summer 2002/2003, a long-term monitoring network of the terrestrial ecosystems (soils, vegetation, active layer thickness) has been established at Victoria Land (VL) across a 〉 500 km latitudinal gradient of coastal sites (73◦–77◦S). In only one decade large ecosystem changes were detected. Climate was characterized by a significant increase of thawing degree days in northern VL and of autumn air temperature. No extreme climatic events (such as hot spells) where detected in the study period. Soil chemistry suffered large quantitative changes, clearly indicating rapid pedogenetic processes. In most soils the upper layers exhibited a strong alkalinization (pH increases up to 3 units) and increases in conductivity, anions and cations (in particular of SO4 and Na). The largest changes were observed in soils with low vegetation cover. Statistically significant differences in soil chemistry were detected between soils with high and low vegetation cover, the former showing lower pH, conductivity, Na and Cl. Most plots exhibited changes of total cover, species richness and floristic composition, with vegetation expansion in soils with low vegetation cover and the largest increase recorded at Apostrophe Island (northern VL). Principal Component Analysis (PCA) identified the main trend of vegetation change, with a shift from lower to higher cover and a secondary trend of change associated with a gradient of water availability, consistent with an increase in water instead of snow. Redundancy analysis (RDA) identified the trend of change in soil chemistry with increases in pH, conductivity, anions and cations associated with the concomitant decrease in C, N, NO3, PO4. The RDA confirmed that soil changes were associated with a gradient of vegetation change (from low to high cover) as well as of water availability, as already indirectly outlined by the PCA. Field manipulation experiments carried out at five locations of the network between 73◦S and 77◦S, simulating increases of precipitation from snow or water additions didn’t induce changes in soil pH, indicating that pulse events of snow accumulation or melting could not trigger persistent soil pH changes. These data allow hypothesize the occurrence of a main ecosystem change occurring at regional scale at Victoria Land. The slight air warming and its consequences on soil chemistry and vegetation, further highlight the sensitivity of the fragile Antarctic ecosystems to the consequences of even small changes in climate.