Proglacial Soils Research Articles

Physico-chemical properties and toxicity of young proglacial soils in the Tropical Andes and Alps

New soils formed after glacier retreat can provide insights into the rates of soil formation in the context of accelerated warming due to climate change. Recently deglacierized terrains (since the Little Ice Age) are subject to weathering and pedogenesis, and freshly exposed sediments are prone to react readily with the environment. This study aims to determine the impact of parent material and time on soil physical and chemical properties of nine proglacial landscapes distributed in the Tropical Andes and Alps. A total of 188 soil samples were collected along chronosequences of deglacierization and from sites that differed in terms of parent material and classified following three parent material groups: (1) Granodiorite-Tonalite (GT), (2) Gneiss-Shales-Schists (GSS), and (3) Mont-Blanc Granite (MBG). We determined physical and chemical soil properties such as contents of clay, silt, sand, organic carbon, bulk density (BD), pH, extractable cation (exCa, exMg, exK), elemental composition by X-ray fluorescence (Al, Si, P, S, K, Ca, Mn, Fe, Cu, Zn, As, Mo, Hg, Pb) and ICP-MS (Al, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Zn), and mineral phase (XRD diffraction analysis). Parent material-controlled particle-size distribution, SOC, pH, available P, exCa, and exMg, whereas time since deglacierization only affected SOC and P, and exMg globally. Most of the significant differences in soil properties between parent material groups occurred within the first 17 years after deglacierization, and then we observed a homogenization between sites. While the higher SOC and P contents observed within the GT Andean sites might be due to the parent material composition leading to faster initial soil formation, we identified potential As, Cu, Mo, and Mn toxicity within those soils. Our study highlights the need to investigate further proglacial soil’s buffering capacity and carbon sequestration to globally inform the conservation and management of novel proglacial ecosystems.

Soil temperature and local initial conditions drive carbon and nitrogen build-up in young proglacial soils in the Tropical Andes and European Alps

Climate warming has accelerated the retreat of mountain glaciers worldwide, exposing new areas to weathering, vegetation colonization, and soil formation. In light of probable climate changes such as warming and new extremes, understanding the factors that control soil organic carbon (SOC) and nitrogen build-up is crucial to comprehend proglacial soils and ecosystem formation. To this end, we examine the evolution of SOC, nitrogen (total N and NH4+), and phosphorus (available P) along nine 120-year chronosequences of deglacierization distributed between the European Alps and Tropical Andes. Our dataset includes geochemical analyses of 188 soil samples, in situ soil temperature data for the period 2019–2022, and hydrographic variables. Although time controls proglacial soil development at all sites, our study highlights distinct pedogenesis dynamics between proglacial landscapes depending on the micro and macro environmental context. Differences in soil development were strongly driven by growing degree days (GDD), maximum soil temperature, and parent material. Notably, we identified a positive effect of GDD on SOC and N (total N and NH4+), while our results indicate a negative effect of maximum soil temperature on SOC and NH4+, suggesting that overly high temperatures reduce microbial mineralization and organic matter input to the soil matrix. We reported the presence of higher initial SOC, total N, and NH4+ in the Andean sites than in the Alps sites, suggesting enhanced soil development at the Andean locations. This comparative study suggests the relative importance of maximum temperature and initial site conditions (e.g., parent materials, glacier biomes) during proglacial pedogenesis. Our findings highlight that soil temperature modulates pedogenesis in a complex way and suggest avoiding simply associating greater soil development with higher soil temperature in proglacial landscapes.

Polycyclic aromatic hydrocarbon dynamics in soils along proglacial chronosequences in the Alps

Polycyclic aromatic hydrocarbons (PAHs) were studied in the soils of three proglacial areas in France (Noir and Chardon Glaciers) and Italy (Miage Glacier). PAH contents, PAH stocks and PAH contents normalized to the total organic carbon contents (PAHs/TOC ratio) were investigated along proglacial soil chronosequences to infer their evolutions with soil age (from 3 to 4200 years), where the PAH contamination was only related to long-range atmospheric transport. Evolutions of PAH and TOC contents, PAHs/TOC ratio and PAH stock were fitted with exponential and logarithmic relations. For the three proglacial areas, PAH contents increased rapidly during the first 150 years of soil development, ranged from 4 to 152 ng·g−1, and showed a strong relationship with total organic carbon (TOC) contents (r = 0.83, p < 0.05). The joint increase of PAH and TOC contents suggested that PAH accumulation in soils were not only driven by PAH inputs but also by the capacity of soils to store these contaminants. PAH contents in the oldest soils (from 1200 BCE and 2200 BCE) were similar than for soils from 1850 CE. The period 1850–2019 CE corresponded to a decrease in the PAHs/TOC ratio suggesting both a faster accumulation of TOC than PAHs and a dilution effect of PAHs already present in soils. For the oldest soils, the PAHs/TOC ratio appeared similar to those for soils from 1850 CE, with values ranging from 0.48 to 2.06 ng·mg−1, suggesting an equilibrium between both parameters for soils older than 170 years. Finally, PAH stocks ranged from 0.41 mg·m−2 to 6.80 mg·m−2 in the youngest and oldest soils, respectively. These results do not allow us to identify the same period of greatest emission as other studies (estimated ~1960), but they revealed changes in the capacity of soils to store these pollutants.

Active microbial ecosystem in glacier basal ice fuelled by iron and silicate comminution-derived hydrogen.

The basal zone of glaciers is characterized by physicochemical properties that are distinct from firnified ice due to strong interactions with underlying substrate and bedrock. Basal ice (BI) ecology and the roles that the microbiota play in biogeochemical cycling, weathering, and proglacial soil formation remain poorly described. We report on basal ice geochemistry, bacterial diversity (16S rRNA gene phylogeny), and inferred ecological roles at three temperate Icelandic glaciers. We sampled three physically distinct basal ice facies (stratified, dispersed, and debris bands) and found facies dependent on biological similarities and differences; basal ice character is therefore an important sampling consideration in future studies. Based on a high abundance of silicates and Fe‐containing minerals and, compared to earlier BI literature, total C was detected that could sustain the basal ice ecosystem. It was hypothesized that C‐fixing chemolithotrophic bacteria, especially Fe‐oxidisers and hydrogenotrophs, mutualistically support associated heterotrophic communities. Basal ice‐derived rRNA gene sequences corresponding to genera known to harbor hydrogenotrophic methanogens suggest that silicate comminution‐derived hydrogen can also be utilized for methanogenesis. PICRUSt‐predicted metabolism suggests that methane metabolism and C‐fixation pathways could be highly relevant in BI, indicating the importance of these metabolic routes. The nutrients and microbial communities release from melting basal ice may play an important role in promoting pioneering communities establishment and soil development in deglaciating forelands.

Ectomycorrhizal utilization of different phosphorus sources in a glacier forefront in the Italian Alps

In deglaciated surfaces, lithology influences habitat development. In particular, serpentinite inhibits soil evolution and plant colonization because of insufficient phosphorus (P) content, among other stressful properties. In nutrient-poor environments, ectomycorrhizal fungi (EMF) play a key role exploring the soil for P beyond the rhizosphere. In this study, we followed the role of EMF in accessing inorganic and organic P along two proglacial soil chronosequences in the Alps (NW Italy), respectively characterized by pure serpentinite till and serpentinite mixed with 10% of gneiss, and colonized by European Larch. The access to inorganic and organic P forms by EMF was studied using specific mesh-bags for fungal hyphae entry, filled with quartz sand and inorganic phosphate (Pi) or myo-inositolhexaphosphate (InsP6) adsorbed onto goethite. They were incubated over 13 months at the organic/mineral horizon interface. After harvesting, EMF colonization via ergosterol analysis and the amount of P and Fe removed from mesh bags were measured. Ergosterol increased along the two chronosequences with slightly greater values on serpentinite and in Pi-containing bags. Up to 65% of Pi was removed from mesh-bags, only partly accompanied by a parallel release of Fe. The amount of InsP6 released was instead less than 45% and mostly removed with goethite. The results suggest that, in extremely P-poor environments, EMF are able to release both inorganic and organic P forms from highly stabilized associations.

Marked Succession of Cyanobacterial Communities Following Glacier Retreat in the High Arctic.

Cyanobacteria are important colonizers of recently deglaciated proglacial soil but an in-depth investigation of cyanobacterial succession following glacier retreat has not yet been carried out. Here, we report on the successional trajectories of cyanobacterial communities in biological soil crusts (BSCs) along a 100-year deglaciation gradient in three glacier forefields in central Svalbard, High Arctic. Distance from the glacier terminus was used as a proxy for soil age (years since deglaciation), and cyanobacterial abundance and community composition were evaluated by epifluorescence microscopy and pyrosequencing of partial 16S rRNA gene sequences, respectively. Succession was characterized by a decrease in phylotype richness and a marked shift in community structure, resulting in a clear separation between early (10-20years since deglaciation), mid (30-50years), and late (80-100years) communities. Changes in cyanobacterial community structure were mainly connectedwith soil age and associated shifts in soil chemical composition (mainly moisture, SOC, SMN, K, and Na concentrations). Phylotypes associated with early communities were related either to potentially novel lineages (< 97.5% similar to sequences currently available in GenBank) or lineages predominantly restricted to polar and alpine biotopes, suggesting that the initial colonization of proglacial soil is accomplished by cyanobacteria transported from nearby glacial environments. Late communities, on the other hand, included more widely distributed genotypes, which appear to establish only after the microenvironment has been modified by the pioneering taxa.

Airborne radionuclides in the proglacial environment as indicators of sources and transfers of soil material

A survey of artificial (137Cs, 238Pu, 239+240Pu, 241Am) and natural (226Ra, 232Th, 40K, 210Pb) radioactive isotopes in proglacial soils of an Arctic glacier have revealed high spatial variability of activity concentrations and inventories of the airborne radionuclides. Soil column 137Cs inventories range from below the detection limit to nearly 120 kBq m−2, this value significantly exceeding direct atmospheric deposition. This variability may result from the mixing of materials characterised by different contents of airborne radionuclides. The highest activity concentrations observed in the proglacial soils may result from the deposition of cryoconites, which have been shown to accumulate airborne radionuclides on the surface of glaciers. The role of cryoconites in radionuclide accumulation is supported by the concordant enrichment of the naturally occurring airborne 210Pb in proglacial soil cores showing elevated levels of artificial radionuclides. The lithogenic radionuclides show less variability than the airborne radionuclides because their activity concentrations are controlled only by the mixing of material derived from the weathering of different parent rocks. Soil properties vary little within and between the profiles and there is no unequivocal relationship between them and the radionuclide contents. The inventories reflect the pathways and time variable inputs of soil material to particular sites of the proglacial zone. Lack of the airborne radionuclides reflects no deposition of material exposed to the atmosphere after the 1950s or its removal by erosion. Inventories above the direct atmospheric deposition indicate secondary deposition of radionuclide-bearing material. Very high inventories indicate sites where transport pathways of cryoconite material terminated.

Origin and Distribution of Methane Entrapped in Calcareous Alpine Proglacial Soils

Origin and Distribution of Methane Entrapped in Calcareous Alpine Proglacial Soils

Microbial dynamics in a High Arctic glacier forefield: a combined field, laboratory, and modelling approach

Abstract. Modelling the development of soils in glacier forefields is necessary in order to assess how microbial and geochemical processes interact and shape soil development in response to glacier retreat. Furthermore, such models can help us predict microbial growth and the fate of Arctic soils in an increasingly ice-free future. Here, for the first time, we combined field sampling with laboratory analyses and numerical modelling to investigate microbial community dynamics in oligotrophic proglacial soils in Svalbard. We measured low bacterial growth rates and growth efficiencies (relative to estimates from Alpine glacier forefields) and high sensitivity of bacterial growth rates to soil temperature (relative to temperate soils). We used these laboratory measurements to inform parameter values in a new numerical model and significantly refined predictions of microbial and biogeochemical dynamics of soil development over a period of roughly 120 years. The model predicted the observed accumulation of autotrophic and heterotrophic biomass. Genomic data indicated that initial microbial communities were dominated by bacteria derived from the glacial environment, whereas older soils hosted a mixed community of autotrophic and heterotrophic bacteria. This finding was simulated by the numerical model, which showed that active microbial communities play key roles in fixing and recycling carbon and nutrients. We also demonstrated the role of allochthonous carbon and microbial necromass in sustaining a pool of organic material, despite high heterotrophic activity in older soils. This combined field, laboratory, and modelling approach demonstrates the value of integrated model–data studies to understand and quantify the functioning of the microbial community in an emerging High Arctic soil ecosystem.

Preliminary Study on Effects of Glacial Retreat on the Dominant Glacial Snow Bacteria in Laohugou Glacier No. 12

One impact of climate change is the rapid shrinking of glaciers, resulting in microorganisms deposited into glacial snow or ice being exposed to new environments such as glacier foreland. A pyrosequencing analysis based on the bacterial 16S rRNA gene showed that bacterial diversity was the highest in proglacial soil, followed by that of glacial snow in ablation zone, then by that of glacial snow in the accumulation area, finally by that of glacial snow in glacier terminus, with the combination of Chao1, ACE, Shannon and Simpson analysis. Eighteen phyla were detected from the 7 samples, but mainly composed of Proteobacteria, Actinobacteria and Bacteroidetes. Flavobacterium, Massilia, Pedobacter, Polaromonas were more abundant in glacial snow samples than in glacial soil sample. Massilia was rarely reported in other environments, implying the necessity for its conservation under scenarios of glacier and snowpack loss induced by climate change.

Soil carbon accretion along an age chronosequence formed by the retreat of the Skaftafellsjökull glacier, SE-Iceland

Climate warming has led to glacial retreat worldwide, where surfaces exposed to the atmosphere are subjected to weathering, vegetation colonization and new soil formation. On young soils developing along the recessional path left by the Skaftafellsjökull glacier, SE-Iceland, we investigated the accretion of soil organic carbon (SOC) and nitrogen (N), representing an age chronosequence of 120years. In total, 54 sampling sites were distributed along three moraines deposited in 1890, 1945, and 2003. For comparison, soil samples were collected from nearby birch woodlands (Betula pubescens Ehrh.), representing soils in a mature ecosystem likely to establish on the moraines in the future. Results show that the average SOC and N concentrations increase with time and at faster rates over the latter part of the chronosequence period investigated (1945–1890). After 120yrs, the soil contains 1.1kgCm−2 in the surface layer (0–10cm), which is still about one third of the 3.2kgCm−2 in soil under the birch woodlands. The N stock estimated at 0.06kgNm−2 after 120yrs is almost one fourth of that under the woodlands. The data suggest that landscape affects vegetation establishment and in turn, both landscape and vegetation affect soil development. Thus, concentrations of SOC, N and noncrystalline oxalate extractable Al and Fe are higher within depressions in the proglacial landscape. The comparison of SOC stock in the moraine soils with that under the birch forest shows that the young proglacial soils still have a large potential to accrete SOC within the developing pedosphere. With the observed accrual rate of 9.1gCm−2yr−1 in the top at 10cm, it may take the moraine soils an additional period of 220yrs to accrue SOC stocks comparable with those under the birch forest. Given the fact that all Icelandic glaciers are receding, assessing SOC accretion in new soil formation may be important to off-setting the greenhouse gas emissions.

Sources and pathways of artificial radionuclides to soils at a High Arctic site.

Activity concentrations, inventories and activity ratios of 137Cs, 238Pu, 239 + 240Pu and 241Am in soil profiles were surveyed in the dry tundra and the adjoining proglacial zones of glaciers at a High Arctic site on Svalbard. Vertical profiles of radionuclide activities were determined in up to 14-cm-thick soil sequences. Additionally, soil properties (pH, organic matter, texture, mineral composition and sorption capacity) were analyzed. Results obtained in this study revealed a large range of activity concentrations and inventories of the fallout radionuclides from the undetectable to the uncommonly high levels (inventories of 30,900 ± 940, 47 ± 6, 886 ± 80 and 296 ± 19 Bq/m2 for 137Cs, 238Pu, 239 + 240Pu and 241Am, respectively) found in two profiles from the proglacial zone. Concentration of these initially airborne radionuclides in the proglacial zone soils is related to their accumulation in cryoconites that have a large ability to concentrate trace metals. The cryoconites develop on the surface of glaciers, and the material they accumulate is deposited on land surface after the glaciers retreat. The radionuclide inventories in the tundra soils, which effectively retain radionuclides due to high organic matter contents, were comparable to the global fallout deposition for this region of the world. The 238Pu/239 + 240Pu activity ratios for tundra soils suggested global fallout as the dominant source of Pu. The 238Pu/239 + 240Pu and 239 + 240Pu/137Cs activity ratios in the proglacial soils pointed to possible contributions of these radionuclides from other, unidentified sources.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-014-3163-6) contains supplementary material, which is available to authorized users.

Early stage development of selected soil properties along the proglacial moraines of Skaftafellsjökull glacier, SE-Iceland

Soil development was studied along a chronosequence in 2010 in a proglacial environment in SE-Iceland. We investigated morphological, physical, chemical and mineralogical changes in the soil representing over 120-year period. In total, 54 sampling sites were distributed along three moraines deposited in 1890, 1945 and 2003. For comparison, samples were collected from a nearby downy birch (Betula pubescens Ehrh.) forest, representing soils in a mature ecosystem likely to establish on the moraines in the future. After 120years since deglaciation and formation of AC horizon sequence, bulk density decreased from 1.36gcm−3 to 1.07gcm−3. Concentrations of soil organic carbon (SOC) and total nitrogen (N) increased with time, from being ~zero up to 1.77% of SOC and 0.10% of N. Soil pH (H2O) declined rapidly and was the only soil property that attained a steady state compared to that under the birch forest. The concentration of oxalate extractable Al and Fe increased over time although at a slower rate of change compared to that for other soil properties. Freshly exposed moraines contained a considerable amount of the extractable elements, indicating a relative abundance of poorly crystalline Al- and Fe-phases in the subglacial moraines. The data support the conclusion that after 120years of soil formation, proglacial soils are still young and may yet need one or two centuries to develop properties typical of well drained volcanic soils.

Early stages of soil development on serpentinite: the proglacial area of the Verra Grande Glacier, Western Italian Alps

PurposeClimate change is driving strong variations in mountain habitats, such as glacier retreat, which is releasing large surfaces soon colonized by vegetation and attacked by weathering and pedogenesis. Many proglacial soil chronosequences have been studied in different parts of the world, but no study is available on early soil development and pedogenesis on serpentinite.Materials and methodsWe analysed the development of the main chemical (pH, organic matter, nutrients and exchangeable cations) and morphological properties in three soil chronosequences in the Verra Grande Glacier forefield (Italian side of the Monte Rosa Group, Western Alps), characterized by slightly different parent materials (pure serpentinite or serpentinite with small gneiss inclusions) and topography (steep lateral moraines or flat basal till).Results and discussionOrganic matter accumulation, acidification and base and metal leaching are the most important pedogenetic processes active during early stages of soil formation on serpentinite in the upper subalpine altitudinal belt. These processes are associated with minor changes in color and structure showing weak mineral weathering. Biocycling of nutrients is limited on pure serpentinite because of weak primary productivity of the plant community. Pedogenesis is quite slow throughout the forefield, and it is slowest on pure serpentinite. On flat surfaces, where slow erosion permits a fast colonization by Ericaceae, the podzolization process begins after few centuries since moraine deposition, while on steep slopes more time is required.ConclusionsPedogenesis on serpentinite is extremely slow. The fast colonization by grassland species increases the speed of pedogenetic trends where serpentinitic till is enriched by small quantities of P-rich gneiss. The encroachment of forest-shrub species increases the speed of pedogenetic trends thanks to a strong nutrient biocycling.

Technical Note: Disturbance of soil structure can lead to release of entrapped methane in glacier forefield soils

Abstract. Investigations of sources and sinks of atmospheric CH4 are needed to understand the global CH4 cycle and climate-change mitigation options. Glaciated environments might play a critical role due to potential feedbacks with global glacial meltdown. In an emerging glacier forefield, an ecological shift occurs from an anoxic, potentially methanogenic subglacial sediment to an oxic proglacial soil, in which soil-microbial consumption of atmospheric CH4 is initiated. The development of this change in CH4 turnover can be quantified by soil-gas profile analysis. We found evidence for CH4 entrapped in glacier forefield soils when comparing two methods for the collection of soil-gas samples: a modified steel rod (SR) designed for one-time sampling and rapid screening (samples collected ∼1 min after hammering the SR into the soil), and a novel multilevel sampler (MLS) for repetitive sampling through a previously installed access tube (samples collected weeks after access-tube installation). In glacier forefields on siliceous bedrock, sub-atmospheric CH4 concentrations were observed with both methods. Conversely, elevated soil-CH4 concentrations were observed in calcareous glacier forefields, but only in samples collected with the SR, while MLS samples all showed sub-atmospheric CH4 concentrations. Time-series of SR soil-gas sampling (additional samples collected 2, 3, 5, and 7 min after hammering) confirmed the transient nature of the elevated soil-CH4 concentrations, which were decreasing from ∼100 μL L−1 towards background levels within minutes. This hints towards the existence of entrapped CH4 in calcareous glacier forefield soil that can be released when sampling soil-gas with the SR. Laboratory experiments with miniature soil cores collected from two glacier forefields confirmed CH4 entrapment in these soils. Treatment by sonication and acidification resulted in a massive release of CH4 from calcareous cores (on average 0.3–1.8 μg CH4 (g d.w.)−1) (d.w. – dry weight); release from siliceous cores was 1–2 orders of magnitude lower (0.02–0.03 μg CH4 (g d.w.)−1). Clearly, some form of CH4 entrapment exists in calcareous glacier forefield soils, and to a much lesser extent in siliceous glacier forefield soils. Its nature and origin remain unclear and will be subject of future investigations.

Synchrotron-based P K-edge XANES spectroscopy reveals rapid changes of phosphorus speciation in the topsoil of two glacier foreland chronosequences

Phosphorus (P) is a crucial element for life on Earth, and the bioavailability of P in terrestrial ecosystems, which is dependent on the soil P stock and its speciation, may limit ecosystem productivity and succession. In our study, for the first time a direct speciation of soil P in two glacier foreland chronosequences has been conducted using synchrotron-based X-ray Absorption Near-Edge Structure (XANES) spectroscopy. The chronosequences are located in the forefields of Hailuogou Glacier (Gongga Shan, China) and Damma Glacier (Swiss Alps). The age since deglaciation of the investigated soils ranges from 0 to 120years at Hailuogou, and from 15 to >700years at Damma. Differences in climate conditions (cooler at Damma, in contrast to Hailuogou precluding the establishment of forest in advanced ecosystem succession stages) and in the chemical composition of the parent material result in different soil contents of total P and Fe/Al oxyhydroxides, which are much smaller at Damma than at Hailuogou. Nevertheless, both chronosequences show similar trends of their topsoil P status with increasing soil age. Our study reveals a rapid change of topsoil P speciation in glacier retreat areas already during initial stages of pedogenesis: Initially dominating bedrock-derived apatite-P and Al-bound P is depleted; Fe-bound P and particularly organically-bound P is accumulated. Organic P strongly dominates in the topsoil of the mature soils outside the proglacial area of Damma Glacier (age 700–3000years), and already 50years after deglacation in the topsoil of the retreat area of Hailuogou Glacier. A key factor for the change in topsoil P speciation is the establishment of vegetation, resulting in soil organic matter (SOM) accumulation as well as accelerated soil acidification and apatite dissolution by organic acids, which are produced by SOM-degrading micro-organisms, mykorrhiza fungi, and plant roots. Particularly the succession of grassland to forest seems to accelerate the transformation of topsoil P from apatite-P into organic P. The conceptual model developed by Walker and Syers (1976) to explain long-term (millennial) changes of P speciation, availability, and turnover in soils and terrestrial ecosystems seems to be valid to describe short-term changes of P speciation and P availability in proglacial topsoils already within a century of initial soil formation. Because the apatite-depleted topsoil horizons in the young proglacial soils are shallow, the change of topsoil P speciation should not seriously affect P availability and the P acquisition strategy of adult trees, whose roots can easily access apatite-containing C horizons. In contrast, P acquisition strategies of fungi, micro-organisms and plants confined to the topsoil probably change from apatite dissolution to mineralization of organic P already within <3000years in a proglacial ecosystem succession from bare soil to grassland (Damma Glacier Chronosequence) or even within <100years in a proglacial ecosystem succession to forest (Hailuogou Glacier Chronosequence).

Comparison of bacterial diversity in proglacial soil from Kafni Glacier, Himalayan Mountain ranges, India, with the bacterial diversity of other glaciers in the world

Two 16S rRNA gene clone libraries (KF and KS) were constructed using two soil samples (K7s and K8s) collected near Kafni Glacier, Himalayas. The two libraries yielded a total of 648 clones. Phyla Actinobacteria, Bacteroidetes, Chloroflexi Firmicutes, Proteobacteria, Spirochaetae, Tenericutes and Verrucomicrobia were common to the two libraries. Phyla Acidobacteria, Chlamydiae and Nitrospirae were present only in KF library, whereas Lentisphaerae and TM7 were detected only in KS. In the two libraries, clones belonging to phyla Bacteroidetes and Proteobacteria were the most predominant. Principal component analysis (PCA) revealed that KF and KS were different and arsenic content influenced the differences in the percentage of OTUs. PCA indicated that high water content in the K8s sample results in high total bacterial count. PCA also indicated that bacterial diversity of KF and KS was similar to soils from the Pindari Glacier, Himalayas; Samoylov Island, Siberia; Schrimacher Oasis, Antarctica and Siberian tundra. The eleven bacterial strains isolated from the above two soil samples were phylogenetically related to six different genera. All the isolates were psychro-, halo- and alkalitolerant. Amylase, lipase and urease activities were detected in the majority of the strains. Long chain, saturated, unsaturated and branched fatty acids were predominant in the psychrotolerant bacteria.

Survival and colonisation potential of photoautotrophic microorganisms within a glacierised catchment on Svalbard, High Arctic

The survival and colonisation potential of photoautotrophic microbes (cyanobacteria and microalgae) were investigated in three terrestrial environments within a glacierised catchment on Svalbard: old vegetation-covered soil, recently deglaciated barren soil and subglacial sediments. One-year reciprocal transplant incubations of photoautotrophic microbial communities from the three soil/sediment environments were conducted in order to reveal the autochthonous or allochthonous origin of the present photoautotrophs. The abundance and taxonomic composition of photoautotrophic microbes and their changes over time and between soil/sediment types and physico-chemical characteristics of the soils/sediments were determined. The recovery time of a photoautotrophic community by import of cells was between several months in subglacial and vegetated soils and up to 27 years in proglacial soils. No active growth was recorded in subglacial sediments, whilst positive growth, and so the potential for autochthonous recovery, was found in proglacial and vegetated soils. The most suitable environment for the survival of transplanted microbes was provided in proglacial soil. We show here that the new proglacial substrata can be successfully colonised by photoautotrophic microbes, and that input of allochthonous cells may, in some cases, exceed in situ microbial growth. Whilst the subglacial environment is rather a conduit for photoautotrophic microbes than a place of growth and production, the supply of viable photoautotrophs in it is relatively high and may serve as a significant resource of nutrients for subglacial microbial communities.

Fungal diversity and deterioration in mummified woods from the ad Astra Ice Cap region in the Canadian High Arctic

Non-permineralized or mummified ancient wood found within proglacial soil near the ad Astra Ice Cap (81°N, 76°W), Ellesmere Island, Canada was investigated to ascertain the identification of the trees, current morphological and chemical characteristics of the woods and the fungi within them. These woods, identified as Betula, Larix, Picea and Pinus, were found with varying states of physical and chemical degradation. Modern microbial decomposition caused by soft rot fungi was evident and rDNA sequencing of fungi obtained from the samples revealed several species including Cadophora sp., Exophiala sp., Phialocephala sp., as well as others. Analytical 13C-labeled tetramethylammonium hydroxide thermochemolysis showed the lignin from the ancient wood was in a high degree of preservation with minor side chain alteration and little to no demethylation or ring hydroxylation. The exposure of these ancient woods to the young soils, where woody debris is not usually prevalent, provides carbon and nutrients into the polar environment that are captured and utilized by unique decay fungi at this Arctic site.

Plant recruitment in the High Arctic: Seed bank and seedling emergence on Svalbard

Abstract. Composition and density of the soil seed banks, together with seedling emergence in the field, were examined on Svalbard. 1213 soil samples were collected from six drymesic habitats in three regions representing various stages of colonization from bare moraines to full vegetation cover and spanning a range of typical nutrient and thermal regimes. Of the 165 vascular plant species native to Svalbard, 72 were present as mature plants at the study sites and of these 70% germinated seed. Proglacial soil had 12 seedlings per m2, disturbed Dryas heath 131, intact Dryas heath 91, polar heath 715, thermophilic heath 3113, and a bird cliff 10437 seedlings. Highest seed bank species richness was at the thermophilic heath (26 species). Seedlings of 27 species emerged in the field, with fewer seedlings in disturbed habitats (60 seedlings per m2) than in intact Dryas heath (142), suggesting that an absence of ‘safe sites’ limited seedling establishment in disturbed habitats. Measurement of seedling emergence in the field increased awareness of which species are able to germinate naturally. This may be underestimated by up to 31% if greenhouse trials alone are used, owing partly to unsuitability of greenhouse conditions for germination of some species and also to practical limitations of amount of soil sampled. Most thermophilic species failed to germinate and some species present at several sites only germinated from the thermophilic heath seed bank, suggesting that climate constrains recruitment from seeds in the High Arctic.