The dynamics of fungal communities during the first 25 years of soil development after de-glaciation were addressed with molecular methods in combination with a cultivation approach. We used amplicon sequencing and isolation of fungi from in-growth mesh bags to identify active fungi in three earliest stages of soil development (SSD) at a glacier forefield (0-3, 9-14, 18-25 years after retreat of glacial ice). Soil organic matter and nutrient concentrations were extremely low, but barren ground harbours a high fungal diversity as soon as it becomes ice-free. Fungal communities of recently de-glaciated soil are significantly different from communities of later stages of soil development, and are rather similar to fungal communities typical for cryoconite or ice. This indicates that cryoconite and melting water must be considered as an important inoculum for native soil close to the glacier tongue. Soil fungal communities are very dynamic during soil development, and they are also subject to a distinct seasonal species composition turnover. Fungal communities are especially active under the snow cover, but a large proportion of these fungal species remains unknown. The obtained pure culture isolates provide a solid base for ongoing functional and taxonomical research. The follow-up FWF project ‘Microbial Interactions in Snow Covered Soil’ (MICINSNOW) with start in May 2019 is focusing on Interactions of Bacteria and Fungi in this environment. The project will be based on Molecular Network analyses and in vitro visualization of interactions using FISH.

See specific Research Poster contribution ID 647: Probst et al. :

Seasonal changes of fungal communities in early soil developmental stages of a receding glacier

Mountain ecosystems have been subject to human impacts in many parts of the world since millennia. The conversion of forests to arable land by hill farming communities has altered relief and soil morphology via levelling, terracing and ploughing. Pastoralism has changed plant communities, in particular replacing forests with grass- and shrubland, and cattle grazing has caused soil compaction and accelerated erosion. Herders use fire as a management tool, which in turn has strong impacts on soil processes. Litter raking, lopping of trees for fodder and grazing were (and in some areas still are) means to transfer carbon and nutrients from remaining forests to agriculture. Impacts of past and recent land use on soil properties of mountain ecosystems are visualized, based on case studies from Central Europe, the Himalayas and Sub-Saharan Africa. Not surprisingly, soil acidification, depletion in soil organic carbon and nutrients and morphological changes of humus forms are long-term consequences of continuous biomass extraction. Arable land having received organic amendments for centuries shows high carbon and nutrient stocks as can be shown in the Himalayan cases. In contrast, farmland in the Ethiopian highlands is severely depleted in carbon and nutrients compared to forest remnants. Even after abandonment of hill farming or reforestation, the legacy of land use affects water, carbon and nutrient cycles, biological soil processes and consequently ecosystem responses to changing climate. Therefore, we have to consider effects of historic land use practices in our interpretation, modelling and predictions of mountain soil patterns and processes.

Humans as a soil-forming factor in mountain ecosystems – Considerations on research questions

Mountain ecosystems have been subject to human impacts in many parts of the world since millennia. For the interpretation of the present status of mountain soils, the understanding of the impact of historic land use is of paramount importance. Meta-analyses of case studies comparing soil properties of mountain sites with known land use history may help to assess the status and the sensitivity of mountain soils to management. While sampling and analyses of some physico-chemical indicators, like soil acidity or soil organic carbon, has been standardized and results can easily be interpreted, proxies for complex soil biological processes need to be refined. Standardized sampling along elevation, latitudinal and land use gradients can definitely improve our scientific understanding in this respect. Manipulation experiments in mountain ecosystems will require long-term monitoring but may provide the best input for the calibration of soil process models.

The ground beneath our feet is still a black box to us, although it provides several ecosystem services, thus supporting human well-being. This holds tree also for (high) mountain soils, which have been sparsely investigated until now. However, understanding the structural and functional characteristic of soil fauna communities living in these harsh environments will help us to better understand effects of ongoing global changes.

Firstly, basic research on the soil macro-invertebrate communities gives us an overview on their biodiversity, abundance and seasonal activity. This can be achieved by taking classical soil core samples and installing pitfall traps. By repeating such samplings for several years, we obtain timeseries and are able to analyse structural changes over time and along succession processes (e.g. abandonment, global warming). Secondly, laboratory methods such as Stable Isotope Analyses (SIA), Near Infrared Reflectance Spectroscopy (NIRS), molecular approaches and mesocosm experiments help us to unravel essential drivers of soil ecosystem functions like litter decomposition, trophic linkages and soil food webs.

Our research group is among the few that are analysing soil fauna in high mountain soils, and we were able to catch a glimpse on litter decomposition patterns and trophic relations. Basically, they seem to be similar to patterns found in lowland soils but are composed in a simpler way. Some taxa like earthworms and millipedes reach their elevational limits and are replaced by other groups, although ecosystem functions can be replaced only in parts. Further, mountain and alpine soil processes run generally slower and the soil fauna has to adapt to these harsher conditions by being less selective regarding food sources and by extending their life cycles. However, more studies on regional as well as global scale are urgently needed to better understand how these ecosystems are affected by global change and how we can protect them.

The Highland research and Development Institute (HRDI) have conducted the community participatory at community highland agriculture 500 – 1,400 MSL of elevation. Major agriculture in North highland is upland rice maize and fruit tree. Upland rice and maize is slash and burn before planting. The maize use intensive herbicide and chemical fertilizer application resulted in environmental pollution and soil fertility declination.

For upland rice HRDI has conducted soil fertility restoration research by cultivating upland rice in combination with soil and water conservation system, using the water harvesting ditches along the contour, growing vetiver grass and cowpea strips across the slope, growing rice bean – upland rice rotation and land preparation without burning. After 3 years, there were increasing of some chemical properties, soil pH from 5.18 to 5.39, organic matter from 4.39 to 5.82 and available P from 3.6 to 4.64 while the exchangeable K, Ca and Mg were reduced. In the maize trials, the crop residues were used as the soil amendment across the slope and the proper nutrient management was applied, by using water harvesting ditches in combination with vetiver grass strips across the slope and growing maize legume relay cropping. After 3 years, there were increasing of soil pH, organic matter, available P and exchangeable K, soil pH from 4.06 to 4.73 organic matter from 1.1 to 3.49%, available P from 2 to 5 mg/kg, exchangeable K from 60 to 84 mg/kg while the exchangeable Ca and Mg were reduced. The participated farmers realized the benefit and usefulness of the crop residues and learned how to grow crops together with soil and water conservation including how to restore soil fertility by using integrated physical and biological methods which fit well with their traditional lifestyles.

Land-use change has led to the conversion of about 90% of the forest in the Atlantic Forest domain, Brazil, with significant impacts on the water and biogeochemical cycles and on ecosystem services. Soil microorganisms play an important role in the cycling of nutrients in terrestrial ecosystems and their community composition and function are shaped by the interaction of a series of biotic and abiotic factors that characterise ecosystems. These interactions are inevitably altered by plantations of exotic species, with consequences for ecological and biogeochemical processes. For instance, species of the genus Pinus from the Northern Hemisphere and their ectomycorrhizal symbionts have been introduced in the native range of Araucaria angustifolia, associated with arbuscular mycorrhizal fungi. Our work aimed at quantifying the effects of replacing native A. angustifolia montane forests with Pinus taeda plantations on (i) soil microbial communities and (ii) the nitrogen cycle. To do this, we quantified microbial biomass C and N and characterised the spatial and seasonal (wet vs. dry) composition of soil bacterial communities and potential N-cycle related enzyme activities in a native montane Araucaria forest stand and in a pine plantation. Sampling was made at the peaks of the wet and dry seasons. DNA extractions were carried out for 96 soil samples (i.e. 12 samples x 2 forest types x 2 soil layers x 2 seasons). We report the results for the native and exotic conifer species for bacterial communities and the frequency / abundance of genes associated with the N cycle, and relate these to quantified soil variables and microbial N and C. We interpret the results in view of their impact on biogeochemistry and how this may potentially affect ecosystem services. We identify experimental work that will be required to address pressing questions in the functional ecology of mountain soils.

Land-use change in tropical forest ecosystems has led to the loss of about 90% of the forest in the Atlantic Forest domain, with significant impacts on the water and biogeochemical cycles and on the provisioning of ecosystem services. Soil microorganisms play an important role in the cycling of nutrients in terrestrial ecosystems and their community composition and function are shaped by the interaction of a series of biotic and abiotic factors that characterise ecosystems. These interactions are inevitably altered by the introduction of exotic species, replacing native forest ecosystems, with consequences for ecological and biogeochemical processes. For instance, species of the genus Pinus from the Northern Hemisphere and their ectomycorrhizal symbionts have been introduced in the native range of Araucaria angustifolia, a phylogenetically much more ancient conifer than pine, associated with arbuscular mycorrhizal fungi. This work aimed at quantifying the effects of replacing native A. angustifolia montane forests with Pinus taeda plantations on (i) soil microbial communities and (ii) the nitrogen cycle. To do this we quantified microbial biomass and mineralisation rates and characterised the spatial and seasonal (wet vs. dry) composition / potential activity of soil bacterial communities in a native montane forest stand and in a pine plantation within the Atlantic Forest biogeographical domain. Mineral soil and the organic layer were sampled at the peaks of the wet and dry seasons. DNA extractions were carried out for 96 soil samples (i.e. 12 samples x 2 forest types x 2 soil layers x 2 seasons). We report the results for the native and exotic conifer species for bacterial communities and the frequency / abundance of genes associated with the N cycle, and relate these to quantified soil variables and microbial N, P and C. We interpret the results in view of their impact on biogeochemistry and how this may potentially affect ecosystem services.

Alpine landscapes are topographically complex, creating heterogenous mosaics of habitats. This complexity and associated diversity in ecosystems contribute to the challenges in understanding the functional ecology of mountain soils discussed in this workshop.

Pressing research challenges, which need to be addressed to understand the nature and sensitivity of mountain soils, include quantifying the potentially different responses of contrasting ecosystems between different habitats at the microtopographic scale and at larger regional or global scales. Temporal scales should also be considered; currently work is often undertaken during the plant growing season, but seasonal dynamics of alpine systems are also important with microbial functions continuing under deep snow cover. This leads into the longer-term challenge of understanding how alpine soils respond to multiple disturbance events and changing conditions, such as changing snow cover regimes, across seasons and years. Responses to changing conditions could also be thought of as resistance, and possibly more importantly as resilience, the ability of a system to recover from a disturbance.

Alpine ecosystems support biodiversity and are large pools old soil organic carbon; however these studies are based on a few regions while mountains cover over 20% of the earth’s land surface. Little is known currently about the basic attributes or functioning of alpine systems globally; coordinated activities and experiments, such as the global FEAST project are important in addressing this. These efforts could also be used to quantify alpine systems’ sensitivity, both under realistic climate scenarios and pushing the systems to extremes.

I am interested in ecosystems’ responses to disturbance and changing conditions, particularly seasonal dynamics of topographic alpine microhabitats, and responses of these contrasting alpine plant-soil systems to changing snow cover regimes in terms of carbon cycling and the functional response of microbial communities.

Functional ecology of alpine soils under changing snow cover regimes

Rosanne C Broyd (Lancaster University, and The James Hutton Institute)

Robert T E Mills (Lancaster University)

Andrea J Britton (The James Hutton Institute)

Andy F S Taylor (The James Hutton Institute)

Nicholas J Ostle (Lancaster University)

Alpine landscapes are topographically complex, creating heterogenous mosaics of habitats. This complexity and associated diversity in ecosystems contribute to the challenges in understanding the functional ecology of mountain soils discussed in this workshop.

Pressing research challenges, which need to be addressed to understand the nature and sensitivity of mountain soils, include quantifying the potentially different responses of contrasting ecosystems between different habitats at the microtopographic scale and at larger regional or global scales. Temporal scales should also be considered; currently work is often undertaken during the plant growing season, but seasonal dynamics of alpine systems are also important with microbial functions continuing under deep snow cover. This leads into the longer-term challenge of understanding how alpine soils respond to multiple disturbance events and changing conditions, such as changing snow cover regimes, across seasons and years. Responses to changing conditions could also be thought of as resistance, and possibly more importantly as resilience, the ability of a system to recover from a disturbance.

Alpine ecosystems support biodiversity and are large pools old soil organic carbon; however these studies are based on a few regions while mountains cover over 20% of the earth’s land surface. Little is known currently about the basic attributes or functioning of alpine systems globally; coordinated activities and experiments, such as the global FEAST project are important in addressing this. These efforts could also be used to quantify alpine systems’ sensitivity, both under realistic climate scenarios and pushing the systems to extremes.

We are interested in ecosystems’ responses to disturbance and changing conditions, particularly seasonal dynamics of topographic alpine microhabitats, and responses of these contrasting alpine plant-soil systems to changing snow cover regimes in terms of carbon cycling and the functional response of microbial communities.

While links between plant community composition and macro and micro-scale variability in climate and resource availability are increasingly well understood, the same cannot be said for below ground biodiversity and fucntion. We have recently been working on undertsanding the above and belowground links across alpine topographical mosaics in oceanic alpine ecosystems in Scotland. In our opinion, understanding the biogeography of alpine soils and their functions is an important pre-requisite for understanding the potential sensitivity of these sytems to global change drivers. Current understanding of the biogeography of alpine soils is spatially patchy and often limited to studies of single driver gradients or areas of limited geographical extent. Increased coordination across networks and comparable sampling approaches are required to advance research in this area and build a global understanding of the nature of mountain soils.

A correct quantification of soil organic carbon (SOC) stocks is important for the evaluation of many soil functions including sequestration of atmospheric C. Traditional methods used for SOC stock quantification in sloped terrain most often do not adequately address site-specific geomorphological conditions. They thus yield incorrect results; most often, the SOC stock is underestimated. The SOC stock quantification problem can be distinguished into three critical issues: (1) Overestimation of profile SOC densities [kg SOC m^-2] due to inadequate, uncorrected soil profile or core sampling. (2) Underestimation of the true soil surface in homogeneously sloped terrain by traditional conversion of profile SOC densities into area-based, regional stocks [Mg SOC km^-2], applying the horizontal projection technique without adequate correction for the slope gradient. (3) Considerable underestimation of true soil surface and SOC stock in heterogeneously sloped, rough terrain by disregarding surface roughness.

We quantify and discuss SOC stock quantification errors in mountainous regions associated with the issues (1), (2), and (3), using the Bavarian Alps (area in horizontal projection: 4,500 km²) as case study. We show that combined (i) correction for the slope gradient during soil sampling in sloped terrain (Issue 1) and (ii) utilization of Digital Elevation Models with high spatial resolution (Issues 2 and 3) minimizes SOC stock underestimation. Taking into account the considerable contribution of sloped terrain on the global scale and particularly in mountainous countries, SOC stocks as well as area-based C fluxes (e.g. CO₂ sequestration or emission) most likely are considerably larger than assumed based on traditional, widely used quantification concepts. We also present a protocol how to minimize the underestimation of stocks of SOC and other soil compounds in mountainous, sloped regions.

My name is Daniel Wasner, I finished my master programme with a background in soil biogeochemistry and carbon and nutrient cycling. Currently I am involved in the early stages of developing a project that will also encompass my PhD thesis.

The main questions that we are interested in are set in the context of early soil development. At what stage does C:N:P coupling occur in soil, under what conditions does it tighten or loosen? What are the functional implications of different degrees of C:N:P coupling in young soils? What main factors shape and drive the development of biogeochemical cycling in early soil development, and what is the importance of geology, climate and biology? What do changes in such driving factors mean for (biogeochemical) soil functions and the trajectory of soil development?

Soils developing in mountain regions in settings of primary succession will provide ideal study systems to approach these questions. Transects covering large gradients of geology and climate will help to identify the major drivers of the processes of interest. We want to combine biogeochemical, microbiological and vegetation perspectives to gain mechanistic insights, and drone-based hyperspectrometry and modelling to integrate our understanding of early soil development over various spatial scales.

I think this workshop will provide an exciting exchange of ideas and might stimulate valuable thoughts for the formulation and orientation of the project that my colleagues and I are developing.

In this project, which is in an early development stage, we would like to investigate what are the main drivers for the spread of vegetation and soil formation in temperate mountain systems and if soil weathering in particular is such a landscape driver. What role are topography and indirectly hydrology as well as parent material play? Furthermore, we would like to understand more about how soil weathering and vegetation are influencing the biogeochemical cycles, especially under a changing climate and if mountain soils might act as C-sinks or C-sources.

High altitude ecosystems generally have a low availability of nutrients in the soil especially of N because of temperature constraints on mineralization processes. On the other hand, nutrient demand by alpine plant communities is low due to small growth rates at low temperatures, making it uncertain to which extent plant growth is actually limited by soil nutrient availability.

Here, we explored the link between soil N and P availability and treeline productivity in the South and Polar Urals, as well as in the Khibiny and Putorana mountains spanning a latitudinal and longitudinal gradient of more than 1500 km. Along elevational gradients reaching from the tundra to ‘closed’ forest, we have determined stand biomass, tree age structures as well as indices of N and P availability in the soil and in foliage.

In the soil, extractable N and P was more than one magnitude greater in treeline ecotones of the boreal than of the subarctic zone. This patterns was also reflected in foliage nutrients. The primary reason seems a smaller soil development and a stronger permafrost in the subarctic mountains caused by harsher winter conditions. Despite these great differences in soil fertility, treeline positions occurred at a similar thermal regime during the growing season, which documents that tree growth at treeline is primarily limited by summer temperatures. Stand productivity in the open and closed forest just below species line, however, showed a different pattern with a pronounced decrease with increasing latitude and increasing continentality. The decreasing stand productivity paralleled the decline in nutrient availability towards the subarctic treeline. These findings strongly suggest that once thermal limitations are relieved, soil nutrient availability ‒ driven by climatic conditions ‒ plays a major role for tree growth and productivity in treeline ecotones.

The production of shade-grown coffee is key to the conservation of mountain ecosystems. In Panama’s Santa Fe National Park, coffee is a traditional crop and one of the main income sources for many family farmers who live in the protected park area and its surroundings. The cultivation of shade-grown coffee ensures environmental, polyculture and agroforestry biodiversity, contributes to soil conservation and plays a crucial role in mitigating and adapting to climate change.

Located in the highlands of the Panamanian Central Cordillera in the Santa Fe district of Veraguas province, the 72 636 ha Santa Fe National Park has proven critical for conveying the need for investment in the conservation and sustainable management of natural resources. It belongs to the Mesoamerican Biological Corridor, a highly biodiversity region that encompasses seven Central American countries and Mexico.

Fundacion CoMunidad works with family farmers engaged in small-scale coffee production in the protected and its surroundings. A buffer zone outside the natural park is a forested area with trees such up to 30 m high and an understorey with many fallen leaves. Hence, this area is a productive system with natural or significant spontaneous woody vegetation. These lands are suitable for the production of coffee, and their humid tropical climate also allows for the production of complementary crops such as citrus, beans, and vegetables. With constant rain throughout the year and favorable soil features, the area also has the good agricultural potential for various forest and fruit plantations.

The work of family farmers engaged in shade-grown coffee generates multiple benefits due to the use of native species, soil conservation and improvement practices, reduced dependence on petrol and derivatives through agro-ecology, practice of polyculture and silvopastoralism, terraced coffee plantations and crop rotation.

One of the major global challenges of the 21^st century is to mitigate the effects of global environmental changes. Predicted temperature changes and weather scenarios will substantially influence important pillars of our society. Soil organic carbon is recognized the largest terrestrial carbon reservoir and has gained much attention because of its importance to mitigate climate change and to secure soil fertility and productivity.

Soil microorganisms including bacteria, archaea and fungi determine numerous nutrient flows in soil ecosystems and significantly affect the stability of the carbon pool. The amount of recalcitrant organic carbon in soil is essentially determined by the abundance and activity of microorganisms. Changing climatic conditions influencing microbial diversity and functionalities, can therefore lead to altered amounts of released or fixed carbon dioxide. The consequences of climate change on microbial diversity and functioning and possible reinforcement mechanisms are therefore very important nevertheless still not understood.

In the present study, we investigated pasture soils in the dry inner-Alpine Matsch Valley (South Tyrol, Italy). Over the past decade, various studies and (climate)-measuring campaigns have been conducted at this research site and it is recognized as a long-term ecological research (LTER) area. We used an elevation gradient (1000, 1500 and 2000 m a.s.l.) within this area to study the effect of temperature on microbial diversity and functional aspects.

The investigation showed that altitude and thus temperature significantly affected the community composition of the study sites. Important soil microorganisms (e.g. Actinobacteria) significantly decreased in their abundance along the elevation gradient while other species (e.g. Verrucomicrobia) came up in return. The phylum Verrucomicrobia accounting for 15% of the relative abundance of soil prokaryotes at the highest sites contains mostly non-cultivable species with thus functional properties yet to be discovered. The changes in microbial communities were accompanied by distinct changes in soil organic carbon.

Invasion of shrubs with ericod mycorrhiza and ectomycorrhiza to the mountain tundra and alpine grass and meadow ecosystems with arbuscular mycorrhiza during the last decades is the widespread phenomenon. The main attention of the researchers studying a role of different types of mycorrhiza in biogeochemical cycles is concentrated on forest ecosystems with dominating of woody plants with ectomycorrhiza or arbuscular mycorrhiza. At the same time, ericoid mycorrhiza is characterized by higher enzymes activity capable to transform and mobilize soil organic matter. Ericoid mycorrhiza can on the other hand also stabilize soil organic matter, producing a large amount of polyphenols forming stable polyphenol-protein complexes in the soil. However studies of the effect of ericoid mycorrhiza on biogeochemical cycles in arctic/subarctic and mountain ecosystems are mainly based on comparison of ecosystems with domination of plants with different types of mycorrhiza. It means their formation in initially different geomorphological or lithological conditions and essentially complicates assessment of mycorrhizal type influence on biogeochemical processes. We assume that appearance of plant species with ericoid mycorrhiza in grass/meadow ecosystems can change soil properties. Such change can influence on soil microbial community and nutrition of the neighboring plant species with arbuscular mycorrhiza or non mucorrhizal species, belonging to different functional groups (forbs, grasses, sedges), promoting change of structure and production of plant community. To check this hypothesis we study how shrubs with ericoid mycorrhiza influence on soil and vegetation characteristics: labile organic and inorganic fractions of carbon, nitrogen and phosphorus in soils; structure and functioning (activity) of soil microbial community; reaction of arbuscular mycorrhizal plants adjoining to shrubs. The study is done in the alpine belt of the Caucasus (the Teberda Reserve) and mountain-tundra belt of Khibiny Mountains within the sites of the alpine and tundra grass/meadow ecosystems on which the shrubs with ericoid mycorrhiza are present.

High mountain ecosystems are disproportionally affected by global warming and changing precipitation conditions. The accelerating thawing of permafrost and deglaciation since the end of the Little Ice Age (LIA) provided new terrain, and has further strong impacts on mountain water cycles and geomorphic processes. These in return are important factors for enabling or limiting soil development or disturbances, such as solifluction, soil erosion, or accumulation processes.

While it is well understood that increased mean annual temperature enhances soil mineralization processes and might even accelerate climatic warming due to positive feedback reactions, the impact of the changing cryosphere on regional and local soil development patterns and important ecological soil functions is insufficiently known. The multitude of interaction factors on the mountain cryosphere occasion a high degree of heterogeneity, which makes it challenging to investigate the reaction patterns of pedosphere changes on climate change.

CryoSoil_TRANSFORM is an inter- and transdisciplinary approach with the aim to (1) provide a high temporal and spatial reconstruction of the cryospheric development since the LIA, (2) define soil formation, disturbances and distribution in the respective areas, linking cryosphere dynamics with soil dynamics, (3) characterize the relationship between high mountain soils and vegetation by analyzing soil biology, soil chemistry, and soil physics, (4) integrate the achieved knowledge into a research-education cooperation between scientists and high school students in Austria.

Soil ecosystems are important for the functioning of the ecosystem Earth. Their microbiome plays a major role in soil ecosystem functioning. During soil development, it is mainly microbes, which can thrive at the extreme habitat conditions of glacier forefronts. They are paving the way for the colonization of young soil by higher organisms. In addition to nutrient limitation, temperature conditions are seasonally dependent. During summer, the soil temperature can be high during the day and close to zero at night. In winter, the thick snow cover keeps the temperatures constant at 0°C, but limits the gas exchange between the soil and air, thereby leading to the accumulation of respiratory products and low oxygen concentrations. Despite the harsh environmental conditions, distinct microbial communities are active in the soil throughout the entire year. While bacteria are dominating during summer, cold-adapted fungi are the most abundant microbes in winter. Especially regarding the cold-adapted fungal community, we have little understanding of the seasonal compositions, dynamics and functionalities in young soil microbiomes. Despite being interesting by itself, this information can improve our predictions of soil ecosystems in the scenario of global warming. Therefore, we analysed the actively growing fungal communities at early stages of soil development at the Rotmoosferner Glacier forefront (0-3, 9-14, 18-25 years), Austria, by Illumina Miseq profiling and measured soil characteristics. Nutrient concentrations were generally low, but increased with soil maturation. Independent of the season, the soil fungal richness increased along the developmental gradient. Nevertheless, characteristic fungal communities for both winter and summer season were found. Based on network analysis, the season also influenced fungal-fungal interactions, even across phyla, which might contribute to the fungal performance in snow-covered young soils. Taken together, our results emphasize the importance of cold-adapted fungi to recently deglaciated ecosystems and soil development.

Fungi are actively growing under snow cover at temperatures around 0°C. Thus, winter is not a period of dormancy for microbial life. Winter-active fungal communities are clearly diverse and dynamic. But is there a distinct core community of fungi growing in snow-covered soil? To answer this question, we compared the winter-active, cultivable soil fungal communities from five different stages of soil development and two distinct sampling sites. Sampling was carried out at the Rotmoosferner glacier forefront at sampling sites with 0-3, 9-14, 18-25 of 150 years of soil development and in Pinus cembra afforestation area in the Sellrain valley (Austrian Central Alps). For successful isolation of winter-active fungi, in-growth mesh bags (MBs) filled with sterile quartz sand were buried in the snow-covered soil for three months. Different growth media and plating techniques were used to obtain pure fungal cultures. The obtained pure cultures were identified morphologically and in addition were characterized by rDNA-ITS sequences. Cultivable fungal communities were species-rich (39-62 OTUs) in all sites during the snow-covered period. Fungal communities consisted mainly of Asco- and Basidiomycota. Our results emphasize that temperature is not the key factor for shaping winter-active fungal diversity. More detailed investigations should be carried out including different parameters and additional sampling sites to elucidate the main factors affecting winter-active soil fungal communities.