The research was triggered by real events in the Swiss Alps. In June 2022, in the Gruobenwald forest near Klosters, a storm with heavy rain and wind felled a barkless, branchless dead tree standing on a slope of roughly 35 degrees. The snag, about 30 metres long with a diameter at breast height of 75 centimetres, slid approximately 120 metres downhill and came to rest on a road of national importance. Two days later, another log of similar dimensions slid down and lodged in a wooden palisade next to a house. During a subsequent helicopter operation to remove dangerous snags, two more logs were mobilised and slid onto the road and a hiking trail. In February 2022, near Rothenbrunnen, a tree slid some 200 metres in altitude, blocked both a road and a railway line, and apparently launched off a small terrace to jump clean over a 3.5-metre-high rockfall barrier.

Until now, no modelling framework existed to describe how mobilised deadwood moves on steep slopes. The team recognised that sliding logs share key mechanical characteristics with rockfall, including gravity-driven acceleration, impact, sliding, and deflection by obstacles, and therefore adapted the RAMMS::Rockfall simulation software. Their approach rests on nonsmooth rigid-body dynamics, combining hard contact laws with Coulomb friction. Each log is modelled as a rigid, convex polytope shaped like a truncated cone, defined by its diameter at breast height, stem length, and wood density, with the top diameter approximated at half the base diameter. The log’s position and orientation are tracked with generalised coordinates and unit quaternions, while its motion obeys the balance of linear momentum and Euler’s equations for rotation.

Contact between the log and the terrain is detected whenever a vertex of the log’s point-cloud geometry touches or penetrates the digital elevation model. At each contact point, the Signorini condition governs the normal force, and a spatial Coulomb friction law determines whether the log sticks or slips. Impacts are handled with a Newtonian impact law using a normal restitution coefficient of zero, consistent with the underlying rockfall model. Standing trees, whose locations and dimensions were extracted from airborne laser scanning data using single-tree detection, are represented as rigid truncated cones that block or deflect sliding logs. Rockfall barriers are included as thin, rigid, platy obstacles. The equations of motion are solved iteratively with Moreau’s time-stepping scheme and Gauss-Seidel iteration on a high-resolution 0.5-metre digital elevation model.

Calibrating the model against the documented events yielded a remarkably narrow range for the effective sliding friction coefficient, between 0.2 and 0.3, which the authors interpret as the typical contact friction between wet terrain and a wet, barkless log. With this value, the simulations reproduced the observed deposition patterns at both sites. In the Klosters case, 20,000 simulated logs were released and 1,829, or 9.1 percent, reached the national road, with average velocities of 14 metres per second and maxima of 30 metres per second. At Rothenbrunnen, the model confirmed that jumping the barrier was physically plausible: fitting a flight parabola between the take-off and landing traces gave a take-off velocity of 24 metres per second, and 178 of 20,000 simulated logs, or 0.9 percent, cleared the barrier, a small but realistic frequency given that such an event had never before been recorded there.

The simulations distilled three prerequisites for sliding deadwood hazards. First, friction must be low, which occurs when terrain or the log itself is wet, whether from rain, wet snow, or foliage cover. Second, slopes must be very steep, with all documented events occurring on gradients of 35 degrees or more; although the calibrated friction coefficient suggests mobilisation is theoretically possible above about 18 degrees, the macroscopic roughness captured by the terrain model raises the practical threshold. Third, and perhaps most intriguingly, the wood must be in a narrow decay-stage window: late stage II or early stage III in the standard classification, when bark and branches have been lost, slashing sliding friction, but the stem still retains enough structural strength to survive impacts without shattering. For spruce killed by bark beetles, this critical window opens roughly two to five years after death, while beech decays significantly faster.

Forest structure emerged as a decisive factor in the hazard equation. When the researchers removed all standing trees from the Klosters simulation, the fraction of logs reaching the road exploded from 9.1 percent to 74.5 percent; at Rothenbrunnen it rose from 23.3 percent to a full 100 percent. The forest, in other words, is a highly effective shield against hazards created by its own deadwood. Yet trees cut both ways: while they arrest logs, they also deflect them, increasing lateral spread. In the Klosters simulations, lateral spread shrank from values of 40 to 60 degrees with the real forest to 18 to 31 degrees without it, meaning that deadwood can traverse slopes far more widely than rocks and strike infrastructure that rockfall models would deem safe. Notably, logs slid further when the simulation used real laser-scanned tree positions rather than a randomly generated forest of identical density, because natural gullies, which are often sparsely vegetated, form preferential sliding corridors that random tree placement would artificially block.

The findings carry pointed implications for forest management, especially as deadwood volumes in Swiss mountain forests have doubled over three decades, from 17 to 35 cubic metres per hectare, and climate-driven disturbances promise still more standing and lying dead timber. The study reveals a genuine trade-off over time: young deadwood is strong and protective against rockfall and avalanches, mid-stage deadwood in the two-to-five-year window is both still protective and maximally prone to sliding, and old, rotten wood loses its protective value while its ecological worth as habitat and seedling substrate keeps climbing. Spatially, the same gullies that channel sliding logs are also prime locations for intercepting rockfall and stabilising snow. The authors argue that targeted interventions, such as felling and securing snags across the slope on wire-cable-supported stumps, or prioritising removal in the lower, steepest sections of forested slopes where logs have little forest left to traverse, can minimise the sliding hazard while preserving most of deadwood’s protective and ecological benefits.

The model is not without limits, and the authors are candid about them. Logs are treated as rigid bodies that never fracture, standing trees never break or dissipate energy by swaying, and the single effective friction coefficient is tied to the 0.5-metre terrain resolution, rising to an 18 percent reach frequency when a coarser 5-metre model was tested. Initial conditions are idealised, releasing logs upright within a 10-metre release polygon rather than simulating the actual toppling process. Yet because the framework is explicitly conditioned on a prior assessment that mobilisation is possible, these simplifications yield deliberately conservative, worst-case estimates of runout and impact frequency. The researchers also note that slender logs concentrate impact loads on small frontal areas, a concern for ring-net barriers with large mesh openings, and that logs left uncleared in nets can shorten the braking distance available for future rockfall. With well-documented events still rare, the team calls for systematic documentation of future incidents, but their message is already clear: sliding deadwood is a real, quantifiable, and increasingly relevant mountain hazard, and for the first time it can be simulated, mapped, and managed.

Subject of Research: Physics-based simulation of sliding deadwood logs as a natural hazard in steep mountain forests

Article Title: Simulation of sliding deadwood logs in mountain forests: towards a quantitative hazard assessment

Article References: Borner, J., Bebi, P., Bührle, L. J., Ringenbach, A., & Leine, R. I. (2026). Simulation of sliding deadwood logs in mountain forests: towards a quantitative hazard assessment. Natural Hazards and Earth System Sciences, 26(10), 4843-4859. https://doi.org/10.5194/nhess-26-4843-2026

Image Credits: AI Generated

DOI: 10.5194/nhess-26-4843-2026

Keywords: deadwood, mountain forests, natural hazards, rockfall simulation, Coulomb friction, nonsmooth dynamics, forest management, wood decay, Swiss Alps, airborne laser scanning, hazard assessment, bark beetle

The story begins with the island’s human history. Whalers Bay was home to a whaling station established in the early twentieth century, and its buildings were constructed largely from wood imported from Europe, North America and South America. Later, these structures were repurposed for scientific research operations in the mid-twentieth century. The researchers suspected that this imported timber, along with animal fodder, provisions and other materials brought during the eras of exploitation and exploration, may have inadvertently ferried temperate-zone fungi into Antarctica. Because wood is essentially absent from the natural Antarctic environment, any decomposer fungi found colonizing these historic structures are likely to have arrived with the materials themselves, or to have been attracted to them as nutrient-rich bait for a resident mycobiota already present on the island.

During the Brazilian Antarctic Operation XXXVII in December 2018, the team collected twelve samples of wood, fabric, rope and soil from various points around Whalers Bay. The samples were frozen at minus twenty degrees Celsius during transport back to the Laboratory of Polar Microbiology and Tropical Connections in Brazil. There, the scientists used enrichment cultures of yeast malt medium, incubated at fifteen degrees Celsius, to coax out the cultivable fungi. They also employed a selective medium containing eight percent ethanol to hunt for ethanol-resistant, fermenting yeasts. Colonies were grouped by their macroscopic characteristics, purified, and preserved in the university’s Microorganism and Cell Collection under the code UFMGCB.

Identification relied on a polyphasic approach combining morphology with molecular markers. The researchers amplified the internal transcribed spacer region of ribosomal DNA for filamentous fungi and the D1/D2 domain of the 26S rDNA gene for yeasts, then sequenced the products by the Sanger method and compared them against reference sequences in GenBank using BLASTn, considering isolates with identity of at least ninety-nine percent to be the same species. The results were striking: forty-seven fungal isolates were recovered, representing sixteen genera and twenty-three taxa spanning the phyla Ascomycota and Basidiomycota. The most abundant genus was Coniochaeta, followed by Cadophora, Pseudogymnoascus, Mrakia and Leucosporidium. Other genera included Ascocoryne, Candida, Cystobasidium, Goffeauzyma, Graphium, Mollisia, Naganishia, Papiliotrema, Phenoliferia and Purimyces.

Diversity statistics painted a picture of a rich and highly structured community. The samples yielded a Fisher’s alpha of 17.80, a Margalef richness index of 5.71 and a Simpson’s dominance index of 0.93, indicating high diversity, richness and dominance of decomposer taxa. Crucially, the species accumulation curve generated with the Mao Tao index did not reach an asymptote, meaning the sampling had not exhausted the fungal diversity present in these substrates. This finding mirrors an earlier culture-independent DNA metabarcoding study of the same samples, which likewise revealed cryptic fungal diversity in the historic wooden structures. Together, the two studies reinforce the idea that imported wood acts as both a refuge for introduced species and a magnet for native Antarctic decomposers seeking an abundant organic nutrient source in an otherwise barren landscape.

Many of the genera recovered are familiar players in Antarctic wood decay. Coniochaeta species have been reported from wood on Deception Island and at Japan’s Syowa Station, and from soils in the McMurdo Dry Valleys, though some members of the genus are opportunistic human pathogens. Cadophora luteo-olivaceae, identified in this study, was previously documented in the old buildings at Whalers Bay by Held and Blanchette, underscoring the group’s capacity to thrive in polar environments when wood is available. Pseudogymnoascus is widespread in cold terrestrial and marine environments of both polar regions and is thought to play a central role in decomposition and nutrient cycling. Mrakia, meanwhile, accounts for roughly thirty-five percent of cultivable fungi isolated from lake sediments and soils of East Antarctica, and Leucosporidium species have been found in Antarctic seawater, soils, bryophytes and flowering plants. Even Naganishia, whose members are described as among the most UV-resistant organisms known, made an appearance.

The biotechnological heart of the study lies in the enzymes. All forty-seven isolates were screened for production of four extracellular enzymes: amylase, cellulase, inulinase and pectinase. Activity was assessed by growing the fungi on media containing specific inducing substrates and measuring halos of hydrolysis after seven days at fifteen degrees Celsius, with an Enzyme Index of two or greater defining a good producer. Amylase production was the most widespread, with thirty-five isolates producing degradation halos, followed by inulinase with thirty-four and cellulase with thirty-three, while pectinase lagged at twelve. Inulinase, however, boasted the highest number of good producers, with eight isolates reaching the threshold. Standout performers included Coniochaeta sp. 2, a good producer of both cellulase and inulinase with enzymatic indices of 2.70 and 2.51 respectively, and the yeast Phenoliferia glacialis, which produced cellulase and pectinase with indices of 2.11 and 2.44.

Several of these findings represent firsts for science. The study appears to be the first report of Coniochaeta isolates capable of producing amylase and inulinase, the first report of a Purimyces isolate as a good inulinase producer, and the first documentation of Phenoliferia glacialis producing inulinase. Because all the detected enzymes were active at low temperatures, they carry considerable industrial promise. Cold-active amylases could serve in cold-water detergents, cold saccharification in food processing, textile desizing and animal feed additives for cold climates. Inulinase can generate fructooligosaccharides for functional foods and support cold-fermentation brewing, while pectinase enables fruit juice clarification at low temperatures, preserving vitamins, flavor and color, and finds use in eco-friendly textile bioscouring. Cellulase applications span cold bio-polishing in textiles, cold-wash laundry detergents and environmentally gentler pulp and paper processing. Enzymes that work at low temperatures reduce energy costs, lower the risk of microbial contamination and can eliminate expensive heating equipment entirely.

Perhaps the most commercially intriguing discovery came from the selective ethanol medium. Two isolates of the yeast Solicoccozyma terricola, a psychrotolerant oleaginous species previously known from soils, mosses and lichens in Antarctica and from glacial sediments in Italy, were recovered in low density from wood fragments and soil. Temperature trials showed the yeast grows across a wide range from five to twenty-five degrees Celsius, with the strongest colonies between fifteen and twenty degrees. When cultured in glucose-rich broth at twenty degrees for nine days and stained with the fluorescent dye Nile Red, the cells revealed lipid bodies under confocal microscopy, confirming intracellular lipid production. Previous work by Tasselli and colleagues reported that at twenty degrees this species achieves lipid yields approaching those of palm oil, making it a candidate feedstock for biofuel production, with additional potential in food, cosmetics and textile industries.

The study’s conclusions carry weight beyond biotechnology. The fungal communities documented in Whalers Bay’s lignocellulosic substrates are dominated by decomposers, consistent with the hypothesis that many taxa arrived with imported construction timber, though the authors acknowledge the fungi could also have arrived as spores dispersed by air currents, birds or human activity, or that the imported substrates may simply have acted as bait for fungi already present. Because the surviving buildings form part of a formally declared Antarctic Historic Monument, Antarctic Treaty nations bear a duty to protect these sites, and wood-degrading fungi pose a direct challenge to their long-term conservation. The researchers call for further genetic studies to identify the genes behind the observed enzyme production and detailed investigations of the lipid metabolic pathways in S. terricola. They also emphasize a broader message: the Antarctic ecosystem shelters microbes of great biotechnological potential, reinforcing the urgency of preserving the region against biological loss driven by local climate change. In the frozen timbers of a whaling station, it seems, the continent has been quietly running an experiment in applied biology for over a century.

Subject of Research: Culturable fungal diversity in Antarctic lignocellulosic substrates and their production of cold-active enzymes and lipids with industrial potential

Article Title: Fungal diversity in Antarctic lignocellulosic substrates and their production of enzymes and lipids with potential industrial applications

Article References: Teixeira, E. A. A., de Souza, L. M. D., de Carvalho, C. R., Rosa, C. A., Convey, P., & Rosa, L. H. (2025). Fungal diversity in Antarctic lignocellulosic substrates and their production of enzymes and lipids with potential industrial applications. Blue Biotechnology, 2(1), Article 11. https://doi.org/10.1186/s44315-025-00035-9

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00035-9

Keywords: Antarctica, fungi, extremophiles, cold-active enzymes, bioprospecting, biotechnology, Coniochaeta, Solicoccozyma terricola, oleaginous yeast, biofuel, Deception Island, wood decay