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Mountain forests have a substantial protective function in preventing natural hazards, in part due to the presence of dead wood on the forest floor. Rates of deadwood accumulation have increased within the Alps and are predicted to rise further, due to natural disturbances. In particular, higher windthrow event frequencies are expected, primarily due to large-scale even-aged forest stands in many alpine regions combined with climate change. We quantified the rockfall protection effect of mountain forests with and without deadwood, in unprecedented detail, in experiments using two rock shapes with important hazard potential and masses of 200–3200 kg. Based on a multi-camera setup, pre- and post-experimentally retrieved high-resolution lidar data, and rock data measured in situ, we precisely reconstructed 63 trajectories. The principal parameters of interest describing the rockfall kinematics were retrieved for each trajectory. A total of 164 tree impacts and 55 deadwood impacts were observed, and the currently applied energy absorption curves – partially only derived theoretically – could consequently be corroborated or even expanded to a greater absorption performance of certain species than hitherto assumed. Standing trees, in general, and deadwood, in particular, were found to strongly impede the notorious lateral spreading of platy rocks. Platy rocks featured a shorter mean runout distance than their compact counterparts of similar weight, even in the absence of deadwood. These results indicate that the higher hazard potential of platy rocks compared with more compact rocks, previously postulated for open-field terrain, applies less to forested areas. Last, reproducing the experimental setting showcases how complex forest states can be treated within rockfall simulations. Overall, the results of this study highlight the importance of incorporating horizontal forest structures accurately in simulations in order to obtain realistic deposition patterns.

Studying how deadwood mitigates the rockfall hazard in mountain forests is key to understanding the influence of climate-induced disturbances on the protective capacity of mountain forests. Both experimental quantification and numerical process modeling are needed to address this question. Modeling provides detailed insights into the rock–deadwood interaction and can therefore be used to develop effective forest management strategies. Here, we introduce an automatic deadwood generator (ADG) for assessing the impact of fresh woody storm debris on the protective capacity of a forest stand against rockfall. The creation of various deadwood scenarios allows us to directly quantify the mitigation potential of deadwood. To demonstrate the functionality of the proposed ADG method, we compare deadwood log patterns, deadwood effective height, and mesoscale surface ruggedness observed in field surveys in a natural windthrow area with their simulated counterparts. Specifically, we consider two sites near Lake Klöntal, Switzerland, where a major windthrow event occurred in 2019. We perform rockfall simulations for the time (a) before, (b) directly after, and (c) 10 years after the windthrow event. We further compare the results with (d) a simulation with complete clearing of the thrown wood: in other words, a scenario with no standing forest remaining. We showcase an integration of deadwood into rockfall simulations with realistic deadwood configurations alongside a diameter at breast height (DBH)- and rot-fungi-dependent maximum deadwood breaking energy. Our results confirm the mitigation effect of deadwood, which significantly reduces the jump heights and velocities of 400 kg rocks. Our modeling results suggest that, even a decade after the windthrow event, deadwood has a stronger protective effect against rockfall than that provided by standing trees. We conclude that an ADG can contribute to the decision-making involved in forest and deadwood management after disturbances.

Forests are rockfall-protective ecological infrastructures as a significant amount of kinetic energy is absorbed during consecutive rock–tree impacts. Although many recent works have considered rock impacts with standing trees, the effect of lying deadwood in forests has not yet been considered thoroughly, either experimentally or numerically. Here, we present a complete examination of induced rockfall experiments with sensor-equipped, 45 kg, artificial rocks on a forested area in three different management stages. The trilogy is conducted in a spruce forest stand (i) in its original state of forest; (ii) after a logging operation with fresh, lying deadwood; and (iii) after the removal of the deadwood. The tests allow us to directly quantify the effect of fresh deadwood on overall rockfall risk for the same forest (slope, species) under three different conditions. The study yields quantitative results on the barrier efficiency of the deadwood logs as only 3.6 % of the rocks surpass the deadwood section. The mean run-out distance is reduced by 42 %. Conversely, the run-out distance increases by 17 % when the cleared stand is compared to the original forest. These results quantitatively confirm the benefits of nature-based mitigation measures integrated into forestry practice, whose detailed effect has to be scrutinized for higher rockfall energies. Based on the experimental results, we extended a modern rockfall code by three-dimensional deadwood logs to incorporate such complex but realistic forest boundary conditions.

Snow avalanche hazard mapping has a long tradition in the European Alps. Hazard maps delineate areas of potential avalanche danger and are only available for selected areas where people and significant infrastructure are endangered. They have been created over generations, at specific sites, mainly based on avalanche activity in the past. For a large part of the area (90 % in the case of the canton of Grisons) only strongly generalized hazard indication maps are available (SilvaProtect), not showing impact information such as pressure. This is a problem when new territory with no or an incomplete historical record is to be developed. It is an even larger problem when trying to predict the effects of climate change at the state scale, where the historical record may no longer be valid. To close this gap, we develop an automated approach to generate spatially coherent hazard indication mapping based on a digital elevation model for the canton of Grisons (7105 km2) in the Swiss Alps. We calculate eight different scenarios with return periods ranging from frequent to very rare as well as with and without taking the protective effects of the forest into account, resulting in a total of approximately 2 million individual avalanche simulations. This approach combines the automated delineation of potential release areas, the calculation of release depths and the numerical simulation of the avalanche dynamics. We find that between 47 % (most frequent scenario) and 67 % (most extreme scenario) of the cantonal area can be affected by avalanches. Without forest, approximately 20 % more area would be endangered. This procedure can be applied worldwide, where high-spatial-resolution digital elevation models, detailed information on the forest and data on the snow climate are available, enabling reproducible hazard indication mapping also in regions where no avalanche hazard maps yet exist. This is invaluable for climate change studies. The simulation results are validated with official hazard maps, by assessments of avalanche experts, and by existing avalanche cadastres derived from manual mapping and mapping based on satellite datasets. The results for the canton of Grisons are now operationally applied in the daily hazard assessment work of the authorities. Based on these experiences, the proposed approach can be applied for further mountain regions.

Surface roughness influences the release of avalanches and the dynamics of rockfall, avalanches and debris flow, but it is often not objectively implemented in natural hazard modelling. For two study areas, a treeline ecotone and a windthrow-disturbed forest landscape of the European Alps, we tested seven roughness algorithms using a photogrammetric digital surface model (DSM) with different resolutions (0.1, 0.5 and 1 m) and different moving-window areas (9, 25 and 49 m2). The vector ruggedness measure roughness algorithm performed best overall in distinguishing between roughness categories relevant for natural hazard modelling (including shrub forest, high forest, windthrow, snow and rocky land cover). The results with 1 m resolution were found to be suitable to distinguish between the roughness categories of interest, and the performance did not increase with higher resolution. In order to improve the roughness calculation along the hazard flow direction, we tested a directional roughness approach that improved the reliability of the surface roughness computation in channelised paths. We simulated avalanches on different elevation models (lidar-based) to observe a potential influence of a DSM and a digital terrain model (DTM) using the simulation tool Rapid Mass Movement Simulation (RAMMS). In this way, we accounted for the surface roughness based on a DSM instead of a DTM, which resulted in shorter simulated avalanche runouts by 16 %–27 % in the two study areas. Surface roughness above a treeline, which in comparison to the forest is not represented within the RAMMS, is therefore underestimated. We conclude that using DSM-based surface roughness in combination with DTM-based surface roughness and considering the directional roughness is promising for achieving better assessment of terrain in an alpine landscape, which might improve the natural hazard modelling.

Gravitational natural hazards such as snow avalanches, rockfalls, shallow landslides and volcanic activity represent a risk to mountain communities around the world. In particular, where documentary records about these processes are rare, decisions on risk management and land-use planning have to be based on a variety of other sources including vegetation, tree-ring data and natural hazard process models. We used a combination of these methods in order to evaluate dynamics of natural hazards with a focus on snow avalanches at Valle Las Trancas, in the Biobío region in Chile. Along this valley, natural hazards threaten not only the local human population, but also the numerous tourists attracted by outdoor recreational activities. Given the regional scarcity of documentary records, tree-ring methods were applied in order to reconstruct the local history of snow avalanches and debris flow events, which are the most important weather-related processes at respective tracks. A recent version of the model Rapid Mass MovementS (RAMMS), which includes influences of forest structure, was used to calculate different avalanche parameters such as runout distances and maximum pressures, taking into consideration the presence or absence of forest along the tracks as well as different modeled return periods. Our results show that local Nothofagus broadleaf forests contribute to a reduction of avalanche runout distances as well as impact pressure on present infrastructure, thus constituting a valuable ecosystem disaster risk reduction measure that can substitute or complement other traditional measures such as snow sheds.

We study how short duration powder avalanche blasts can break and overturn tall trees. Tree blow-down is often used to back-calculate avalanche pressure and therefore constrain avalanche flow velocity and motion. We find that tall trees are susceptible to avalanche air blasts because the duration of the air blast is near to the period of vibration of tall trees, both in bending and root-plate overturning. Dynamic magnification factors for bending and overturning failures should therefore be considered when back-calculating avalanche impact pressures.

Snow avalanches break, uproot and overturn trees causing damage to forests. The extent of forest damage provides useful information on avalanche frequency and intensity. However, impact forces depend on avalanche flow regime. In this paper, we define avalanche loading cases representing four different avalanche flow regimes: powder, intermittent, dry and wet. Using a numerical model that simulates both powder and wet snow avalanches, we study documented events with forest damage. First we show that in the powder regime, although the applied impact pressures can be small, large bending moments in the tree stem can be produced due to the torque action of the blast. The impact area of the blast extends over the entire tree crown. We find that, powder clouds with velocities over 20 m s-1 can break tree stems. Second we demonstrate that intermittent granular loadings are equivalent to low-density uniform dry snow loadings under the assumption of homogeneous particle distributions. The intermittent regime seldom controls tree breakage. Third we calculate quasi-static pressures of wet snow avalanches and show that they can be much higher than pressures calculated using dynamic pressure formulas. Wet snow pressure depends both on avalanche volume and terrain features upstream of the tree.

In this study, we assess the climate mitigation potential from afforestation in a mountainous snow-rich region (Switzerland) with strongly varying environmental conditions. Using radiative forcing calculations, we quantify both the carbon sequestration potential and the effect of albedo change at high resolution. We calculate the albedo radiative forcing based on remotely sensed data sets of albedo, global radiation and snow cover. Carbon sequestration is estimated from changes in carbon stocks based on national inventories. We first estimate the spatial pattern of radiative forcing (RF) across Switzerland assuming homogeneous transitions from open land to forest. This highlights where forest expansion still exhibits climatic benefits when including the radiative forcing of albedo change. Second, given that forest expansion is currently the dominant land-use change process in the Swiss Alps, we calculate the radiative forcing that occurred between 1985 and 1997. Our results show that the net RF of forest expansion ranges from −24 W m−2 at low elevations of the northern Prealps to 2 W m−2 at high elevations of the Central Alps. The albedo RF increases with increasing altitude, which offsets the CO2 RF at high elevations with long snow-covered periods, high global radiation and low carbon sequestration. Albedo RF is particularly relevant during transitions from open land to open forest but not in later stages of forest development. Between 1985 and 1997, when overall forest expansion in Switzerland was approximately 4%, the albedo RF offset the CO2 RF by an average of 40%. We conclude that the albedo RF should be considered at an appropriately high resolution when estimating the climatic effect of forestation in temperate mountainous regions.

Over the years, Dorsal Inlay Graft (DIG) urethroplasty has gained worldwide acceptance for primary hypospadias repair. However, its safety and effectiveness for revision surgery are yet to be proven. The aim of the study is to assess and compare complication rates and functional outcomes of DIG surgery in revision versus primary hypospadias repair. We carried out a retrospective analysis of data collected from 53 consecutive DIG urethroplasties performed by a single surgeon at our institution. Patients were stratified in two groups – primary repair and redo-urethroplasty. For each group, we recorded standard pre-operative characteristics, surgical technicalities, complication rates and uroflowmetry parameters. Out of 53 DIG urethroplasties, 21 (39.6 %) where primary and 32 (60.4 %) were re-do. As expected, the two groups differed for median age at surgery: 20 months for primary and 68.5 months for revision surgery (p < 0.001). Additionally, all 21 (100 %) primary interventions were performed with a preputial graft, whereas among revision DIG urethroplasties only 2 (6.3 %) where preputial and 30 (93.8 %) were buccal (p < 0.001). Catheterization time (7 vs 8 days, p = 0.155) and postoperative complication rates (14.3 % vs 9.4 %, p = 0.581) were comparable between the primary and revision surgery group, respectively (all p >.05). Forty-two of the 53 patients underwent uroflowmetry during follow-up. Of these, 19 (63 %) patients presented with abnormal uroflowmetry and 11 (37 %) had equivocal parameters with no difference between the two groups. Dorsal Inlay Graft urethroplasty has long been known to be safe and effective for primary hypospadias repair. On the other hand, data on dorsal inlay graft urethroplasty as a salvage surgery after primary hypospadias repair failure is scarce. Surprisingly, according to our findings, surgical outcomes and complication rates are comparable between primary and revision hypospadias cases. Additionally, our results in the redo group are absolutely encouraging if compared to those reported in the literature for the same subset of patients. According to our findings, DIG urethroplasty is a safe and effective option to treat revision hypospadias repair. [ABSTRACT FROM AUTHOR]

Ureterocele is a cystic dilatation of the intravesical submucosal ureter, with an obstructed orifice. Endoscopic treatment is one of the most common option for surgical treatment. In intravesical ureterocele, the punctures must be made just above the junction between the ureterocele and the bladder floor. We commonly use a 8–9.8 Fr cystoscope, with a 5 Fr working channel, a metallic needle for bulking agent injection 3.7 Fr. In selected cases we also use electric or laser probes to decompress the ureterocele. When evidence of decompression is verified and vesicoureteral reflux is excluded, antibiotic prophylaxis is stopped. If, despite decompression, a large ureterocele is subsequently obstructing the bladder neck a surgical excision is necessary. Forty-four patients (92%) were treated endoscopically. Ureterocele puncture was performed with a metallic needle for bulking agent injection in 30 cases (63%), with a laser fiber in 7 cases (15%), with an electrified ureteral catheter in 4 cases (8%), and with Bugbee in 3 cases (6%). A success rate after one procedure was achieved in 40 children (83%). Adequate opening of the ureterocele with complete decompression of the reno-ureteral system is the goal of endoscopic treatment. An overaggressive incision or puncture could result in an increased chance of secondary vesicoureteral reflux. [ABSTRACT FROM AUTHOR]

Natural disturbances play an important role in shaping the dynamics of mountain forests, yet their effects on essential ecosystem services, such as protection against natural hazards, can be significant. With the challenges posed by climate change and increasing disturbances, as well as the complexities of salvage logging, there is a growing interest in understanding post-disturbance development in unsalvaged mountain forests, alongside the advancement of decision support systems aimed at ensuring sustained provision of ecosystem services. In this study, we combined a space-for-time substitution approach with long-term monitoring data to evaluate regeneration processes and development of deadwood decay following three distinct windthrow events in Central European mountain forests that were locally unsalvaged (specifically Vaia in 2018, Kyrill in 2007, and Vivian in 1990). Our unique dataset additionally provided insights into the long-term effects of disturbance legacies and tree regeneration on protection against natural hazards. Deadwood cover gradually decreased with time since disturbance, from an average of 50% two years after Vaia to 25% twelve years after Kyrill and 15% thirty years after Vivian. Similarly, deadwood height above ground significantly decreased over time, with median values dropping from 1 to 2 m immediately after the disturbance to 25–30 cm three decades later. The decay stage and diameter of deadwood significantly influenced tree regeneration, with larger diameters of logs and deadwood in more advanced decay stage (especially less solid/soft to very loose stage), facilitating seedling establishment, thus a second wave of tree regeneration. About a quarter of saplings grew on deadwood thirty years after disturbance. The analysis of post-windthrow stand development showed an increase in tree cover and height with time since disturbance, with distinct patterns observed across different windthrow events and sites. Three decades post-disturbance, the number of trees had notably increased, with tree cover reaching 50%. Although Norway spruce remained the dominant species, the forest composition had shifted towards a predominance of broadleaves, particularly evident at lower elevations and areas with moderate browsing pressure. Our findings underscore the critical role of post-disturbance forest recovery and deadwood dynamics in promoting uneven-aged mixed forest structures, thereby enhancing forest regeneration, structural diversity, and protection against natural hazards. Emphasizing the vital importance of retaining deadwood, our study suggests that its role as a valuable substrate for enhancing resilience and ecosystem services is likely to grow in the future. • Deadwood cover and height above ground decreased with time since windthrow. • Decay stage and diameter of deadwood significantly influenced tree regeneration. • At lower elevations, windthrow led to higher shares of broadleaves. • Deadwood supports tree establishment and heterogeneity of forest structure. • Avoiding salvage logging enhanced forest recovery and avalanche protection. [ABSTRACT FROM AUTHOR]

The present study focused on the research publications of women faculty in the field of physics, Astrophysics, Astronomy and Atmospheric Science in India. To collect the data we have covered the women faculty of Central Universities, State Universities, IITs, NITs, IISER's, NISER's, research institutes, laboratories and some selected deemed universities. The first fact we found was that the number of women were very less as compare to male staff. To see the publication productivity of women authors we tried to analyze the year-wise productivity, authorship pattern, preferred journals, place and designation and the research papers received highest citations for the period of five years from 2011- 2015. Year 2014 found to be the most productive year and in authorship pattern, women authors preferred to publish their research in collaboration. Highest number of research papers was published in Journal of Applied Physics. [ABSTRACT FROM AUTHOR]

Highlights • Snow penetration resistance was measured repeatedly below bark beetle killed trees. • Variability in snow stratigraphy was quantified with a new layer matching algorithm. • Spatial variability in snow stratigraphy is driven by percentage of canopy cover. • Leaving dead trees in protection forests contributes to avalanche protection. • Salvage logging can result in snow stratigraphy more prone to avalanche release. Abstract Healthy, dense forests growing in avalanche terrain reduce the likelihood of slab avalanche release by inhibiting the formation of continuous snow layers and weaknesses in the snowpack. Driven by climate change, trends towards more frequent and severe bark beetle disturbances have already resulted in the death of millions of hectares of forest in North America and central Europe, affecting snowpack in mountain forests and potentially reducing their protective capacity against avalanches. We examined the spatial variability in snow stratigraphy, i.e., the characteristic layering of the snowpack, by repeatedly measuring vertical profiles of snow penetration resistance with a digital snow micro penetrometer (SMP) along 10- and 20-m transects in a spruce beetle-infested Engelmann spruce forest in Utah, USA. Three study plots were selected characterizing different stages within a spruce beetle outbreak cycle: non-infested/green, infested > 3 years ago/gray stage, and salvage-logged. A fourth plot was installed in a non-forested meadow as the control. Based on our SMP measurements and a layer matching algorithm, we quantified the spatial variability in snow stratigraphy, and tested which forest, snow and/or meteorological conditions influenced differences between our plots using linear mixed effects models. Our results showed that spatial variability in snow stratigraphy was best explained by the percentage of canopy covering a transect (R2 = 0.71, p < 0.001), and that only 14% of the variance was explained by the stage within the outbreak cycle. That is, differences between green and gray stage stands did not depend much on the reduction in needle mass, but spatial variability in snow stratigraphy increased significantly with increasing forest canopy cover. At both study plots, a more heterogeneous snow stratigraphy developed, which translates to disrupted and discontinuous snow layers and, therefore, reduced avalanche formation. We attribute this to the effect that small fine branches and twigs still present in the canopy of gray stage trees have on snow interception and unloading, and especially on canopy drip. In contrast, salvage logging that reduced the canopy cover to ∼25%, led to a spatially less variable and similar snow stratigraphy as observed in the meadow. At these two study plots, a homogeneous snow stratigraphy consisting of distinct vertical and continuous slope-parallel soft and hard snow layers including weak layers had formed, a condition which is generally more prone to avalanche release. Our findings therefore emphasize advantages of leaving dead trees in place, especially in protection forests where bark beetle populations have reached epidemic levels. [ABSTRACT FROM AUTHOR]

The research output of the women scientists of the selected Indian research institutes in the field of physics and astronomy is analyzed for a period of 2011 to 2015. It is observed that the strength of women scientists (12.35%) are less in compare to men scientists (87.65%), as only 73 women scientists out of total 583 staff. These women scientists have published total number of 713 research articles, and the current study reveals the contribution of each scientist individually. The highest numbers of papers (144) were published by National Physical Laboratory but Indian Institute of Astrophysics got the highest number of citations for fewer publications (2018 for 129 articles). The majority of these articles were published in collaboration with other institutes of national and international level. To understand the collaboration between these and other institute the collaboration coefficient is calculated (CC) and found that these institute have average CC ~0 .7480. On the basis of analysis of 713 publications of women scientists, the Journal of Astronomy and Astrophysics is assigned as rank one because maximum articles were published in this journal, and in term of most productive authors, Aditi Sen De from Harish Chandra Research Institute with maximum 38 publications is allocated as rank one among all women scientists. Additionally, this study also presents detailed information on the corresponding and first authorship of all these papers. [ABSTRACT FROM AUTHOR]

The study presents a bibliometric analysis of 270 papers presented at the international conference "Information Technology: Yesterday, Today and Tomorrow" organized by the Defence Scientific Information and Documentation Center (DESIDOC), Delhi, of the Defence Research and Development Organization (DRDO) during February 19-21, 2015. The study indicates that more than half of the total presentation was contributed by academic institutions (universities and colleges). Distribution of contributions by country and Indian States indicates that out of 270 papers, only seven were from foreign countries and rest 263 from India. Delhi topped the list among the contributing cities, while DESIDOC topped the list among the contributing institutions. Output of authors by gender indicates that male authors contributed more than female authors. The distribution of references cited in the papers shows that among the different information sources, journal citations were the highest and highest number of cited journals was in the discipline of library and information science. The highest number of cited journals was being published from the USA. [ABSTRACT FROM AUTHOR]

The present study aims to bring out the contribution of women faculty in the discipline of Physics in select institutions of Delhi. The study covers a total of 44 women faculties and their 802 publications during the period of 2011-2015 collected from various sources. The study presents a scientometrics analysis of 463 journal articles. The study focuses on authorship pattern, research interest areas, most productive authors, most used journals etc. The study indicates that multi-authored papers were dominated. Ratnamala Chatterjee from IIT Delhi found to be the most productive author and Journal of Applied Physics is the most preferred journal. CSIR-National Physical Laboratory was leading institution in publishing journal articles (145). It was noticed that majority of women authors preferred to be the second author while writing the paper jointly. [ABSTRACT FROM AUTHOR]

Mountain forests are among the most important ecosystems in Europe as they support numerous ecological, hydrological, climatic, social, and economic functions. They are unique relatively natural ecosystems consisting of long-lived species in an otherwise densely populated human landscape. Despite this, centuries of intensive forest management in many of these forests have eclipsed evidence of natural processes, especially the role of disturbances in long-term forest dynamics. Recent trends of land abandonment and establishment of protected forests have coincided with a growing interest in managing forests in more natural states. At the same time, the importance of past disturbances highlighted in an emerging body of literature, and recent increasing disturbances due to climate change are challenging long-held views of dynamics in these ecosystems. Here, we synthesize aspects of this Special Issue on the ecology of mountain forest ecosystems in Europe in the context of broader discussions in the field, to present a new perspective on these ecosystems and their natural disturbance regimes. Most mountain forests in Europe, for which long-term data are available, show a strong and long-term effect of not only human land use but also of natural disturbances that vary by orders of magnitude in size and frequency. Although these disturbances may kill many trees, the forests themselves have not been threatened. The relative importance of natural disturbances, land use, and climate change for ecosystem dynamics varies across space and time. Across the continent, changing climate and land use are altering forest cover, forest structure, tree demography, and natural disturbances, including fires, insect outbreaks, avalanches, and wind disturbances. Projected continued increases in forest area and biomass along with continued warming are likely to further promote forest disturbances. Episodic disturbances may foster ecosystem adaptation to the effects of ongoing and future climatic change. Increasing disturbances, along with trends of less intense land use, will promote further increases in coarse woody debris, with cascading positive effects on biodiversity, edaphic conditions, biogeochemical cycles, and increased heterogeneity across a range of spatial scales. Together, this may translate to disturbance-mediated resilience of forest landscapes and increased biodiversity, as long as climate and disturbance regimes remain within the tolerance of relevant species. Understanding ecological variability, even imperfectly, is integral to anticipating vulnerabilities and promoting ecological resilience, especially under growing uncertainty. Allowing some forests to be shaped by natural processes may be congruent with multiple goals of forest management, even in densely settled and developed countries. [ABSTRACT FROM AUTHOR]

Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25–115 years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15–40 years in all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and expanding forest areas since the mid-19th century have - along with climatic changes - contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium. [ABSTRACT FROM AUTHOR]

Disturbances are among the most important processes that shape forest dynamics and landscapes. However the historic ranges of variability (HRV) of many coniferous forests in Europe and specifically in the mountains on the Balkan Peninsula are not well understood. We present the first overview of available data on disturbance events in coniferous forests in the high mountains in southwestern Bulgaria. Our study included data from historical publications, documents and archives, newer documentary data obtained through interviews with foresters and verified using satellite images, published studies and new tree-ring data. We documented at least 188 abiotic disturbance events in the Bulgarian mountains including fires (39%), windthrows (31%) and avalanches (20%) and fewer disturbances caused by snow and ice. Fires primarily affected Pine-dominated ecosystems, especially pure Pinus sylvestris and mixed Pinus sylvestris-Pinus nigra forests. Our tree-ring analysis also provided evidence for repeated fires in subalpine Pinus heldreichii and Pinus peuce forests during the last 500 years. Some of these fires affected different valleys within the same year, suggesting either large-scale events or the simultaneous occurrence of fires related to appropriate fuel and climate conditions. We also found data on several large fires in Picea abies -dominated ecosystems. Most of the fires were less than 100 ha, but some were larger, the most extensive of which was the Batalach fire (year 1890, approximately 9000 ha) in the Western Rhodopes. The highest frequency of fires was in 1880–1910, 1940–1950 and 2000–2010. We found evidence for at least 59 windthrows greater than 1 ha, mainly in pure Picea abies and mixed Picea abies-Pinus sylvestris forests. There was high variability in the size of windthrows, ranging from small-scale, gap-sized blowdowns to large and infrequent disturbances affecting more than 300 ha, the largest of which was the Beglika windthrow (1961, 3000 ha). Although avalanches are considered important for subalpine forests on steep slopes they were generally poorly documented and data were limited to several avalanche cycles in 1955, 1963–1974 and in the last two decades. Snow-related damage was important mostly for young pine forests in which several events affected a high stock of wood in the 1930s, 1987, 1988 and 2015. Our data show that natural disturbances of various types and of a range of sizes are part of the natural dynamics of coniferous forests in Bulgaria. Further, our study contributes to the understanding of the historic range of variability of mountain forests in Europe. [ABSTRACT FROM AUTHOR]