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Natural disturbances are among the most important factors that shape forest dynamics and forest landscapes. However, the natural disturbance regime of Norway spruce (Picea abies (L.) Karst.) forests in Europe is not well understood. We studied the disturbance regimes in three forest reserves in Bulgaria (Parangalitsa, Bistrishko branishte, and Beglika), which are representative of the range of conditions typical for P. abies ecosystems in central and southern Europe. Our data indicated that large-scale disturbances were most numerous in forests that were between 120 and 160 years old, those with unimodal diameter at breast height (DBH) distributions, and especially those located in vulnerable topographic settings. Wind disturbances ranged up to 60 ha, followed in one case by a 200 haIps typographus (Linnaeus, 1758) outbreak. Older forests and those with more complex structures (i.e., reverse-J DBH) were characterized by numerous small gaps but were also affected by a few larger disturbances. In some old-growth forests at highly productive sites, gaps could be so numerous that the long-term existence of old trees may become an exception. Over the past centuries, the natural range of variability of these Norway spruce forests in Bulgaria appears to have been shaped mostly by wind and bark beetle disturbances of various sizes. Key words: disturbances, windthrow, Ips typographus, Picea abies, Europe. Les perturbations naturelles sont parmi les plus importants facteurs qui determinent la dynamique forestiere et le paysage forestier. Cependant, le regime de perturbation naturelle des forets d'epicea commun (Picea abies (L.) Karst.) en Europe est mal connu. Nous avons etudie les regimes de perturbation dans trois reserves forestieres de la Bulgarie: Parangalitsa, Bistrishko branishte et Beglika, qui sont representatives de la gamme de conditions typiques des ecosystemes de P. abies dans le centre et le sud de l'Europe. Nos donnees indiquent que les perturbations a grande echelle ont ete plus nombreuses dans les forets agees de 120 a 160 ans, dans celles dont la distribution des dhp est unimodale et particulierement dans celles qui sont situees dans des contextes topographiques vulnerables. Les perturbations causees par le vent couvraient jusqu'il 60 ha, suivies dans un cas par une epidemie d'Ips typographus (Linnaeus, 1758) couvrant 200 ha. Les forets plus vieilles et celles dont la structure est plus complexe (c.-a-d. dont la distribution des dhp est en forme de J inverse) etaient caracterisees par de nombreuses petites trouees, mais elles etaient aussi touchees par quelques perturbations plus vastes. Dans certaines forets anciennes situees sur des stations tres productives, les trouees pouvaient etre tellement nombreuses que l'existence a long terme des vieux arbres pourrait devenir une exception. Au cours des derniers siecles, l'ampleur naturelle de la variabilite de ces forets d'epicea commun en Bulgarie semble avoir ete faconnee par des perturbations de dimension variee causees par le vent et les scolytes. [Traduit par la Redaction] Mots-cles: perturbations, chablis, Ips typographus, Picea abies, Europe., Introduction Natural disturbances are among the most important processes that guide forest dynamics. Disturbances shape species composition, structural properties, nutrient cycling, carbon storage, and biodiversity (Oliver 1996; Foster et al. [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2007.05.019 Byline: Adrienne GrA*t-Regamey (a), Peter Bebi (b), Ian D. Bishop (c), Willy A. Schmid (a) Keywords: Alpine regions; Ecosystem services; Environmental management; Geographic information system; Economic valuation; Land-use change; Scenarios Abstract: Planning frequently fails to include the valuation of public goods and services. This can have long-term negative economic consequences for a region. This is especially the case in mountainous regions such as the Alps, which depend on tourism and where land-use changes can negatively impact key ecosystem services and hence the economy. In this study, we develop a semi-automatic procedure to value ecosystem goods and services. Several existing process-based models linked to economic valuation methods are integrated into a geographic information system (GIS) platform. The model requires the input of a digital elevation model, a land-cover map, and a spatially explicit temperature dataset. These datasets are available for most regions in Europe. We illustrate the approach by valuing four ecosystem services: avalanche protection, timber production, scenic beauty, and habitat, which are supplied by the 'Landschaft Davos', an administrative district in the Swiss Alps. We compare the impacts of a human development scenario and a climate scenario on the value of these ecosystem services. Urban expansion and tourist infrastructure developments have a negative impact on scenic beauty and habitats. These impacts outweigh the benefits of the developments in the long-term. Forest expansion, predictable under a climate change scenario, favours natural avalanche protection and habitats. In general, such non-marketed benefits provided by the case-study region more than compensate for the costs of forest maintenance. Finally, we discuss the advantages and disadvantages of the approach. Despite its limitations, we show how this approach could well help decision-makers balance the impacts of different planning options on the economic accounting of a region, and guide them in selecting sustainable and economically feasible development strategies. Author Affiliation: (a) Eidgenossiche Technische Hochschule Zurich (ETHZ), ETH Honggerberg, LEP, 8093 Zurich, Switzerland (b) WSL Swiss Federal Institute for Snow and Avalanche Research, Research Unit Ecosystem Boundaries, 7260 Davos, Switzerland (c) Department of Geomatics, University of Melbourne, Vic. 3010, Australia Article History: Received 22 November 2005; Revised 12 May 2007; Accepted 15 May 2007

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) no maps are available. This is a problem when new territory with no or 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 spatial continuous 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. This approach combines the automated delineation of potential release areas, the calculation of release depths and the numerical simulation of the avalanche dynamics. 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. [ABSTRACT FROM AUTHOR]

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 on a forested area in three different management stages. The trilogy is conducted in a spruce forest stand (i) in its original state, (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 runout distance is reduced by 42 %. Conversely, the runout 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 and we show how modern rockfall codes can be extended to incorporate such complex, but realistic forest boundary conditions. [ABSTRACT FROM AUTHOR]