Michaela Teich

Winter Tourism and Climate Change in the Alps: An Assessment of Resource Consumption, Snow Reliability, and Future Snowmaking Potential

Abstract The winter tourism industry is facing considerable challenges with climate change; it is increasingly responding with investments in snowmaking facilities. We present a study on 3 tourism destinations in the Swiss Alps that addressed resource consumption of snowmaking, snow reliability, and future snowmaking potential in a warmer climate. The energy consumption of snowmaking in the ski resorts was in the lower range of what could be expected from literature values. It comprised ∼0.5% of the respective municipalitys energy consumption and was moderate compared with other tourism-related activities. Water consumption, however, was in the higher range with regard to what was expected from literature values and was also high compared with other water uses (eg 36% compared with drinking water consumption in one community). Natural snow cover was partly critical for winter sports at low elevations at ∼1200 masl, but uncritical at higher elevations above 2000 masl. Snow cover will become even more critical in a warmer climate but will probably still be sufficient above 2000 masl until 2050. Snowmaking may become critical at lower elevations in the early months of the season (November and December) due to warmer temperatures that can be expected in the coming decades. But, at higher elevations, the potential for snowmaking will probably remain sufficient. Our study provides straightforward and feasible approaches to assess resource consumption and snow cover. Careful consideration of resource consumption and snow cover can foster technical and economical advances as well as more sustainable development in mountains regions. Snow production can represent a valuable adaptation strategy at high-altitude destinations. However, given the increasing economic competition and the changing climate, it will be crucial to use specific regional strengths to provide high-quality winter and summer tourism activities.

Snow Avalanches in Forested Terrain: Influence of Forest Parameters, Topography, and Avalanche Characteristics on Runout Distance

Abstract Mountain forests are recognized as an effective biological protection measure against snow avalanches. To investigate how forests decelerate snow avalanches, we analyzed two data sets from the European Alps. The first data set contained 43 small to medium avalanches which released in forests and either stopped in forested terrain within 50 to 400 m or ran through forests and stopped in unforested terrain with a maximum runout distance of 700 m. The second data set consisted of 44 medium to large avalanches (360 to 1800 m in runout distance) which all stopped within forests, but started above treeline. Statistical dependencies between predictor variables on forest conditions, terrain features and avalanche characteristics (60 in total), and the response variable avalanche runout distance were investigated. Clear differences between avalanches that released in forests and avalanches that released above forests were observed. Forest structural parameters, in particular the starting zone stem density of trees with small diameters (1–15 cm), had a significant effect on runout distances of small to medium avalanches, which released in evergreen coniferous and mixed forests (rs = -0.3; p = 0.015). Beyond a threshold of 200 m this effect was negligible for runout distances of avalanches which were still in motion. In contrast, forest structure did not affect runout distances of medium to large avalanches, which started above treeline, but forests in general were still able to slow avalanche speeds and limit avalanche runout. Furthermore, runout distance was significantly affected by avalanche size characteristics for medium to large avalanches, while avalanche size was less important in determining the runout distance of small avalanches, which released in forest openings. These results emphasize that it is important to treat these two cases differently in protection forest as well as natural hazard management.

Volatile and Within-Needle Terpene Changes to Douglas-fir Trees Associated With Douglas-fir Beetle (Coleoptera: Curculionidae) Attack.

Abstract Mass attack by tree-killing bark beetles (Curculionidae: Scolytinae) brings about large chemical changes in host trees that can have important ecological consequences. For example, mountain pine beetle (Dendroctonus ponderosae Hopkins) attack increases emission of terpenes by lodgepole pine (Pinus contorta Dougl. ex Loud.), affecting foliage flammability with consequences for wildfires. In this study, we measured chemical changes to Douglas-fir (Pseudotsuga menziesii var. glauca (Mirb.) Franco) foliage in response to attack by Douglas-fir beetles (Dendroctonus pseudotsugae Hopkins) as trees die and crowns transitioned from green/healthy, to green-infested (year of attack), to yellow (year after attack), and red (2 yr after attack). We found large differences in volatile and within-needle terpene concentrations among crown classes and variation across a growing season. In general, emissions and concentrations of total and individual terpenes were greater for yellow and red needles than green needles. Douglas-fir beetle attack increased emissions and concentrations of terpene compounds linked to increased tree flammability in other conifer species and compounds known to attract beetles (e.g., α-pinene, camphene, and D-limonene). There was little relationship between air temperature or within-needle concentrations of terpenes and emission of terpenes, suggesting that passive emission of terpenes (e.g., from dead foliage) does not fully explain changes in volatile emissions. The potential physiological causes and ecological consequences of these bark beetle-associated chemical changes are discussed.