Artificial Snow - the science bit...Artificial snow is increasingly used to guarantee the snow cover of a resort for the entire season but only a few investigations have been carried out systematically to specify the environmental impacts.
Rixen et al made a study in 2003 about the ecological implications of ski piste preparation and of artificial snow production. They found that main direct impacts of ski piste preparation on the vegetation were related to the compaction of the snow cover caused by the piste grooming; namely the induction of soil frost, the formation of ice layers, mechanical damage and a delay in plant development. The vegetation reacts with changes in species composition and a decrease in biodiversity. However, artificial snow modifies some of these impacts; the soil frost is mitigated due to an increased insulation of the snow pack and the mechanical impacts of snow-grooming vehicles are mitigated due to the deeper snow cover. The deeper snow cover reduces the disturbance to the vegetation below. The snow melt of the piste is postponed through a combination of compression and artificial snow and thus vegetation development is delayed though not damaged. Furthermore, they found that artificial snow induces new impacts to the alpine environment. The longer artificial snow had been used on ski pistes the higher the moisture and nutrient levels. Changes in indicator values for soil nutrients and moisture could be considered beneficial for plant growth. Artificial snow is often made from river water with a high mineral content; when it melts it increases the input of water and ions to ski pistes, which can have a fertilizing effect and hence change the plant species composition. Increasingly, snow additives made of potentially phytopathogenic bacteria are used in artificial snow and they enhance ice crystal formation due to their ice nucleation activity. Although sterilised, additives affected the growth of some alpine plant species in laboratory experiments, although it is inconclusive whether this impact is negative. No effects of artificial snow on plant productivity could be detected. The impact of artificial snow on diversity was ambiguous. Salts are applied to improve the snow quality for ski races. The environmental impacts of most salts have not yet been investigated, but a commonly used nitrate salt has intense fertilising properties. Again this could be non-beneficial to the vegetation; however, this has yet to be clarified. Rixen et al made another study in 2004 to investigate snow depth and density from groomed ski pistes with compacted snow and their effects on ground temperatures and timing of snowmelt. They analysed groomed pistes with and without artificial snow as well as adjacent ungroomed off-piste control plots beside the piste. On pistes with natural snow, the thin and compacted snow cover led to severe and long lasting seasonal soil frost. On pistes with artificial snow, soil frost occurred less frequently because of increased insulation due to the greater snow depth. However, due to the greater snow mass, the beginning of the snow-free season was delayed by more than 2 weeks. Average winter ground temperatures under a continuous snow cover were decreased by approximately 1°C on both piste types compared with off-piste control plots. The results suggest that the heat balance of alpine soils is changed by both piste types, either by an extensive heat loss on pistes with natural snow or by prolonged snow cover on pistes with artificial snow. They did not conclude whether the impact was positive or negative – merely that there was a difference. Keller et al 2004 conducted a similar study in central Switzerland to analyse whether the soil below groomed ski slopes with artificial snow may be subjected to more pronounced cooling than the soil below a natural snowpack. They found that snow density, snow hardness and thermal conductivity were significantly higher on the ski slope than in the natural snowpack. However, these differences did not affect the cooling of the soil, since no difference was observed between the ski slope and the natural snow cover. This might be because cold periods were rare and short and thus any snowpack could protect the soil from freezing. The major impact of the ski-slope grooming was a 4 week delay in snowmelt and soil warming at the end of the season. The study demonstrates that there is no site-independent answer as to whether a groomed snowpack affects the thermal conditions in the soil. Thus, it can be seen that there is no clear answer. All types of ski piste management cause deviations from the natural structure and composition, however it is inconclusive whether the impacts are positive or negative. The impacts of ski pistes in general and of artificial snow in particular appear comparatively moderate, but are by no means negligible. Conclusions to be drawn are that machine grading without the protection of the top soil should be avoided at all costs and tree clearance should only be conducted with an environmental impact analysis to balance the loss of one habitat with the gain of another. Artificial snow should be created with renewable energy sources, using water from sustainable sources that do not impact the biodiversity in natural streams and planned with care to not litter the mountainside with equipment. Long term snow production should be banned in areas where any increase in the supply of nutrients and water is a concern and pistes should not be allowed where any changes in composition or decrease in species richness cannot be tolerated. Return to The Ski Factors - Artificial Snow |
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