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Piste pressure on alpine plants

By Fiona Proffitt

 

 

 

Machine-produced snow takes longer to melt (SLF/Christian Rixen)

The impacts of ski piste preparation on alpine plants are long-

lasting and greatest at higher altitudes, Swiss researchers report.

 

The effects are likely to worsen as global warming forces ski

operators to use more artificial snow and open higher runs, the

scientists say.

 

They compared the vegetation on and off-piste at 12 Swiss ski

resorts, in the biggest study of its kind.

 

Overall, they found 9% less plant cover and 11% fewer plant species

on-piste.

 

Woody plants and early-flowering species were seen to be worst-

affected.

 

These differences were more pronounced at higher altitudes,

suggesting greater future impacts as skifields move upwards.

 

The work was undertaken by a team from the Swiss Federal Institute

for Snow and Avalanche Research (SLF), the University of Zurich and

the University of Potsdam in Germany.

 

It has been published online in the Journal of Applied Ecology.

 

Artificial snow

 

Damage caused by grading machines, used to smooth out underlying rock

and soil, was particularly severe, the team found.

 

The effects we found will be a lot more dramatic in coming years

 

Christian Rixen, SLF

Machine-graded pistes had five times more bare ground than ungraded

pistes and had not fully recovered 30 years after grading, even on

slopes that had been re-sown.

 

" At higher altitudes, especially above timberline, it's really

difficult to re-vegetate areas that have been graded, " SLF botanist

Christian Rixen told the BBC News website. " The higher you are, the

more difficult it is. "

 

Because it lies longer than natural snow, artificial snow favoured

snowbed plants such as the alpine snowbell (Soldanella alpine) and

later-flowering species such as heather (Calluna vulgaris) over

gentians and other early-flowerers.

 

These shifts in species composition became more prominent the longer

snowmakers had been used.

 

Wider impacts

 

Such changes in vegetation are likely to have wider impacts, the

researchers report.

 

Decreasing the plant cover on ski slopes could make the soil more

prone to erosion and reduce their value to summer users, including

farmers and hikers, said Dr Rixen.

 

 

A summer picture reveals the damage done by mechanical grading at

Zermatt (SLF/Christian Rixen)

His team recommended that extensive machine-grading and artificial

snow-making be avoided and that ski pistes should not be established

in areas of high conservation value.

 

" The effects we found will be a lot more dramatic in coming years, "

warned Dr Rixen, because artificial snow production is increasing and

ski runs are being developed at higher altitudes, where the

vegetation and soils are more sensitive.

 

The level of reliable snow is predicted to rise by 300-600m in

Switzerland over the next 30-50 years because of global warming,

according to a United Nations Environment Programme report.

 

Already, the lower countries such as Austria and Italy use artificial

snow on about 40% of ski runs and the figure, though lower, was

rising rapidly in Switzerland, said Dr Rixen.