摘要：Alpine grasslands are an important source of fodder for the cattle of Alpine
farmers. Only during the short summer season can these pastures be used for
grazing. With the anticipated climate change, it is likely that plant
production – and thus the fodder basis for the cattle – will be influenced.
Investigating the dependence of biomass production on topoclimatic factors
will allow us to better understand how anticipated climate change may
influence this traditional Alpine farming system. Because small-scale
topoclimatological variations of the main meteorological variables:
temperature, humidity, precipitation, shortwave incoming radiation and wind
speed are not easily derived from available long-term climate stations in
mountainous terrain, it was our goal to investigate the topoclimatic
variations over the pastures belonging to the Alp Weissenstein research
station north of the Albula Pass in the eastern Swiss Alps. We present a
basic assessment of current topoclimatic conditions as a site
characterization for ongoing ecological climate change studies. To be able to
link short-term studies with long-term climate records, we related
agrometeorological measurements with those of surrounding long-term sites run
by MeteoSwiss, both on valley bottoms (Davos, Samedan), and on mountain tops
(Weissfluhjoch, Piz Corvatsch). We found that the Davos climate station north
of the study area is most closely correlated with the local climate of Alp
Weissenstein, although a much closer site (Samedan) exists on the other side
of the Albula Pass. Mountain top stations, however, did not provide a
convincing approximation for the climate at Alp Weissenstein. Direct
comparisons of near-surface measurements from a set of 11 small weather
stations distributed over the domain where cattle and sheep are grazed
indicate that nocturnal minimum air temperature and minimum vapor pressure
deficit are mostly governed by the altitudinal gradient, whereas daily maxima
– including also wind speed – are more strongly depending on vegetation
cover and less on the altitude.
