Snow Depth and Vegetation Pattern in a Late-melting Snowbed Analyzed by GPS and GIS in the Giant Mountains, Czech Republic

Abstract

A large, late-melting snowbed and famous landmark was analyzed on a south-facing slope in the Giant (Krkonose/Karkonosze) Mountains, the High Sudetes, Czech Republic. So far, only its maximum snow depth, reportedly between 4 and 20 m, had been merely estimated. Wire probes can be reliably used up to snow depths of 3 m only. To get more realistic data, two digital models using kinematic carrier phase–based GPS measurements were developed: (1) a model for snow surface data, applied at the end of five winter seasons from 2000 to 2004, and (2) a model for the underlying snow free ground surface, applied after the snow melt in August 2000. These two models, overlaid in the GIS environment, have identified snow depths for each of the 111 phytosociological relevés in plots 2 m × 2 m in size. The snow depth maxima recorded in the above given winter seasons were 15.7, 6.1, 13.4, 7.6, and 14.2 m, respectively. To determine the effect of the obtained variables on the vegetation pattern, the relevant snowpack thickness together with snow melting rate, position of the relevé, amount of soil skeleton, depth of litter horizon, and depth of the soil profile were used as environmental variables in the Canonical Correspondence Analysis (CCA), which explained 23.1% of the species data variability. The most powerful environmental variables were soil parameters. The vegetation cover significantly decreased as a function of the snow depth. The tiny forb Gnaphalium supinum and the grasses Avenella flexuosa, Deschampsia cespitosa, and Nardus stricta appeared to be the most tolerant species surviving under the deep snow layer and possessing a short vegetation season. Comparison with an earlier study suggested a stabilized pattern of the snow-patch vegetation even after about 50 years.