Snow and soil frost depth in two types of shelterwood and a clear-cut area

In this study, the snow and soil frost conditions in three different forest stand treatments in northern Sweden were investigated during winter and spring 1998/99. In total, 49 frost tubes and 25 snow gauges were used in one clear-cut area, one multilayered shelterwood of mixed Scots pine (Pinus sylvestris) and Norway spruce (Picea abies), and one single-layered shelterwood of old Scots pine. The snow cover was thicker and smoother and less soil frost was observed in the clear-cut area than in the shelterwoods. In the multilayered shelterwood the mean snow cover was shallower than in the single-layered shelterwood, but with larger spatial variation in snow depth related to the canopy density and with patches of snow and soil frost that lasted until early summer. Close to the shelter trees in the single-layered shelterwood the deepest soil frost was observed during the winter and early start of snow melting and soil frost thawing in spring. In conclusion, the snow and soil frost depths in the shelterwoods were related to the stem density. The single-layered shelterwood of large pines appeared to promote an earlier snowmelt and thawing of the soil frost than the multilayered shelterwood of mixed pine and spruce.