Związek zanikania pokrywy śnieżnej z rozwojem runa w zbiorowiskach grądowych Puszczy Białowieskiej

The study is concemed with the relation between the time of snow cover disappearance and the growth rate of herb layer in deciduous forest stands. The observations were made on a system of permanent study areas in the period 1963-1988 at 5-day’s intervals in 4 ecological units of Tilio-Carpinetum plant communities. It was found that the beginning of the vegetative period of herb layer is strong connected with the time of snow cover disappearance. The ground vegetation appeared first in those places where only the snow cover vanished (Tab. 1). The later snow cover disappeared in early spring the shorter vegetation period of herb layer. This rule was especially pronounced in Tilio-Carpinetum corydaletosum. The relation between the date of last day with snow cover and proportion of control area covered with herb layer diminishes as the time goes by. The date of maximum extent of herb layer is not connected with the date of last day with snow cover. The differences in the herb layer cover on the control areas were greater than those observed in snow cover during the time of its disappearance (Fig. 1, 2). The study confirmed that snow cover is important ecological factor, which modifies the vegelation period of herb layer.