<1> The influence of vegetable cover on propagation ofelectromagnetic waves in the Earth-ionosphere wave channel isstudied in the scope of the model of a homogeneous isotropic"forest layer" with effective value of the dielectric permeabilityεf=1.2 and electric conductivityσf (t oC)depending on theenvironmental temperature according to the results obtained in thispaper. It is shown that the character of the electromagnetic fieldbehavior in the presence of large forests is of a well-pronouncedseasonal character additionally complicated by the diurnalvariations of the field depending on the environmental temperaturevariations.