  A general form of the kinetic equation for filament number density
considering the effects of their generation and decay is stated. It is consists
of the phenomenological parameters, which have been determined from the direct
numerical simulation of propagation of a high-power femtosecond laser pulse
(HPFLP) based on the stationary nonlinear Schr\"odinger equation (NSE) for a
series of the threshold particular cases.
