Restoration of phase portrait structure for the dynamics of a forest pest, the pine moth (Dendrolimus pini L.)

In this paper we consider the method for the restoration of phase portrait structure of population dynamics and apply this method for analysis of experimental data on the population dynamics of Dendrolimus pini L. The method is based on the results of phenomenological theory of forest insect population dynamics (Isaev, A.S., 1979. Lesovedenie 3, 27–42; Isaev, A.S., 1984. Nauka, 74–82.) and includes the elements of statistics, cluster analysis and knowledge of trajectoryʹs behavior of ordinary differential equationʹs systems. Using the method allows determination of such important features of phase plane as the value of stable level, structure and boundaries of the stable zone, behavior of the threshold curve which separates the stable and outbreak zones and coordinates of ‘point of escape’ etc.