Home – Home – Jornals – Siberian Journal of Forest Science 2021 number 5

Models of the population dynamics of forest insects are considered based on the concept of an outbreak as a first order phase transition of the (this sentence is not complete) As objects of the studies, the population of the Siberian silkmoth in Siberia and the Far East, the population of the pine moth in Europe, the population of the gypsy moth in the Urals, and the population of the gray larch leaf worm in the Alps are considered. In this work, models fo same species of forest insects are considered, that make it possible to estimate the critical population densities and, in this regard, to propose algorithms, on the basis of which it is possible to make decisions on the implementation of protective measures. A model of the population dynamics is considered as an analog of a phase transition in physical systems to describe the dynamics of the population. An algorithm for transforming of population dynamics time series is proposed to reduce the level of errors in the course of density counting of pest populations. A state function is proposed as a characteristic of population dynamics, calculated as the reciprocal of the probability of finding a population in a state with a given population density. The functions of the state of populations with modes of outbreaks are characterized by the presence of two local minima and one local maximum - a potential barrier. A method is proposed for calculating the functions of state of populations based on data from time series of population dynamics, characteristics of state functions are described, such as local stable densities, critical and semi-critical density, susceptibility of the state function to changes in population density, and the half-width of the potential barrier. Indicators are introduced - indicators of the risk of outbreaks. Assessments of the risks of outbreaks are given for the studied species of phyllophagous insects.