Long-term dynamics of forest insect populations in Krasnoturanskiy pine forest

Abstract

The experience of a long-term study of the population dynamics of phyllophagous insects in Krasnoturansky pine forest (the southern part of Krasnoyarsk Krai) is discussed in the paper. Over the course of 40 years (1978–2016), regular counts of the abundance of five species of phyllophages were carried out in five landscape structures. Based on the data obtained, models of population dynamics of these species were proposed. The models were based on the idea of the existence of positive and negative feedbacks in populations. This approach made it possible to ignore the impact of parasites on insects. For calculations, an autoregressive (AR) model was proposed, according to which the current density linearly depends on the densities of previous years. The model coefficients were calculated using data from long-term surveys. It has been shown that most populations are characterized by the influence of the density of the past season on the current density in the form of a positive feedback and the influence on the current density of the density of the previous season in the form of a negative feedback. The characteristics of the stability of population dynamics of individual species in various habitats are considered. Stability margin indicators, widely used in control theory, were used as stability characteristics. It has been shown that the margin of resistance for sawflies (Tenthredinidae Latreille) is slightly greater than for other groups of species, which is consistent with the smaller dispersion of the population sizes of these species during long-term censuses. The use of AR models and characteristics of the stock of stability made it possible to classify landscape structures on the territory of the Krasnoturansky forest according to the risks of outbreaks of mass reproduction in these landscapes.

Keywords

• forest insects – phyllophages
• population counts
• long-term dynamics
• models
• autoregression
• stability margin