In this study we have analyzed the spatial dynamics of the forests disturbed by Siberian Silk Moth (Dendrolimus sibiricus Tschetverikov (Lepidoptera: Lasiocampidae)) in Central Siberia and obtained model equations that fit this dynamics. We considered three sites that experienced silk moth outbreaks in 1993–1996, 2015–2018 and 2018–2020 and used satellite data (NOAA/AVHRR, Terra/MODIS, Landsat/ETM/OLI), field data, digital elevation model, and maps of predominant forests. Silk moth-disturbed areas were classified using NDVI that was calculated for each 15-day period during growing season (April–September). Time series of disturbed forest areas were obtained for three sites located in Krasnoyarsk region (Central Siberia, Russia). Total damaged areas for these sites were 41, 430 and 470 thousand hectares.
We obtained formalized descriptions for the temporal dynamics of disturbed area. Coefficients for the model solution were optimized using the Lagrange multiplier method and non-linear generalized downgrading gradient method. It is shown that the systems of empirical solutions adequately (R2~0.97) fit field data and can be used to simulate silk moth outbreaks under similar conditions. We have tested model regression equations for predicting the azimuthal spread of damaged area with a confidence level of r = 0.60–0.68.
It was shown that it is necessary to additionally identify and analyze interseasonal periods of disturbed area dynamics to improve the accuracy of the model. Individual seasons should be considered as independent sub-periods, which must be accompanied by refined coefficients of model equations when forming a general solution. A set of obtained solutions reflects the probable range of silk moth outbreak scenarios under given conditions.
