Siberian Federal University: Krasnoyarsk Scientists Improve the Model for Predicting Outbreaks of the European Spruce Bark Beetle

Scientists of Siberian Federal University, as part of an international research team, have taken part in the development of a model of the dynamics of damage to mountain forests in the Tatra National Park (Slovakia) and Šumava National Park (Czech Republic) by a dangerous spruce pest — the European spruce bark beetle Ips typographus L. The model based on the use of only two variables helped describe the processes in different outbreak foci of the pest on the territory of the Tatras with an accuracy of up to 90%. This model also allows assessing the risk of damage caused by the bark beetle to European spruce plantations.

The study was conducted by a Czech-Russian-Slovak research team. A trigger for the work was a speech at an international conference by Czech entomologist Roman Modlinger who told about his model of damage to the mountain forests of the Tatras by this bark beetle. The model turned out to be very confusing, required knowledge of a large number of characteristics of the forest and insect populations, and at the same time was not very accurate and poorly described the observed processes.

“The Krasnoyarsk scientists, in particular, Doctor of Biological Sciences Vladislav Sukhovolsky and Candidate of Engineering Anton Kovalyov, who are researchers at the V.N. Sukachev Institute of Forest (SB RAS), and I, as a researcher at Siberian Federal University, proposed a way to simplify the model and at the same time increase the accuracy of calculations. A joint work was done on modeling the dynamics of forest damage by pests based on data on damage in the Tatras. By the way, we published a basic monograph on modeling the dynamics of the number of forest insects in Wiley and Suns, a very prestigious New York publishing house,” said Olga Tarasova, co-author of the study, professor of the Department of Ecology and Environmental Management at SibFU.

The European spruce bark beetle is one of the serious pests of spruce. Outbreaks of xylophagous insects cause enormous economic damage to the forests of Scandinavia, natural and artificial plantings in the European part of Russia and mountain forests of Central Europe. During outbreaks of mass reproduction of these insects, many trees die, which affects the functioning of the forest ecosystem. The explosive growth in the number of bark beetles is often associated with various forest disturbances – fires, windstorms, periods of drought, etc.
The Krasnoyarsk scientists noted that the population of the European spruce bark beetles can be observed in two phases — the phase of normal existence and the phase of outbreak. At the first stage, the number of insects is extremely low, they infect a small number of suitable trees (for example, fir trees in the case of Ips typographus L.). An outbreak occurs when the mass of insects exceeds a certain critical threshold and insects destroy all forage resources available in a given area. At the same time, no work has previously proposed methods for theoretical calculations of the critical density of the insect population.

“We used the annual mortality of trees (the volume of damaged wood) as an indirect indicator to calculate the population size of spruce bark beetle. The developed model was applied in practice, studying outbreaks of this species in the Czech Republic and Slovakia. In addition, we hope to use this model to describe outbreaks of mass reproduction of xylophagous insects in the forests of Russia,” stressed the authors.

According to experts, the proposed models have previously been used to simulate the dynamics of the number and outbreaks of mass reproduction of needle-gnawing insects. For models of this type, various authors used such factors as the number of bark beetles and predators dangerous to them as variables. Another classical system, in addition to the described predator – prey, is the resource — consumer model, where the beetle population is considered a consumer, and spruce is a resource. However, the model proposed by the Krasnoyarsk researchers employed other key factors — the volume of damaged wood and the weather in spring, since these indicators, unlike the density of the population of bark beetles, are quite easy to measure.

“Calculations performed within the framework of the proposed model have shown that the use of a fairly small amount of data on forest damage in past seasons and meteorological parameters allows us to predict the current damage to spruce plantations caused by an outbreak of spruce bark beetle reproduction. In our opinion, with the help of the proposed model, it is possible to improve the forecasting system of the destructive activity of forest insects. After all, as we know, it is better to prevent an environmental problem than to deal with its consequences,” concluded Olga Tarasova.

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