How can the volume of bark beetle logging be estimated

In recent years, periods of intense drought and high temperatures have increased the vulnerability of forest stands to pathogen and insect pest attacks, particularly from bark beetles. The spruce bark beetle population has significantly increased in Europe over the last two decades and has become a major factor influencing the structure of logging operations.

The combination of climate stress and pest infestations has led to widespread tree mortality, fundamentally altering the options and methods for utilizing commercial forests. In many regions, the volume of accidental logging has surpassed that of intentional logging, resulting in considerable ecological and economic consequences, along with heightened demands for wood processing logistics. Therefore, a timely and accurate estimate of the extent of accidental logging is essential for effective planning and stabilization of the timber market.

Scientists from VÚLHM, v. v. i., have developed an innovative prognostic model based on the idea of utilizing regular reports from landowners to the Forest Protection Service for predicting accidental tree fellings. Their findings were published in the article titled “Využití průběžných hlášení množství zpracovaných kůrovcových těžeb smrkového dříví pro predikci celoročních objemů” (Utilization of interim reports on processed spruce bark beetle salvage logging for prediction of annual volumes), which appeared in the journal Reports of Forestry Research, Volume 1, 2026.This article was supported by the research project of the Ministry of Agriculture of the Czech Republic, NAZV QK23020126.

In their study, the scientists examined the relationship between continuous reports (specifically semi-annual and three-quarter reports) and the final annual volumes of accidental bark beetle harvesting, using time series data from 2007 to 2024.

While commonly used monitoring methods, such as pheromone traps and other trapping techniques, as well as advanced remote sensing methods, can provide valuable data, they often face practical limitations in operational conditions. Conversely, administrative data from continuous records of accidental harvesting, which are standard in forestry, can serve as a readily available source of information, although its potential has not been fully realized.

Biologically, the first half of the year is critical for the development of the bark beetle crisis, as it is during this time that spring swarming occurs, leading to the emergence of the first generation of the pest. Therefore, it can be anticipated that the volume of bark beetle wood recorded during this period holds significant predictive information about the total annual volume of bark beetle harvesting.

The results indicate that continuous records of accidental bark beetle harvesting from spruce wood offer reliable information on the total annual volume of bark beetles. Both monitored periods demonstrated a remarkably high agreement with the overall annual values. However, significant differences emerged in the interpretation of semi-annual and three-quarter data.

The three-quarter values show nearly ideal alignment with theoretical expectations. By the end of September, most of the seasonal bark beetle population has already been documented, as pest activity typically concludes at this time.

From a practical standpoint, the researchers concluded that three-quarter data provide a more accurate and stable estimate of the annual volume of bark beetle harvesting compared to semi-annual reports. Therefore, three-quarter data serve as a more suitable foundation for making annual predictions.

Continuous data on the volume of bark beetle fellings, systematically collected and published by the Forest Protection Service, serve as both a valuable statistical resource and an effective tool for predicting the total annual volume of fellings.

The article titled “Využití průběžných hlášení množství zpracovaných kůrovcových těžeb smrkového dříví pro predikci celoročních objemů” (Utilization of interim reports on processed spruce bark beetle salvage logging for prediction of annual volumes is available for download here.

Authors: Lubojacký, Adam Véle, Jakub Špoula, and Miloš Knížek from VÚLHM, v. v. i. For inquiries, you can reach Jakub Špoula at spoula@vulhm.cz

According original, prepared by Jan Řezáč, VÚLHM, v. v. i., rezac@vulhm.cz

An illustrative photo: Forests in the Vysočina region affected by spruce bark beetle, author Jan Řezáč