For the fourth consecutive year, the volume of spruce bark decreased in forests
According to records submitted by forest owners and managers to the Forest Protection Service, which cover approximately 70% of the forested area in the Czech Republic, the total volume of accidental logging in 2024 reached nearly 4.6 million cubic meters (m³).
Photo: NPR Rejvíz is among the most problematic areas in the northeastern Czech Republic regarding the current bark beetle situation (Jeseníky Region, October 2024), LOS archive
Of this, the volume of registered spruce bark beetle wood was 1.436 million m³, reflecting a year-on-year decrease of almost 60%. For context, in 2023, this volume was 3.201 million m³; in 2022, it was 5.558 million m³; in 2021, it was 9.540 million m³; and in 2020, it was 14.894 million m³.
In 2024, the volume of harvested wood affected by spruce bark beetles in the Czech Republic was converted to account for the total forest area, which is reported to cover 70% of the land. This conversion revealed that over two million cubic meters of spruce bark beetle wood were harvested.
According to records from the same year, approximately 1.73 million cubic meters of wood mass were damaged by various biotic harmful factors. This marks a significant decrease of 50% compared to the previous year; in 2023, the damage was recorded at 3.42 million cubic meters. The data for previous years show even higher figures: 5.79 million cubic meters in 2022, 9.78 million cubic meters in 2021, 15.41 million cubic meters in 2020, and 14.86 million cubic meters in 2019. Most of this damage can be attributed to the long-term overpopulation of bark beetles.
Photo: High concentration of defence measures during the spruce bark beetle outbreak (Brdy, June 2024), LOS archive
The year 2024 experienced much higher-than-average temperatures, with a deviation of +2.0 °C, and received above-average precipitation at 113% of normal levels. However, if we exclude the exceptionally wet September, the precipitation would only be 96% of normal.
The flight activity of spruce bark beetles began extremely early due to the unusually warm weather in March and April. However, in mid-April, a strong cold snap interrupted this activity for two weeks, after which it resumed. The lack of sustained high temperatures (above 25 °C) limited and slowed down the flight activity of the spruce bark beetles.
The peak of spring swarming for bark beetles occurred in early May. The daughter generation of beetles took to the air in the second half of June, with their flight activity reaching its highest point during a heat wave in mid-July. Extreme precipitation in mid-September marked the definitive end of flight activity for bark beetles in 2024.
Although precipitation was unevenly distributed, it helped maintain and enhance the overall physiological condition of spruce trees in most areas. However, the developmental stages of bark beetles faced increased mortality due to feeding, which was influenced by both intra-population competition and various external abiotic and biotic factors.
Photo: Extensive deforestation of the Ondřejník Mountain due to random bark beetle logging (Frýdek-Místek region, September 2024), LOS archive
For a better understanding of the situation, it is important to recognize that spruce bark beetles remain in a catastrophic state throughout the entire region. Current estimates indicate that the average volume of bark beetle-infested wood in the spruce stands of all ages in the Czech Republic is approximately 1.7 m³/ha. This figure is more than eight times higher than the baseline value of 0.20 m³/ha established by the Ministry of Agriculture’s Decree No. 101/1996 Coll., as amended.
In 2024, a variety of defensive and protective measures were implemented to combat spruce bark beetles. This included the installation of approximately 293,000 cubic meters of traps and around 30,000 poisoned traps. Additionally, about 23,000 pheromone traps were set up, and approximately 172,000 cubic meters of infested material was debarked. Furthermore, around 256,000 cubic meters of material underwent chemical remediation. Before transportation, roughly 30% of the extracted bark material was cleaned either directly in forest stands or at wood transfer storage locations.
Photo: Early signs of feeding by the spruce bark beetle (Opava Region, April 2024), LOS archive
In 2024, the highest recorded volumes of harvested spruce bark were reported by region: – Pilsen Region: 309 thousand m³ (down from 700 thousand m³ in 2023) – Moravian-Silesian Region: 197 thousand m³ (up from 167 thousand m³ in 2023) – Olomouc Region: 193 thousand m³ (down from 392 thousand m³ in 2023). Additionally, the South Bohemian Region recorded over 100 thousand m³ at 122 thousand m³ (down from 238 thousand m³ in 2023), and the Zlín Region had 112 thousand m³ (down from 183 thousand m³ in 2023).
At the district level, the highest volumes of harvested spruce bark wood in 2024 were reported in: – Klatovy District: 125 thousand m³ (down from 241 thousand m³ in 2023) – Šumperk District: 101 thousand m³ (down from 131 thousand m³ in 2023).
More than 50 thousand m³ were recorded in the following districts: – Bruntál: 95 thousand m³ (down from 104 thousand m³ in 2023) – Frýdek-Místek: 93 thousand m³ (up from 52 thousand m³ in 2023) – Tachov: 87 thousand m³ (down from 219 thousand m³ in 2023) – Vsetín: 68 thousand m³ (up slightly from 67 thousand m³ in 2023) – Prachatice: 65 thousand m³ (down from 133 thousand m³ in 2023) – Jeseník: 58 thousand m³ (down from 183 thousand m³ in 2023) – Karlovy Vary: 54 thousand m³ (down from 78 thousand m³ in 2023).
Photo: September 2024 – debris on vegetation beneath a spruce tree that has been primarily attacked by the spruce bark beetle (Přerov Region, LOS archive)
The main species responsible for the current bark beetle calamity has been the spruce bark beetle. Accompanying species include the glossy bark beetle and the northern bark beetle. These three species are frequently found together on the same tree throughout most of the Czech Republic. Typically, the spruce bark beetle dominates the basal and trunk areas of the tree, while the northern bark beetle and the glossy bark beetle are more commonly found in the thinner crown parts, which are less appealing to the spruce bark beetle.
In the northeastern region of the Czech Republic, the decline of spruce trees and long-term outbreaks of bark beetles have significantly impacted the landscape over recent decades. At lower and middle altitudes, spruce is typically found only in very sparse stands with low stem density. In these areas, the „northern bark beetle“ is often more prevalent than the „spruce bark beetle“.
According to a recent report, the northern bark beetle contributed to the volume of bark beetle-infested wood in 2024, which saw a year-on-year decrease of approximately 50%. About 65 thousand cubic meters of affected wood were recorded in 2024, compared to approximately 135 thousand cubic meters in 2023. However, these figures are estimates, as the beetle’s spread and increasing significance are ongoing.
Photo: Extensive clearings resulting from random bark beetle logging (Bruntálsko, October 2024), LOS archive
Conclusion
The bark beetle situation has gradually improved over the past four years due to several key factors: more favourable climatic conditions, a better wood market situation, stabilization of wood prices, and an increase in logging, transportation, and processing capacities. Additionally, the loss of the most attractive older spruce stands at lower and middle elevations has significantly reduced the food supply for the spruce bark beetle during the current calamity. Despite these year-on-year improvements, it is important to note that we cannot yet claim to have regained complete control over bark beetle populations.
In 2025, the first beetles were observed in mid-April, with swarming occurring in full force around late April and early May. According to developmental models, we can expect one complete generation of spruce bark beetles at the highest elevations and two generations at lower elevations this year.
The precipitation levels during the winter and the first half of this year were well below the long-term average, leading to recurring drought periods. This, combined with other influencing factors, could potentially lead to a resurgence in bark beetle numbers. However, it is more likely that the trend in 2025 will mirror that of the previous four years. The early onset of swarming, coupled with several interruptions of varying lengths, appears to indicate a positive trend, allowing more time to process the infested wood.
Photo: Developing feeding of the bark beetle Ips amitinus (Opava Region, May 2024), LOS archive
(The article presents data based on reports received from owners and managers of forest properties, which cover approximately 70% of the total forest area in the Czech Republic.)
These reports detail the occurrence of forest pests as recorded by the Forest Protection Service. For more information on biotic damage in forests, you can refer to the publication “Forest Protection Report – Supplement 2025,” available for download here.
The chapter titled “Bark Beetles on Spruce,” which served as the basis for this press release, is authored by Ing. Jan Lubojacký, Ph.D., e-mail: lubojacky@vulhm.cz
The original preparation of this content was done by Ing. Jan Řezáč, e-mail: rezac@vulhm.cz