The condition of forests has improved over the last five years. What further developments can we anticipate?
The extremely warm and dry years of 2015 and 2018 caused a decline in forest health and triggered an extreme bark beetle outbreak in the Czech Republic. Although 2024 was one of the warmest years on record, like 2023, forest health has shown slight improvement since 2020. According to data from ICP Forests, Scots pine remains in the worst condition, with 54% of this tree species severely damaged, down from 62% in 2020. In contrast, the health of oak has improved significantly, with the percentage of severely damaged trees decreasing from 28% in 2020 to just 10%.
Photo: Dry trees of Scots pine in the Central Bohemia, author Jan Řezáč
Data from the Forest Protection Service (LOS), covering 70% of the forest area, indicate that the recorded volume of trees damaged from felling decreased from 5.9 million m³ in 2023 to 4.6 million m³ in 2024. Most of this damage was caused by winds, amounting to 2.1 million m³. Additionally, the volume of trees affected by bark beetles in spruce stands dropped by nearly 60% year-on-year, totalling 1.4 million m³ in 2024. This is significant, considering that at the peak of the bark beetle crisis in 2020, the volume was 14.9 million m³. Conversely, forest damage caused by fungal pathogens, particularly by honey fungus on Norway spruce and pine needle-cast fungus in the case of Scots pine, is on the rise, and ash dieback, exacerbated by the ascomycete fungus, continues to be a concern. The importance of the Forest Protection Service is further underscored as we celebrate the 30th anniversary of the LOS in its current form this year.
Doc. Ing. Vít Šrámek, Ph.D., Director of VÚLHM, v. v. i., stated: “Although there is a relatively positive trend in the health of forests, the risks remain quite high. Forest ecosystems are sensitive to changes in meteorological conditions and the presence of harmful factors. In particular, significant drought periods during the spring or summer could rapidly reverse the current favourable trend.”
Graph: Development of the health status of individual tree species, source: VÚLHM, v. v. i.
How is the health of forests changing, and what changes can we expect in the growth of tree species because of climate change?
The year 2024 marked the highest global temperatures on record in the history of meteorological measurements, including in the Czech Republic. Despite these high average temperatures, the health of forests in the Czech Republic has shown a slight improvement over the past five years. This positive change can be attributed to sufficient precipitation, particularly in the first half of the growing season, which prevented significant drought conditions that could harm trees and promote pest development.
Data from the international ICP Forests program indicate that the extremely warm and dry years of 2015 and 2018 resulted in a severe decline in forest health. In 2019, notable foliage loss, or defoliation, was observed in 62% of pines, 28% of oaks, and 18% of spruces. However, during the warmer yet more moisture-friendly years from 2020 to 2024, there has been a slight recovery. The proportion of trees experiencing severe defoliation decreased to 54% for pines, 10% for oaks, and 14% for spruces.
In addition to assessing the condition of tree crowns, another important indicator of tree vitality is their growth. Analysing annual rings allows us to evaluate how meteorological factors influence the growth of different tree species and to model potential changes based on various climate development scenarios. Results from the climate-controlled process model, VS-Lite, show that our main forest tree species have the potential to increase their growth even amidst climate change. During the period from 2046 to 2055, we can expect an increase in the average annual ring width of up to 7%, primarily due to an extended growing season. However, for certain tree species, particularly spruce and pine, the model also predicts a significant decline in growth during years with extreme climatic conditions, potentially decreasing by up to 10%. This increased sensitivity to climate extremes suggests a higher likelihood of mortality among these tree species.
Graph: Development of bark beetle logging from 1990 to 2024, source: VÚLHM, v. v. i.
The end of the bark beetle disaster in the Czech Republic? What to expect in the coming period?
Data from the Forest Protection Service, covering approximately 70% of the total forest area in the Czech Republic, indicate a significant year-on-year decrease in damage volume. The estimated damage decreased from 5.9 million m³ of wood mass in 2023 to 4.6 million m³ in 2024.
Last year, abiotic factors caused approximately 2.9 million m³ of recorded damage. Wind was again the predominant factor, accounting for about 2.1 million m³ of damage. Drought-related damage was reported at around 560,000 m³. Additionally, ongoing yellowing of spruce trees was noted over a total area of approximately 20,000 hectares.
In 2024, approximately 1.7 million cubic meters of wood were damaged by biotic factors. The main culprit was the overpopulation of bark beetles affecting spruce trees. Over 1.4 million cubic meters of spruce were harvested due to bark beetle infestations, indicating a nearly 60% decrease compared to the previous year. Additionally, other coniferous tree species are increasingly being attacked by bark beetles, with around 24,000 cubic meters of pine also reported as infested and harvested.
Photo: Where Norway spruce is at home, there it thrives, Ore Mountains, author Jan Řezáč
Leaf-eating insects were observed again in 2024, but only in minimal areas, typically below the economic damage threshold. Notably, among the sucking insects, the rapidly spreading invasive oak lace bugs was particularly prevalent in South Moravia. Additionally, damage caused by adults (imags) of pine weevil was significant, affecting approximately 2,400 hectares of young coniferous stands.
In 2024, there was a remarkably high incidence of fungal pathogens. For instance, approximately 195,000 m³ of harvested wood was recorded as infested by honey fungus on Norway spruce. There was also a frequent occurrence of leaf spots, with the most significant being the pine needle-cast fungus affecting Scots pine, as well as powdery mildew found on oak trees. Unfortunately, ash trees continue to die, primarily because of an ascomycete fungus, with little hope of improvement in this situation.
Is the term “forest protection” synonymous with nature protection, or is it the opposite?
Forest management and nature conservation are often seen as opposing approaches, particularly when it comes to protecting forests from commercial pests. However, this perception does not have to be the case. The misunderstanding largely arises from historical practices that harmed non-target species, including beneficial ones, during forest protection efforts. Today, the principles of forest protection and nature conservation are being integrated, with alternative methods and natural predators being implemented. These strategies are now viewed as essential components of integrated forest management. Utilizing natural enemies can be both effective and cost-efficient. As a result, VULHM is actively monitoring their presence, assessing their impact on forest pests, and exploring support options in commercial forests.
Photo: Anthills play a role in integrated forest protection. Author: Jan Řezáč
Forest ants are a particularly protected species, and their foraging activities are crucial for forest conservation, as they effectively regulate populations of leaf-eating insects. Our new findings also reveal that they can protect trees from bark beetle attacks. Additionally, woodpeckers serve as important predators in this ecosystem. The results of another study we participated in indicate that supporting economically less valuable deciduous tree species can enhance their presence in spruce forests. Monitoring of leaf-eating insect populations conducted in recent years has confirmed that parasitoids—organisms that develop within the bodies of their hosts—can significantly reduce the populations of harmful species. Management strategies that support natural enemies, such as maintaining forest clearings, also promote the diversity of many other organisms, aligning with nature conservation goals.
Saving the red yew: A rare tree species of our forests
Today, we often see the red yew in gardens or parks, but not everyone is aware that it is a native tree species of our forests. In the past, deliberate felling, clear-cut management practices, and increased game populations have led to the disappearance of many of its natural habitats. As a result, the red yew has been classified as a specially protected species since 1958. Currently, there are only about 12,500 native yews reported in the Czech Republic, found in 10 to 15 distinct areas, primarily in the Křivoklát region, the Moravian Karst, and the Middle Povltaví. Additionally, most of these populations are aging, and their size is either decreasing or remaining stagnant.
Photo: Red yew in the National Natural Preserve (NPR) Drbákov, author Jan Řezáč
To ensure effective protection of the red yew, more detailed knowledge regarding its physiology, ecology, and genetics is needed.
Since 2015, the employees at VÚLHM, v. v. i. have been researching the growth of yew trees in the Lusatian Mountains (Lužické hory Mts.) and conducting DNA analyses of the populations of this species. Additionally, since 2022, they have been co-organizing seminars focused on the conservation management of the red yew.
Starting in 2025, in collaboration with the Landscape Research Institute, they will conduct a comprehensive research project aimed at protecting the remaining yew population in Podyjí.
Forest Protection Service (LOS) – first aid for owners in the field of forest protection
The Forest Protection Service (LOS) is a consulting service that offers free support to all owners and managers of forest properties, professional forest managers, and state forest administration bodies in the Czech Republic. This year marks the 30th anniversary of LOS in its current form. The activities and results of LOS are documented in various publications, including the Forest Protection Newsletter and methodological guidelines addressing specific forest harmful factors. Additionally, we share information through articles in professional journals and instructional videos.
Photo: Vital oak forest stand in Central Bohemia, author Jan Řezáč
The LOS staff organizes several seminars, including a nationwide seminar with international participation titled “Harmful Agents in the Forests of the Czech Republic.” They collaborate with colleagues from abroad and participate in “calamity teams” during extraordinary events, which has a direct impact on forestry practices. A notable example is the ongoing calamity situation caused by an overgrowth of bark beetles, particularly affecting spruce stands. They engage directly with forestry practices during field surveys and provide recommendations for specific protection strategies. Additionally, they develop and test new methods for protecting against pests, such as the rapidly spreading invasive oak lace bugs.
For more information about LOS activities, please visit this link.