Damage caused by bark beetles, fire, and other causes of disturbance are undermining climate and biodiversity policy targets, warn the authors of a recent study. Climate change amplifies many of the studied disturbances.
The EU-funded1 study adds to evidence that forest disturbance is on the rise. Some natural damage from disturbance - caused by fire, windfall, or disease, for example - is vital to the health of a forest, as fresh gaps in the canopy let sunlight through and dead trees return nutrients to the soil.
However, too much disturbance is harmful, as it threatens the supply of vital ecosystem services, such as carbon storage and habitat provision for wildlife. Excessive disturbance makes it harder to reach policy goals that depend upon healthy forests. In the EU, these policies include notably the EU Biodiversity Strategy for 2030, the EU Forest strategy for 2030, the proposals for a Nature Restoration law and for an EU framework for forest monitoring and strategic plans and the Regulation on land, land use change and forestry (LULUCF).
A comprehensive forest-disturbance monitoring system would help forest managers and policymakers to better understand the links between climate and disturbance, says the study. In turn, this system would support strategies to ensure that forests continue to supply ecosystem services.
To support this goal, the researchers created an online, free-to-use database of forest disturbances. Covering 34 European countries, the new resource updates the Database of Forest Disturbances in Europe (DFDE) (2000) to 2019, using data from scientific studies and a network of experts. The resulting dataset contains 173 506 records from 600 sources and, notably, improves the picture for countries such as Estonia, Latvia, Lithuania, Slovakia, Slovenia and Serbia, where data had previously been difficult to access.
Covering five common sources of disturbance, including wind, fire, European spruce bark beetles, and other biotic and abiotic agents (i.e. fungi, nematodes, drought, frost or hail), and using a combination of machine learning algorithms and expert knowledge to fill data gaps, the researchers calculated that these disturbances caused losses between 52.4 million cubic metres (Mm3) and 62.1 Mm3 of timber each year, on average, over the 70-year period. The range in results varies according to the exact calculation method, with machine learning leading to a higher figure when not combined with expert knowledge.
When the researchers looked at changes in losses, they recorded some alarming trends. On average, timber losses grew by 845 000 m3 per year. In the last 20 years, the total amount of wood damaged per year has averaged 80 000 000 m3 –enough to build Europe’s tallest wooden building, the 18-storey Mjøstårnet, Lake Mjøsa, Norway, 15 times over.
Wind caused the most damage, accounting for 46% of timber volume disturbed. The 1990s and 2000s had particularly high rates of wind disturbance (47.8 and 38.3 Mm3/year, respectively). Both extreme events and chronic damage increased over the study period.
Fire was the second most significant disturbance, accounting for 24% of timber volume damage. Its impact increased significantly, with large peaks in the 1970s and 1990s onwards. Improved fire-management strategies have been used since the 1990s, but they are being countered by the effects of climate change.
Bark beetles also caused a big increase in disturbance. They accounted for 17% of timber volume disturbed, mainly due to huge outbreaks in the last decade. Climate change also drives this trend by creating more hospitable conditions for the beetles.
Other biotic disturbances accounted for 8% of timber volume damaged, with a sharp increase after the 1980s. The average timber volume damaged by other abiotic disturbance increased almost six-fold, from around 630 000 m3/year in the 1950s to 3.7 Mm3/year in the 2010s.
Given these results, the study recommends that forest managers and policymakers place new adaptation strategies at the heart of practice. The researchers suggest that a harmonised, consistent and near-real-time pan-European monitoring and reporting system of forest disturbances is needed, combining ground-based observations and remote sensing to develop our understanding of, and ability to respond to, disturbance dynamics2.
- This study received funding from the following EU projects:
- For a policy brief and summary of the study, see: Patacca, M., Lindner, M., Nabuurs, G.-J. and Schelhaas, M.-J. 2023. Significant increase in forest disturbances since 1950s. Policy Brief 4. European Forest Institute. Available from: https://doi.org/10.36333/pb4 [Accessed 6 July 2023].
Patacca, M., Lindner, M., Lucas-Borja, M. E., Cordonnier, T., Fidej, G., Gardiner, B., Hauf, Y., Jasinevičius, G., Labonne, S., Linkevičius, E., Mahnken, M., Milanovic, S., Nabuurs, G.-J., Nagel, T. A., Nikinmaa, L., Panyatov, M., Bercak, R., Seidl, R., Ostrogović Sever, M. Z., Socha, J., Thom, D., Vuletic, D., Zudin, S., and Schelhaas, M.-J. (2023). Significant increase in natural disturbance impacts on European forests since 1950. Global Change Biology, 29: 1359–1376. DOI: 10.1111/gcb.16531. Available from: https://onlinelibrary.wiley.com/doi/10.1111/gcb.16531 [Accessed July 5 2023].
To cite this article/service:
“Science for Environment Policy”: European Commission DG Environment News Alert Service, edited by the Science Communication Unit, The University of the West of England, Bristol.
Notes on content:
The contents and views included in Science for Environment Policy are based on independent, peer reviewed research and do not necessarily reflect the position of the European Commission. Please note that this article is a summary of only one study. Other studies may come to other conclusions.
- Datum der Veröffentlichung
- 2. August 2023
- Generaldirektion Umwelt