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Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
The high precipitation in 2023 and 2024 benefited nature. Nevertheless, the forest condition did not improve. This shows the Forest Condition Report 2025, which the Federal Minister of Agriculture, Food and Regional Identity (BMLEH), Alois Rainer, presented today. The Thünen Institute of Forest Ecosystems co-ordinates the annual survey and analysis.
Eberswalde/Berlin (June 11, 2025). The dry years of 2018 to 2020 and 2022 left a lasting impact: since then, scientists recorded a significant increase in the level of damage in the annual Forest Crown Condition Survey. Alongside this trend, the proportion of spruce is decreasing. However, there is also good news: Forests are becoming more and more diverse. This is shown by the data from 2024, analysed in the current Forest Crown Condition Report by the Thünen Institute on behalf of the BMLEH. Yet, the challenge remains to reforest the damaged area to guarantee their development into climate-stable mixed forests providing important ecosystem services such as carbon storage or enabling sustainable wood utilisation.
The weather in 2023 and 2024
According to the German Weather Service (DWD), 2023 set a new record. It was the warmest year in Germany since records began. However, in contrast to the previous warm years of 2018 to 2020, it was not characterised by droughts and heatwaves but by warm and humid weather with large amounts of precipitation.
Spring 2024 was once again a record-breaker: It was the warmest spring since weather recording began in 1881. Some regions experienced ample extreme rainfall events, especially in May following heavy thunderstorms. Heavy continuous rain led to dramatic flooding in areas of the Saarland and Rhineland-Palatinate. Oak trees in particular suffered from the late frost in April.
Significant defoliation remains high
Although the weather in 2024 was favourable, it did not turn the trend persisting since 2019 and the proportion of trees with a significant crown defoliation remained at a high level. As in the previous year, 36 per cent of the trees showed a significant defoliation. Defoliation is classed as significant when the defoliation is above 25 per cent. 43 per cent of the trees fell in the warning level (over 10 to 25 per cent defoliation) (previous year: 44 per cent) and only 21 per cent of the trees were without damage signs.
Within the sample, trees older than 60 years show a higher than average defoliation. They are as well more likely to show previous damage and seem to lack the ability to recover. 43 per cent of them show a significant defoliation. By comparison, only 16 per cent of the trees under 60 years of age had significantly defoliated crowns.
Mean defoliation of individual tree species
Compared to the previous year, the researchers found a slight improvement in the average defoliation of spruce and the so-called ‘other broadleaved species’ such as ash, birch, alder, and others. The proportion of moderately damaged spruce trees decreased from 28.6 to 27.2 per cent. The defoliation of ‘other broadleaved species’ decreased from 26 to 23.6 per cent. The apparent improvement of spruce could, however, also be an effect of the widespread spruce mortality as dead trees are being replaced by young ones.
Pine and beech showed roughly the same level of average defoliation in 2024 as in the previous year: 22.5 per cent for pine and 28.5 per cent for beech. Pines had the best average crown condition among the species groups analysed, even though their condition has deteriorated significantly since 2019.
Oaks also fared considerably worse. The proportion of trees with medium defoliation increased from 27.6 per cent to 29.3 per cent. The proportion of so-called ‘other conifers’ such as larch, Douglas fir, and silver fir also increased – from 22.7 per cent to 25.3 per cent.
Oaks suffered badly
Oak is the tree species with the highest mean defoliation. A conspicuously high proportion of 51 per cent even show a significant defoliation, 33 per cent are within the warning level, and only 16 per cent show no defoliation. The cause of this are the so-called oak-feeding insect communities. In particular, the oak splendour beetle and its interaction with mildew severely affected oaks in some areas. The late frost at the end of April also impacted the trees. However, oak is the species with the on average oldest individuals in Germany's forests and is therefore particularly susceptible to pests and increasing temperature.
Overall, there were minimal improvements in the proportion of damaged trees in spruce, beech, and ALB. Slight deteriorations were visible in pine and ANB. However, the improvement in spruce must be attributed to the trees that had already died and were no longer in the sample.
Dieback rate increases in oak
The rate of dead trees overall decreased. The peak values seen during the periods of severe drought from 2018 to 2020 were no longer reached – although this is due to the fact that large parts of the spruce stands already died. Spruce and other conifers showed the highest dieback rates at 1.64 and 1.67 percentage points, respectively. These also increased compared to the previous year. The dieback rate for oak increased as well. It now stands at 0.58 per cent. The percentages for other broadleaved species, pine, and beech have remained unchanged or have decreased compared to the previous year.
Strong fructification
Scientists observed pronounced fructification in all tree species. Beech trees produced many fruits for the third year in a row – this is unique in the time series since 1985 and is considered as a stress reaction. The causes include high nitrogen inputs and high summer temperatures due to climate change, which lead to the increased formation of flower buds.
Loss rate and deadwood
The removal rate, the proportion of trees harvested as planned as well as trees lost due to storm damage, drought, and bark beetle infestation, fell further from 4.7 to 3.6 per cent in 2024. For spruce trees, this rate fell even more sharply from 9.0 to 5.7 per cent. Around half of the damaged trees were infested by the bark beetle.
The proportion of deadwood in the forests remained high in 2024 at 2.7 per cent.
Thünen Institute of Forest Ecosystems, Eberswalde
Dr. Nicole Wellbrock
nicole.wellbrock@thuenen.de
Telefone: +49 3334/38 20 304
https://www.thuenen.de/en/institutes/forest-ecosystems/fields-of-activity/soil-p... Method of the forest condition survey
https://blumwald.thuenen.de/wze/aktuelle-ergebnisse-der-wze Diagrams for download and results tables of the forest condition survey (only in German)
Frost damage on oak leaves.
Thünen Institute/Tanja Sanders
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Frost damage on oak leaves.
Thünen Institute/Tanja Sanders
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