Drought and pests are affecting German forests. Only one in five trees is completely healthy. This is shown by the 2025 forest condition survey now published by the Federal Ministry of Agriculture, Food and Community. The report shows a slight recovery for beech and spruce trees, while the treetops of oak and pine trees have become thinner compared to the previous year. Older trees are particularly badly damaged.
Around a third of Germany’s area is covered by forests. They form the habitat of numerous animals, serve as recreational areas for us humans and provide wood for the forestry industry. They also make an important contribution to climate protection: During photosynthesis, trees bind large amounts of CO2 and store it in their biomass for decades. However, if the forests are destroyed, be it through forest fires, drought or insect infestation, they release the stored carbon. Since 2017, German forests have changed from a carbon sink to a carbon source. The drought years 2018 to 2020 were particularly devastating. The lack of water weakened the trees so much that they have not yet fully recovered and are more susceptible to pests.
Health inventory in the forest
In order to monitor the health of forests, the Federal Ministry of Agriculture, Food and Community issues an annual forest condition survey. The now published report for 2025 shows: The forests in Germany continue to be severely damaged. Slight improvements can be observed in some areas, but things continue to decline in others. “Despite the comparatively favorable weather with more rain, especially in July 2025, the condition of the trees is still worse than in the years before the major drought of 2018 to 2020,” reports Nicole Wellbrock from the Thünen Institute for Forest Ecosystems, who led the survey. “In 2025, the visible needle and leaf losses from the treetops will continue to be at a very high level and, overall, have changed little compared to 2024.”
For the survey, the researchers assessed the condition of 46,531 trees distributed throughout Germany in a grid of eight by eight kilometers – around four times as many trees as in previous years. “This increases the statistical certainty of our statements,” says Wellbrock. A total of 38 tree species were recorded. More than three quarters of the trees evaluated were one of the four main tree species: spruce, pine, beech and oak. The so-called crown thinning serves as a measure of the health of the trees. Zero percent lightening means a tree crown that is completely leafy; with 25 percent lightening, a quarter of the normally expected leaf or needle mass is missing. If the crown thinning is above this, the trees’ vitality has already been significantly weakened.
Tree crowns continue to thin
The current forest condition report shows: Compared to 2024, the average crown thinning has hardly changed across all tree species. In 2025 the value was 25.2 percent, in the previous year it was 25.7 percent. Beech and spruce trees had slightly better foliage in 2025 than in 2024: in beech trees, the average crown loss fell from 28.5 percent to 25.6 percent, and in spruce trees from 27.2 percent to 25.2 percent. Pines and oaks, on the other hand, achieved the worst values since the awards began in 1984. For pines, the average light loss rose from 22.5 percent to 24.2 percent, for oaks from 29.3 percent to 30.1 percent. Of the oak trees over 60 years old, 59 percent were more than a quarter defoliated.
In addition to the aftereffects of the dry period and forest fires, biological causes such as pests also contribute to the forest damage: “We assume that the trees continue to suffer from pests such as the oak beetle and other so-called oak feeding communities,” says Wellbrock. Only 13 percent of oak trees have complete foliage. Across all tree species, the proportion of intact tree crowns is 21 percent. This means that only about one in five trees is completely healthy.
One positive news, however, is that significantly fewer trees died completely compared to the previous year. Accordingly, the natural mortality rate fell from 0.86 percent to 0.29 percent. However, this may also be due to the fact that many spruce trees in particular have already died in previous years and have been replaced by younger trees in the sample, as the team explains.
Source: Forest condition survey 2025Federal Ministry of Agriculture, Food and Homeland