State of German forests still worrying

deciduous forest

Deciduous forest after a storm. © Petra Dühnelt/ Thünen Institute

In the last drought years from 2018 to 2020, the German forests suffered considerably – but even in 2021 the tree population hardly recovered, as the current forest condition report shows. The condition of the conifers in particular has deteriorated further despite sufficient rain and hardly any storms in the past year. Among the deciduous trees, beeches in particular are among the species with clear crown thinning.

How are our forests doing? In recent years there has been increasing evidence that climate change in particular is clearly affecting many trees in Germany. In particular, the particularly dry and warm years 2018 to 2020 caused entire forest areas to dry up in many places and forest fires to become more frequent. In addition, the mild winters and the weakened condition of the trees made it easy for pests such as the bark beetle to multiply en masse.

The state of the forest in Germany has been regularly examined since the 1980s by the federal government’s forest state report. For this purpose, forest sections throughout Germany are inspected in July and August, all trees are measured and their state of foliage is determined. The crown thinning indicates the deviation of the examined trees from a healthy tree with full needles or full leaves and is considered an indicator of the health of a tree. The inventory teams estimate the extent to which the defoliation of the crowns has progressed in five percent increments.

Little improvement, record thinning in conifers

The Thünen Institute for Forest Ecosystems has now evaluated and published the data from the forest condition survey for 2021. According to these, the proportion of trees with clear crown thinning is still high, but has decreased by two percent compared to the previous year. In 2021, 35 percent of the trees showed a decrease in foliage of 25 percent or more. For the trees over 60 years old, where damage is particularly evident, the assessors also observed a slight improvement. Compared to the previous year with 45 percent, in 2021 only 42 percent were affected by a clearly insufficient foliage of the crowns.

In the case of deciduous trees, the beech has been particularly badly affected since 2019, according to the Thünen Institute. In the case of conifers, the condition of the spruce in particular deteriorated again in 2021. In 2021, it reached a maximum of 29.8 percent for crown thinning and thus the highest value since monitoring began in 1984. But the pine also increased significantly and at 22.9 percent also reached a record value.

The drought of recent years is having an effect

According to the forest experts, these results show that the forests have still not fully recovered from the dry years of 2018-2020. Although there was plenty of rain in 2021 and the trees were largely spared from drought and strong storms, the condition of German forests is still rather poor. “The forest does not forget that easily and certainly not quickly. The damage caused by drought and bark beetles will be noticeable and visible for a long time to come. The damage to the forest shows us what the climate crisis means for us,” comments Cem Özdemir, Federal Minister of Food and Agriculture.

However, if the weather develops favorably for the trees in 2022, as it did last year, this could promote the recovery of the forests. But Nicole Wellbrock, coordinator of the forest condition survey, is optimistic: “Despite the favorable weather in 2021, the development of the forest condition in 2022 is uncertain. The soil water reservoir was not completely filled up in some regions of Germany in 2021 either”. In particular, due to further amounts of damaged wood as a result of the winter storms in February 2022, it can be assumed that no improvement in pest infestation, especially from the bark beetle, is to be expected. The resulting damaged areas permanently reduce the ecosystem functions of the forest and it is becoming increasingly difficult to react to environmental changes.

Source: Johann Heinrich von Thünen Institute, Federal Research Institute for Rural Areas, Forests and Fisheries; Forest condition report 2021

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