Foreign tree species needed to save Germany's forests, gov't advisors say

Germany should actively introduce tree species from warmer and drier climates to bolster its forests against rising temperatures, drought and pests, a government advisory body said. 

The Scientific Advisory Board for Forest Policy (WBW) presented its report to Germany's agriculture and forestry ministry, urging policymakers to embrace "assisted migration" – the deliberate introduction of tree species from other climatic regions – to future-proof forests against climate change. 

The call comes as native species face sustained pressure. Beech and oak have shown declining vitality for more than two decades, with the 2024 national forest condition survey recording significant crown thinning in 46 percent of beech trees.

Tree species do migrate naturally, but far too slowly to keep up with shifting conditions – requiring dispersion of thousands of metres per year against natural rates well below 500 metres annually, according to the report. 

The advisory body identified around 10 to 15 candidate species, including Oriental beech, Turkey oak and Atlas cedar, drawn from warmer and drier regions of Europe and beyond. But it stressed the approach must be carefully managed. Importing seeds carries risks of introducing disease and pests, with studies finding insect larvae in roughly 30 percent of incoming batches. Specialist native species and biodiversity also tend to fare worse in forests dominated by introduced trees.  

The report recommended a stepwise approach, prioritising better-adapted varieties of existing native species before turning to more distant alternatives. The WBW also cautioned that new tree species could only ever be one element of a broader response, with the development of diverse, mixed forests remaining the overarching goal. 

Healthy forests, which are a carbon sink, are seen as key to Germany meeting its climate targets. Germany's forests only recently returned to being a net carbon sink in 2025 after years of droughts, storms and bark beetle damage turned them into net CO2 emitters, according to the Federal Environment Agency (UBA).