Is Storm Ylenia a Danger to Our Forests?

Mr. Merker, how dangerous are the current storms for the forests?

Reinhard Bingener

Political correspondent for Lower Saxony, Saxony-Anhalt and Bremen based in Hanover.

Trees are actually well-armed against strong winds thanks to their flexibility. We foresters only prick up our ears at speeds of 120 kilometers per hour. It gets really dangerous from 150 kilometers per hour – and we now have these speeds in some places.

What else is used to measure how dangerous a storm is ultimately for trees?

A steady, strong wind is less dangerous than many gusts that gradually loosen the roots. It becomes particularly critical when the tree and its root plate are already at an angle after a gust and then the next gust follows immediately. A further complication is that the soil is very damp and soft. Trees are better protected against a winter storm when the ground is frozen. The danger of a hurricane depends on several factors.

Klaus Merker is President of the Lower Saxony State Forests.

Klaus Merker is President of the Lower Saxony State Forests.

Image: dpa

Are all tree species equally endangered?

Basically, a storm can be dangerous for all tree species. During winter storms, deciduous trees have the advantage that they are less exposed to the wind than conifers, which are covered with needles and may even have wet snow on them.

What should citizens pay attention to?

I warn every citizen against entering a forest in the next few days! And the danger isn’t over when the storm ends. If the roots have been loosened, a tree can fall over even days later. There may also be branches that have already broken but only come loose later and then fall. I myself have seen half a crown fall out of a tree two days after a storm. However, after the past few summers, we also have numerous forests in which there are dead trees whose roots no longer provide much support and whose wood is brittle. The danger there is really hellish and I can only warn: In such places there is still danger to life for days.

Can you already estimate whether the damage in the forests will be similar to that caused by the devastating storm Kyrill in 2007?

Wind speeds of up to 170 kilometers per hour have been announced for the higher mountain regions such as in the Harz Mountains. That’s worrying us. But because the damage caused by a storm depends on several factors, as described, it is still too early for an assessment at this point in time, especially since the storm “Zeynep” has been announced for Saturday, and it could be even stronger. And just like for the citizens, it also applies to us foresters that we are currently not going into the forest because it is far too dangerous. I suspect that we won’t know how extensive the damage is until next week.

Heavy gusts of wind are expected.

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