Because of climate change: The forest needs a lifesaver
Created: 05/21/2022, 07:04
By: Max Wochinger
Love for the forest: Wilhelm Seerieder does everything to stop the trees dying in Forstenrieder Park.
© Robert Brouczek
Like many other forests in the region, Forstenrieder Park is also in danger: the trees are dying.
With the four-tree principle, the foresters are arming themselves against global warming.
It's a generational project.
County – The spruce trees in Forstenrieder Park are in bad shape.
"They are in an extremely unstable condition," says Wilhelm Seerieder.
He heads the Munich State Forestry Service and is in charge of 18,360 hectares of forest.
The high temperatures put a heavy strain on the bread tree in forestry, drought and severe storms do the rest. In this environment, the bark beetle also has easy prey.
Seerieder (62) also drives into the forest on this warm May day, the radio announces another climatic horror message: global temperatures are expected to rise even faster.
The UN's World Weather Organization (WMO) sees a 50 percent chance that the temperature rise will exceed the critical 1.5 degree mark in at least one of the next five years.
The bark beetle is already waiting
The strain on the spruces begins after just three weeks without rain, explains forest manager Seerieder.
And the pest is already waiting: the bark beetle.
"The tree then sends a kind of signal to the bark beetle: 'I'm weakened'." The pest pounces on the unstable tree and bores a tunnel in the trunk;
they lay their eggs in the so-called ramming chamber.
Two generations per year are usual, but in hot weather it can be three or more.
Seerieder emphasizes that the beetle is actually part of the ecosystem.
"It becomes a problem when masses of it grow." If a tree is infested, the district managers and forest workers have to react quickly: From the first infestation to the onward flight to the next tree, it only takes four weeks, says the forest scientist.
“We are looking for the neuralgic point”: brown drill dust on the ground or resin on the trunk are indications of the intruder.
The sick trees must be removed from the forest quickly;
During the peak period of the bark beetle in August, Seerieder sometimes imposes a holiday ban.
Identification via smartphone
Overview via app: Spruces infested with the bark beetle are marked in red.
Other tree species are drawn in blue, these trees may have been knocked over by the wind.
© Robert Brouczek
The forestry company no longer uses unwieldy maps to mark the diseased trees - but an app.
Trees that are infested with the bark beetle or have been damaged by the wind are marked with red and blue dots and stars - the forest workers use the harvester to get the infested trees out of the forest.
A look at the smartphone shows the extent of the climate change in Forstenrieder Park - the map is covered with red and blue markings.
"The bark beetle moves around quickly," says Seerieder.
In 2018 alone, the Munich forestry service removed 100,000 solid cubic meters of pest infestation from the forest.
The spruces here are particularly susceptible to the beetle: the trees store little water.
The reason for this is the soil.
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Trees cannot have deep roots
The Forstenrieder Park is located in the so-called Munich gravel plain, the ground is only half a meter deep - underneath is gravel from the Ice Age.
The trees cannot have deep roots.
"The groundwater is 20 meters below us," says Seerieder in the forest.
The roots cannot reach the water far below in the ground, so the trees depend on water from above.
Only, the rain stays away more and more often.
In addition, violent storms are raging: "Since 2005 there have been three major storms," says Seerieder.
After each of the storms, the bark beetle was able to spread particularly well.
For around 20 years, the trees would also suffer from drought damage - they simply dry out.
Four-tree concept: That's what's behind it
However, the Bavarian state forests are arming themselves against climate change – with the four-tree concept.
Because a pure stand of spruce is particularly vulnerable to pests, the foresters convert the forest.
In this way, Forstenrieder Park is gradually being transformed into a more climate-stable mixed forest, and the company has been working on this since the 1980s.
It is a huge generational task.
On information boards, walkers can find out things worth knowing about the promotion of oak trees, for example why the oak tree is so valuable for nature conservation and the function of the fences.
© Robert Brouczek
With the four-tree concept, the forest is mixed with at least four different tree species - at least three must be climate-tolerant tree species.
Beech, fir or Douglas fir, for example.
The forestry company also plants oaks, which, according to Seerieder, have the greatest tolerance of all native tree species to rising temperatures and drought.
15,000 euros for one hectare of oak culture
Global warming has its price: planting one hectare with oak trees costs 15,000 euros.
In some years, the forest enterprise planted 250,000 seedlings.
Just 50 years ago, 70 percent of the Forstenrieder Park was spruce, but now the proportion has fallen to 55 percent, says Seerieder.
The goal: only 40 percent in 2070. The forest manager calls the plan “quite sporty”.
desire for a rethink
Spruce or beech: Wilhelm Seerieder thinks that "a different environmental policy" by the state government would be better than the conversion of the forest.
The head of Forstenrieder Park hopes that people who love the forest will change their minds: “We have to change our behavior when it comes to energy”.
More news from the district of Munich can be found here.