The future of the German spruce

Much smaller spruce stocks from 2035

There are forecasts that spruce will disappear from German forests at a rapidly increasing rate, especially until 2035. “Up until 2035, large volumes of spruce will be available on the market, but after that, supply will decrease drastically. Then, we will reach a tipping point, since the regrowth will take place on ever smaller areas and volumes,” Dr. Andreas Bolte, Head of the Institute of Forest Ecosystems at the Thünen Institute in Hamburg, says.

Halved stocks and supply from 2050

The Thünen Institute predicts a halving of the current spruce stocks by 2050: That would be only 500 million m³. In this scenario, only 25 million m³ of spruce/fir logs would be available on the market each year – instead of the usual 50 million m³ a year. Added to that are an annual 10 million m³ of pine logs.

Looking ahead to 2100, experts such as Ralf Petercord, from the North Rhine-Westphalian Ministry of Agriculture, assume that spruce can only be grown on 30% of the current area. That would essentially reduce the growing areas to the Alps and the Alpine foothills, and maybe the mountains along the border with the Czech Republic. “In the short and medium term, there is no objective shortage of raw materials. The timber industry, in particular, has time for an orderly transformation and transition,” Petercord analyzes.

Changing the composition of forests is inevitable. The way it is done varies considerably from region to region, but forests below an altitude of 600 m will need to be prioritized. As temperatures rise, spruce trees’ vitality is increasingly at risk, especially in low-lying areas.

Caution is crucial – beetles also dangerous in the mountains

Developments in Alpine regions show that even the high mountains are no longer safe from bark beetles. In Upper Carinthia, East Tyrol and South Tyrol, extensive damage has been caused at higher altitudes and in native, mostly natural spruce forests. This shows that bark beetles are a powerful enemy, which must be fought intensively. In the past, it was assumed that only one generation of beetles could survive at those altitudes. Nowadays, however, there are sometimes three generations even at 1000 m.

So, intensive forest protection is the only way. For Petercord, one example of successful beetle control is the consistent bark beetle management in the BaySF forestry district of Wasserburg after Storm Niklas in 2015.

Shortage of popular small-diameter logs

It is already clear that stocks of the medium-sized ranges with diameters of up to 40 cm at chest height, which are in particularly high demand, have decreased significantly between the two National Forest Inventories in 2012 and 2022. For spruce trees, a decrease in stocks can even be observed in the diameter range of 50 to 59.9 cm. In the high diameter classes, however, the 4th National Forest Inventory showed increases – the higher the diameter class, the greater the increase in stocks.

So, initially, there will be a lot of large-diameter log wood. Then, the shorter harvest cycles will lead to increasing volumes of smaller diameter wood being available. “In the future, the rotation period for spruce will be 50 rather than 120 years,” Petercord predicts.

More damaged wood than what used to be the norm

“The years when damaged wood accounted for 20% of the total logging volume are a thing of the past. We have to prepare for a share of 40% from biotic damage alone, and any storm damage will be added to that,” Bolte predicts. So, there will always be damaged wood. However, not all German federal states are prepared for this. Apart from Bavaria, there are hardly any approved storage areas.

What German forest owners have built up since 2019 is what you might call a “Chinese export valve”. Up until 2019, Germany used to be a net importer. In the years when volumes of damaged wood peaked, however, up almost 12 million m³ a year were exported to China.

From establishment to stability and harvest in shorter cycles

The management of spruce forests will change in the coming decades. “We have to let spruce stands grow strong. That means establishing stands with a small number of trees and tending them very early on. The trees will be harvested when they reach a usable strength class of 2a or 2b, and then that’s it. We can only let a handful of few trees grow any older than that,” Petercord is convinced. For him, use according to target strength class is the only way. Forests should be much more structured and have trees of different ages. Age class forests are obsolete.

Many forests already neglected, effectively out of use

When it comes to the question of how the structure of forests is to be changed, the type of ownership is an important factor. In Germany, 48% of forests are privately owned, 33% are the property of states or federal institutions, and 19% are owned by the municipalities. “Public forests have clearly made the most progress,” Petercord says. Large private forest owners who make a living from forests will also be actively involved. Petercord is, however, concerned about small private forest owners as they lack not only the knowledge of the urgency of the issue at hand and the money to make the necessary changes. Sometimes, they also lack interest.

According to the 4th National Forest Inventory, 40% of German forests have not been maintained in the last ten years. Dr. Carsten Merforth, spokesman of Arbeitsgemeinschaft Rohholz: “The 4th National Forest Inventory also shows that 690,000 hectares or 6% of the forested area in Germany have not been managed before 2022 and are not expected to be managed in the future either.”

Great times for the wood-based materials industry – everything can be used

The forests of the future will be significantly more diverse in terms of tree species. This means that classic processing methods will reach their limits. Petercord therefore sees a “great future ahead for the wood-based materials industry”. Our explanation: It is always possible to chip wood.

Since we need wood products more urgently than ever before in the face of climate change, Petercord recommends choosing “tree species with the strongest growth possible. We should also always try to include a high proportion of coniferous species”.