Germany particularly at risk

Spruce suffers the most from higher temperatures in summer and fewer precipitations in the past years. Why? Mostly because it is difficult for the shallow-rooted spruce (20 to 60 cm) to reach water in the ground when the topsoil does not contain any water anymore after long periods of drought.

Mainly affected because there are too many

In Germany, Austria and the Czech Republic, spruce is the most widespread tree species (e.g. Germany: 25%), which is why it is also the most affected. Spruce is the dominant type of tree because it grows in a wide range of areas (Germany: “from the Zugspitze to Rügen”), has the fastest growth and ideal strength characteristics for constructive purposes.

All of these characteristics lead to the following developments:

• Spruce can often be found in areas outside its natural habitat.
• Often, planting material, which is not suitable (reforestation after WWII), was used and
• the wrong forestry strategies (trees planted too closely to each other) were adopted.

With more than 100 million m³ of damaged wood, Germany is most affected by the calamities of the past two years. Why is the situation so bad there? On the one hand, there is an overall growing stock of 3.7 billion m³ (according to the federal forest inventory BMI 3/2012). The country has not had this much wood in centuries. The downside, however, is that over the decades too many fast-growing and lucrative spruce trees were planted in areas where they simply do not belong. When there are unusually dry summers, massive problems in those areas are inevitable.

Tough times below an altitude of 600 m

If global temperatures rise by 2°C, as is expected by climate researchers and European politics (Paris climate agreement), spruce will not be the main species in forests at altitudes of under 600 meters anymore. In special locations, such as wetter valleys and northern slopes, spruce might grow under this mark. Here, Germany will again be hit particularly hard, since almost 70% of all spruce trees, i.e. 805 million m³, grow at altitudes of under 600 meters.

Outlook is similarly bleak for the Czech Republic which has a growing stock of around 700 million m³, 60% of which are spruce trees. In a very pessimistic statement, the Czech environment minister predicted that “there won’t be spruce trees anymore in 15 years”.

It is getting worse in the Czech Republic

Last year, an estimated 30 million m³ of damaged wood accumulated. In 2017, only 10 million m³ were recorded. If one believes the forecasts of the think tank Czech Forest, there are going to be between 40 and 60 million m³ this year – with a tendency towards a further increase.

Austria has a little advantage thanks to its topography. In the country, “only” 16% of spruce stocks, i.e. 100 million m³, are located at altitudes of under 600 meters. The majority of spruce stocks, almost 590 million m³, grow at higher altitudes. “Many of our forests are located in mountainous areas. So far, we had a disadvantage of 10 €/m³ due to a more costly harvest and transport. With climate change, however, this could actually be an advantage,” comments Dr. Rudolf Freidhager, head of ÖBf.

In all countries, it is mainly the combination of already existing damages (mostly due to droughts, but also due to storm and snow damage) and a subsequent infestation by the European spruce bark beetle (Ips typographus) which led to big volumes of damaged wood. In Germany and Austria, Ips typographus caused 90% of damage. In the Czech Republic, and already in Bavaria too, the Northern bark beetle (Ips duplicatus) is active as well. Bark beetles are getting active ever earlier and at ever higher altitudes. There are reports from the Czech Republic, according to which the European spruce bark beetle was active until November in some places. A video filmed in the Waldviertel shows bark beetles waking up under the bark at the end of January. In combination with a big “iron population”, this results in a very high infestation pressure.