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Bitten by the same bug – German spruce in jeopardy

“Scientists alarmed by bark beetle boom” (ScienceDaily, 2019), “French forests scarred as heatwaves bring bark beetle infestation” (Euronews, 2019a), “Czech forest owners face $1.7 billion loss this year from bark beetle crisis” (Euronews, 2019b) and finally “Merkel promises €500m to revitalise German forests” (Guardian, 2019) – these were only some of the many forest-related headlines in European news in the past months.

It is obvious: How weather affects our forests, would not have made it to the news ten years ago – but following the unprecedented hot temperatures, long dry spells as well as severe storm events in Central Europe, everybody was talking about the state of our forests. These extreme weather events are a not only a huge burden for human health but also for entire natural ecosystems. In Germany, extreme temperatures contributed to the extremely dire state of about 180,000 ha of forested area and taxpayer support of 800 million Euros for reforestation measures (FAZ, 2019). In the past, evolution gave flora and fauna the opportunity to adapt to changing environmental conditions and climates but the pace and scale of climatic changes that we experience today, give our natural world a mountain to climb, regardless of the money thrown at the problem.

Spruce (Picea abies) – the so-called bread and butter species of the German forester – is one of the species that has been very negatively affected by a combination of extreme temperatures and low rainfalls. As a result of these calamities, the weakened trees do not produce sufficient amounts of resin, which is the natural defense tool of Picea abies, and as a consequence fails to effectively fend off bark beetle attacks, which so heavily damage and at some point, kill the tree. Across Central Europe bark beetles had a field day with Picea abies. Looking into our forests now, we can observe a lot of weak and dead trees, whereby the local Kottenforst in North Rhine-Westphalia is no exception. It is more than telling that at the beginning of this year, the regional forestry office had to cut 140,000 dead spruce trees in the Kottenforst (GA, 2019).

We heard a lot about how dire the state of most spruce trees is, yet, it is impossible to make predictions about the future state of cultivation of Picea abies in Germany. To find answers on how to make Picea abies, among others, more resilient towards calamities pose a huge challenge for forestry researchers and practitioners. Our team at EFI Bonn collaborates with other research institutes in the EU-funded Horizon 2020 project B4EST with the objective to enhance forest health and resilience under climate change and natural disturbances. The project focuses on new tree breeding strategies and generates knowledge on societal demands towards improved forest reproductive material. This new knowledge is indispensable as adapted tree breeding and newly developed forest reproductive material has to be accepted among the forest owners and managers.

Partner countries in B4EST

In order to better understand the needs of both forest managers and owners, we conducted a survey across nine countries (Finland, France, Germany, Italy, Norway, Portugal, Spain, Sweden and the United Kingdom). Our research yielded 241 answers in Germany, including 44 open-ended responses telling us about main expectation regarding improvements of spruce forest reproductive material. Across Europe, respondents are divided between an expectation towards increased timber quality and more biomass volume on the one hand, on the other hand, there is an expectation towards more climate and pest resistant reproductive material. For Germany, we counted five responses in the group speaking for timber quality and biomass compared to 30 respondents for the climate and pests’ resistant group. For spruce, this does not come as a very big surprise, especially after considering the recent calamities.

Regardless of these differences, looking at all responses, the most preferred forest management strategy to adapt to climate change is diversification of tree species. Thus, we can say that the two worldviews regarding spruce reproductive material were bitten by the same bug, as they all have developed an agreement on the forest management strategy for the years to come. It will be moving from monocultural forests towards mixed deciduous and coniferous forests. More on this will follow as we currently work on a publication on perceptions of climate change in European forests.

Featured image: Spruce in Bohemian Switzerland (by @Dennis Roitsch)

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