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News Article

Swiss forests must adapt to cope with climate change

New study compares Silver fir, Norway spruce and European beech

It is widely anticipated that climate change will make forests in temperate regions, such as Switzerland, drier and warmer.  In order to continue to thrive at their current location, trees in these areas will need to adapt genetically to the changing climate, although this is likely to take some time – a single tree generation can take at least 100 years.  Therefore, it is important to determine how well adapted to the future climate the trees already are today, as this will be key to the future of the forests’.

A team of researchers from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) investigated the climate change induced risk faced by the three most important tree species within the Swiss timber industry and forestry sector – Norway spruce, Silver fir and European beech.  They looked at how well the trees had adapted to the climate conditions in their respective locations over many tree generations.  If a tree exhibits strong genetic adaptation, it indicates that the tree population relies on certain environmental conditions, whereas a slight adjustment suggests an ability to thrive in certain conditions.  Using climate scenarios, the team then estimated the tree populations’ risk of being poorly adapted to each of the climate outcomes that have been predicted, by the end of this century. 

In order to study the risk, the researchers established two forest nurseries and planted 16,000 seedlings.  They examined the growth characteristics of 92 Norway spruce, 90 Silver fir and 77 European beech populations from areas across Switzerland.  These locations differed in terms of water availability and temperature.  The team studied the seedlings growth and monitored the timing of the bud break in spring, growth cessation in late summer (for beech and spruce) and the timing of leaf colouration in the Autumn (Beech).  When the populations showed major differences in these characteristics and these matched the climates at the trees area of origin, this indicated local adaptation and therefore a high risk of climate change, resulting in the respective tree species being less than optimally adapted to future local conditions.

While previous studies had found that on the Swiss Plateau, Norway spruce will be vulnerable to rising temperatures and drier conditions, the new research suggests that the species is actually exposed to this climatic risk throughout Switzerland.  Norway Spruce in Switzerland has adapted very closely to the local climates over the past millennia, which the researchers believe will mean that their decendants will be increasingly unadapted to the rising temperatures that are expected within the coming years, particularly in areas that are already warm today.

The European beech is also vulnerable to climate risks, albeit less so than Norway spruce.  In contrast, Silver fir was found to have hardly adapted its growth patterns to local climates.  Therefore, it appears likely that the silver fir will have the ability to cope well with climate change.

The findings are important for forestry practice.  The researchers anticipate that Norway spruce, the most important tree species within Swiss forestry, which was shown to adapt well to the local climate, will become endangered throughout the country by advancing climate change by the year 2100.

Action therefore needs to be taken in order to prime spruce forests for climate change.  The researcher team suggest that Norway spruce should only be grown in areas that have a good water supply.  Another option involves using seeds that originate in warmer habitats and growing them in sites that are still cooler today, as long as they are adequately frost-resistant to cope with potentially harsher climatic conditions at their new site. The origin of the seeds can be indigenous, from a valley-floor and planted at higher altitude or from a warmer region outside Switzerland.

A similar procedure could be applied for European beech, using seeds from areas that are already dry.  "If we use seeds from trees in warmer and drier regions, we will at least have a chance for these species to thrive for yet another forest generation. This way, our forests will remain stable and protect us against natural hazards," explains study co-author Caroline Heiri. "However, there is no miracle provenance of Norway spruce or European beech," says Aline Frank, lead-author of the study. "So, we must also consider the possibility of switching to other tree species." Therefore, due to its low climatic fixation, the Silver fir could become the forest practitioners hope for the future.

Looking for further information? Subscribers to the Forest Science database can use the searchstring "climate change" AND ("Picea abies" OR "Abies alba" OR "Fagus sylvatica") AND adaptation which yields 153 records.  A selection of these is provided in the further reading section below.

Journal Reference

Aline Frank, Glenn T. Howe, Christoph Sperisen, Peter Brang, J. Bradley St. Clair, Dirk R. Schmatz, Caroline Heiri. Risk of genetic maladaptation due to climate change in three major European tree speciesGlobal Change Biology, 2017; DOI: 10.1111/gcb.13802

Article details

  • Author(s)
  • Stephanie Cole
  • Date
  • 02 October 2017
  • Source
  • Swiss Federal Institute for Forest, Snow and Lands
  • Subject(s)
  • Forest trees
  • Management