What will the forest of the future look like in Switzerland?

Almost a third of Switzerland is covered by forests. foundation

Switzerland is experimenting with the classification of flora species into zones that characterize areas with a drier climate. Promising idea?

This content was published on 01 June 2022 – 07:00

What species of trees are so resistant to heat and drought that even in a hundred years they will be able to perform the functions assigned by nature to the forest in the ecosystem (reinforcement of slopes, accumulation of moisture, regulation of the regional microclimate, serves as a source of raw materials etc.); Switzerland is seeking an answer to this question by experimenting with the regionalization of flora species that characterize areas with drier climates. We went to a special experimental site to see how promising this idea is.

Peter Brang (Peter BrangExternal report) moves slowly forward, constantly looking around and trying to see something between the tree trunks. More than a year has passed since he was last here now, and on this hot spring day here it is not very easy for him to navigate the lush thickets. “Here we are,” he finally says. Let us know: Peter Brang is an expert in synergism, ie the structural characteristics of natural processes observed in forest ecosystems.

He shows us a wire mesh attached to wooden poles. This is a fence that encloses the area of ​​his laboratory in the countryside. Once upon a time, strong pines grew here, but now they have been cut down. Only a few logs left. The pines have been replaced by Lebanese cedars (Cedrus libani), a species of evergreen conifer native to the Middle East. Some trees have already spread out and reach three meters in height, others are still quite small – up to the knees. There is also a completely dried sapling.

We are located in the area of ​​the village Mutrux (Mutrux) External reportin the French-speaking canton of Vaud in western Switzerland near Lake Neuchâtel. In 2012, about three hectares of land here were planted with six exotic tree species from Turkey, Bulgaria and the USA. It was an example of so-called controlled migration. “We have accelerated the pace dramatically, this process alone would have taken at least a thousand years,” explains P. Brang, a researcher at the Swiss Federal Research Institute for Forests, Snow and Landscapes (Eidgenössische Forschungsanstft Wür Land). .

“We need to understand which plants could replace important Swiss tree species that are currently suffering from changing climatic parameters.” Global warming is leading to drier, hotter summers, which are becoming more intense, larger and more frequent, and this is affecting the tree species that are familiar to the Swiss latitudes, which are common in the more temperate climates of the European middle zone. According to Peter Brang, the forest in Switzerland will not disappear anywhere, but there is a risk that it will no longer be able to perform its important functions for humans (reinforcement of slopes, accumulation of moisture, regulation of the regional microclimate, use as a source of raw materials) .

Caucasian fir. swissinfo.ch

Robert Jenni, a researcher at the Swiss Federal Office for the Environment (Bundesamt für Umwelt), who accompanies us, explains that the Swiss strategy is not to completely replace native trees with new species, but to regularly and locally enrich the forest with new exotic types. “The forest is a very stable ecosystem. “And we want to give species that are already naturally growing and have some adaptability the best possible chance of surviving in the new climate.”

We move on to a neighboring plot where several Caucasian firs (Abies Bornmuelleriana) are planted. This variety of coniferous trees is located in the mountains of northern Turkey, withstands long periods of drought and can withstand temperatures down to -18 ° C. Therefore, the Caucasian spruce can be considered a good substitute for the European spruce or white spruce, while the most common tree species in Switzerland.

“Maybe in time the fir tree will appear in our homes even as a Christmas tree,” says Peter Brang. He further explains that the species planted in Mutrux were selected on the basis of specific ecological and economic criteria. In particular, these tree species are now common where the climate already corresponds to the 2 ° C heating scenario. Experts say that such climatic conditions are likely to prevail in Switzerland in the future. All species, mainly, are non-invasive and so far are resistant to all species of pathogenic microorganisms.

“Lucky Dought” 2018

The Mutrux Experimental Site is part of an international project coordinated by the Bavarian State Institute of Forestry and Forestry (Bayerische Landesanstalt for Wald and ForstwirtschaftExternal report). German and Austrian research institutes and universities are participating in the research, which is being conducted in five locations in different countries. The same specimens from the same areas were planted everywhere and only in Switzerland was an additional species added to them. “There are not so many such experiments in the world,” says Peter Brang.

Peter Brang, researcher at the Swiss Federal Research Institute on Forests, Snow and Landscape. swissinfo.ch

The advantage of this natural laboratoriesExternal report Outdoor networking is that they increase the likelihood that scientists will record extreme weather events and then make it possible to compare the results with the results of research in other locations. Drought and long periods of unusual heat are of particular research interest in this regard. Peter Brang says that the extremely hot and dry summer of 2018 was a great “luck” in this regard. “Everyone involved in forestry, of course, will disagree with me. “But I still hope we have more of these climate events.”

Indeed, the heat of summer 2018 affected many Western European countries at the same time. Regular meteorological measurements in Switzerland began in 1864 and if we take into account all the statistics that have accumulated since then, it turns out that the summer of that year took an honorable third place in the ranking of the hottest summer seasons. Due to the high temperatures, which reached + 34 ° C in the valleys from late July to mid-August, excessive mortality was observed in Europe (about 200 “excessive” deaths were recorded compared to a normal year in terms of flight temperatures). In many parts of the Alps there was not enough water, so the Armed Forces had to come to the rescue: the army provided water in places even with the help of helicopters. The drought severely damaged forage crops, and the fall of the Rhine disrupted normal flow of goods into the river.

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The drought four years ago has affected forests and especially trees such as white fir and beech. According to an analysis by the Federal Institute for Forest, Snow and Landscape Research, 10% of trees in the forests of Central Europe have partially or completely lost their leaves prematurely. The worst affected areas were central and eastern Germany (Trier-Leipzig) and the Czech Republic. In the Swiss mountains, it was less hot and dry, so the damage to the forests was much less, but still noticeable. And if such phenomena are repeated regularly, then the prospects for spruce, beech and fir do not look very bright.

The timber industry is looking for alternatives

The Swiss forestry is in danger of losing one of its most sought after tree species. Conifers provide two-thirds of the country’s timber used in construction, furniture and thermal energy production. In 2020 alone, Swiss forests provided the country with 4.8 million cubic meters of timber. For comparison: in 2019, the Swedish furniture company IKEA alone used 21 million cubic meters of wood to produce its furniture.

Thomas Lädrach, president of the Swiss Woodworking Industry Association (Dachverband der Schweizer Holzindustrie), believes that the economy can not do without the use of softwood, since hardwood can be used, say, in capital construction, only under certain conditions. Therefore, local firs need to look for an alternative right now.

Among the possible candidates is the so-called Douglas fir (Pseudotsúga), which grows in the highlands of North America, Japan and China. It can reach a height of up to six tens of meters, withstands the heat of summer well and resists drought better than fir and white firs. In Switzerland, this tree is not yet very common, but Peter Brang claims that in the future the Douglas fir could occupy up to 10% of Swiss forests.

Cedar forests in Switzerland?

Other candidate: Lebanese cedar. This is just one of the many species grown in Mutruksa. The strength of its wood is similar, and perhaps even greater, to the wood strength of common trees grown in Swiss forests used for industrial purposes. According to the Swiss specialized magazine Baublatt, Lebanese cedar may well be a substitute for spruce and pine, especially in capital construction.

Lebanese cedars. swissinfo.ch

But will this and other species be able to settle in Switzerland? The first evaluation took place in 2018, six years after the start of the project. In all the experimental plots in Switzerland, Germany and Austria, a significant increase in mortality was observed in some tree species. As for the cedar, out of every four saplings that came from a Bavarian nursery, three did not take root. “Obviously, this species does not tolerate transplanting into new soil and simply dries. “We did not know that,” said Peter Brang.

“In general, there is still no evidence that all the species planted here are not at all suitable for our latitudes,” says P. Brang. He would of course like to avoid the unpleasant surprise that happened to the black pine (Pinus nigra). Thirty years after it’s seemingly successfully planted in Switzerland, its needles became infected with a fungal disease and now this species is gradually disappearing into the country. “But it is important not to jump to conclusions. Are the trees we planted today really durable? “This will only become known after 50 or even 100 years,” P. Brang sums up.

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