Primary and old-growth forests in Europe, although occupying a very limited area, are irreplaceable in harbouring biological diversity, stabilising terrestrial carbon storage, regulating hydrological regimes, enabling ecosystem adaptation to disturbances, and public health benefits.

The European Union aims to strictly protect all old-growth forests by 2030. However, no European-wide standard to assess the level of old-growthness exists.

The Life Prognoses project develops, tests and evaluates a set of indicators of old-growthness. Moreover, the differences between managed and unmanaged forests in the quality of delivered ecosystem services will be investigated.

The test sites for the old-growth indicators and ecosystem assessment comprise a specifically selected set of component parts and adjacent buffer zones of the World Heritage site “Ancient and Primeval Beech Forest of the Carpathians and Other Regions of Europe”, covering the wide range of managed and unmanaged beech forest types and biogeographical zones.

How do we assess whether a forest can be called an old-growth forest?

Based on the literature on old-growth forest indicators, a set of parameters have been selected. For more details, you can check the PROGNOSES report on old-growth definitions and indicators.

Some of the structural features being measured are canopy cover and layering, biomass, tree species composition, presence of very large trees, quantity and qualities of lying and standing deadwood and presence of tree-related microhabitats.

For assessing the indicators, sites in different biogeographical regions were chosen:

• Atlantic region: the Sonian Forest in Belgium.

• Alpine region: National Park Kalkalpen in Austria, Krokar & Snežnik Zdrocle in Slovenia, Central Balkan National Park in Bulgaria, and Chornohora in Carpathian Biosphere Reserve in Ukraine.

• Continental region: National Park Hainich and Kellerwald National Park in Germany.

• Mediterranean region: Abruzzo National Park in Italy

Based on the measurements, threshold and reference values can be derived for different climatic and edaphic (regarding the soil) contexts. For example, in high mountainous regions, trees tend to remain smaller due to climatic conditions. In this case, the threshold value and density of very large trees will be lower. At the same time, there might be an abundance of cavities in the trunks, and high coverage by epiphytes (plants that grow on other plants, often trees, without adversely affecting them), resulting in high scores for the indicators on tree-related microhabitats.

The use of multiple indicators allows accounting for the distinct manifestations and levels of old-growthness.

How will we investigate the differences in microclimatic effect between managed and unmanaged forests?

The climate in a forest undergoes less extreme and less rapid shifts compared to areas without forest cover. In comparison with the urban or agricultural area, the average temperature is significantly lower in the forest on a hot summer day, and higher in cold periods during the winter months.

On three test sites in German UNESCO beech forests, our colleagues from Eberswalde University have been measuring these temperature differences on gradients covering open land, forest edges, managed forests and set-aside beech forests. The measurements are continued for several months during spring, summer, and autumn, with the help of temperature data loggers. Based on the results, we will be able to assess the effect of forest cover and forest size and see if there are significant differences between the set-aside forest patches and the managed forest.

How do we assess the differences in carbon storage between managed and unmanaged forests?

The carbon stock is the amount of carbon a forest stores in its aboveground and belowground biomass, and soil. The carbon in the aboveground biomass of unmanaged forests will be compared to managed forests based on the data collected for the old-growth assessment. This will result in tree volumes per ha. To transform this data into carbon stocks, wood density has to be taken into account. This can be done by taking tree cores, very thin cylinders reaching the core of the trunk on which all year rings are visible. To compare the belowground carbon stock between managed and unmanaged forests, soil samples of different soil layers are taken and analysed for organic carbon content.

How will we investigate the differences in biodiversity between managed and unmanaged forests?

Direct assessment of species richness is time-consuming and requires the involvement of a large group of specialists. Moreover, they are often incomplete (due to sampling limitations) or focused on a limited set of species groups. Therefore, indirect assessments of biodiversity are often applied. Species richness is strongly correlated with the variety and density of available habitat structures. Examples of specific habitats are lying and standing large trunks or cracks and cavities in the trunks of trees. Instead of directly measuring the species richness, we combine data on stand structure and microhabitats as “proxies” (a measurable variable that allows estimating the value of another, strongly correlated variable) for potential species richness in paired comparisons of adjacent managed and unmanaged forest stands.

How will we estimate the added value an old-growth forest can signify for the visitors?

Tourism and recreation are considered ecosystem services as well. To estimate the value of forest in this sense, approximation methods are used such as the “willingness-to-pay”, or the “travel-distance-method”. These are assessed based on visitor interviews. Based on several questions and scenarios the visitors can express their appreciation for a certain type of forest in a systematic and quantifiable way. More than 600 visitors and tourists were interviewed in this way at National Park Abruzzo in Italy, National Park Kalkalpen in Austria, and the Sonian forest in Belgium. Besides the research purposes, taking the interviews also showed to be an effective way of getting into contact with the visitors for scientific outreach, as well as being informed about their views on the forest and their preferences.

What comes next?

The collected data will be organised in a central database and analysed. Through the analyses, information about the characteristics and importance of old-growth forests will be extracted. This way the answers to questions such as “Is there a significant difference between managed and unmanaged forests in terms of recreation?” or “Which indicators of old-growthness perform well in mountainous areas?” can be provided. The analyses will be performed in 2023 and 2024. By June 2024, the results of our research will be available.

“It was the sound of Birch talking to fir. Birch was saying, ‘hey, can I help you?’ And the fir said, ‘yeah, can you send me some of your carbon ‘cause somebody threw a shade cloth over me.’, explained Simard. 

During her TED talk, Suzanne Simard says: ” Underground, there is this other world. A world of infinite biological pathways that connect trees and allow them to communicate and allow the forest to behave as though it’s a single organism. It might remind you of a sort of intelligence.” 

S. Simard discovered that trees ‘converse’ with each other via extensive networks of fungal threads or mycelia, exchanging nutrients and water. “Mycelium infects and colonizes the roots of all the trees and plants, and where the fungal cells interact with the root cells, there’s a trade of carbon for nutrients. That fungus gets those nutrients by growing through the soil and coating every soil particle. The web is so dense that there can be hundreds of kilometres of mycelium under a single footstep.”

Some trees communicate aboveground. Arthur De Haeck of the Institute for Nature and Forest Research (INBO), found that Acacias in the African Savannah produce substances when they are eaten by giraffes. Those substances evaporate and are picked up by other trees. Those alarmed, surrounding trees create substances that make giraffes less fond of their leaves.

Tree researcher Henk Hillhorst of the University of Wageningen says that genetic properties which are a result of millions of years of adaptation play a role in the specific height of different tree species. This is confirmed by forest researcher Hans Verkerk from the European Forest Institute in Finland. “Some trees shoot up as fast as they can because they compete heavily for light. For example, think of the Scots pine and the birch. Many forests have been created in a short time. The trees are therefore of more or less the same height. The same goes for trees that are alongside lanes.”

It is the interplay of forces between gravity on one hand and the suction effect that trees create when water evaporates from the leaves and needles on the other hand, that regulate the height of the trees.

Hans Verkerk also states that natural forests are more complex because it contains trees that are more resistant to shade, such as beech trees, in the midst of light-loving trees. This already causes different tree heights. The difference in age causes variation as well. “Such forests are more resistant to strong gusts of wind. They can absorb the wind better because the trees support each other.”, continues Verkerk.

In her TED talk, Simard proposed 4 simple solutions to save our forests; we need to …

1. get out in the forest more.
2. save our old-growth forests
3. save the legacies
4. regenerate our forests

Want to see the full TED-talk? Visit: https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_each_other?language=nl

Want to read the full article in the Belgian press? Visit: https://www.standaard.be/cnt/DMF20220224_97697263?utm_source=standaard&utm_medium=newsletter&utm_campaign=ochtendupdate&utm_content=small_4&utm_term=1-0&adh_i=2792dc818607e28724c027d4fed0e88e&imai=&M_BT=34878501590&articlehash=uk5%2F7CZuNX1zt5%2B%2FuXLDtDbRpWxOm%2BzeLhpMtkfcbfjxFW0m2bfbAk43tFJ3WjzlPNXZi1mbg9d06q1eJHmFDcYvL3eIOljRIvC3Sfw3emkasnMecZWyLBJogwy5g%2BfF84QUFM33ARUsq1JrYDxGXrsHsR%2BscfePPO2WvT7RIghkF89ayTE63Hj2yCH3RuhlV2nDsstYKNp5tfNbxT%2FNnn8tSQ7J5oJbEIuvtNuGAAvoxbM6Wj2vjfXrv2yW8MOVqezfVTlmVkyI7Kb0xHvmgNXp293O1YchWCwByOPTDoLCN2SJHVqgr3aAYxh3tSf0ZbK0zFtoNfivkUjXmpMZfg%3D%3D

UNEP (UN Environment Programme) and GRID-Arendal published a report in which they state that climate change and land-use change are the reason that wildfires are worse. Moreover, they anticipate a global increase of extreme fires even in areas that were previously unaffected. Wildfires can be destructive to people, biodiversity and ecosystems. Plus, they contribute significant greenhouse gasses to the atmosphere.

UNEP urges governments to rethink their approach to extreme wildfires. According to them a new ‘Fire Ready Formula’ need to be made and the important role of ecosystem restoration need to be recognised. Being better prepared and a better ‘after-event’-plan, is key to minimizing the risk of these wildfires.

“Current government responses to wildfires are often putting money in the wrong place. Those emergency service workers and firefighters on the frontlines who are risking their lives to fight forest wildfires need to be supported”, said Inger Andersen, UNEP Executive Director. “We have to minimize the risk of extreme wildfires by being better prepared: invest more in fire risk reduction, work with local communities, and strengthen global commitment to fight climate change”.

Climate change and wildfires aggravate each other. Wildfires are made worse by climate change through increased drought, high air temperatures, lightning and strong winds. All resulting in hotter, drier and longer fire seasons. Climate change in its turn is made worse by wildfires, by ravaging sensitive and carbon-rich ecosystems. Turning landscapes into tinderboxes.

Furthermore, wildlife and its natural habitats are not spared from wildfires. Some animal and plant species have been driven closer to extinction due to the fires. It is a necessity to better understand the behaviour of wildfires. Combining policies, legal framework and incentives that encourage land and fire use are required in order to come to achieving and sustaining adaptive land and fire management.

Want to read more on this issue? Visit;

https://www.unep.org/news-and-stories/press-release/number-wildfires-rise-50-2100-and-governments-are-not-prepared

And/or

https://www.unep.org/resources/report/spreading-wildfire-rising-threat-extraordinary-landscape-fires

Due to numerous climate-sensitive processes, simulation studies have shown that forests will change profoundly and nonlinearly in the future. Small-scale windthrow or insect outbreaks in mixed forests (i.e. low to moderate severity disturbances) may magnify structural and compositional complexity (Čada et al., 2016; Halpin & Lorimer, 2016). Development towards structurally and functionally complex forest, which is found in old-growth forests, is believed to buffer the effects of climate change when comparing them with younger and/or less complex forests (Bauhus et al., 2009; Thom et al., 2019).

Evidence that the Earth will warm in the coming decades is indisputable. However, climate models have improved greatly over the past decades, which reduces the uncertainties in future climate projections.

Three objectives and three hypotheses were put forward in this study. Firstly, forest dynamics at BGNP continues to accelerate, since climate change was found to be a major driver of past forest change. Secondly, natural disturbances are important drivers of future forest change. Thirdly, future variability in the forest is expected to be greater than the future variability in climate, in which dampening feedbacks on climate sensitivity are outweighed by amplifying feedbacks between ecosystem processes.

The authors found that “forest dynamics will continue to accelerate in the coming decades, with a trend towards denser, structurally more complex and more species-rich forests. However, changes in forest structure levelled off in the second half of the 21st century regardless of climate scenario.”

Want to read the full article? Go to: https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.16133#:~:text=We%20found%20that%20forest%20dynamics,century%20regardless%20of%20climate%20scenario

In this video beautiful images of our Croatian partner can be seen accompanied by relevant information spoken in the national language. However, when turning the subtitles on Youtube one who cannot speak nor understand the Croatian language can follow just fine. 

Here is a small excerpt of the video:  “The Beech forests of Paklenica National Park (sites Oglavinovac – Javornik and Suva Draga – Klimenta) represents an exceptionally preserved and undisturbed forest ecosystem whose authenticity and integrity have been secured by years of protection. They are a vulnerable, part of the European primeval Beech forest and an important haven for many species such as the bear, lynx, wolf, stack beetle, Longhorn beetle and holly, peony and forest orchids. Some of those are even endangered worldwide.”

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Check out the entire video by clicking on this link:  https://www.youtube.com/watch?v=IObKuXPPuAc 

Next to climate change several other threats have been mentioned in the article, such as:

• new diseases and pests due to global warming
• invasive species
• long droughts that exhaust or die the trees
• a greater risk of forest fires
• the danger of storms

Making our forests stormproof is not about finding the best solution, because there isn’t one. It should be done in different ways. One of those methods is called “mixing”, which is the sufficient mixing of different species. It is a matter of spreading the risks. “This is often brought forward in international working groups. This is usually a good measure for stability,”, says professor Bart Muys (KULeuven). Even if one supertree would exist, choosing only that one is not the answer. 

According to Kris Verheyen from the Ugent, a supertree is an illusion. “Monoculture is not a good thing.” It comes down to choosing various types with various structures too. This comes down to high versus low, or wider versus narrower.”

It all comes down to trees that remain vital and strong. Choosing the right trees in the right place, because every soil is different. Creating more space for trees to develop, they will become wider and the centre of gravity will be lower. 

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Want to read the full dutch article? Click this link: https://www.vrt.be/vrtnws/nl/2022/02/17/hoe-kunnen-we-onze-bossen-stormproof-maken/

It has been estimated that not more than 0.7% of the forest area in Europe are primeval forest (Sabaatini et al., 2018). Most importantly are the World Natural Heritage sites of the ‘Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe’. Germany’s National heritage sites show a high potential to contribute to the German National Strategy on Biological Diversity (NBS), aiming at wilderness areas (2%) and forested areas left to natural development (5%) (BMU, 2007). In the past, many of these areas used to be military training areas, comprising large and relatively undisturbed landscapes of forests and open habitats (Meyer et al., 2021). In order to increase the naturalness degree, the majority of these forests are still managed with ‘leaving them to natural development’ as the ultimate goal (Culmsee et al., 2015). 

The research of Meyer and colleagues aimed to develop and apply an indicator to quantify the old-growthness of forest structure on beech forest sites in Central Europe. Structural variables were derived from sample plot inventories in European primeval beech forests, classified as old-growth, of Eastern Slovakia and from 39 comparison stands with different characteristics, such as management intensity, age and tree species composition, of the North German lowlands. 

They concluded that the old-growth indicator is suitable to scrutinise the pace and direction of forest development toward old-growthness (Meyer, 2018). A high degree of old-growthness should coincide with low management intensity, which should be a general rule (Meyer, 2018). It is undeniable that the old-growth state coming from small-scale disturbances and maturation is a central element of a natural forest landscape. 

Meyer et al. does not claim that their approach is sufficient to cover all aspects of the complex notion of naturalness, however, it influences a solution to quantify naturalness in respect of a certain state of natural forests that is highly important for the conservation of biodiversity. 

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Want to read the full article? Visit: https://www.sciencedirect.com/science/article/pii/S1470160X21002405?via%3Dihub

On 12/10/2020, an article appeared in the Flemish magazine ‘EOS Wetenschap’ concerning the research of Kris Vandekerkhove, forest expert of INBO (Institute for Forest and Nature Research). He and his team did a remarkable discovery in the Belgian Sonian Forest. In the oldest part of this forest reserve, there is a clump of twenty beeches with a diameter of more than 120 cm. There even is one beech tree measuring 150 (!) cm in diameter. In addition, beeches can have lengths up to 50 meters, making them among the highest in Europe.  

Vandekerkhove researches Flemish forests, showing that things are going in the right direction. Strangely it is because more trees are allowed to die. Due to the intensively managed forests, trees were not able to grow very big and thick for centuries. Back in the day, deadwood was taken from the forest to serve as firewood. “In the past 500 years, and perhaps even in the last thousand years, there has never been more deadwood in our forests than today”, says Kris Vandekerkhove. “Deadwood is vital for biodiversity.”  

In an average forest, more than 15 cubic meters of deadwood per hectare can be found. When all dying trees are left in the forest, the amount of deadwood will increase by one to one and a half cubic meters per hectare annually. European forest reserves that have been left alone for more than thirty years on average, the amount of deadwood rises to an average of 75 cubic meters per hectare whereas this amount can easily be more than 100 to 200 cubic meters in primeval forests.  

A lot of plant and animal species take advantage of the available deadwood such as the Tawny Owl, the Lesser Spotted Woodpecker and Black Woodpecker. Until a few years ago, the Flat Bark Beetle (Cucujus cinnaberinus) is resurfacing here, after being driven back in reserves in Central Europe.  

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Want to read more about this and how it is evolving?  

Find the complete Dutch article here: https://www.eoswetenschap.eu/natuur-milieu/hoera-er-gaan-weer-bomen-dood

For now, it is impossible to predict the future conditions, let alone the impacts on forests. Scenario analysis, however, provides a guideline for policymakers in decision making. By comparing different scenarios to the business as usual scenario, we can have an idea of what actions can help forests to adapt to global changes, and which actions do not. The FAO and UNECE publish a scenario analysis presenting a lookout up to 2040.

Discover here what the different scenarios could lead to in 18 years from now: SP-51-2021-11_0.pdf (unece.org)

Although younger forests have a substantial potential ahead to sequester additional carbon, older and old-growth forests have been sequestering carbon over centuries. Disturbances can lead to high losses of this stored carbon to the atmosphere.

“European Forests for biodiversity, climate change mitigation and adaptation”, a recent forest publication of the European Commission, summarizes the latest studies on the importance of Europe’s forest for biodiversity and ecosystem services. Find out more about the potential of our European forests here:

https://ec.europa.eu/environment/integration/research/newsalert/pdf/issue-25-2021-11-european-forests-for-biodiversity-climate-change-mitigation-and-adaptation.pdf