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Response: Nature is our ally in addressing climate change

A natural peatland stores carbon that have been accumulating for millennia.
A natural peatland stores carbon that have been accumulating for millennia. Source: Edgar Karofeld

Natural scientists write in response to the commentary "Unmanaged forests now emit more CO2 than they absorb" that the species richness of forests that are managed less intensively or not managed at all will help to ensure a more holistic functioning of natural processes and most effectively mitigate the negative effects of climate change.

Population increase and the rapid expansion of the global economy have left us with two major crises. The first is the global warming crisis. The natural habitat emergency is the second.

The key problem is determining how to proceed without exacerbating one crisis at the expense of the other, while also considering people's well-being.

Ecologically sound and well-functioning ecosystems are our most powerful allies in this fight.

In previous decades, it was believed that sustainable development could be achieved by striking a balance between the natural habitat, the economic development and social fairness. Today, it is clear that sustainability should not be viewed as a tripod, but as a pyramid. At the bottom, the foundation level, is a holistic natural environment, which supports both the economy and social fairness.

Inflating the economy at the expense of the natural environment compromises both economic and social sustainability, just as building a house on a shaky ground will inevitably result in its collapse.

Major scientific communities such as the IPCC (Intergovernmental Panel on Climate Change) and IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services) reached the conclusion that functioning ecosystems are the cheapest and most effective method for addressing environmental issues and ensuring economic sustainability.

Estonian University of Life Sciences (EMU) representatives presented counter-arguments to this vision. According to their article, ecosystems in good natural condition are ineffective at mitigating climate change, and intensive forest management is required to solve the crisis.

Moreover, the restriction of intensive forest management, according to the authors of the commentary, poses a threat to property income and investment.

At first glance, it appears to be a tempting solution: continue and intensify current efforts to address the climate crisis while also profiting from it. Unfortunately, the foundations of such a solution, i.e., functional ecosystems dependent on biodiversity, suffer as a result.

In the case of forests, the principal cause of biodiversity loss is intensive management practices centred on clear-cutting and drainage.

The authors of the article specifically mention peatland and grassland restoration as a climate-unfriendly process that will result in less land for managed forests. However, both peatlands and grasslands are known to be important carbon sinks that function efficiently in the face of rising CO2 emissions.

Viru Bog (Viru Raba) lies wholly within Lahemaa National Park. Source: ERR

Here, we provide a science-based and conflict-free vision of the future that considers the potential of ecosystems to maintain lasting physical cycles, reduce the effects of climate change, provide habitats for wild species and support responsible economic development.

Climate change solutions do not always have to exacerbate the habitat crisis.

Extensive forest management is not economically viable. It only provides short-term benefits. If we want our children and grandchildren to be able to manage forests, we must adhere to the principles of ecology.

To begin, it is worth noting that although Estonia's forests have recently become carbon emitters (more carbon is released now from forests than is sequestered by them, and the total carbon stock is decreasing), it is related to the current intensive forest management (link in Estonian).

This clearly contradicts the main point of the commentary article by the Estonian University of Life Sciences researchers.

Mait Klaassen, Marek Metslaid, Ahto Kangur, Endla Reintam and Allan Sims discuss in their commentary the requirement of the land use, land use change, and forestry (LULUCF) sector to sequester at least as much carbon as it emits.

In reality, the sector already faces a greater challenge: it must capture more carbon in Estonia than it emits in order to offset emissions from other sectors.

We must think carefully about how to achieve this, because only nature, not technology, is currently capable of sequestering CO2. It is worth noting that our forests were sequestering significantly more CO2 ten years ago than the current target.

According to researchers at the University of Life Sciences (EMU), the best answer is intensive forest management. After all, new trees soon grow in place of the felled ones, sequestering carbon as they do so.

On the surface, the solution is sensible: the more trees are cut down, the more new trees sprout to replace them. But this approach ignores the fact that carbon sequestration, long-term storage and carbon stock are different things. Old-growth forests have much greater carbon stocks than young forests.

If we cut down trees and use them for heating or short-lived products, which is the case for 80 percent of felling in Estonia (about 55 percent is burned, and 25 percent is used to produce cellulose products with a lifespan of a few years), we will have to rely on the new forest to absorb the same amount of carbon from the atmosphere as the previous forest did.

This may be a good way to make a quick profit, but it is far from the most effective way to address the climate crisis. In addition to being powerful carbon sinks, old trees are also capable of sequestering carbon. For instance, investigations of carbon fluxes in Sweden and the United States have revealed that in managed forest landscapes, it is old, 100-year-old forests that sequester carbon very well.

For wood harvested from managed forests to be "climate-friendly," the carbon it contains must remain in products for a long time. Given the European Union's half-life values for products, the weighted average retention of carbon in harvested wood products in Estonia is less than ten years. This is shorter than, say, natural decomposition of wood in a forest.

Proponents of forestry intensification also often cite the substitution effect (wood products and energy can replace those made from fossil raw materials), however scientific research indicates that its potential impact is transient and often poorly understood.

Also, in terms of financial profit the authors' proposed method is neither sustainable nor the only viable option. As the Estonian forestry sector has become a carbon emitter rather than a carbon sink in the eyes of the European Union, we will soon have to pay for forest management if the current forest use continues, i.e. carbon quotas will become a significant cost for the state rather than a source of revenue.

Actually, it is simple to control this cost: let's not release carbon trapped in old trees for decades and centuries in order to manufacture wood pellets.

In many cases, not doing things in nature is the best way to control costs and even generate revenue.

A reduction in the intensity of forest management is not necessarily accompanied by a decline in employment or even forest income. The amount of wood processed per worker in Estonia's forestry industry is among the highest in Europe. Graphs from a few years ago illustrate a reduction in employment during a period of growing deforestation. This is where efficiency did not benefit us.

Cutting through wood quickly does not add value to the bio-resource, and such apparent productivity does not maximize our returns.

What is maximized in this management model is possibly the very short-term gain to (some) people, but the long-term cost to the rest of society through environmental degradation. If we want to leave our children a world at least as good as the one we inherited from our parents, we should not compromise on this. The current fast profit comes at the expense of future generations.

The national question we should be addressing now is how to create more forest-related jobs in a sustainable way. There are options, such as recreation, tourism, nature education, innovative solutions for using Estonian woods, and recognizing the importance of keeping forests growing (e.g. offering opportunities for carbon credit investments).

We could try to generate revenue and maintain jobs while allowing old carbon-storing forests to grow. These forests would provide us with 'ecosystem services' such as habitat preservation, berry-hiking opportunities, carbon storage, and, indeed, carbon sequestration. Old trees produce trunks and branches, twigs and leaves, tree-feeding organism biomass and forest soil — and to do so, it takes material from carbon dioxide captured from the atmosphere.

The species richness of less intensively managed or even unmanaged forests helps to integrate natural processes and mitigates the negative effects of climate change and other environmental threats.

Species diversity is linked to the abundance and diversity of functions — plants, animals and soil organisms with different traits and life histories each have their own "niche" for carbon sequestration, storage and other tasks needed in nature; therefore, diversity, the abundance of various species and their characteristics, helps to preserve resilient and functional ecosystems.

The abundance of plant-dependent species is one of the forest floor's most important carbon sinks.

For example, root-feeding worms (nematodes) supply food for the following links in the food chain and extensive clear-cutting is a disaster for them; all of the carbon stored in that food chain is lost, and recovery is a lengthy process.

Even when the trees are the same age in managed and unmanaged forests, the soil in managed forests has been proven to retain much less root-associated carbon.

Natural, species-rich stands are much more tolerant to the effects of climate change, including insect outbreaks, droughts, and extreme weather events, than species-impoverished, intensively managed forests. Species diversity has a favorable effect on wood volume as well: data from Estonian forests show that forests with higher species richness in soil fungi, plants and mosses contain more wood than those with fewer species.

Autumn forest. Source: Minupilt.err.ee/Raili Raidma

In forests, trees are not the exclusive carbon sinks. Particularly peat soils contain a considerable part of the carbon in forest ecosystems. Intensive management degrades the soil and its microbial ecosystems, which leads to the exposure of logging sites to sun radiation.

Decomposing fungal mycelium and tree roots emit enormous quantities of carbon dioxide, resulting in a 10-20 percent decrease in the soil's carbon content. In most situations, soil carbon reserves require more than 50 years to replenish.

In light of the climate crisis peatland restoration plays multiple crucial functions.

We will cut the present amount of carbon dioxide generated by peat breakdown due to drainage, which is at least equivalent to the emissions of the entire Estonian transportation industry.

Restoring peatlands is also the least expensive method of permanently removing carbon from the atmosphere by sequestering it in healthy peat.

In light of prolonged droughts, peatlands' harmonising effect on the water regimes of more intensively used landscapes and rivers is becoming increasingly important. The reforestation of already drained peat soils into peat swamp forests that are typical of the Estonian landscape, is highly desirable since it will increase both carbon sequestration in trees and long-term carbon storage in peat soils.

Continued indiscriminate drainage of peat soils, on the other hand, will result in a large release of carbon, nutrients and sediments that have been stored in peat for millennia. We should think carefully about renewing drainage on peaty or drought-prone soils.

The authors of the article are right in that we should look for ways to mitigate the climate crisis: we propose adopting methods that are successful, based on science and do not compromise natural habitats or economic sustainability.

Our solution entails making optimal use of the self-sustaining mechanisms of entire ecosystems, which function most efficiently without excessive human intervention.

Ecosystems that are in good working condition are our best allies in attempting to address the climate crisis and other man-made environmental challenges.

Tuul Sepp, ecologist; Marko Kohv, wetlands restorer; Evelyn Uuemaa, geo-informatics; Meelis Pärtel, ecologist; Martin Zobel, ecologist; Raul Rosenvald, forestry researcher; Mari Moora, ecologist; Ülo Mander, physical geography; Urmas Saarma, biology, Tiit Tammaru, human geography; Ain Kull, physical geography; Leho Tedersoo, soil micro-biology; Marko Mägi, avian ecology; Aveliina Helm, habitat restoration expert; Laimdota Truus, wetlands researcher; Mati Ilomets, wetlands researcher; Ivika Ostonen-Märtin, ecophysiology. 

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Editor: Kristina Kersa

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