Research updates

Assisted tree migration can preserve the European forest carbon sink under climate change

Assisted migration aims to enhance the resilience of forest tree populations to climate change by transferring seeds or seedlings from regions with suitable climatic conditions, based on species-specific limits and local adaptations. Chakraborty et al. project that Europe’s annual forest carbon sink could decline by 30–40% by 2061–2080, depending on the climate scenario, if forest restoration relies solely on local tree populations. However, if seed provenances adapted to future climates are used, current sinks could be maintained or even increased.

Tree species abundance changes at the edges of their climatic distribution

Climate change is affecting trees at the edges of their climate limits, but its impact is unclear. A study in Spain analyzed 445,000 trees over 25 years to see how climate, traits, and forest regrowth influence tree abundance. Overall, tree numbers increased, especially in colder, wetter areas. Forest regrowth was key, but climate change favored species that prioritize fast resource uptake. This shows past forest use shaped today’s tree amounts, but climate change now selects which species thrive.

Marteloscopes as sites of encounter between climate activists and forest managers

John et al. used silvicultural training sites, marteloscopes, to study deliberate communication on multifunctional forest management between foresters and young climate activists. Their study suggests that simulated decision-making, combined with being in the forest, can lead to shared experiences where non-professional participants can both learn about and experiment with professional forestry knowledge. They also observed a noticeable knowledge hierarchy, which is a potential barrier to open deliberative processes.

Identifying suitable areas for plenter forest management

Plenter forests, or steady-state uneven-aged forest management, enhance resilience and resistance to disturbances compared to even-aged forest. Leiter et al. outline a method to identify suitable areas for plenter forest management in central European mixed forests, considering ecological, technical, and climate factors. They estimate that 28.1% of Styria's forests are currently suitable for plenter forest with silver fir and at least one additional shade tolerant species. However, this potential decreases under future climate scenarios, due to silver fir’s adaptation difficulties. These findings can guide forest management under climate change.

Agroforestry and urban forestry can share more and learn from each other

Agroforestry and urban forestry have evolved mainly as separate disciplines, sharing a long history of tree cultivation in man-made environments. Both have potential to enhance multifunctional landscapes. Substantial research gaps offer opportunities for collaboration, such as tackling challenges in quantifying the monetary and socio-cultural value of ecosystem services and addressing issues related to environmental justice.

Small woody features in agricultural areas: Agroforestry systems of overlooked significance in Europe

Small woody features (SWF) like hedgerows and riparian buffers are vital yet underrecognized elements of agricultural landscapes. Rubio-Delgado et al. used LUCAS 2015 data to map agroforestry systems with SWF (AFSWF) across the EU, categorizing them into arable crops, grazed/ungrazed grasslands, and permanent crops. AFSWF cover 10% of the EU's land area, significantly exceeding common agroforestry systems. Results reveal diverse SWF types and regional disparities, emphasizing their role in biodiversity and productivity.

Economic performance of agroforestry practices in Europe and North America

Thiesmeier and Zander reviewed the literature published on the economic performance of temperate agroforestry (AF) systems in Europe and North America. The results show that generally AF is not able to compete with agricultural land use but there are exceptions. Compared to forestry, AF is generally able to achieve better economic outcomes. The economic performance depends on ecosystem service payments and policy support, as well as on soil and site characteristics, prices and profitability of individual system components.

Reconciling the EU forest, biodiversity, and climate strategies

Gregor et al. combined forest management simulations with robust multi-criteria optimization to develop strategies for multi-functional forests in Europe under climate change. The derived management portfolios reconcile demands for wood production and EU targets for biodiversity protection, climate change mitigation, and ecosystem services provision. Findings highlight significant conflicts between the various demands placed on European forests, requiring additional measures to alleviate the pressure on forests.

The enduring world forest carbon sink

By absorbing CO₂, forests play a crucial role in slowing climate change. By analysing forest data from boreal, temperate, and tropical regions, Pan et al. found that global forest carbon absorption was steady at around 3.5 to 3.6 Pg C per year in the 1990s to 2010s. The global land carbon sink has grown, implying an increase in the non-forest-land carbon sink, but its stability may be threatened by aging forests, ongoing deforestation, and increasing disturbances.

Through smoke to policy: Framing the EU forest fire policy landscape

New study analysed 354 legally and non-legally binding EU policy documents to see how forest fires are framed. Analysis resulted in six key frames, e.g. ‘Climate adaptation and resilience’ and ‘risk mitigation and protective governance’. The identified frames highlight different impacts, like effects on biodiversity or timber supply. The framing of forest fires is therefore interlinked with specific policy domains and the knowledge communities shaping these discussions.

Impacts of wildfire severity on plant community

Trotta et al. studied 35 field plots and satellite data for fire severity in the Karst forests of northeast Italy, one year after a large wildfire in 2022. They examined tree species, herbaceous diversity and functional traits, and found that some species, like downy oak, were more resistant to fire, while others, like smoke bush, were resilient through resprouting. Areas affected by higher fire severity had greater species richness and higher alien plant cover as a consequence, while native plant cover remained stable. 

Silvicultural regime shapes understory functional structure in European forests

Chianucci et al. analysed data from over 2000 plots across 11 European countries and found that different silvicultural regimes influence different facets of understory functional features. Intensive silvicultural regimes are associated with a decrease in functional diversity and an increase in functional redundancy in the forest understory, which may limit the range of ecosystem responses to environmental changes. Low harvesting intensity regimes maintained functional diversity and redundancy values compared to unmanaged conditions. The findings also show the importance of maintaining, promoting and monitoring unmanaged forests to assess their ecological properties and benchmark active silvicultural practices.

A technological biodiversity monitoring toolkit for biodiversity credits

The biodiversity credit market offers a crucial funding source for biodiversity conservation projects. Ford et al. reviewedmonitoring technologies commonly cited by biodiversity credit methodologies, e.g. (e)DNA metabarcoding, passive acoustic monitoring and other remote sensing methods. Technological solutions for biodiversity monitoring are not (yet) a cure-all but are key for verifiable monitoring at scale and should be combined with ground validation and human-collected ecological data.

3775-year-old wood burial supports “wood vaulting” as a durable carbon removal

Trees and plants capture carbon dioxide as they grow, but most of it is released quite quickly as foliage and wood decay. Zeng et al. found a 3775-year-old ancient wood log buried 2 metres below ground. Nearly perfectly preserved, its carbon loss was less than 5% compared to a modern sample. The authors suggest a hybrid nature-engineering approach for carbon removal by burying woody biomass in an environment without oxygen, like clay, to create wood vaults that may prevent degradation. 

Changes in planned and unplanned canopy openings are linked in Europe’s forests

Seidl & Senf investigated canopy disturbances at forest stand level identified in Europe using Landsat over the period 1986–2020 and covering 417,000 km². They distinguish between planned and unplanned canopy openings, i.e., disturbance by human land use versus by wind, bark beetles, and wildfire. They show that canopy openings by humans dominate the European forest disturbance regime, and that planned and unplanned canopy openings are not changing independently but do so as linked disturbances. This has implications for forest policy and forest risk management.

The relationship between forest structure and naturalness in the Finnish national forest inventory

To protect biodiversity, accurate identification of natural forests is crucial. Myllymäki et al. explored ways to measure forest “naturalness” in the Finnish forest inventory. They analysed tree sizes and spatial patterns using various metrics, and tested machine learning to help predict naturalness. Their results show that natural forests have a wider range of tree sizes and more clustered tree groupings compared to "near-natural" or "non-natural" ones. Their results highlight the need to enhance field recording of naturalness to improve both forest mapping and the quality of NFI assessments.

Historical maps improve the identification of forests with potentially high conservation value

To support forest conservation efforts in the Carpathians and beyond, Grabska-Szwagrzyk et al. used mid-19th century maps and remote sensing data to identify forests over 150 years old, minimizing the need for detailed fieldwork. Their method, applied to a 20,000 km² area in the Polish Carpathians—home to many high-value, unprotected forests—revealed 4200 km² of continuous forest cover since the mid-19th century, with half of this area lying outside protected zones.

Integrated global assessment of the natural forest carbon potential

Mo et al. combined ground-sourced and satellite-derived approaches to evaluate the scale of global forest carbon potential outside agricultural and urban lands. The study indicates that the total potential for additional forest carbon storage is 226 Gt. 61% of this can be achieved by protecting existing forests and allowing them to regrow to maturity. The remaining 39% can be achieved by reconnecting fragmented landscapes through community-driven ecosystem restoration and management.

Post-disturbance canopy recovery and the resilience of Europe’s forests

In the first continental-scale analysis of post-disturbance forest recovery in Europe, Senf and Seidl used satellite data from 1986–2018 across 35 countries. Their analyses show that 69% of Europe's forests recover from disturbances within 30 years, but 14% have low or critical resilience. With climate change potentially increasing natural disturbances, enhancing forest resilience should be a priority for management, by reducing the intensity of harvest and planting trees after disturbances.

Growing stock monitoring by European National Forest Inventories

Throughout history, wood resources have been essential for human welfare. The volume of growing stock (GS) is considered one of the most important forest attributes monitored by National Forest Inventories (NFIs) to inform policy decisions and forest management planning. Gschwantner et al. provide an up-to-date review focusing on large-area GS monitoring, from the history of European NFIs to current methods, as well as an outlook under changing climate and forest-based bioeconomy objectives.

Carbon carrying capacity in primary forests shows potential for achieving Green Deal 2030 target

Carbon accounting in the land sector needs a reference level to calculate past carbon losses and potential gains. The carbon carrying capacity of primary forests is an ecologically-based reference, estimating mitigation potential achievable through implementing forest protection and restoration measures. Analysing tree inventory data from 7,982 sites across Europe, Keith et al. found that protecting and restoring forests could yield 309 megatons of CO₂ equivalents annually, exceeding current sinks and aligning with the Green Deal 2030 target.

Simulating future wood consumption and the impacts on Europe's forest sink to 2070

The annual wood harvest in the EU was 1.1 m³ per year per capita in 2021. Rougieux et al. assess future management options and their impacts on the forest carbon sink. Their scenarios indicate that an intensified use of non-merchantable wood resources would reduce the area affected by direct management activities, and the forest carbon sink would almost meet the EU LULUCF target for forest land. Thereafter, however, the forest carbon sink will deteriorate rapidly due to increased wood consumption. Only a reduction in wood consumption appears to be compatible with the forest carbon budget which ensures meeting of the EU targets until 2050, while increase in harvesting intensity and wood utilisation could undermine those targets. 

Harmonization and variation of deadwood density and carbon concentration

For German forest greenhouse gases reporting, deadwood carbon stock is calculated using volume, deadwood density, and carbon concentration for each decay class. Herrmann et al. developed a method to harmonize data collected from literature to supplement and improve the German data. Their meta-analysis on Central European tree species found the IPCC default value of 50% might under- and overestimate the real carbon concentration of spruce, pine and beech, depending on the decay class, by about 4% at the maximum.

Could changes in forest management regimes enhance carbon sequestration and stock capacity?

Dalmonech et al. used a state-of-the-art biogeochemical forest growth model to simulate the effect of different management practices on productivity and carbon storage in European forests under 20 climate change scenarios. The study findings suggest that the business-as-usual forest management practices may be a close-to-optimum scheme for maintaining both the carbon uptake and woody stocks in forests, even under a changing climate. The results indicate that there is little further leeway to increase the carbon sink capacity in the forests without sacrificing the existing carbon storage. Instead, the authors emphasize that it is today crucial for EU countries to preserve forests’ functionalities under the pressure of the rapidly changing climate conditions, in order to maintain the climate mitigation potential and the supply of wood products and many ecological goods and services. The study highlights the limited potential for simultaneously increasing both net primary productivity (NPP) and potential carbon woody stocks (pCWS) through intensified management practices.

The structure of mountain forests across the Alps and the role of disturbance and recovery

Stritih et al. used spaceborne lidar data to identify forest structure patterns across the European Alps, covering over 10.5 million ha. They identified two alternative states: tall, closed-canopy forests (76%) and short, open-canopy forests (24%). Within 35 years after disturbance, 72% of forests recovered to a closed-canopy state, except in submediterranean forests where recovery is slower. As climate warming increases disturbances and causes thermophilization of vegetation, transitions to open-canopy conditions could become more likely in future. This could pose a challenge for forest management, as open-canopy forests have lower capacities for providing important ecosystem services.

Tree crown defoliation in forest monitoring

Tree crown defoliation is an important parameter in monitoring forests and climate disturbances, eg within the pan-European ICP Forests programme. Defoliation is defined as the loss of needles or leaves compared to a reference tree and serves as an unspecific indicator of tree health and vitality. Bussotti et al. highlight the need to connect defoliation levels with the physiological functioning of trees, as it integrates various intrinsic and extrinsic factors.  The authors propose a set of physiological indicators for application in forest monitoring programs, including water relations, photosynthesis and carbon metabolism, growth, and mineral nutrients of leaves. They emphasize the importance of integrating these physiological measurements with traditional visual assessments to improve the prediction of tree mortality and forest decline under changing climatic conditions.

Reporting carbon fluxes from unmanaged forest

Unmanaged land areas are not included in current national reports on greenhouse gas emissions for the Paris Agreement. Nabuurs et al. argue that CO₂ fluxes from all forest land need to be recorded to help track progress towards global climate targets and fill the knowledge gap. They propose a gradual 4-step transition process to start in 2-3 years’ time, including adequate financial support for developing countries to improve their monitoring systems. 

Early monitoring of forest wood-boring pests with remote sensing

Remote sensing technology is a powerful tool for monitoring different stages of pest disturbance in a timely manner. Luo et al. evaluate remote sensing platforms, such as ground instruments to monitor needles, unmanned aerial vehicles for stand evaluations, manned aircraft and satellites for larger scales, as well as sensor technology (eg LiDAR, radar) and detection models. Precisely identifying host tree species or differentiating between wood-boring pests causing similar damage is challenging.  

A synthesis of multi-taxa management experiments to guide forest biodiversity conservation in Europe

To develop ecologically sustainable forest management practices, it is important to understand the management impacts on forest-dwelling organisms.Tinya et al. study metadata from 28 experimental field studies on the effects of forestry treatments on multi-taxa biodiversity. Based on the results they pose 8 research questions for management- and ecology-oriented studies which could be upscaled to the European level, and set out 11 knowledge gaps which require additional field experiments. 

Sustainable economy trade-offs and conflicts in and with the forest

In the transition towards a sustainable economy, forests and their ecosystem services play a vital role. Schulz et al. propose a conceptual framework to describe and classify the potentially competing demands on forests and forest management, and the conflicts that may result. They suggest differentiating between goal conflicts at the policy formulation level, and trade-off situations in forest management and planning. They further distinguish between conflicts and trade-offs that occur “in” or “with” the forest.  

Laser scanning reveals potential underestimation of biomass carbon in temperate forest

Accurate assessments of above-ground biomass carbon stocks are needed to quantify the climate mitigation benefits of e.g. forest restoration. Calders et al. use 3D laser measurements across the full range of tree size and shape in a typical UK temperate forest to assess tree size-to-mass allometric models, used since the 1960s for biomass calculation. They find 1.77 times more biomass than expected, due to bias towards small trees in the original models, and more abundant large trees from changes in forest management.  

The European forest carbon budget under future climate conditions and current management practices

To meet carbon neutrality goals, the EU27 net carbon sink from forests should increase to −450 Mt CO2_eq yr⁻¹ by 2050. Pilli et al. use a meta-modelling approach to show that if current management practices are continued, the EU27 + UK forest carbon sink would decrease to c. −250 Mt CO_2eq yr⁻¹ in 2050 and −80 Mt CO2eq yr⁻¹ by 2100. However, climate change adds a considerable uncertainty, potentially nearly doubling or halving the sink associated with management.  

Temperature extremes of 2022 reduced carbon uptake by forests in Europe

Van der Woude et al. investigate the impact of the 2022 summer drought in central and SE Europe on carbon exchange between European forests and the atmosphere, using ground-and space-based monitoring platforms. They find a reduction of net biospheric carbon uptake, despite partial compensation by a warm autumn. Comparison to the 2018 drought suggests this is no longer an exceptional situation, and important to factor into Europe’s plans for net-zero greenhouse gas emissions that rely on carbon uptake by forests. 

Possibilities of mapping old-growth temperate forests by remote sensing in Europe

The EU Biodiversity strategy for 2030 calls for strict protection for primary and old-growth forests in Europe, leading to more efforts to identify and monitor them. Remote sensing offers a wide range of data and methods which can support the mapping of forests and their properties. Hirschmugl et al. explore parameter-based approaches such as using airborne laser scanning (ALS) data, direct approaches using machine learning algorithms, and indirect approaches via predictions based on existing data. 

Where are we now with European forest multi-taxon biodiversity and where can we head to?

Harmonised statistics and maps of forest biomass and increment in Europe

Assessing supply and demand shocks on roundwood prices in 5 European countries

The unexpected inflow of wood resources from disturbance-induced salvage logging (e.g. windthrow or bark beetle outbreak) can undermine the stability of forest-based value chains. Asada et al.’s econometric analysis examined short-term value chain resilience in AT, CZ, DE, FI and SE under such supply shocks. The results illustrate the importance of distinguishing quality grades of wood as lower quality pulpwood tends to decrease in price, while higher quality roundwood increases in price through a shortage effect.

Standardizing forestry terms and definitions across European biodiversity studies

The multitude of forestry terms used in European biodiversity studies hinders comparability and makes the assessment of the impacts of forest management on biodiversity highly context-dependent. Trentanovi et al. developed a harmonized terminology for vegetation and forest management-related information by taking a novel bottom-up and top-driven review process. The standards they propose could be adapted to other geographical areas and extended to other forest interventions.

Continuous forestry can boost carbon sequestration in Finnish peatlands

Trees outside forests contribute to European tree cover and woody biomass

A simple concept for estimating deadwood carbon in forests

Post-fire recovery of soil microbial functions is promoted by plant growth

Increasing evidence shows fires cause a shift in soil microbial communities which play a central role in forest carbon and nutrient cycling. To test how soil heating affects microbial functions, researchers heated a forest soil at 200°C or 450°C. Soil heating temporarily altered microbial functions and reduced soil functional diversity. Heating-induced nutrient availability stimulated grass growth, which increased the response to several substrates and increased functional diversity to values similar to unheated controls.

Increasing aridity causes larger and more severe forest fires across Europe

In a European-scale analysis of fire activity in response to increasing summer aridity, Grünig et al. used a multi-decadal, spatially explicit dataset of 64,448 fire events mapped from satellite data. They found that consistent climate sensitivity of forest fire regimes across biomes is significant, projecting that potential maximum fire size and maximum burn severity will increase across all biomes of Europe. The authors see a need for improved fire management and firefighting strategies.

Filling the gap on consistent and spatially explicit insect and disease forest disturbance data

Change of focus in remote sensing science could increase user-uptake in forestry

Remote sensing science often focuses on a particular data source or methodological development rather than the operational use of derived information. Fassnacht et al. see slow user-uptake, technical issues related to forest inventories, and map validation as challenges in using remote sensing in forest inventory and monitoring programmes. They recommend sharing success stories, addressing real-world problems, and promoting best practices to increase the user-uptake of new technologies.

Further understanding on soil C stabilization process and microbial processes needed

With 45% of global forest carbon stock in soil organic matter, we must consider the impact of planned management practices on soil processes and avoid turning soils from a Carbon and GHG sink into a source. Current modelling of climate change mitigation potential in forest soils considers stand biomass effects and climate-driven decomposition rates. Mäkipää et al. propose that future soil monitoring and modelling focus on linking processes of soil C stabilization with the functioning of soil microbiota.

Examining the environmental and economic complexities that define the forest industry

A deeper understanding of forest ecosystems and their complex interaction with social-economic dimensions and benefits is needed to support forestry and the forest industry to contribute holistically to sustainable development goals. Raihan reviews the ways in which forestry contributes to society economically and explores recent dynamics in European forest resources and European forestry industry trends, as well as the European policy context.

Capturing the effects of forest management on species richness

The effects of forest management on biodiversity are difficult to measure. However, many forest species rely on specific structures that may be modified by forest management. Zeller et al. analysed 85 studies to identify above-ground structural attributes that could be used to further develop biodiversity monitoring and forest management. Canopy gaps and structural attributes related to old-growth forests (e.g., stand age, share of large old trees) were mostly positively correlated with species richness.