The study, led by Mathilde Pau of the University of Liège’s Gembloux Agro-Bio Tech together with colleagues at UCLouvain, the Canadian Forest Service and INRAE, used a process-based forest model called HETEROFOR to peer 120 years into the future. Unlike purely statistical growth models, HETEROFOR simulates individual trees, tracking carbon fluxes, water cycling, light competition and tree-to-tree interactions in spatially explicit stands. That level of detail matters when the question is not simply whether a forest survives, but whether it regenerates, produces timber, stores carbon and maintains a varied structure under the combined stresses of warming and herbivory.

The researchers ran their simulations across six representative stands typical of Western European broadleaved forests dominated by European beech (Fagus sylvatica) and oaks (Quercus species). These are the workhorses of temperate European forestry, ecologically and economically, and they are increasingly vulnerable. Climate change is already altering growth patterns across the continent, with drought and heat events linked to declining vitality in beech in particular. At the same time, populations of red deer, roe deer and wild boar have risen sharply in many regions, and their browsing on seedlings and saplings can quietly erase an entire generation of trees long before foresters notice the gap.

To capture this interplay, the team built a factorial experiment of unusual scope. Each stand was simulated under three climate scenarios drawn from the shared socio-economic pathways: SSP1-2.6 representing low warming, SSP2-4.5 an intermediate trajectory, and SSP3-7.0 a high-warming future. On top of that, they applied four levels of ungulate browsing pressure, from negligible to intense. And across all of these combinations they tested three silvicultural strategies: a business-as-usual even-aged approach mirroring current practice in the studied public forests; an oak-oriented strategy promoting moderate species diversification; and a more ambitious diversification scheme combining species enrichment with increased structural heterogeneity, the kind of close-to-nature management many European foresters advocate as the path to resilience.

Performance was judged with 32 indicators, distilled into six scores covering productivity, profitability, economic sustainability, carbon storage, species diversity and structural diversity. This multidimensional scorecard is what makes the study’s central finding so striking. The diversification strategies did exactly what their proponents promise: they enhanced species diversity while keeping the forest economically sustainable. But their benefits were strongly conditional on browsing pressure. Under low to moderate ungulate densities, diversification delivered the best balance of ecological and economic outcomes. Under high browsing intensity, those advantages vanished, and the diversified stands suffered marked declines in productivity, carbon storage, economic sustainability, and both species and structural diversity.

The reason lies in the biology of regeneration. Diversification strategies depend on successfully establishing a wider range of tree species, many of which are precisely the seedlings deer prefer to eat. Palatable species such as oaks and various broadleaved companions face a browsing gauntlet that unpalatable or simply more abundant competitors may escape. When deer numbers are high, the carefully planted or naturally recruited mixture collapses toward whatever the animals leave behind, undermining both the species mix and the structural complexity the strategy was designed to create. Even-aged conventional management, by contrast, proved less sensitive to browsing, partly because large clearcut-style regenerations can overwhelm browsers with sheer seedling numbers, but it produced the lowest species diversity of the three approaches, locking forests into a less adaptable future.

The economic dimension adds a layer of urgency. Diversification is expensive: it requires more labour, more planting, more careful tending, and it delays returns compared with conventional even-aged forestry. Economic uncertainty is a major reason adoption remains limited despite widespread scientific endorsement. The study’s results suggest that foresters and policymakers who invest in diversification while ignoring ungulate management may be pouring resources into forests that cannot convert that investment into actual diversity. Conversely, where browsing pressure is genuinely low, the simulations indicate diversification can pay off across nearly the whole scorecard, from carbon to profitability.

These findings arrive at a moment when European forest policy is pushing hard toward mixed, structurally complex stands. The rationale is well supported: diverse forests tend to resist disturbances better, buffer drought through complementary water use, support more biodiversity and may store carbon more reliably. But the Belgian study adds a crucial third variable to the equation. Climate scenarios alone did not determine outcomes; the interaction between climate, management and browsing did. A forest could be given the right species mix and the right structure on paper, yet fail to regenerate into that vision if ungulates browse the future away. The authors emphasize that diversification alone is unlikely to ensure forest adaptation where ungulate pressure remains high.

The implications reach well beyond Belgium. Rising ungulate densities are a continent-wide phenomenon, driven by factors including reduced hunting pressure in some areas, milder winters, abundant forest-edge habitat and fragmented landscapes that favour deer. Previous research has documented how browsing shapes climate-change impacts on forest biodiversity elsewhere in Europe, and how ungulate herbivory can manipulate vegetation trajectories for decades. What this study adds is a quantitative, forward-looking framework that puts herbivory on equal footing with climate and management in long-term forest projections, something few simulation studies have attempted at this resolution.

For forest managers, the practical message is a sequencing one: get ungulate pressure under control first, or at least simultaneously, before committing to costly diversification programs. That may mean coordinated hunting regimes, fencing, or landscape-level population management, all of which carry their own social and economic challenges. For scientists, the study demonstrates the value of process-based, tree-level models like HETEROFOR for stress-testing management strategies against multiple simultaneous uncertainties rather than one factor at a time. And for anyone who imagines that planting the right trees is enough to climate-proof a forest, the Belgian Ardennes offer a cautionary tale: the forest of 2146 will be written not only by the seeds foresters choose, but by what the deer leave standing.

Subject of Research: Silvicultural diversification, ungulate browsing and climate change effects on temperate broadleaved forest regeneration

Article Title: Impact of contrasting silvicultural strategies on broadleaved forest regeneration under various levels of ungulate pressure and changing climate in Belgium

Article References: Pau, M., Jonard, M., André, F., Fortin, M., de Coligny, F., & Ligot, G. (2026). Impact of contrasting silvicultural strategies on broadleaved forest regeneration under various levels of ungulate pressure and changing climate in Belgium. Regional Environmental Change, 26(4), Article 190. https://doi.org/10.1007/s10113-026-02673-0

Image Credits: AI Generated

DOI: 10.1007/s10113-026-02673-0

Keywords: forest regeneration, silviculture, climate change, ungulate browsing, forest diversification, HETEROFOR model, beech, oak, Belgium, carbon storage, forest management, species diversity

The study, published in Nature, examined 290 trees from 18 species growing in forests that receive between 1,000 and 4,000 millimetres of rain each year. This natural gradient allowed the researchers to compare trees exposed to substantially different levels of water availability without relying solely on short-term laboratory experiments. Across the sampled trees, the team measured 11 hydraulic traits associated with the movement, regulation and loss of water through plants. Together, these traits provide a detailed picture of how trees manage the tension between capturing carbon dioxide for photosynthesis and avoiding catastrophic dehydration.

Drought is especially dangerous for trees because water transport through the plant can fail in several ways. Trees move water from the soil to their leaves through a continuous column inside microscopic conduits in the xylem. When drought creates sufficiently negative pressure in this water column, air bubbles can form and spread through the conduits, a process known as embolism. Once enough conduits become blocked, water can no longer reach the leaves and tissues above the damaged region. Severe hydraulic failure can eventually stop photosynthesis, cause tissue death and, in extreme cases, kill the entire tree.

One of the most important measurements in the study was embolism resistance, which describes how much negative pressure a tree’s water-transport system can withstand before it begins to fail. The researchers also examined stomatal safety margins, the distance between the water potential at which a tree closes its stomata and the level at which serious hydraulic damage occurs. Stomata are microscopic pores on leaves that regulate gas exchange. By closing them, trees reduce water loss, but they also limit carbon uptake and photosynthesis. A wider safety margin means that a tree can continue exchanging gases while remaining farther from the point of hydraulic failure.

The results challenge a long-standing assumption based largely on research in temperate forests. Earlier studies had often found limited variation within a species in traits such as resistance to xylem embolism. That apparent uniformity raised the possibility that hydraulic traits were strongly constrained by evolution, leaving species with only limited capacity to adapt to changing climates. The Puerto Rican data tell a different story. Substantial differences occurred among individuals of the same species, and those differences were organized along the rainfall gradient rather than appearing as random noise.

Most of the species examined showed greater embolism resistance in the drier forests. Trees living where rainfall was lower also tended to maintain wider stomatal safety margins, indicating that their leaves and water-transport systems were better positioned to avoid damage during periods of water stress. These shifts were not restricted to differences between species, such as a wet-forest species being replaced by a naturally drought-tolerant species. Instead, many of the same species appeared to express different hydraulic characteristics depending on the environments in which they grew.

That distinction is crucial for predicting the future of tropical forests. If scientists consider only species turnover, they may assume that a forest becomes more drought resistant mainly because vulnerable species disappear and drought-tolerant species become more common. The new findings suggest that forests can also change through adjustment within species. Individuals of a single species may differ in the construction and operation of their hydraulic systems, allowing populations to persist across a wider environmental range than their average traits would suggest.

The study does not imply that all trees can adapt indefinitely or that tropical forests are protected from climate change. Intraspecific variation may arise from genetic differences, developmental conditions, environmental plasticity or a combination of these factors, and the research does not establish that every observed difference will be inherited by future generations. There may also be limits to how far a tree can shift its hydraulic traits before growth, reproduction or carbon gain are compromised. A tree that closes its stomata early may avoid embolism, for example, but it may also photosynthesize less and grow more slowly.

The researchers therefore emphasize that species lacking meaningful hydraulic variation could be especially vulnerable as droughts intensify. Climate models increasingly project changes in rainfall patterns, longer dry seasons and more frequent extreme droughts in many tropical regions. Forests that appear stable under present conditions may cross critical thresholds when atmospheric demand for water rises or when soils remain dry for longer periods. Forecasting those changes will require models that represent not only which species are present, but also how individuals within each species differ in their capacity to transport and conserve water.

The findings offer a more dynamic view of forest resilience, in which tropical trees are neither hydraulically identical nor locked into a single drought strategy. Instead, resilience emerges from the combined effects of species composition and variation among individuals. By incorporating both sources of diversity, scientists may be able to identify forests with hidden adaptive capacity, detect populations at greatest risk and improve predictions of which ecosystems will withstand a hotter and drier future. For tropical forests facing accelerating climate pressure, the most important survival trait may not belong to a species as a whole, but to the variation hidden within it.

Subject of Research: Intraspecific variation in hydraulic traits and drought resistance among tropical forest trees.

Article Title: Species intraspecific variation drives tropical forest drought resistance.

Article References: Smith-Martin, C.M., Muscarella, R., Brodribb, T.J. et al. Species intraspecific variation drives tropical forest drought resistance. Nature (2026). https://doi.org/10.1038/s41586-026-10870-4

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41586-026-10870-4

Keywords: Tropical forests, drought resistance, climate change, tree mortality, hydraulic traits, embolism resistance, stomatal safety margins, intraspecific variation, forest resilience, Puerto Rico.

A promising alternative gaining traction is continuous-cover forestry (CCF), a method inspired by natural forest dynamics. This approach emphasizes selective tree harvesting that creates small-scale, spatially discrete canopy disturbances, such as gaps measuring only a few hundred square meters, rather than extensive clear-cut areas. By maintaining a continuous canopy cover, CCF helps preserve the forest’s cool, humid microclimate, which is critical for many forest-dependent species and ecological processes. This management style supports a more naturalistic successional trajectory, balancing timber production with conservation goals.

Yet, implementing continuous-cover forestry in oak-dominated ecosystems presents unique challenges, primarily because sessile oak (Quercus petraea) and related species exhibit specific light requirements and regeneration patterns. Unlike shade-tolerant species, oaks demand ample light to regenerate effectively. However, overly large openings in the canopy may favor the rapid growth of competing woody and herbaceous plants, potentially suppressing young oak saplings. Thus, identifying the optimal gap size and shape that promote oak establishment while minimizing competitive pressures is a critical question for foresters aiming to transition to CCF.

A groundbreaking study by the Forest Ecology Research Group at the HUN-REN Centre for Ecological Research seeks to address these challenges through rigorous experimental investigation. Conducted in the sessile oak–hornbeam forests of Hungary’s Pilis Mountains, this research forms part of the broader Pilis Gap Experiment, which explores how manipulated canopy gaps influence microclimate, vegetation dynamics, and tree regeneration processes. The research team, working in concert with forest practitioners from Pilis Park Forestry Company, tested the effects of gap size and geometry, comparing circular and elongated openings of varying dimensions.

The experimental results reveal nuanced interactions between gap characteristics and forest regeneration outcomes. Large circular gaps initially provide the most favorable abiotic conditions—enhanced light availability and increased soil moisture—that stimulate vigorous oak sapling growth. When competing vegetation is carefully managed through tending, oak saplings in these large gaps demonstrate rapid development, reflecting the surfeit of resources. However, the very qualities that favor oak growth also promote the proliferation of competitive species such as hornbeam (Carpinus betulus), dogwood (Cornus sanguinea), and bramble (Rubus fruticosus agg.).

This intense competition quickly diminishes the advantages conferred by the large circular gaps as dense shrub layers inhibit oak seedlings’ access to light and moisture. Consequently, while large circular gaps can initiate oak regeneration, sustaining this regeneration demands intensive and ongoing vegetation control, which may be labor-intensive and economically taxing. This finding highlights the trade-offs between optimizing growth conditions and management effort inherent in canopy gap design.

Interestingly, the study identifies elongated gaps as a more balanced alternative. These gaps provide high light availability comparable to circular gaps of equal area, but they induce a more moderate increase in soil moisture. This moderation limits the spread of competitive understory species, reducing the necessity for intensive maintenance. Among elongated gap treatments, smaller-sized openings showed even less competition pressure due to their more constrained light regime, further easing management burdens.

Despite the slower initial growth rates observed in oaks regenerating within small elongated gaps, the researchers argue that such early growth differences are relatively minor within the context of oaks’ extended lifespans. Sessile oaks typically reach harvest maturity after over a century; thus, initial growth velocity may be less critical than long-term survival and site establishment. The controlled pioneering environment within these smaller elongated gaps facilitates steady progression without succumbing to aggressive competitors.

The study also underscores that these small elongated gaps may require adaptive management strategies. After five to six years, as oak saplings grow and their light-demand increases, the limited light environment in the initially smaller gaps may no longer suffice. The authors suggest that carefully planned gap enlargement at this stage could sustain favorable growth conditions while maintaining the benefits of continuous forest cover. Such dynamic management interventions would reflect a more nuanced, long-term perspective on forest regeneration.

Beyond microclimatic and competitive considerations, small elongated gaps offer an overlooked advantage: they enhance seed dispersal and acorn settlement from adjacent mature oak trees. The elongated form likely facilitates seed rain penetration deeper into the gap center, ensuring more uniform regeneration across the gap and potentially supporting greater genetic diversity within regenerating cohorts. This spatial configuration could thus improve the success rate and resilience of natural oak recruitment.

Overall, these findings provide compelling evidence that carefully designed canopy gap geometries can simultaneously promote natural oak regeneration and maintain continuous canopy cover, a cornerstone objective of continuous-cover forestry. By integrating experimental evidence with practical forester experience, the research offers actionable guidelines to optimize forest disturbance patterns, balancing ecological function with economic viability. The authors emphasize that this approach aligns with a broader vision of forest management fostering mixed-species stands rather than near-monocultures typical of traditional rotation forestry.

In embracing species-diverse forest compositions, management can harness complementary ecological interactions that bolster forest resilience, reduce pest outbreaks, and stabilize economic returns under variable climatic conditions. The Pilis Gap Experiment thus contributes valuable insights into the mechanistic underpinnings of forest dynamics and the practical pathways to sustainable forestry in the face of climate change and evolving societal expectations.

Flóra Tinya, lead author and research fellow at the Forest Ecology Research Group, encapsulates the study’s broader significance: transitioning from well-established rotation forestry systems to innovative continuous-cover approaches requires not just conceptual shifts but also rigorous, science-based evidence to guide practice. This work exemplifies the synergy between fundamental ecological research and applied forestry, supporting a future in which forests remain vibrant, productive, and resilient across generations.

By demonstrating that elongated, small-scale canopy gaps offer an optimal balance between abiotic conditions and management effort, this research charts a promising course for forest managers worldwide seeking to reconcile timber production with biodiversity conservation and climate adaptation. Its implications resonate far beyond the Pilis Mountains, offering a model for restoring naturalistic forest structures in temperate regions and beyond.

Subject of Research:
Article Title: Elongated gaps provide a good compromise between abiotic and competitive conditions for sessile oak regeneration
News Publication Date: 16-May-2026
Web References: http://dx.doi.org/10.1016/j.fecs.2026.100472
References: [Forest Ecology Research Group, Pilis Gap Experiment publications]
Image Credits: Photo: Flóra Tinya
Keywords: continuous-cover forestry, oak regeneration, canopy gaps, sessile oak, forest management, ecosystem resilience, microclimate, competition, selective thinning, sustainable forestry, Pilis Mountains, forest biodiversity

Forest disturbances—such as wildfires, storms, pest outbreaks, and pathogen invasions—are natural ecological phenomena that reset successional stages and influence biodiversity. Traditionally, their occurrence and intensity have fluctuated within ecological thresholds. However, climate change is pushing these disturbances beyond historical norms in both severity and frequency. Warmer temperatures, altered precipitation patterns, and increased atmospheric CO2 concentration are creating conditions conducive to more destructive and widespread disturbances, threatening forest stability and the economic returns derived from timber production. This evolution represents a profound risk to Europe’s forests, which support substantial economic activities and provide critical ecosystem services.

The economic implications of these climatic shifts are profound. Timber-based forestry is a significant contributor to European economies, not only in rural employment but also in supplying raw materials to various industries including construction, paper, and bioenergy. The study under discussion projects that forest disturbances driven by climate change could result in losses of up to €247 billion across Europe’s forestry sector. This staggering figure underscores a looming crisis that could destabilize economic systems dependent on reliable timber supplies. It also signals potential knock-on effects for industries and communities reliant on forest-related livelihoods, highlighting an urgent need for adaptive management and policy interventions.

However, the story is not uniformly bleak. Some regions in Europe are poised to experience an increase in forest productivity, attributable to factors such as longer growing seasons, elevated CO2 fertilization effects, and enhanced nutrient availability under certain climatic scenarios. This positive productivity response can partially offset the negative impacts of disturbances, leading to a net balance or even gains in timber yield in specific locales. The interplay between disturbance regimes and productivity gains underscores the heterogeneity of climate change impacts on forests, necessitating localized assessments and tailored adaptation strategies.

To unravel these complex dynamics, researchers employed a sophisticated modeling approach integrating climate projections, disturbance regimes, and forest growth parameters. By synthesizing vast datasets and utilizing advanced Earth system models, they simulated future forest conditions under various climate scenarios extending into the coming decades. This methodology allows for nuanced quantification of potential timber losses and productivity changes both regionally and continent-wide, offering critical insights into risk hotspots and opportunities for resilience building.

One noteworthy finding from these simulations is the predicted intensification of disturbance events, with scenarios indicating a doubling or even tripling of wildfire occurrences in southern and southeastern Europe. These areas, already prone to dry conditions and heatwaves, face exacerbated drought stress that sensitizes forests to fire ignition and spread. The consequences are severe: not only are volumes of marketable timber reduced, but forest structures and species composition may shift irreversibly, threatening long-term forest viability. This ecological turnover could compromise the regenerative capacity of forests, with successive disturbance events leaving little time for recovery.

Similarly, northern and central European forests are expected to confront heightened storm damage and pest outbreaks as warming trends enable invasive species and pathogens to proliferate. Warmer winters reduce natural pest mortality, permitting population surges that defoliate vast tracts of forest. Combined with the physical uprooting of trees during more frequent and intense storms, this creates a compounded disturbance effect that undermines timber stocks. The economic ramifications here are equally significant, as industries in these regions rely heavily on spruce and pine species vulnerable to such stresses.

Conversely, some parts of Europe, notably those in mid-to-northern latitudes characterized by cooler baseline climates, might benefit from warming-driven growth acceleration. Enhanced photosynthetic rates due to elevated CO2 and extended periods of suitable growth conditions can increase biomass accumulation. This increased carbon sequestration potential aligns with mitigation goals in climate policy frameworks. Yet, even in these “winner” regions, uncertainty remains regarding the sustainability of productivity gains, given the unpredictable nature of disturbance interplay and resource limitations like soil nutrients and water availability.

The research further emphasizes the importance of incorporating disturbance dynamics into forest management and economic planning. Traditional timber harvest projections that omit disturbance considerations risk grossly overestimating future yields and underestimating economic vulnerabilities. Adaptive strategies, including diversifying species composition, adopting silvicultural practices that enhance resilience, and intensifying monitoring of pest and fire outbreaks, emerge as critical responses. Moreover, integrating economic models with ecological simulations aids policymakers in balancing immediate forest utilization with long-term sustainability.

The potential €247 billion loss estimate, while alarming, is not a fixed destiny but a projection contingent on emissions trajectories, mitigation efforts, and management responses. This figure encapsulates cumulative impacts over several decades, reflecting both the direct timber value at market prices and indirect economic effects stemming from supply chain disturbances. It places forest ecosystems squarely at the center of the climate adaptation dialogue, reinforcing the need for concerted action at local, national, and European Union levels.

Importantly, this study highlights the value of cross-disciplinary collaboration, bridging climatology, ecology, forestry, and economics to address multifaceted challenges. The increased severity of forest disturbances serves as a potent reminder that climate change is not an abstract distant threat but a present-day disruptor of vital economic sectors. In the context of the European Green Deal and global commitments to carbon neutrality, these findings provide a pragmatic foundation for integrating ecosystem resilience into broader sustainability agendas.

Technological advancements, including remote sensing, high-resolution climate modeling, and genetic forest improvement, offer promising avenues to monitor, predict, and mitigate disturbance impacts. For instance, real-time fire detection satellites and pest surveillance systems can enable rapid response, reducing timber losses. Simultaneously, breeding and planting tree species with enhanced drought and pest resistance might buffer forests against climate stressors. Yet, such interventions require significant investment, policy support, and stakeholder engagement to realize their full potential.

Public awareness and community involvement also emerge as pivotal components in forest disturbance mitigation. Many forested landscapes are intertwined with rural populations whose livelihoods and cultural identities are linked to forestry. Empowering these communities with knowledge, resources, and participation opportunities fosters stewardship and resilience. Furthermore, this social dimension ensures that economic losses do not translate into social crises but rather galvanize localized innovation and adaptation.

In sum, Europe stands at a crossroads, facing a dual-edged future for its forests under climate change. While escalating disturbance regimes threaten substantial timber-based economic value, regional productivity enhancements provide a glimmer of hope. Understanding the nuances of these interactions, grounded in robust scientific inquiry, paves the way for informed policy decisions and sustainable forest management. The magnitude of potential losses demands urgency but also inspires innovation to safeguard Europe’s forests as pillars of ecological health and economic vitality in a warming world.

As climate action intensifies globally, integrating forest disturbance risk into adaptive frameworks will be essential for aligning conservation objectives with economic resilience. By addressing these challenges proactively, Europe can not only mitigate anticipated timber losses but also harness opportunities to transform its forest sector into a model of sustainable, climate-smart resource management for the 21st century and beyond.

Subject of Research: The economic and ecological impacts of climate change–induced forest disturbances on Europe’s timber-based forestry sector, including projections of timber loss and regional productivity changes.

Article Title:

Article References:

Image Credits: AI Generated

DOI:

Keywords: Climate change, forest disturbances, timber economy, Europe, forest productivity, wildfire, pest outbreaks, storm damage, forest resilience, ecological modeling