Forest disturbances under climate change

Shifts in resource allocation and aggravation of foliage development restrict the growth rate of Picea abies under increasing atmospheric humidity at high latitudes

Global warming is accompanied by rising precipitation, atmospheric water vapour content, and specific humidity at high latitudes. The rising amount and frequency of rainfall increase the air relative humidity (RH) on a local scale, especially within forest canopies. We studied the effects of artificially elevated environmental humidity (RH and soil moisture) on leaf gas exchange, stomatal responses and growth of young Picea abies trees at the Free Air Humidity Manipulation site in eastern Estonia. Manipulation did not affect the net assimilation rate (An) but affected the stomatal responses, net photosynthetic efficiency (An/ci), and photosynthetic water-use efficiency (WUE). At an elevated air humidity (H), trees exhibited the highest stomatal conductance (gS) and lowest WUE, An/ci, and stomatal sensitivity to air vapour pressure deficit compared to trees growing under ambient conditions (C) and elevated soil moisture (I). Compared to C trees, H trees demonstrated reduced height growth, foliage biomass, and enhanced investments in fine roots referring to worsening soil nutrient availability. Tree growth decline can be explained by (1) foliage development retardation, (2) resource allocation changes, causing a shift in the photosynthetic to non-photosynthetic tissue ratio in favour of the latter, and (3) impaired nutrient uptake from the soil. Changes in stomatal responses make trees grown in a higher RH more vulnerable to weather extremes, also limiting tree growth and forest productivity. Increasing precipitation with concomitant increase in atmospheric humidity at high latitudes counteracts the expected enhancement of tree growth due to climate warming in mesic northern forests.

TimberTracer: a comprehensive framework for the evaluation of carbon sequestration by forest management and substitution of harvested wood products

BACKGROUND

Harvested wood products (HWPs) have a pivotal role in climate change mitigation, a recognition solidified in many Nationally Determined Contributions (NDCs) under the Paris Agreement. Integrating HWPs' greenhouse gas (GHG) emissions and removals into accounting requirements relies on typical decision-oriented tools known as wood product models (WPMs). The study introduces the TimberTracer (TT) framework, designed to simulate HWP carbon stock, substitution effects, and emissions from wood decay and bioenergy.

RESULTS

Coupled with the 3D-CMCC-FEM forest growth model, TimberTracer was applied to Laricio Pine (Pinus nigra subsp. laricio) in Italy's Bonis watershed, evaluating three forest management practices (clearcut, selective thinning, and shelterwood) and four wood-use scenarios (business as usual, increased recycling rate, extended average lifespan, and a simultaneous increase in both the recycling rate and the average lifespan) over a 140 year planning horizon, to assess the overall carbon balance of HWPs. Furthermore, this study evaluates the consequences of disregarding landfill methane emissions and relying on static substitution factors, assessing their impact on the mitigation potential of various options. This investigation, covering HWPs stock, carbon (C) emissions, and the substitution effect, revealed that selective thinning emerged as the optimal forest management scenario. In addition, a simultaneous 10% increase in both the recycling rate and half-life, under the so-called "sustainability" scenario, proved to be the optimal wood-use strategy. Finally, the analysis shows that failing to account for landfill methane emissions and the use of dynamic substitution can significantly overestimate the mitigation potential of various forest management and wood-use options, which underscores the critical importance of a comprehensive accounting in climate mitigation strategies involving HWPs.

CONCLUSIONS

Our study highlights the critical role of harvested wood products (HWPs) in climate change mitigation, as endorsed by multiple Nationally Determined Contributions (NDCs) under the Paris Agreement. Utilizing the TimberTracer framework coupled with the 3D-CMCC-FEM forest growth model, we identified selective thinning as the optimal forest management practice. Additionally, enhancing recycling rates and extending product lifespan effectively bolstered the carbon balance. Moreover, this study emphasizes the necessity of accounting for landfill methane emissions and dynamic product substitution, as failing to do so may significantly overestimate the mitigation potential of implemented projects. These findings offer actionable insights to optimize forest management strategies and advance climate change mitigation efforts.

Fire directly affects tree carbon balance and indirectly affects hydraulic function: consequences for post-fire mortality in two conifers

The mechanistic links between fire-caused injuries and post-fire tree mortality are poorly understood. Current hypotheses differentiate effects of fire on tree carbon balance and hydraulic function, yet critical uncertainties remain about the relative importance of each and how they interact. We utilize two prescribed burns with Douglas-fir and ponderosa pine to examine: the relative evidence for fire-caused changes in hydraulic function and carbon dynamics, and how such impacts relate to fire injuries; which impacts most likely lead to post-fire mortality; and how these impacts vary by species and burn timing (fall vs spring). We find that fire-caused impacts to non-structural carbohydrates (NSC) are immediate, persistent, correlated with crown injury severity, and strongly related to post-fire mortality. By contrast, hydraulic impacts are delayed and not directly attributable to fire-caused injuries, although some burned trees do exhibit signs of increased hydraulic dysfunction and water stress before death. This suggests that fire may indirectly affect tree water relations, possibly through an interaction with direct fire impacts on NSC. These findings offer a more nuanced understanding of fire's effect on post-fire tree function and mortality and are important in the context of increased fire activity in forests globally.

Divergent Climate Sensitivity and Spatiotemporal Instability in Radial Growth of Natural and Planted Pinus tabulaeformis Forests Across a Latitudinal Gradient

A deeper understanding of growth-climate relationships in natural forests (NFs) and planted forests (PFs) is crucial for the prediction of climate change impacts on forest productivity. Yet, the mechanisms and divergences in climatic responses between these forest types remain debated. This study investigated P. tabulaeformis NFs and PFs in China using tree-ring chronologies to analyze their radial growth responses to climatic factors and associated temporal-spatial dynamics. The results reveal significant negative correlations between radial growth and mean temperatures (Tmean) in August of the previous year and June of the current year, and positive correlations were observed with the September standardized precipitation evapotranspiration index (SPEI) of the previous year and May precipitation (PPT) and SPEI of the current year. Compared with NFs, PFs exhibited a heightened climatic sensitivity, with stronger inhibitory effects from prior- and current-year growing-season temperatures and greater SPEI influences during the growing season. Moving window analysis demonstrated higher temporal variability and more frequent short-term correlation shifts in PF growth-climate relationships. Spatially, NFs displayed latitudinal divergence, autumn Tmean shifted from growth-suppressive in southern regions to growth-promotive in the north, and winter SPEI transitioned from positive to negative correlations along the same gradient. However, PFs showed no significant spatial patterns. Relative importance analysis highlighted water availability (PPT and SPEI) as the dominant driver of NF growth, whereas temperature, moisture, and solar radiation co-regulated PF growth. These findings provide critical insights into climate-driven growth divergences between forest types and offer scientific support for the optimization of NF conservation and PF management under accelerating climate change.

Positive feedback from woodpeckers on deadwood decomposition via invertebrates

Plant matter decomposition is a linchpin of global carbon cycling,1,2 yet the role of vertebrates remains poorly understood.3 Woodpeckers are ubiquitous vertebrate inhabitants of forests, where they hack into deadwood to forage for small animals. Our study in a temperate forest revealed not only how this behavior significantly impacts deadwood decomposition through mechanical breakdown but also how its species specificity leads to positive feedback on decomposition rates. Investigating large logs from six conifer species over 6 years in a tree cemetery, we found that woodpeckers accelerated decomposition (both mass and volume losses) selectively in softer, more decomposable deadwood like that of Norway spruce (Picea abies), which hosted abundant wood-boring beetle larvae relative to the abundances in other tree species. This selectivity triggers a positive feedback loop: bottom-up drivers (low wood density and high water-holding capacity) foster abundant invertebrate prey, promoting top-down woodpecker foraging that fragments logs and exposes inner tissues to microbial decay. Positioning woodpeckers as a potential keystone wood decay agent, our study supports the growing call for integrating vertebrate contributions into global carbon cycling models.4 As the first study to elucidate the complex interactions between deadwood traits, invertebrate populations, and woodpecker activities, we aim to galvanize further research into their often-overlooked functional role as deadwood fragmenters. The conservation implications of these findings are profound, especially in light of the historical context where vertebrates that once performed key ecological functions are now endangered or extinct due to widespread anthropogenic activities.5,6,7,8,9.

Global risk of wildfire across timber production systems

Timber is worth $1.5 trillion US Dollars annually with demand rising, but wildfires increasingly threaten production. Plantations occupy 3% of forests globally and produce 33% of the world's timber, but a critical question is whether they are more vulnerable to stand-replacing wildfires than natural production forests. We combine forest management and wildfire data to estimate that 15.7 (14.7-16.7) million hectares of natural production forests and 1.4 (1.26-1.64) million hectares of plantations suffered stand-replacing wildfires between 2015 and 2022. Using statistical matching for 17 countries representing 50% of global production and 75% of burned timber-producing forest, we find plantations in temperate regions were twice as likely to suffer stand-replacing wildfires than natural production forests, including in vital timber-producing nations like China and Russia. Plantations in tropical regions showed no clear effect, with national differences ranging from 75% lower to 58% higher risk of burning. Given increasing global reliance on plantation timber, preventing wildfires through landscape-level planning, fire management, and increased plantation diversity is critical for global wood security.

Temperate forests can deliver future wood demand and climate-change mitigation dependent on afforestation and circularity

Global wood demand is expected to rise but supply capacity is questioned due to limited forest resources. Additionally, the global warming potential (GWP) impact of increased wood supply and use is not well understood. We propose a framework combining forest carbon modelling and dynamic consequential life-cycle assessment to evaluate this impact. Applying it to generic temperate forest, we show that afforestation to double productive forest area combined with enhanced productivity can meet lower-bound wood demand projections from 2058. Temperate forestry value-chains can achieve cumulative GWP benefit of up to 265 Tg CO2-equivalent (CO2e) by 2100 per 100,000 ha of forest (if expanded to 200,000 ha through afforestation). Net GWP balance depends on which overseas forests supply domestic shortfalls, how wood is used, and the rate of industrial decarbonisation. Increased wood-use could aid climate-change mitigation, providing it is coupled with a long-term planting strategy, enhanced forest productivity and efficient wood use.

Coping with five mismatches between policy and practice in hemiboreal forest stands and landscapes

Maintenance of forest ecosystems revolves around the long-term persistence and resilience of their components, structures and functions. Focusing on Europe's hemiboreal forests, we evaluate mismatches between naturally dynamic forest ecosystems and current forest management systems forming obstacles for developing closer-to-nature forest management. Using Lithuania as a case study, we (i) quantify the main forest vegetation community types using soil types, ground layer flora, and tree and shrub species, (ii) review the relationships among these vegetation communities and their predicted natural disturbance regimes, (iii) analyse changes in tree species composition, (iv) compare the life expectancy of trees with harvest age, and (v) compare the contemporary stand age distributions with predicted natural disturbance regimes stand age distributions. Results show five mismatches between current practices and policy visions. Despite identifying 17 natural hemiboreal forest vegetation communities only eight dominant stand tree species were reported in current forestry reporting. The areal extents of three different natural disturbance regimes were: gap dynamics - mixed broadleaved forests on wet-mesic very fertile sites (22%), succession - mixed spruce forests on fertile sites (49%), and cohort dynamics - Scots pine forest on poor fertility sites (30%). Changes in tree species composition showed declines of primary tree species of 12-71% for the three disturbance regimes. The ratio of natural expected life expectancy to harvest age varied from two-fold to eight-fold across different tree species. Stand age distributions in naturally dynamic forests and managed forests revealed a current dramatic deficit of old-growth stands. Coping with the five identified mismatches between natural forests and current forest management requires multiple solutions: (1) closer-to-nature forest management that emulate natural disturbance regimes at tree and stand scales, (2) landscape planning, and (3) multi-level governance approaches.

The state of wildfire and health research: emerging trends, challenges and gaps

BACKGROUND

The increasing frequency and severity of wildfires, exacerbated by climate change, population growth and land use changes, have escalated public health risks. These events are associated with respiratory and cardiovascular diseases and adverse mental health outcomes. Vulnerable populations, including children, older people and those with pre-existing health conditions, face particularly high risks.

METHODS

This study evaluates the existing literature on wildfire-related health impacts. Key variables include publication frequency, geographic distribution, collaborative networks and funding patterns.

RESULTS

Findings reveal a concentration of research in high-income regions, particularly North America and Europe, with limited studies from wildfire-prone but under-represented areas such as Latin America, Oceania, Africa and the Caribbean. This geographical disparity restricts comprehensive understanding and effective public health responses to wildfire impacts. The analysis also underscores the need for interdisciplinary approaches.

CONCLUSIONS

Wildfires continue to pose significant global public health challenges. There is a critical need for more inclusive research efforts, enhanced international collaboration and a stronger focus on health-specific outcomes, especially in under-represented regions. Expanding research in these areas is essential to inform effective public health policies and interventions that address the health risks posed by wildfires worldwide.

Temperature Drives Seagrass Recovery Across the Western North Atlantic

Climate-driven shifts in herbivores, temperature, and nutrient runoff threaten coastal ecosystem resilience. However, ecological resilience, particularly for foundation species, remains poorly understood due to the scarcity of field experiments conducted across appropriate spatial and temporal scales that investigate multiple stressors. This study evaluates the resilience of a widespread tropical marine plant (turtlegrass) to disturbances across its geographic range and examines how environmental gradients in (a)biotic factors influence recovery. We assessed turtlegrass resilience by following recovery rates for a year after a simulated pulse disturbance (complete above- and belowground biomass removal). Contrary to studies in temperate areas, higher temperature generally enhanced seagrass recovery. While nutrients had minimal individual effects, they reduced aboveground recovery when combined with high levels of herbivore grazing (meso and megaherbivore). Belowground recovery was also affected by combined high levels of nutrients and grazing (megaherbivores only). Light availability had minimal effects. Our results suggest that the resilience of some tropical species, particularly in cooler subtropical waters, may initially benefit from warming. However, continuing shifts in nutrient supply and changes in grazing pressure may ultimately serve to compromise seagrass recovery.

Local Stabilising Density Effects in the Context of Ecological Disturbance and Community Assembly

The maintenance of species diversity in ecological communities has many promising explanations, including certain types of local biotic interactions that generate differential effects on the performance of conspecific and heterospecific individuals. To date, most studies of these local biotic interactions have focused on relatively stable systems, such as mature forests or undisturbed grasslands. However, many ecosystems are far from a stable state, especially under accelerating global climate change. Here, we present a synthesis of local differences between conspecific and heterospecific interactions following disturbances-and how disturbances may alter the strength and scaling of these effects to population growth and species diversity. First, we clarify terminology and categorise disturbances based on their primary mode of impact on species interactions. Second, we leverage existing literature to develop a framework for understanding how disturbances may alter the strength and role of local biotic interactions in regenerating communities. Third, we use prominent examples of disturbance: drought, windthrow and wildfire, to highlight remaining gaps in knowledge. Finally, we discuss implications for future populations and communities in unstable states. We emphasise the need for empirical studies to further integrate disturbance and local conspecific density effects within broader ecological models of community assembly and functioning.

Context-dependent disturbance synergies: Subcortical competitors may constrain bark beetle outbreaks following wildfires

Wildfires and bark beetles have historically interacted to create complex and resilient forests. However, recent record-breaking wildfires in western North America raise concerns that the large areas of injured and dead trees could facilitate increases in insect populations that respond to resource pulses. Populations of Douglas-fir beetle (Dendroctonus pseudotsugae), the primary mortality agent of Douglas-fir (Pseudotsuga menziesii), often irrupt following fires due to the resultant ephemeral pulses of defensively compromised hosts. Other subcortical phloeophagous insects are also attracted to fire (e.g., woodboring Coleoptera: Buprestidae, Cerambycidae) and similarly colonize damaged trees. Although Douglas-fir beetle and woodboring beetle species are known to colonize the phloem of injured trees, the potential for interactions among them following fire is relatively unknown. Rapid colonization by woodborers of the bark beetle niche following fires could constrain bark beetle population growth, potentially suppressing population irruptions through subcortical competition. To evaluate this hypothesis, we studied three wildfire complexes in mature Douglas-fir forests that burned in British Columbia in 2017. We found that Douglas-fir beetle preferentially colonized mature stands containing large-diameter trees with moderate fire injury and that these trees were frequently co-colonized by woodborers. In the absence of woodborers, we found that potential rates of increase in Douglas-fir beetle populations (i.e., offspring per female) were sufficient to lead to a local population irruption. Conversely, when woodborers were common (>50% of trees infested per stand), potential rates of increase in Douglas-fir beetle populations fell below replacement. These findings suggest that competition by woodboring beetles may suppress irruptions of Douglas-fir beetle in fire-injured forests. Our results reveal complex, context-dependent interactions among disturbance agents and indicate that population irruptions by resource pulse-driven bark beetles following fire may depend upon the response of local subcortical competitors. Forest management practices that enhance the diversity and abundance of non-irruptive phloeophagous insects such as many woodboring beetle species may limit the potential for wildfires to contribute to subsequent bark beetle outbreaks.

Non-native Douglas fir seedlings outcompete native Norway spruce, silver fir and Scots pine under dry and nutrient-poor conditions

Climate change is expected to significantly alter forest ecosystems, reducing the suitability of the key economic tree species Norway spruce (Picea abies) and European beech (Fagus sylvatica) in low- and mid-elevation forests of Central Europe. As these species face increasing pressures from drought, storms, and pests, it is crucial to identify alternative tree species that are economically viable and capable of maintaining primary ecosystem services. This study investigated the potential of Douglas fir (Pseudotsuga menziesii), a non-native conifer, to establish from seed and compete with native broadleaf and conifer species during the early regeneration stage under differing resource availabilities. We assessed the growth performance and phenotypic plasticity of Douglas fir seedlings over three years in a controlled common-garden experiment. Seedlings of Douglas fir, along with seven native species - Norway spruce, silver fir (Abies alba), Scots pine (Pinus sylvestris), European beech, pedunculate oak (Quercus robur), sessile oak (Q. petraea), and sycamore (Acer pseudoplatanus) - were grown for three years under factorial combinations of high and low availabilities of light, nutrients, and water. Seedling height, biomass allocation to shoots and roots and phenotypic plasticity of these traits were measured to evaluate the competitive ability of individual species and their potential to adapt to changing environmental conditions. While Douglas fir seedlings exhibited strong growth performance compared to the conifers Norway spruce and silver fir, their biomass production and height growth was considerably lower than that of the broadleaved sycamore and beech. However, Douglas fir's height growth rate in the third year exceeded all species except sycamore. This was particularly pronounced under dry and/or nutrient-poor conditions, indicating a potential competitive advantage under expected future climatic conditions. In agreement with field studies, our results indicate that non-native Douglas fir may sustainably establish in dry, nutrient poor European lowland forests due to its superior early growth performance under these conditions and the high phenotypic plasticity, of its root system. This holds especially in situations where the species competes with other conifers, while its ability to successfully compete with broadleaves appears to be largely restricted to nutrient-poor sites.

The Ecological Restoration Strategies in Terrestrial Ecosystems Were Reviewed: A New Trend Based on Soil Microbiomics

Soil microorganisms play a pivotal role in the biogeochemical cycle and serve as crucial indicators of ecological restoration in terrestrial ecosystems. The soil microbial community is regarded as a pivotal participant in environmental processes, offering both positive and negative feedback to diverse media within the ecosystem. This community can serve as a potential indicator in ecological monitoring and restoration processes. Consequently, an increasing number of scholars are directing their research towards the field of soil microbial ecology in diverse ecosystems and fragile areas, with the aim of elucidating the intricate interactions between microbes and vegetation. However, the implementation of soil microbiome in ecological restoration remains in the experimental stage due to the interference of extreme events and the complexity of governance measures. Consequently, a comprehensive evaluation of existing research is imperative. This review aims to address the ecological crises currently experienced by diverse terrestrial ecosystems and to provide a comprehensive overview of the specific practices of soil microorganisms in the context of ecological restoration. We also incorporate them into fragile habitats and identify urgent issues that need to be addressed in the ecological restoration process of fragile areas.

Dynamics of soil carbon stock in response to land use conversion in European woodland and shrubland in the last decade

Soil carbon sequestration and its monitoring is important to improve climate resilience and mitigate global warming. According to the European Environment Agency (EEA), soils in Europe are losing carbon that could hamper achieving the EU climate targets. Hence, it is necessary to explore the dynamics of soil organic carbon (SOC) storage in different ecosystems so that the EU policymakers can observe the progress towards achieving EU Green Deal objectives. The aim of this research was to quantify the ΔSOC-S in woodland and shrubland in the last decade (2009-2018) and to study the ΔSOC-S due to the land use conversion. In this regard, revisited sampling points between 2009 and 2018 from the topsoil (0-20 cm) of woodland and shrubland of the EU + UK soil database named Land Use/Land Cover Area Frame Survey (LUCAS) was used. The analysis revealed that broadleaved-woodland to coniferous- or mixed-woodland conversion in 2018, and shrubland to woodland conversion in 2015 increased SOC-S. Overall, we found a net accumulation of SOC-S in woodland (2184.08 ton ha-1) and shrubland (302.78 ton ha-1) soil with 7.78% increment in woodland and 12.56% in shrubland between 2009/12 and 2018. Also, in central Europe, mean annual temperature (MAT) increased and precipitation (MAP) decreased between the study periods. The relationship between precipitation and temperature showed that precipitation and SOC-S in woodland had no relationship, but with the rising temperature, SOC-S in both land types significantly decreased revealing warming can significantly affect SOC-S.

Quantifying disturbance effects on ecosystem services in a changing climate

Disturbances, such as hurricanes, fires, droughts and pest outbreaks, can cause major changes in ecosystem conditions that threaten Nature's contributions to people (ecosystem services). Climate change is intensifying disturbances, posing risks to ecosystem services. To assess those risks, we develop a flexible, functional trait-based approach to quantify ecological, ecosystem service and economic impacts from disturbance regimes. Our broadly applicable approach integrates knowledge from disturbance ecology and ecosystem service valuation, and we highlight the pitfalls of using either perspective in isolation. We demonstrate our approach by quantifying impacts to timber and recreational enjoyment from extreme windstorms in a midlatitude forest. While we predict large potential losses to these services under historical and future disturbance regimes, common ecological metrics of compositional and biomass stability are inadequate for predicting these impacts. We then provide a roadmap for applying our approach across different social-ecological systems, illustrating the approach for crop pollination, flood hazard mitigation and cultural values from coral reefs-which all face intensifying disturbances. This study highlights and provides tools to address the pressing need to consider disturbances in future ecosystem service assessments.

Bark beetle infestation alters mycobiomes in wood, litter, and soil associated with Norway spruce

Recent exceptionally hot and dry summers provoked massive bark beetle outbreaks in German forests, which killed many conifers, forcing to clear-cut complete non-mature stands. The importance of fungi in ecosystems in particular in association with trees is widely recognized, but the ecology of how insect infestations of trees affect their mycobiomes remains poorly understood. Using Illumina MiSeq sequencing, we investigated fungal communities in soil, litter, and stem wood at early and late stages of bark beetle infestation in a Norway spruce [Picea abies (L.) Karst] stand in Central Germany. Fungal diversity decreased from soil to wood, with the highest proportion of unknown fungi in stem wood. Lifestyles, particularly of those fungi associated with stem wood, clearly changed depending on the infestation stage. The answer of tree-associated fungi to beetle infestation was characterized by an increasing community dissimilarity among all three habitats, i.e. it concerned not only the above-ground fungal communities directly connected to the tree. Our study, thus, pinpoints the cascading effects of tree infestations by bark beetles and subsequent tree diebacks on the proximate and distant mycobiomes of the plant soil system, which should be entirely considered to tackle the effects of environmental events on tree health.

New saga in Finland: The rise of Diplodia sapinea in Scots pine

The intensity of fungal virulence is likely to increase in northern forests as climate change alters environmental conditions, favoring pathogen proliferation in existing ecosystems while also facilitating their expansion into new geographic areas. In Finland, Diplodia sapinea, the causal agent of disease called "Diplodia tip blight", has emerged as a new pathogen within the past few years. To reveal the current distribution of the novel fungal pathogen, and the effect of temperature and rainfall on its distribution, we utilized citizen science for the detection and collection of symptomatic Scots pine (Pinus sylvestris) shoots. The Finnish culture collection of D. sapinea was initiated using in vitro cultured symptomatic samples, and selected strains were studied for their virulence and disease cycle. Furthermore, the mycobiome of selected symptomatic and asymptomatic Scots pine shoots was studied using amplicon sequencing and the presence of D. sapinea was confirmed with culturing, qPCR, and species-specific PCR. Based on over 500 Scots pine shoots testing positive for D. sapinea, the distribution of this fungal pathogen is concentrated along the coastal areas of Finland, extending up to 200 km inland from the coastline. The observed presence of D. sapinea followed the period of highest average temperatures recorded in Finland in 2023 and was also found to be related to less precipitation. The amplicon sequencing showed that abundance of D. sapinea was higher in the healthy tissues of symptomatic shoots compared to visually healthy shoots. Similarly, the abundance was higher in samples collected from coastal areas in Southwestern Finland, which are the most heavily impacted by this disease. Here, we show that the presence of D. sapinea is more extensive than previously assumed, and lastly illustrate the hypothesized disease cycle of the fungal pathogen in Finland based on observations made in the field from 2021 to 2024 and in vivo and in vitro studies.

Genetic Architecture Underlying Response to the Fungal Pathogen Dothistroma septosporum in Lodgepole Pine, Jack Pine, and Their Hybrids

In recent decades, Dothistroma needle blight (DNB), a pine tree disease caused by the fungal pathogen Dothistroma septosporum, has severely damaged lodgepole pine (Pinus contorta Dougl. ex. Loud.) in British Columbia, Canada, and raised health concerns for jack pine (Pinus banksiana Lamb.). The pathogen has already shown signs of host shift eastward to the hybrid populations between lodgepole pine and jack pine (Pinus contorta × P. banksiana), and possibly into pure jack pine. However, we have little knowledge about mechanisms of resistance to D. septosporum, especially the underlying genetic basis of variation in pines. In this study, we conducted controlled inoculations to induce infection by D. septosporum and performed a genome-wide case-control association study with pooled sequencing (pool-seq) data to dissect the genetic architecture underlying response in lodgepole pine, jack pine, and their hybrids. We identified candidate genes associated with D. septosporum response in lodgepole pine and in hybrid samples. We also assessed genetic structure in hybrid populations and inferred how introgression may affect the distribution of genetic variation involved in D. septosporum response in the studied samples. These results can be used to develop genomic tools to evaluate DNB risk, guide forest management strategies, and potentially select for resistant genotypes.

The Iceberg Model of Change: A taxonomy differentiating approaches to change

Change is a ubiquitous phenomenon, but different scientific communities conceptualize change differently, which hampers conceptual clarity. This conceptual paper, which is based on a review of the literature on change, addresses this problem by developing the 'Iceberg Model of Change'. This framework distinguishes three approaches to change: objectification, distinction, and unfolding. The objectification approach treats processes of change as things with symbolic properties, which can be used to steer societal and political discourse, reveal thematic relationships across studies, and emphasize the significance of work. This approach also tends to consider change as a variable (dependent or independent) that can be used to understand antecedents and consequences. The distinction approach conceptualizes change as a series of discrete states of an entity or system at multiple points in time or as phases, enabling comparison of those states. The unfolding approach considers how change processes develop, including the complex, interrelated mechanisms underpinning change. Here, line graphs, visualizations of interaction mechanisms, and trajectories are used to capture change. This framework contributes to research, a) by enabling a comprehensive consideration of change phenomena, b) by promoting interdisciplinary collaboration when project partners differ in their assumptions about change, and c) by emphasizing the need for methodological reflexivity.

Timber harvesting was the most important factor driving changes in vegetation composition, as compared to climate and fire regime shifts, in the mixedwood temperate forests of Temiscamingue since AD 1830

Context

The vegetation composition of northeastern North American forests has significantly changed since pre-settlement times, with a marked reduction in conifer-dominated stands, taxonomic and functional diversity. These changes have been attributed to fire regime shifts, logging, and climate change.

Methods

In this study, we disentangled the individual effects of these drivers on the forest composition in southwestern Quebec from 1830 to 2000 by conducting retrospective modelling using the LANDIS-II forest landscape model. The model was run based on pre-settlement forest composition and fire history reconstructions, historical timber harvest records, and climate reanalysis data. We compared counterfactual scenarios excluding individual factors to a baseline historical scenario.

Results and Conclusions

Our results indicated that timber harvesting had the greatest impact on forest dynamics over the past centuries. In the absence of timber harvesting, pre-settlement species abundances were largely maintained, preserving key functional traits like fire and shade tolerance that contribute to ecosystem resilience. Increased fire activity during the settlement period contributed to the increase of early-successional aspen (Populus tremuloides), but timber harvesting played the dominant role. Fire exclusion had no influence on vegetation composition, suggesting mesophication unfolds over longer timescales than those captured in this study. Climate change, characterized by modest increases in temperature and precipitation, had a minor effect on vegetation shifts, as increased precipitation might have mitigated the adverse effects of rising temperatures. However, future climate change is projected to become a more significant driver of forest composition. These findings underscore the importance of forest restoration and continued research on past forest dynamics to better understand current and future changes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10980-025-02043-x.

How ambient temperature rise affects mercury dynamics and its pools in secondary forests

The forest ecosystem is a significant pool for capturing atmospheric mercury (Hg) deposition, with most Hg accumulating in forest soils. As secondary forests now dominate global forest cover, they are particularly sensitive to changes in ambient temperature. However, the impact of these changes on Hg dynamics in secondary forests remains poorly understood. Here, we quantified Hg inputs, outputs, and mass balances in two secondary forests in China, each with different ambient temperatures. We found that elevated ambient temperature (∼1.0℃) advanced the germination of leaves by 2-3 days and extended the growing season by approximately one week, resulting in increased litterfall biomass by 1.18 Mg hm-2 yr-1 and a thicker litterfall layer by 0.22 cm over 34 years. This temperature rise also facilitated Hg methylation within forest and enhanced methylmercury (MeHg) export, heightening the potential risk of MeHg exposure to surrounding ecosystems. Additionally, higher ambient temperature not only increased soil Hg emissions (2.75 µg m-2 yr-1) but also led to significant Hg deposition via litterfall (9.26 µg m-2 yr-1), resulting in a net annual Hg deposition of 6.88 µg m-2 yr-1. This net Hg deposition accumulated in the topsoil, increasing the Hg pool by 0.51 mg m-2 in organic and 0-10 cm mineral soil horizons. Our findings suggest that even a ∼1.0℃ temperature rise could enhance the role of secondary forests as atmospheric Hg sink by 45.10 %. Therefore, the impact of ongoing climate warming on Hg cycling and pools in forests should receive increased attention and warrants further research.

Advancing forest carbon projections requires improved convergence between ecological and economic models

Forests have the potential to contribute significantly to global climate policy efforts through enhanced carbon sequestration and storage in terrestrial systems and wood products. Projections models simulate changes future in forest carbon fluxes under different environmental, economic, and policy conditions and can inform landowners and policymakers on how to best utilize global forests for mitigating climate change. However, forest carbon modeling frameworks are often developed and applied in a highly disciplinary manner, e.g., with ecological and economic modeling communities typically operating in silos or through soft model linkages through input-output parametric relationships. Recent disciplinary divides between economic and ecological research communities confound policy guidance on levers to increase forest carbon sinks and enhance ecosystem resilience to global change. This paper reviews and summarizes the expansive literature on forest carbon modeling within economic and ecological disciplines, discusses the benefits and limitations of commonly used models, and proposes a convergence approach to better integrating ecological and economic systems frameworks. More specifically, we highlight the critical feedback loops that exist when economic and ecological carbon models operate independently and discuss the benefits of a more integrated approach. We then describe an iterative approach that involves the sharing of methodology, perspectives, and data between the regimented model types. An integrated approach can reduce the limitations or disciplinary bias of forest carbon models by exploiting and merging their relative strengths.

Divergent trajectories of regeneration in early-successional forests after logging and wildfire

Increases in forest disturbances have altered global forest demography rates, with many regions now characterized by extensive areas of early-successional forest. Heterogeneity in the structure, diversity, and composition of early-successional forests influence their inherent ecological values from immediately following disturbance to later successional stages, including values for biodiversity and carbon storage. Here, using 14 years of longitudinal data, we describe patterns in the structure, richness, and composition of early-successional forests subject to one of three different disturbance types: (1) clearcut logging followed by slash burn, (2) severe wildfire followed by salvage logging, and (3) severe wildfire only, in the Mountain Ash (Eucalyptus regnans) and Alpine Ash (Eucalyptus delegatensis) forests of southeastern Australia. We also documented the influence of disturbance intervals (short, medium, and long) on early-successional forests. Our analyses revealed several key differences between forests that regenerated from wildfire versus two different anthropogenic perturbations. Most ash-type plant communities were resilient to wildfire within historical fire-regimes (75-150 years), exhibiting temporal trends of recovery in plant structure, richness, and composition within the first decade. In contrast, the richness, occurrence, and abundance of some plant lifeforms and life history traits were negatively associated with clearcut logging and salvage logging, relative to forests disturbed by wildfire alone. These included resprouting species, such as tree ferns and ground ferns. However, Acacia spp. and shrubs were more abundant after clearcut logging. Our findings also provide evidence of the pronounced negative impact of salvage logging on early-successional plant communities, relative to that of both clearcut logging and wildfire. Notably, plant richness declined for over a decade after salvage logging, rather than increased as occurred following other disturbance types. Early-successional forests provide the template for the stand structure and composition of mature forests. Therefore, altered patterns of recovery with different disturbance types will likely shape the structure and function of later-successional stages. Predicted increases in wildfire will increase the generation of early-successional forests and subsequent salvage logging. Therefore, it is pertinent that management consider how different disturbance types can produce alternate states of forest composition and structure early in succession, and the implications for mature stands.

Optimizing the utilization of harvested wood products for maximum greenhouse gas emission reduction in a bioeconomy: A multi-objective optimization approach

Climate change mitigation in a bioeconomy can be attained by increased use of harvested wood products. Thereby, substitution effects can contribute to reducing the Global Warming Potential, and storage effects can prevent direct carbon emissions to the atmosphere. Substitution and storage effects are often only considered as marginal changes. However, an absolute upper limit exists for these effects due to limited harvesting of forests. The maximum emission reduction potential of these two effects depends on the distribution of wood across wood value chains. This study investigates how wood can be distributed optimally across value chains to achieve the maximum climate change mitigation potential by substitution and storage effects, taking a multi-objective optimization approach. Results indicate that sawable wood should be utilized in sawnwood applications to achieve the highest GHG emission reduction, while non-sawable wood contributes to maximal storage effects when used in material applications. The highest substitution effects occur when non-sawable wood is used for energy production. Both substitution and storage effects lead to a substantial mitigation effect, whereby storage effects yield a higher total reduction. The presented optimization method overcomes the limitations of marginal considerations and highlights opportunities for climate change mitigation within these limits. This study emphasizes the importance of taking a systems perspective on climate change mitigation in a bioeconomy and of understanding the limits of these effects regarding environmental policies and management.

Do wood-boring beetles influence the flammability of deadwood?

Global warming increases the risk of wildfire and insect outbreaks, potentially reducing the carbon storage function of coarse woody debris (CWD). There is an increasing focus on the interactive effects of wildfire and insect infestation on forest carbon, but the impact of wood-boring beetle tunnels via their effect on the flammability of deadwood remains unexplored. We hypothesized that the presence of beetle holes, at natural densities, can affect its flammability positively through increased surface area and enhanced oxygen availability in the wood. To test this, wood-boring beetle holes were mimicked experimentally in decaying logs of two coniferous species, and flammability variables of these treated logs were compared. We found that wood-boring beetles partly increased the flammability of CWD of both species (via promoting deadwood smoldering combustion) when their holes were parallel with the airflow. Even when accounting for the influences of wood density and cracks, these radial holes continued to have a notable impact on deadwood flammability. While these holes did not make the wildfire more intense, they significantly increased carbon loss during combustion. This suggests that wood-boring beetles will enhance carbon release from deadwood into the atmosphere during wildfire.

Early-successional species show higher tolerance of drought than late-successional species across Europe

Climate change is exacerbating forest disturbances through more frequent and more intense droughts and fires, undermining their ability to recover from such disturbances. The response of fast-growing early-successional species to drought is poorly understood, despite their key role in ecological succession and their ability to enhance ecosystem resilience. Here, we compared the growth responses to drought events of three early-successional species (silver birch, black poplar, and Scots pine) with that of one late-successional species (European beech) across their natural distribution ranges in Europe. We used tree-ring widths of 6340 trees from 109 forest sites to establish species-specific tree-ring chronologies. We then used multiple linear regression to analyze which climatic or growth variables (pre-drought growth and growth during drought) best explained the tree responses to drought. Silver birch, Scots pine, and black poplar showed superior drought tolerance, with a slight, non-significant growth reduction under drought, whereas European beech showed a significant decrease in growth. The variables that influenced growth during and after the drought were species-specific. Annual precipitation and growth variables were key predictors of post-drought growth for Scots pine, black poplar, and European beech. Scots pine and silver birch grew better with increasing latitude, i.e., in Northern Europe than in Central Europe, while European beech and black poplar showed more growth at sites with high precipitation during the vegetation and dormant period, respectively. This study provides insights into the drought tolerance of early-successional species and highlights their ability to promote ecological succession and facilitate the transition to drought-resistant, late-successional forest ecosystems.

A trans-Atlantic perspective on successful plantation establishment in boreal ecosystems: lessons learned and research opportunities

Boreal forests, which account for one-third of the world's forested areas, play a crucial role in global climate regulation and provide significant ecological, economic, and cultural benefits. However, boreal ecosystems face substantial threats from climate change, leading to increased disturbances such as wildfires, insect outbreaks, and disease. In response, reforestation emerges as a vital strategy for maintaining and restoring forest cover. In this perspective paper, we summarize some recent research on plantation establishment in boreal ecosystems of eastern North America and Scandinavia, emphasizing the effectiveness of mechanical site preparation (MSP), species-specific responses, and soil nutrient dynamics. We suggest key areas for future research, including the long-term sustainability of MSP, the development of adaptive strategies to climate variability, species-specific optimization of planting techniques, and integration of technological advances. Addressing these research needs will support the development of adaptive silviculture practices that enhance boreal stands resilience and productivity, helping to meet reforestation objectives and mitigate the impacts of climate change. We aim to stimulate regional, national, and international research initiatives, contributing to the resilience and sustainability of boreal ecosystems.

Disturbance impacts on Mediterranean forests across climate and management scenarios

In the climate-vulnerable Mediterranean basin, the severity and frequency of disturbances such as windthrows, droughts and fires are intensifying. Forests are generally resilient, but struggle to adapt to abrupt changes, which can impact their functionality and service provision. Various forest management alternatives aim to reduce forest vulnerability to disturbances, but few studies have evaluated the impact of management alternatives on multiple disturbances and service provision simultaneously. We aimed at filling this gap by conducting simulations of forest dynamics between 2020 and 2100 for 261 pine-dominated forest plots in Catalonia (NE Spain), under two emissions scenarios (RCP4.5 and RCP8.5) and four management scenarios (business-as-usual, promotion of bioenergy, maximum carbon storage, and ecohydrological forest management). We used the annual simulated output of forest structure and composition and future climatic projections to produce annual estimates of six ecosystem services, and we determined the annual potential impact on forests of the three main abiotic disturbances in the Mediterranean region: fire, droughts, and windstorms. We also evaluated trade-offs and synergies between disturbance impact and the provision of ecosystem services. Our simulations predicted a greater influence of management over climate scenario on the potential impact caused by all disturbances. The business-as-usual scenario consistently predicted higher impacts than the other three management scenarios, regardless of the disturbance considered or the climate scenario (fire impact 175% higher, drought impact 300%; wind impact 130%). The other three management scenarios showed similar patterns in predicted impact, but differences among them increased under more severe climate conditions. In general, there was a positive correlation between the impact by the three disturbance agents, particularly drought and fire (Pearson's r = 0.69). We observed that the provision of some services is highly correlated to disturbance impacts, suggesting that, under certain management schemes, service provision may be compromised due to abiotic disturbance impacts. Our work supports the need for an "adaptation-first" model in which the promotion of forest adaptation is placed at the core of forest management as the only way to ensure forest persistence and the delivery of services.

Forest disturbance regimes and trends in continental Spain (1985-2023) using dense landsat time series

Forest disturbance regimes across biomes are being altered by interactive effects of global change. Establishing baselines for assessing change requires detailed quantitative data on past disturbance events, but such data are scarce and difficult to obtain over large spatial and temporal scales. The integration of remote sensing with dense time series analysis and cloud computing platforms is enhancing the ability to monitor historical disturbances, and especially non-stand replacing events along climatic gradients. Since the integration of such tools is still scarce in Mediterranean regions, here, we combine dense Landsat time series and the Continuous Change Detection and Classification - Spectral Mixture Analysis (CCDC-SMA) method to monitor forest disturbance in continental Spain from 1985 to 2023. We adapted the CCDC-SMA method for improved disturbance detection creating new spectral libraries representative of the study region, and quantified the year, month, severity, return interval, and type of disturbance (stand replacing, non-stand replacing) at a 30 m resolution. In addition, we characterised forest disturbance regimes and trends (patch size and severity, and frequency of events) of events larger than 0.5 ha at the national scale by biome (Mediterranean and temperate) and forest type (broadleaf, needleleaf and mixed). We quantified more than 2.9 million patches of disturbed forest, covering 4.6 Mha over the region and period studied. Forest disturbances were on average larger but less severe in the Mediterranean than in the temperate biome, and significantly larger and more severe in needleleaf than in mixed and broadleaf forests. Since the late 1980s, forest disturbances have decreased in size and severity while increasing in frequency across all biomes and forest types. These results have important implications as they confirm that disturbance regimes in continental Spain are changing and should therefore be considered in forest strategic planning for policy development and implementation.

Vulnerability of Global Pine Forestry's Carbon Sink to an Invasive Pathogen-Vector System

The substantial contribution of northern forest growth to the global increase of biomass carbon stock is well documented. However, the ecological consequences of pest- and disease-related losses in these forests have not received comparable attention. This study highlights that pine species are major contributors to carbon stocks in Northern Hemisphere. The total carbon storage of Pinus in the Northern Hemisphere was estimated at 70,726 teragrams of carbon (TgC; 17.7% of the total forest carbon 478,012 TgC), accounting for 4.9%, 28.4%, and 12.5% of the total carbon storage in the forests of Asia, Europe, and North America, respectively. However, pine trees were under threat from an invasive complex involving the pine wood nematode (Bursaphelenchus xylophilus) and Japanese pine sawyer beetle (Monochamus spp.). Since 1977, this complex resulted in a carbon sink deficit of 1857 TgC (18% of the carbon currently stored in Europe's live tree biomass) in northern pine ecosystems. The carbon losses attributed to B. xylophilus exceeded those caused by wildfires, which are typically regarded as the primary factor of forest disturbances. Furthermore, the contributions of environmental variables indicate that the expected northward shift in precipitation patterns will exacerbate B. xylophilus threats, endangering 78% of the boreal forests across Eurasia by 2100. Among these high-risk areas, 62% contributed significantly to global carbon sink, and 42% was protected forests. Following the present trend, carbon losses caused by the B. xylophilus complex could exceed 39% of the total carbon storage in terrestrial ecosystems. This study provides comprehensive datasets that detail the global distribution and high-risk habitats of pine species and B. xylophilus vector beetles in affected countries. Our findings underscore the substantial risk of carbon losses posed by B. xylophilus to northern pine forests, with potential implications for global carbon dynamics and the achievement of international goals related to "carbon peak" and "carbon neutrality."

Contrasting forest management strategies: Impacts on biodiversity and ecosystem services under changing climate and disturbance regimes

Natural disturbances may compromise the past and ongoing efforts to increase carbon sequestration and halt biodiversity loss in boreal forests. Measures to minimize the effects of forest disturbances i.e., adaptive management, offer solutions to secure future timber yields. However, the consequences of adaptive management on biodiversity, the climate change mitigation potential of forests, and other ecosystem services are not well understood. In addition, the impact of climate change and disturbances on future forest-based mitigation potential is not well known. We compared the effects of forest management options emphasizing climate change mitigation or adaptation on boreal forests in changing climate and disturbance regimes in southern Finland. We used the process-based forest landscape and disturbance model iLand to dynamically model interactions between climate change and disturbances together with forest management and protection options, and examined the consequent effects on forest carbon storage, berry yields, recreation, and structural attributes important for biodiversity. Mitigation managements resulted in up to one-fifth higher carbon stocks, even after accounting for disturbances by wind and bark beetles, but halved annual harvests over the 80-year simulation period. Adaptive managements reduced bark beetle disturbances, but in some cases the disturbed volumes were even higher than under business-as-usual management due to increased wind damage. The effects of proactive risk management depended on the time horizon considered, the adaptive management option chosen and the climate change scenario. In general, the mitigation managements had positive effects on the biodiversity indicators studied, while the effects of adaptive management were mixed. Our results highlight the complex interactions between disturbance risk prevention, biodiversity, carbon sequestration and storage, and other ecosystem services. The results guide forest managers and policymakers to plan mitigation and adaptation strategies optimizing multiple benefits, and strengthening forest resilience in a changing climate.

Can Thinning Foster Forest Genetic Adaptation to Drought? A Demo-Genetic Modelling Approach With Disturbance Regimes

In managed populations-whether for production or conservation-management practices can interfere with natural eco-evolutionary processes, providing opportunities to mitigate immediate impacts of disturbances or enhance selection on tolerance traits. Here, we used a modelling approach to explore the interplay and feedback loops among drought regimes, natural selection and tree thinning in naturally regenerated monospecific forests. We conducted a simulation experiment spanning three nonoverlapping generations with the individual-based demo-genetic model Luberon2. Luberon2 integrates forest dynamics processes driving survival and mating success, including tree growth, competition, drought impacts and regeneration, with genetic variation in quantitative traits related to these processes. We focused on two variable traits: individual vigour, determining diameter growth potential without stress as the deviation from average stand growth, and individual sensitivity to drought stress as the slope of the relationship between diameter growth and drought stress level. We simulated simplified thinning scenarios, tailored to even-aged stands. Considering plausible genetic variation and contrasting drought regimes, the predicted evolutionary rates for both traits aligned with documented rates in wild plant and animal populations. Thinning considerably reduced natural selective pressures caused by competition and drought compared to unthinned stands. However, the conventional thinning practice of retaining the larger trees resulted in indirect anthropogenic selection that enhanced genetic gain in vigour and lowered sensitivity by up to 30%. More intensive thinning aimed at reducing drought stress by reducing stand density hampered the selection against sensitivity to drought, potentially hindering long-term adaptation. Conversely, avoiding the early, nonselective thinning step-thereby promoting both natural and anthropogenic selection-ultimately resulted in better stand performance while maintaining long-term evolvability. This study emphasises the potential of evolution-oriented forestry strategies to combine drought stress mitigation with genetic adaptation. It provides general insights into how population management, disturbance regimes and eco-evolutionary responses interfere, aiding sustainable decision-making amid environmental uncertainties.

Pervasive fire danger continued under a negative emission scenario

Enhanced fire-prone weather under greenhouse gas warming can significantly affect local and global carbon budgets from increased fire occurrence, influencing carbon-climate feedbacks. However, the extent to which changes in fire-prone weather and associated carbon emissions can be mitigated by negative emissions remains uncertain. Here, we analyze fire weather responses in CO2 removal climate model experiments and estimate their potential carbon emissions based on an observational relationship between fire weather and fire-induced CO2 emissions. The results highlight that enhanced fire danger under global warming cannot be restored instantaneously by CO2 reduction, mainly due to atmospheric dryness maintained by climatic inertia. The exacerbated fire danger is projected to contribute to extra CO2 emissions in 68% of global regions due to the hysteresis of climate responses to CO2 levels. These findings highlight that even under global cooling from negative emissions, increased fire activity may reinforce the fire-carbon-climate feedback loop and result in further socio-economic damage.

Pre-drought effects on northern temperate trees and vine invasion in forest gaps hindering regeneration

Northern temperate coniferous forests serve as crucial connectors between boreal and temperate forests, yet they are vulnerable to various stressors such as climate change and human activities. Severe drought poses a significant threat to plant species within these forests, prompting recent research into its impacts. However, many studies lack explicit definitions of post-disturbance vegetation processes and fail to identify potential interactions with disturbance factors, necessitating comprehensive discussions. This study examines the effects of drought on tree growth patterns of the main dominant species in northern temperate regions: Abies nephrolepis and Picea jezoensis, along with two commonly associated Betula ermanii, and Quercus mongolica. Additionally, new disturbance factors in forests inhabited by these species (A. nephrolepis and P. jezoensis) were evaluated based on community classification. The study sites were located in the Mt. Baekdu (Changbai) and South Korea regions, which are positioned at the southern limit of the phytogeographical patterns of target species. Results indicate that A. nephrolepis and P. jezoensis exhibit high levels of recovery and resilience, while B. ermanii and Q. mongolica demonstrate high resistance. Species-specific responses align with drought intensity, with resistance, recovery, and resilience decreasing notably with increasing pre-drought radial growth. South Korean forests, the invasion of the vine species Tripterygium regelii after the death of A. nephrolepis in the overstory vegetation threatens the regeneration of new trees. However, certain environmental factors, such as high rock exposure and dense overstory canopy, limit vine invasion. Based on the results, pre-drought radial growth emerges as a key determinant in how trees respond to drought. Additionally, the results suggest the potential for new disturbances to emerge in forest gaps due to overstory vegetation mortality induced by global warming. These findings contribute to a deeper understanding of increasing drought stress, aid in identifying climate refugia, and inform conservation priorities based on habitat characteristics.

Effects of climate and forest development on habitat specialization and biodiversity in Central European mountain forests

Mountain forests are biodiversity hotspots with competing hypotheses proposed to explain elevational trends in habitat specialization and species richness. The altitudinal-niche-breadth hypothesis suggests decreasing specialization with elevation, which could lead to decreasing species richness and weaker differences in species richness and beta diversity among habitat types with increasing elevation. Testing these predictions for bacteria, fungi, plants, arthropods, and vertebrates, we found decreasing habitat specialization (represented by forest developmental stages) with elevation in mountain forests of the Northern Alps - supporting the altitudinal-niche-breadth hypothesis. Species richness decreased with elevation only for arthropods, whereas changes in beta diversity varied among taxa. Along the forest developmental gradient, species richness mainly followed a U-shaped pattern which remained stable along elevation. This highlights the importance of early and late developmental stages for biodiversity and indicates that climate change may alter community composition not only through distributional shifts along elevation but also across forest developmental stages.

Complex imprint of air pollution in the basal area increments of three European tree species

The impact of atmospheric pollution on the growth of European forest tree species, particularly European beech, Silver fir and Norway spruce, is examined in five mesic forests in the Czech Republic. Analyzing of basal area increment (BAI) patterns using linear mixed effect models reveals a complex interplay between atmospheric nitrogen (N) and sulphur (S) deposition, climatic variables and changing CO2 concentrations. Beech BAI responds positively to N deposition (in tandem with air CO2 concentration), with soil phosphorus (P) availability emerging as a significant factor influencing overall growth rates. Fir BAI, on the other hand, was particularly negatively influenced by S deposition, although recent growth acceleration suggests growth resilience in post-pollution period. This fir growth surge likely coincides with stimulation of P acquisition following the decline of acidic pollution. The consequence is the current highest productivity among the studied tree species. The growth dynamics of both conifers were closely linked to the stoichiometric imbalance of phosphorus in needles, indicating the possible sensitivity of exogenous controls on nutrient uptake. Furthermore, spruce BAI was positively linked to calcium availability across sites. Despite enhanced water-use efficiency under elevated CO2, spruce growth is constrained by precipitation deficit and demonstrates weakening resilience to increasing growing season air temperatures. Overall, these findings underscore the intricate relationships between atmospheric pollution, nutrient availability, and climatic factors in shaping the growth dynamics of European forest ecosystems. Thus, incorporating biogeochemical context of nutrient availability is essential for realistic modelling of tree growth in a changing climate.

Applications of CRISPR Technologies in Forestry and Molecular Wood Biotechnology

Forests worldwide are under increasing pressure from climate change and emerging diseases, threatening their vital ecological and economic roles. Traditional breeding approaches, while valuable, are inherently slow and limited by the long generation times and existing genetic variation of trees. CRISPR technologies offer a transformative solution, enabling precise and efficient genome editing to accelerate the development of climate-resilient and productive forests. This review provides a comprehensive overview of CRISPR applications in forestry, exploring its potential for enhancing disease resistance, improving abiotic stress tolerance, modifying wood properties, and accelerating growth. We discuss the mechanisms and applications of various CRISPR systems, including base editing, prime editing, and multiplexing strategies. Additionally, we highlight recent advances in overcoming key challenges such as reagent delivery and plant regeneration, which are crucial for successful implementation of CRISPR in trees. We also delve into the potential and ethical considerations of using CRISPR gene drive for population-level genetic alterations, as well as the importance of genetic containment strategies for mitigating risks. This review emphasizes the need for continued research, technological advancements, extensive long-term field trials, public engagement, and responsible innovation to fully harness the power of CRISPR for shaping a sustainable future for forests.

Archetypal typology of European forest ecosystems integrating management intensity and naturalness

The crises of climate change and biodiversity loss have pushed the aim for increasing the resilience of forest ecosystems high on the agenda of foresters and policymakers. At the same time, synergistic opportunities for restoring forests and biodiversity are emerging to safeguard these ecosystems. Naturalness is a key characteristic of forest ecosystems, which should be considered when estimating benchmarks for resilience and biodiversity conservation. The naturalness of forest ecosystems is highly dependent on the intensity of human activity, as different levels of management intensity can change the original traits of forest ecosystems. This paper presents an archetypal typology of forest ecosystems, describing the association between management and naturalness. Both features are represented as gradients covering the full spectrum observed in European forests. The array of forest ecosystem archetypes was verified using case studies across Europe. The typology provides useful information for setting targets for resilience and restoration of forest ecosystems.

Contrasting Future Growth of Norway Spruce and Scots Pine Forests Under Warming Climate

Forests are essential to climate change mitigation through carbon sequestration, transpiration, and turnover. However, the quantification of climate change impacts on forest growth is uncertain and even contradictory in some regions, which is the result of spatially constrained studies. Here, we use an unprecedented network of 1.5 million tree growth records from 493 Picea abies and Pinus sylvestris stands across Europe to predict species-specific tree growth variability from 1950 to 2016 (R2 > 0.82) and develop 21st-century gridded projections considering different climate change scenarios. The approach demonstrates overall positive effects of warming temperatures leading to 25% projected conifer growth increases under the SPP370 scenario, but these additional carbon gains are spatially inhomogeneous and associated with geographic climate gradients. Maximum gains are projected for pines in Scandinavia, where growth trajectories indicate 50% increases by 2071-2100. Smaller but significant growth reductions are projected in Mediterranean Europe, where conifer growth shrinks by 25% in response to warmer temperatures. Our results reveal potential mitigating effects via forest carbon sequestration increases in response to global warming and stress the importance of effective forest management.

Adaptive forest management improves stand-level resilience of temperate forests under multiple stressors

Forests are expected to be strongly affected by modifications in climate and disturbance regimes, threatening their ability to sustain the provision of essential services. Promoting drought-tolerant species or functionally diverse stands have recently emerged as management options to cope with global change. Our study aimed at evaluating the impact of contrasting stand-level management scenarios on the resilience of temperate forests in eastern North America and central-western Europe using the individual process-based model HETEROFOR. We simulated the evolution of eight stands over 100 years under a future extreme climate according to four management scenarios (business as usual - BAU; climate change adaptation - CC; functional diversity approach - FD; no management - NM) while facing multiple disturbances, resulting in a total of 160 simulations. We found that FD demonstrated the greatest resilience regarding transpiration and tree biomass, followed by CC and then BAU, while these three scenarios were equivalent concerning the net primary production. These results were however dependent on forest type: increasing functional diversity was a powerful option to increase the resilience of coniferous plantations whereas no clear differences between BAU and adaptive management scenarios were detected in broadleaved and mixed stands. The FD promoted a higher level of tree species diversity than any other scenario, and all scenarios of management were similar regarding the amount of harvested wood. The NM always showed the lowest resilience, demonstrating that forest management could be an important tool to mitigate adverse effects of global change. Our study highlighted that tree-level process-based models are a relevant tool to identify suitable management options for adapting forests to global change provided that model limitations are considered, and that alternative management options, particularly those based on functional diversity, are promising and should be promoted from now on.

Long-term annual estimation of forest above ground biomass, canopy cover, and height from airborne and spaceborne sensors synergies in the Iberian Peninsula

The Mediterranean Basin has experienced substantial land use changes as traditional agriculture decreased and population migrated from rural to urban areas, which have resulted in a large forest cover increase. The combination of Landsat time series, providing spectral information, with lidar, offering three-dimensional insights, has emerged as a viable option for the large-scale cartography of forest structural attributes across large time spans. Here we develop and test a comprehensive framework to map forest above ground biomass, canopy cover and forest height in two regions spanning the most representative biomes in the peninsular Spain, Mediterranean (Madrid region) and temperate (Basque Country). As reference, we used lidar-based direct estimates of stand height and forest canopy cover. The reference biomass and volume were predicted from lidar metrics. Landsat time series predictors included annual temporal profiles of band reflectance and vegetation indices for the 1985-2023 period. Additional predictor variables including synthetic aperture radar, disturbance history, topography and forest type were also evaluated to optimize forest structural attributes retrieval. The estimates were independently validated at two temporal scales, i) the year of model calibration and ii) the year of the second lidar survey. The final models used as predictor variables only Landsat based metrics and topographic information, as the available SAR time-series were relatively short (1991-2011) and disturbance information did not decrease the estimation error. Model accuracies were higher in the Mediterranean forests when compared to the temperate forests (R2 = 0.6-0.8 vs. 0.4-0.5). Between the first (1985-1989) and the last (2020-2023) decades of the monitoring period the average forest cover increased from 21 ± 2% to 32 ± 1%, mean height increased from 6.6 ± 0.43 m to 7.9 ± 0.18 m and the mean biomass from 31.9 ± 3.6 t ha-1 to 50.4 ± 1 t ha-1 for the Mediterranean forests. In temperate forests, the average canopy cover increased from 55 ± 4% to 59 ± 3%, mean height increased from 15.8 ± 0.77 m to 17.3 ± 0.21m, while the growing stock volume increased from 137.8 ± 8.2 to 151.5 ± 3.8 m3 ha-1. Our results suggest that multispectral data can be successfully linked with lidar to provide continuous information on forest height, cover, and biomass trends.

Fuel for collective action: A SWOT analysis to identify social barriers and drivers for a local woody biomass supply chain in an Italian alpine valley

The role of woody biomass in the clean energy transition is substantial in the EU. Forest residues are one of the main biomass sources that can be used for energy production, but their use to support the energy transition is still limited for several reasons. Research has shown that the use of forest residues in energy production can be effectively stimulated through collective actions that aim to develop short and local supply chains. This study aims to identify the barriers and drivers for the development of a local supply chain for forest residues in an Italian alpine valley, gathering and analysing the perspectives of all involved local actors, that is, (i) suppliers - the communities that own the forest resources, (ii) intermediaries - the forest professionals providing extension and advice services to owners and the harvesting companies; and (iii) the final consumers, in this case the local municipalities and hospitality enterprises. Data are analysed using a SWOT analysis. The results show that the suppliers identified opportunities especially, while the final consumers focused more on strengths, weaknesses, and threats. The SWOT categories in terms of the number of different factors were weaknesses (37 %), strengths (27 %), threats (18 %), and opportunities (17 %). Opportunities and strengths were considered as drivers, while threats and weaknesses were barriers. Several drivers emerged, such as a general predisposition toward the development of a local supply chain for forest residues, social homogeneity in terms of knowledge and management of the land, and common challenges. Barriers also emerged in the form of limited know-how on the supply chain potential, but also in limited availability to concede control between different forest owners over their property. The SWOT results are useful to design strategies to support the development of the supply chain: four possible strategies, amongst which flexible cooperation processes between different categories of stakeholders, and the organisation of a buying group of the hospitality enterprises, were suggested.

Integrating evolutionary genomics of forest trees to inform future tree breeding amid rapid climate change

Global climate change is leading to rapid and drastic shifts in environmental conditions, posing threats to biodiversity and nearly all life forms worldwide. Forest trees serve as foundational components of terrestrial ecosystems and play a crucial and leading role in combating and mitigating the adverse effects of extreme climate events, despite their own vulnerability to these threats. Therefore, understanding and monitoring how natural forests respond to rapid climate change is a key priority for biodiversity conservation. Recent progress in evolutionary genomics, driven primarily by cutting-edge multi-omics technologies, offers powerful new tools to address several key issues. These include precise delineation of species and evolutionary units, inference of past evolutionary histories and demographic fluctuations, identification of environmentally adaptive variants, and measurement of genetic load levels. As the urgency to deal with more extreme environmental stresses grows, understanding the genomics of evolutionary history, local adaptation, future responses to climate change, and conservation and restoration of natural forest trees will be critical for research at the nexus of global change, population genomics, and conservation biology. In this review, we explore the application of evolutionary genomics to assess the effects of global climate change using multi-omics approaches and discuss the outlook for breeding of climate-adapted trees.

Probability and severity of climate change threats to natural world heritage sites vary across site specifics and over time

This study contributes a first comparison of current and potential threats to Natural World Heritage Sites from climate change, as assessed by experts, when site and location characteristics (size, year of inscription to the World Heritage list, continent, climate zone and kind of site) are controlled for. The probability of a threat as well as its intensity is analysed. Another novelty lies in the use of data from the IUCN Conservation Outlook Assessment, covering all 245 Natural and Mixed World Heritage Sites across the world for three points in time: 2014, 2017 and 2020. The threat of climate change is broadly defined and includes temperature extremes, rising temperatures, disappearing glaciers, coral bleaching, droughts, desertification, and rising sea levels. Results based on a simultaneous Probit model with random effects show that the probability of actual and potential climate change threats increases over time, but with differences for size, kind of site and location. The probability that a threat is identified is highest for marine and coastal sites, and for those in Latin America, while it is significantly lower for sites on the African continent. Larger sites have a higher probability of being assessed as at risk and the severity of threats is found to be lower for recently inscribed sites. The rate at which the likelihood of a threat assessment increases is consistent for both current and future situations, while the probability of the most severe threat is larger for the current than the future period. A serious threat from climate change is assessed as highest for locations in the tropical monsoon (current period) or the tropical savannah climate (future period). Estimations also show that pure descriptive statistics or bivariate correlations may not correctly identify the risk or the dignity of a threat.

Carbon, climate, and natural disturbance: a review of mechanisms, challenges, and tools for understanding forest carbon stability in an uncertain future

In this review, we discuss current research on forest carbon risk from natural disturbance under climate change for the United States, with emphasis on advancements in analytical mapping and modeling tools that have potential to drive research for managing future long-term stability of forest carbon. As a natural mechanism for carbon storage, forests are a critical component of meeting climate mitigation strategies designed to combat anthropogenic emissions. Forests consist of long-lived organisms (trees) that can store carbon for centuries or more. However, trees have finite lifespans, and disturbances such as wildfire, insect and disease outbreaks, and drought can hasten tree mortality or reduce tree growth, thereby slowing carbon sequestration, driving carbon emissions, and reducing forest carbon storage in stable pools, particularly the live and standing dead portions that are counted in many carbon offset programs. Many forests have natural disturbance regimes, but climate change and human activities disrupt the frequency and severity of disturbances in ways that are likely to have consequences for the long-term stability of forest carbon. To minimize negative effects and maximize resilience of forest carbon, disturbance risks must be accounted for in carbon offset protocols, carbon management practices, and carbon mapping and modeling techniques. This requires detailed mapping and modeling of the quantities and distribution of forest carbon across the United States and hopefully one day globally; the frequency, severity, and timing of disturbances; the mechanisms by which disturbances affect carbon storage; and how climate change may alter each of these elements. Several tools (e.g. fire spread models, imputed forest inventory models, and forest growth simulators) exist to address one or more of the aforementioned items and can help inform management strategies that reduce forest carbon risk, maintain long-term stability of forest carbon, and further explore challenges, uncertainties, and opportunities for evaluating the continued potential of, and threats to, forests as viable mechanisms for forest carbon storage, including carbon offsets. A growing collective body of research and technological improvements have advanced the science, but we highlight and discuss key limitations, uncertainties, and gaps that remain.

Response of stream habitat and microbiomes to spruce budworm defoliation: New considerations for outbreak management

Defoliation by eastern spruce budworm is one of the most important natural disturbances in Canadian boreal and hemi-boreal forests with annual area affected surpassing that of fire and harvest combined, and its impacts are projected to increase in frequency, severity, and range under future climate scenarios. Deciding on an active management strategy to control outbreaks and minimize broader economic, ecological, and social impacts is becoming increasingly important. These strategies differ in the degree to which defoliation is suppressed, but little is known about the downstream consequences of defoliation and, thus, the implications of management. Given the disproportionate role of headwater streams and their microbiomes on net riverine productivity across forested landscapes, we investigated the effects of defoliation by spruce budworm on headwater stream habitat and microbiome structure and function to inform management decisions. We experimentally manipulated a gradient of defoliation among 12 watersheds during a spruce budworm outbreak in the Gaspésie Peninsula, Québec, Canada. From May through October of 2019-2021, stream habitat (flow rates, dissolved organic matter [DOM], water chemistry, and nutrients), algal biomass, and water temperatures were assessed. Bacterial and fungal biofilm communities were examined by incubating six leaf packs for five weeks (mid-August to late September) in one stream reach per watershed. Microbiome community structure was determined using metabarcoding of 16S and ITS rRNA genes, and community functions were examined using extracellular enzyme assays, leaf litter decomposition rates, and taxonomic functional assignments. We found that cumulative defoliation was correlated with increased streamflow rates and temperatures, and more aromatic DOM (measured as specific ultraviolet absorbance at 254 nm), but was not correlated to nutrient concentrations. Cumulative defoliation was also associated with altered microbial community composition, an increase in carbohydrate biosynthesis, and a reduction in aromatic compound degradation, suggesting that microbes are shifting to the preferential use of simple carbohydrates rather than more complex aromatic compounds. These results demonstrate that high levels of defoliation can affect headwater stream microbiomes to the point of altering stream ecosystem productivity and carbon cycling potential, highlighting the importance of incorporating broader ecological processes into spruce budworm management decisions.

Carbon Dioxide Capture and Conversion Using Metal-Organic Framework (MOF) Materials: A Comprehensive Review

The escalating threat of anthropogenic climate change has spurred an urgent quest for innovative CO2 capture and utilization (CCU) technologies. Metal-organic frameworks (MOFs) have emerged as prominent candidates in CO2 capture and conversion due to their large specific surface area, well-defined porous structure, and tunable chemical properties. This review unveils the latest advancements in MOF-based materials specifically designed for superior CO2 adsorption, precise separation, advanced photocatalytic and electrocatalytic CO2 reduction, progressive CO2 hydrogenation, and dual functionalities. We explore the strategies that enhance MOF efficiency and examine the challenges of and opportunities afforded by transitioning from laboratory research to industrial application. Looking ahead, this review offers a visionary perspective on harnessing MOFs for the sustainable capture and conversion of CO2.

Mapping the natural disturbance risk to protective forests across the European Alps

Mountain forests play an essential role in protecting people and infrastructure from natural hazards. However, forests are currently experiencing an increasing rate of natural disturbances (including windthrows, bark beetle outbreaks and forest fires) that may jeopardize their capacity to provide this ecosystem service in the future. Here, we mapped the risk to forests' protective service across the European Alps by integrating the risk components of hazard (in this case, the probability of a disturbance occurring), exposure (the proportion of forests that protect people or infrastructure), and vulnerability (the probability that the forests lose their protective structure after a disturbance). We combined satellite-based data on forest disturbances from 1986 to 2020 with data on key forest structural characteristics (cover and height) from spaceborne lidar (GEDI), and used ensemble models to predict disturbance probabilities and post-disturbance forest structure based on topographic and climatic predictors. Wind and bark beetles are dominant natural disturbance agents in the Alps, with a mean annual probability of occurrence of 0.05%, while forest fires were less likely (mean annual probability <0.01%), except in the south-western Alps. After a disturbance, over 40% of forests maintained their protective structure, highlighting the important role of residual living or dead trees. Within 30 years after wind and bark beetle disturbance, 61% of forests were likely to either maintain or recover their protective structure. Vulnerability to fires was higher, with 51% of forest still lacking sufficient protective structure 30 years after fire. Fire vulnerability was especially pronounced at dry sites, which also had a high fire hazard. Combining hazard and vulnerability with the exposure of protective forests we identified 186 Alpine municipalities with a high risk to protective forests due to wind and bark beetles, and 117 with a high fire risk. Mapping the disturbance risk to ecosystem services can help identify priority areas for increasing preparedness and managing forests towards lower susceptibility under an intensifying disturbance regime.

Resilience and vulnerability: distinct concepts to address global change in forests

Resilience and vulnerability are important concepts to understand, anticipate, and manage global change impacts on forest ecosystems. However, they are often used confusingly and inconsistently, hampering a synthetic understanding of global change, and impeding communication with managers and policy-makers. Both concepts are powerful and have complementary strengths, reflecting their different history, methodological approach, components, and spatiotemporal focus. Resilience assessments address the temporal response to disturbance and the mechanisms driving it. Vulnerability assessments focus on spatial patterns of exposure and susceptibility, and explicitly address adaptive capacity and stakeholder preferences. We suggest applying the distinct concepts of resilience and vulnerability where they provide particular leverage, and deduce a number of lessons learned to facilitate the next generation of global change assessments.