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Forests provide important ecosystem services (ESs), including climate change mitigation, local climate regulation, habitat for biodiversity, wood and non‐wood products, energy, and recreation. Simultaneously, forests are increasingly affected by climate change and need to be adapted to future environmental conditions. Current legislation, including the European Union (EU) Biodiversity Strategy, EU Forest Strategy, and national laws, aims to protect forest landscapes, enhance ESs, adapt forests to climate change, and leverage forest products for climate change mitigation and the bioeconomy. However, reconciling all these competing demands poses a tremendous task for policymakers, forest managers, conservation agencies, and other stakeholders, especially given the uncertainty associated with future climate impacts. Here, we used process‐based ecosystem modeling and robust multi‐criteria optimization to develop forest management portfolios that provide multiple ESs across a wide range of climate scenarios. We included constraints to strictly protect 10% of Europe's land area and to provide stable harvest levels under every climate scenario. The optimization showed only limited options to improve ES provision within these constraints. Consequently, management portfolios suffered from low diversity, which contradicts the goal of multi‐functionality and exposes regions to significant risk due to a lack of risk diversification. Additionally, certain regions, especially those in the north, would need to prioritize timber provision to compensate for reduced harvests elsewhere. This conflicts with EU LULUCF targets for increased forest carbon sinks in all member states and prevents an equal distribution of strictly protected areas, introducing a bias as to which forest ecosystems are more protected than others. Thus, coordinated strategies at the European level are imperative to address these challenges effectively. We suggest that the implementation of the EU Biodiversity Strategy, EU Forest Strategy, and targets for forest carbon sinks require complementary measures to alleviate the conflicting demands on forests. [ABSTRACT FROM AUTHOR]

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long‐term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground‐based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m3 of disturbed timber volume per year over the 70‐year study period. This value is likely a conservative estimate due to under‐reporting, especially of small‐scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m3/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long‐term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes. [ABSTRACT FROM AUTHOR]

Biochar (BC) is often proposed as a tool for climate change mitigation, due to the expected long lifetime in the environment. However, BC's stability can vary depending on feedstock type and the presence of labile carbon fractions. In this study, we verify the recent methods with new possible tools for biochar stability assessment on six different biochars derived from commonly available Europe biomass sources. Elemental composition (CHNO), dissolved organic carbon (DOC) and water-soluble carbonates content (WSC), volatile organic compounds (VOCs) composition, and mid-infrared spectra (MIR) were performed to estimate the persistence of biochars. Under similar conditions of pyrolysis, biochar properties can vary depending on a feedstock origin. Less aromatic structure and higher contents of labile carbon fractions (DOCs and WSC) in food waste biochars affected the lower stability, while biochars derived from high lignocellulose materials (straw, wood, and grass) were strongly carbonized, with persistent, aromatic structure. Labile carbon pool content (DOC, WSC) and spectral analysis can be useful tools for biochar stability assessment, giving similar information to the standard molar ratio method. Biochars obtained from agriculture and forestry management biomass should be considered as highly stable in soil and are appropriate for long-term carbon sequestration purposes. [ABSTRACT FROM AUTHOR]

• The nexus between forest-based climate mitigation and health is poorly researched. • This scoping review identified exposure pathways and health co-benefits from forests. • There is potential for synergies between forest management and health benefits. • Interdisciplinary efforts are required for advancement of research and understanding. Climate change is a pressing global challenge with profound implications for human health. Forest-based climate change mitigation strategies, such as afforestation, reforestation, and sustainable forest management, offer promising solutions to mitigate climate change and simultaneously yield substantial co-benefits for human health. The objective of this scoping review was to examine research trends related to the interdisciplinary nexus between forests as carbon sinks and human health co-benefits. We developed a conceptual framework model, supporting the inclusion of exposure pathways, such as recreational opportunities or aesthetic experiences, in the co-benefit context. We used a scoping review methodology to identify the proportion of European research on forest-based mitigation strategies that acknowledge the interconnection between mitigation strategies and human impacts. We also aimed to assess whether synergies and trade-offs between forest-based carbon sink capacity and human co-benefits has been analysed and quantified. From the initial 4,062 records retrieved, 349 reports analysed European forest management principles and factors related to climate change mitigation capacity. Of those, 97 studies acknowledged human co-benefits and 13 studies quantified the impacts on exposure pathways or health co-benefits and were included for full review. Our analysis demonstrates that there is potential for synergies related to optimising carbon sink capacity together with human co-benefits, but there is currently a lack of holistic research approaches assessing these interrelationships. We suggest enhanced interdisciplinary efforts, using for example multideterminant modelling approaches, to advance evidence and understanding of the forest and health nexus in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]

Robinia pseudoacacia is one of the most frequent non‐native species in Europe. It is a fast‐growing tree of high economic and cultural importance. On the other hand, it is an invasive species, causing changes in soil chemistry and light regime, and consequently altering the plant communities. Previously published models developed for the potential distribution of R. pseudoacacia concerned 2070, and were based mainly on data from Western and Central Europe; here we extended these findings and included additional data from Eastern Europe. To fill the gap in current knowledge of R. pseudoacacia distribution and improve the reliability of forecasts, we aimed to (i) determine the extent to which the outcome of range modeling will be affected by complementing R. pseudoacacia occurrence data with sites from Central, Southeastern, and Eastern Europe, (ii) identify and quantify the changes in the availability of climate niches for 2050 and 2070, and discuss their impacts on forest management and nature conservation. We showed that the majority of the range changes expected in 2070 will occur as early as 2050. In comparison to previous studies, we demonstrated a greater eastward shift of potential niches of this species and a greater decline of potential niches in Southern Europe. Consequently, future climatic conditions will likely favor the occurrence of R. pseudoacacia in Central and Northeastern Europe where this species is still absent or relatively rare. There, controlling the spread of R. pseudoacacia will require monitoring sources of invasion in the landscape and reducing the occurrence of this species. The expected effects of climate change will likely be observed 20 years earlier than previously forecasted. Hence we highlighted the urgent need for acceleration of policies aimed at climate change mitigation in Europe. Also, our results showed the need for using more complete distribution data to analyze potential niche models. [ABSTRACT FROM AUTHOR]

The optimal forest management strategies for mitigating climate change are hotly debated during political negotiations, because afforestation and forest management can increase atmospheric CO 2 removal, and the wood produced can provide a substitute for fossil fuel. Studies quantifying the carbon balance of the forest sector apply a wide variety of management and wood-use scenarios. Some model studies include future climate change effects on forest growth, but others ignore them. Here, a conceptual empirical model of sequestration efficiency, the fraction of net primary production stored in the biosphere and anthroposhere, simulates European forest carbon pools and fluxes. The sensitivity of the sequestration efficiency of European forests was quantified by varying model parameters along the forest growth and wood transformation chain: environment and climate change, harvest intensity, rotation length, fraction of harvest residues left on site and substitution efficiency. Irrespective of the evolution of the sink, the forest sector as a whole remains a net carbon absorber in 99% of the simulations at a time horizon of 100 years, even if in 25% of the simulations the forests themselves become sources. However, if the goal is to enhance the current sequestration efficiency to mitigate emissions, only in 25% of the simulations the sink efficiency was found to be enhanced. If the current sink were to reverse to a source, no management action or change in wood use would result in an increase in the current forest sequestration efficiency. In all other cases, increasing harvest levels would lead to an increase in forest sector carbon emissions, highlighting the pivotal role of the baseline used to set the emission reduction targets. Our results show that the uncertainty on the response of European forest to climate change undermines the quest for a carbon-optimal management strategy. The uncertainty in whether climate change will maintain the current forest sink or turn it into a carbon source is largely overlooked in the debate over the best forest management strategy to reduce the growth of atmospheric CO 2 concentration, yet it is large enough to change the merit order of different alternatives. [ABSTRACT FROM AUTHOR]

The ongoing global climate change is challenging all sectors, forestry notwithstanding. On the one hand, forest ecosystems are exposed to and threatened by climate change, but on the other hand, forests can influence the course of climate change by regulating the water regime, air quality, carbon sequestration, and even reduce climate extremes. Therefore, it is crucial to see climate change not only as a risk causing forest disturbances and economic consequences but also as an opportunity for innovative approaches to forest management, conservation, and silviculture based on the results of long-term research. We reviewed 365 studies evaluating the impact of climate change on European forest ecosystems, all published during the last 30 years (1993–2022). The most significant consequences of climate change include more frequent and destructive large-scale forest disturbances (wildfire, windstorm, drought, flood, bark beetle, root rot), and tree species migration. Species distribution shifts and changes in tree growth rate have substantial effects on ecosystem carbon storage. Diameter/volume increment changed from −1 to +99% in Central and Northern Europe, while it decreased from −12 to −49% in Southern Europe across tree species over the last ca. 50 years. However, it is important to sharply focus on the causes of climate change and subsequently, on adaptive strategies, which can successfully include the creation of species-diverse, spatially and age-wise structured stands (decrease drought stress and increase production), prolongation of the regenerative period, or the use of suitable introduced tree species (e.g., Douglas fir, black pine, and Mediterranean oaks). But the desired changes are based on increasing diversity and the mitigation of climate change, and will require significantly higher initial costs for silviculture practices. In conclusion, the scope and complexity of the topic require further comprehensive and long-term studies focusing on international cooperation. We see a critical gap in the transfer of research results into actual forest practice, which will be the key factor influencing afforestation of forest stands and forest growth in the following decades. What our forests will look like for future generations and what the resulting impact of climate change will be on forestry is in the hands of forest managers, depending on supportive forestry research and climate change policy, including adaptive and mitigation strategies. • We review main factors influencing forest growth processes under climate change (CC). • We concentrate on potential direct and indirect impacts of CC on forest ecosystems. • Consequences of CC include large-scale forest disturbances and tree species migration. • Review is focused on management adaptive strategies and mitigation of CC. • Opportunity and risk of introduced tree species are discussed. [ABSTRACT FROM AUTHOR]

The comprehensive analysis of carbon stocks and fluxes of managed European forests is a prerequisite to quantify their role in biomass production and climate change mitigation. We applied the Carbon Budget Model (CBM) to 26 European (EU) countries, parameterized with country information on the historical forest age structure, management practices, harvest regimes and the main natural disturbances. We quantified C stocks for the five forest pools plus Harvested Wood Products (HWP), and the fluxes among these pools, from 2000 to 2030. The aim is to quantify the main C fluxes as affected by land-use changes, natural disturbances and forest management and to asses the impact of specific harvest and afforestation scenarios after 2012 on the mitigation potential of the EU forest sector. Substitution effects and the possible impacts of climate are not included in this analysis. Results show that for the historical period (2000-2012) the net primary productivity (NPP) of the forest pools at the EU level is on average equal to 639 Tg C yr-1, the losses are dominated by heterotrophic respiration (409 Tg C yr-1) and fellings (110 Tg C yr-1 due to removals), with direct fire emissions being only 1 Tg C yr-1, leading to a net carbon stock change (i.e. sink) of 110 Tg C yr-1. Fellings also transferred 28 Tg C yr-1 of harvest residues from biomass dead organic matter pools. The average annual forest Net Sector Exchange (NSE), i.e. the carbon stock changes in the forest pools plus HWP, equals 122 Tg C yr-1 (i.e., about 19% of the NPP) for the historical period and in 2030 reaches 126 Tg C yr-1, 101 Tg C yr-1 and 151 Tg C yr-1, assuming respectively a constant, increasing (+20%) and decreasing (-20%) scenario of both harvest and afforestation rates compared to the historical period. Under the constant harvest rate scenario, our findings show an incipient aging process for the forests existing in 1990: despite the NPP is still increasing (+7%) the greater increase of heterotrophic respiration (+13%) leads to a decrease of the sink in the forest pools (-6%) in 2030 compared to the historical period. The detailed picture of the C fluxes within the EU forest sector condensed in this study, and their evolution under different harvest scenarios, provide a useful framework for more detailed future analyses (spatially or temporally) on the mitigation potential of the forest sector. Overall, our study confirms that, in the majority of European countries, the build-up of biomass stocks results from woody NPP exceeding losses by timber harvest and natural disturbances. However, at the country level, we highlighted some statistical differences, suggesting that this relationship cannot be assumed as constant for all European countries. Specific forest conditions, such as the harvest rate, the current age structure and forest composition, may have a different impact on the country-specific evolution of biomass stocks. [ABSTRACT FROM AUTHOR]

Today, European forests face many challenges but also offer opportunities, such as climate change mitigation, provision of renewable resources, energy and other ecosystem services. Large-scale analyses to assess these opportunities are hindered by the lack of a consistent, spatial and accessible forest structure data. This study presents a freely available pan-European forest structure data set. Building on our previous work, we used data from six additional countries and consider now ten key forest stand variables. Harmonized inventory data from 16 European countries were used in combination with remote sensing data and a gap-filling algorithm to produce this consistent and comparable forest structure data set across European forests. We showed how land cover data can be used to scale inventory data to a higher resolution which in turn ensures a consistent data structure across sub-regional, country and European forest assessments. Cross validation and comparison with published country statistics of the Food and Agriculture Organization (FAO) indicate that the chosen methodology is able to produce robust and accurate forest structure data across Europe, even for areas where no inventory data were available. [ABSTRACT FROM AUTHOR]

• carbon uptake by above-ground biomass is higher in unmanaged beech stands. • thinning does not alter growth-climate sensitivity. • resistance to extreme weather events decreases with increasing tree productivity. • close-to-nature forestry may be preferable at sites with higher incidence of heat and drought events. European beech plays a prominent role in the adaptation of European forests to and mitigation of climate change. Forest management may increase the mitigation potential of beech forests by accelerating carbon accumulation in tree biomass, but little is known about the interaction between the rate of biomass expansion in beech and its sensitivity to climate variation or its resistance to extreme drought episodes. A 60-year thinning experiment in beech forests in Central Europe was used to generate tree-ring width series describing past radial growth of dominant, co-dominant and sub-dominant beech trees. Randomisation applied to daily climate data was used to find the period of the year during which climate best explains beech growth. Results show that carbon uptake by above-ground biomass is higher in unmanaged stands and that thinning does not affect beech growth sensitivity to climate. Further, this study shows that average daily temperature amplitude and precipitation in March-July are the best predictors of radial growth in beech at lower-elevation sites. In a key finding, this research shows that site quality and thinning intensity increase tree size, which in turn lowers their resistance to drought. Using forest management to increase the productivity of European beech may thus increase its vulnerability to climate change. [ABSTRACT FROM AUTHOR]

• Decision-making survey on motivations, challenges and targets in forest management. • Respondents focus on climate change, biodiversity loss and forest regeneration. • Managers need to consider role of herbaceous understory to address these issues. • Requirement for a decision support tool that accounts for understory dynamics. Numerous decision-makers have an interest in how forest biodiversity and functioning will alter under environmental change. These decision-makers may have varied motivations underlying their management response to environmental change by focusing on contrasting management challenges and targets. Decision-makers may use different tools to aid their decision-making when facing uncertainty. We specifically investigate whether decision-makers in forest management across Europe consider the understory (i.e. herbaceous layer) in decision making, as this component constitutes the vast majority of floral biodiversity in temperate forests, and has an important functional role. To address this question, we distributed an online questionnaire to more than 800 forest management decision-makers across Europe, and received 100 completed responses. We assess what objectives drive management decisions, and whether these are consistent depending on respondents' occupations. Interestingly, regardless of respondent profile, biodiversity loss and climate change are expected to permeate management decisions in the coming decades, motivated primarily by a sense of environmental protection. Priority management targets did not vary across respondent profiles (i.e. occupation) either, and focused on biodiversity values, adaptation and mitigation to climate change, and forest regeneration. The majority of respondents identified the understory as an "Important" target for forest management decisions. Respondents used a mix of personal experience and literature sources to base management decisions on, while infrequently using recognised decision support systems (DSS). No utilised system considered the understory at the moment. Indeed, our review of available forest management DSS, conducted in parallel to the questionnaire, shows that an understory DSS tool, especially one that can consider changing socio-environmental conditions, is lacking for decision-makers. Based on (1) forest management decision-makers' wide concern around biodiversity loss, climate change and forest regeneration, (2) the known functional role of temperate forest understories, and (3) an apparent lack of existing DSS with an understory component, we identify the requirement for an agile tool that accounts for understory dynamics. Such a tool, especially when integrated into existing DSS, will strongly support decision-makers in their quest to attain more biodiverse, functional and resilient forests for the future. [ABSTRACT FROM AUTHOR]

A recent article by Luyssaert et al. (Nature 562:259–262, 2018) analyses the climate impact of forest management in the European Union, considering both biogeochemical (i.e., greenhouse gases, GHG) and biophysical (e.g., albedo, transpiration, etc.) effects. Based on their findings, i.e. that additional net overall climate benefits from forest management would be modest, the authors conclude that the EU "should not rely on forest management to mitigate climate change". We first explain that most of the additional EU GHG mitigation effort by 2030 is expected to come from emission reductions and only a very small part from forestry, even when forest bioenergy is allowed for. Nevertheless, the inclusion of forest management in climate change mitigation strategies is key to identifying the country-specific optimal mix, in terms of overall GHG balance, between strategies focused on conserving and/or enhancing the sink and strategies focused on using more wood to reduce emissions in other GHG sectors. Then, while acknowledging the importance that biophysical effects have on the climate, especially at the local and seasonal scale, we argue that the net annual biophysical climate impact of forest management in Europe remains more uncertain than the net CO2 impact. This has not been adequately emphasized by Luyssaert et al. (2018), leading to conclusions on the net overall climate impact of forest management that we consider premature and applied to a partially biased perception of European policy towards forestry and climate change. To avoid further confusion in the debate on how forestry may contribute to mitigating climate change, a more constructive dialogue between the scientific community and policy makers is needed. [ABSTRACT FROM AUTHOR]