Dr. Clemens Blattert

The EU Biodiversity Strategy (EUBDS) for 2030 aims to conserve and restore biodiversity by protecting large areas throughout the European Union. A target of the EUBDS is to protect 30 % of the EU’s land area by 2030, with 10 % being strictly protected (including all primary and old growth forests) and 20 % being managed 'closer to nature'. Even though this will have a positive impact on biodiversity, it may negatively impact the EU’s wood-based bioeconomy. In this study, we analyze how alternative interpretations and distributions of the EU's protection targets may affect future woody biomass harvest levels, exports of wood commodities, and the spatial distribution of managed areas under wood demands aligned with SSP2-RCP1.9. Using the  model GLOBIOM-Forest, we simulate scenarios representing a variety of interpretations and geographic distributions of the EUBDS targets. The EUBDS targets would have a limited impact on EU harvest levels since the EU can still increase its wood harvest between 21 % and 24 % by 2100. With strict protection of 30 % of the area, the EU harvest level can still be increased by 10 %. Moreover, the most likely scenario (10 %/20 % protection within each MS) will result in increased net exports in the coming decades, but a slight decline after 2050. However, if protection is intended to also represent site productivity or to re-establish a green infrastructure, then EU net exports will also decline before 2050. With the decreased EU roundwood harvest, increased harvest will occur in other biomes and mostly leaking into boreal regions.

Die prognostizierte Zunahme von extremen Störungsereignissen wie Borkenkäferbefall und Windwurf im Kontext des Klimawandels stellt die Schweizer Waldbewirtschaftung vor grosse Herausforderungen. Besonders betroffen sind fichtendominierte Gebirgswälder, die grossflächig verbreitet sind und häufig eine zentrale Schutzfunktion gegenüber Naturgefahren erfüllen. Die WSL erarbeitet zusammen mit der Praxis Grundlagen für die Priorisierung der Bewirtschaftung dieser Wälder unter dem Einfluss von extremen Störungen. Dazu werden räumliche Daten zu Waldstruktur, Standort, Störungsanfälligkeit und Naturgefahren auf Landschaftsebene mit waldbaulichen, planerischen und ökonomischen Aspekten verknüpft und in einem interaktiven Dashboard visualisiert. Dieser inter- und transdisziplinäre Ansatz wird hier anhand eines Fallbeispiels im Schilstal (Kanton St. Gallen) vorgestellt.

Management of spruce-dominated mountain forests in the context of extreme disturbances
The predicted increase in extreme disturbance events, such as windthrow and bark beetle infestations in the context of climate change poses major challenges for Swiss forest management. Mountain forests dominated by Norway spruce, which are both widespread and often fulfil an essential protective function against natural hazards, are particularly at risk. In response, the WSL is collaborating with practitioners to develop a framework for prioritising the management of these forests under the influence of extreme disturbances. This involves integrating spatial data on forest structure, site conditions, susceptibility to disturbance and natural hazards at the landscape level with silvicultural, planning and economic aspects. These insights are visualised through an interactive dashboard. This interand transdisciplinary approach is presented here with a case study from the Schilstal in the Canton of St. Gallen.

Close-to-nature forestry (CNF) is considered an effective strategy to adapt forests to climate change while sustaining ecosystem services and biodiversity (BES). However, for forest management it remains unclear whether current CNF strategies sufficiently reduce forests' predisposition to climate-change-induced shifts in disturbance regimes. To address this increasing complexity, we introduce the integration of a climate-sensitive forest gap model with assessments of predisposition to fire, bark beetle, and windthrow disturbances, as well as BES provision. We conducted simulations for a forest enterprise in the Central Swiss Alps, covering a large elevation gradient, under three climate scenarios (historical, SSP2–4.5, and SSP5–8.5). The simulations additionally considered six management strategies, including CNF variants with different management intensities and climate-adapted approaches. Our results indicate that climate change will dynamically alter disturbance predisposition across elevation gradients. Site-related predisposition to fire and bark beetle infestation generally increased under climate change, while stand-related predisposition to all disturbances varied with climate scenario and elevation. Under moderate warming (SSP2–4.5), stand-related predisposition to fire and windthrow increased across all elevations. In contrast, under severe warming (SSP5–8.5), long-term reductions in stand-related predisposition to fire, bark beetle infestation, and windthrow occurred at lower elevations due to climate-change-induced shifts in forest dynamics, while predisposition increased at higher elevations with improved growing conditions. Our results further show that increasing management intensity generally reduces stand-related disturbance predisposition but focusing purely on disturbance mitigation can also lead to trade-offs, such as reduced BES provision. We conclude that climate-adapted forest management must account for both stand-related and site-related predisposition to prioritize disturbance-prone 'hotspots', especially in areas of high BES value. Proactively reducing disturbance predisposition may involve trade-offs regarding BES provision but may be crucial to avoid potential BES losses from severe disturbances. As climate change may alter trade-offs between BES and disturbance mitigation, we underscore the need for decision support systems in long-term forest planning to account for conflicting management objectives.

Strategic long-term planning of mountain forests in the European Alps requires a balancing act between sustaining forest biodiversity and ecosystem services (BES) and mitigating disturbance risks, particularly under climate change. Multi-criteria decision support systems (DSSs) address this challenge by integrating climate-sensitive forest modelling into frameworks for the evaluation of BES provision under simulated climate and management trajectories. Recent developments incorporate assessments of disturbance predisposition into DSSs, accounting for risks from bark beetle infestations and windthrow. These DSS frameworks have proven flexible applicability across various forest models, spatial scales, forest types, and environmental conditions. However, climate-change-induced transitions of disturbance regimes require adaptations of existing DSS frameworks by accounting for emerging disturbance agents, such as forest fires. Here, we introduce the integration of a fire predisposition assessment system (PAS) into a DSS, incorporating factors such as topography, climatic conditions, wildland–urban interface, and stand structural characteristics. Particularly in the context of long-term planning in mountain forests, the expanded DSS could enable the identification of conflicting forest management objectives related to BES provision and disturbance mitigation efforts under climate change, leading to more informed management decisions.

• A predisposition assessment system for assessing multiple predisposing factors of forest fires is presented.
• The fire PAS enables an integrated evaluation with disturbance predisposition to bark beetle infestations and windthrow, as well as BES provision.
• The modular structure of the fire PAS enables adaptation and application to various spatial scales, as well as integration with different forest models.

Close-to-nature forestry (CNF) has a long tradition in European Alpine forest management, playing a crucial role in ensuring the continuous provision of biodiversity and forest ecosystem services, including protection against natural hazards. However, climate change is causing huge uncertainties about the future applicability of CNF in the Alpine region. The question arises as to whether current CNF practices are still suitable for adapting forests to climate change impacts while also meeting the increasing societal demands regarding Alpine forests, including their potential contribution to climate change mitigation. To answer this question, we simulated forest development using the ForClim forest model at two Alpine study sites, together representing a large biogeographic gradient from high-elevation inner Alpine forests (Switzerland) to lower-elevation south-eastern Alpine forests (Slovenia). The simulations considered three climate scenarios (historical climate, SSP2-4.5 and SSP5-8.5) and six alternative management strategies, including both current CNF management practices and climate-adapted versions. Using an indicator based multi-criteria decision analysis framework, we assessed the joint impacts of climate and management on biodiversity and key ecosystem services of the investigated regions, including carbon sequestration (CS) inside and outside the forest ecosystem boundary. The joint effects of climate change and CNF varied, both among and within the study sites along the biogeographical gradient. While CS was more resistant to climate change under current CNF at the south-eastern Alpine site, it was more sensitive at the inner Alpine site, where CS potentials decreased at lower elevations. This adverse effect could be partly mitigated by fostering the use of climate-adapted tree species. However, current CNF and adaptations of it did not meet multiple management objectives equally well: while protection from gravitation hazards and timber production also benefited from this silvicultural practice, biodiversity benefited from CNF variants with low-intensity or no management. In conclusion, CNF has a high potential to continue fulfilling its crucial role in European Alpine forests. A differentiated approach will be needed in the future, however, to identify forest stands where adaptive measures are required, especially at sites particularly vulnerable to climate change. In combination with less intensively managed or unmanaged areas, CNF provides a management portfolio that will help European Alpine forests to meet the demands of future society.

Mountain forests provide not only wood as a raw material but also numerous ecosystem services, such as protection against natural hazards, recreation and carbon sequestration, and they are important hosts for biodiversity. To manage these forests efficiently and in a target-oriented manner, both forest management planning and efficient harvesting operations are required. However, in most cases these two aspects are handled independently from each other. To link planning with forest operations, it is essential to divide forests into smaller areas with characteristics that are as homogeneous as possible, so-called forest management units (FMUs). The goal is that each FMU has self-contained fine access (e.g. skid roads, cable roads), and that the FMUs can be managed and planned independently. The aim of this study was to develop a spatial optimisation model that automatically identifies FMUs. The optimisation has three goals: [I] FMUs should be as compact as possible (spatially contiguous as the best case); [II] forest management should be technically and operationally coordinated within an FMU; and [III] FMUs should be as homogeneous as possible, for example regarding site properties, ecosystem service provided, and administrative affiliation. Results showed that our presented spatial optimisation model is a capable method for automatically identifying FMUs. The approach used to set up the model based on a p-median problem formulation (mixed integer linear programming) led to clearly comprehensible solutions that can be achieved in a reasonable computation time. Three solving strategies for successful computation implementation are described. Although the raw results must be reviewed by experts, they facilitate the planning process. More scenarios can be evaluated compared with the classical manual planning approach, ultimately leading to higher-quality solutions.

Ein gut geführter Forstbetrieb stellt bereits während der Planung effiziente Arbeitsabläufe sicher. Vor allem in topographisch anspruchsvollem Gelände oder im stufigen Wald ist es jedoch nicht immer einfach, die operationelle Ausführung auf der Fläche mit der waldbaulichen Planung und Kontrolle zu verbinden. Mit der automatisierten Ausscheidung von Bewirtschaftungseinheiten haben Planende eine leistungsfähige Methode zur Hand die individuellen Bedürfnisse des Forstbetriebs in einer optimalen Flächeneinteilung abzubilden.

MultiOptForest is an open-source software designed to simplify building and solving multi-objective optimization problems for forest planning. It aims to find the optimal portfolio of management regimes that balance the objectives regarding multiple forest ecosystem services and biodiversity. The software flexibly imports data, allowing for the use of a variety of forest simulator outputs. The user provides preference information through a user-friendly graphical interface, where the range of possible values for each objective is provided. MultiOptForest solves the optimization problem producing a set of Pareto optimal solutions, i.e., solutions where none of the objectives can be improved without compromising others. MultiOptForest is versatile enough to design a Pareto optimal forest plan for a small holding to assess management and the trade-off between multiple policy objectives impacting the future development of forests across regions and countries.

The European Union (EU) set clear climate change mitigation targets to reach climate neutrality, accounting for forests and their woody biomass resources. We investigated the consequences of increased harvest demands resulting from EU climate targets. We analysed the impacts on national policy objectives for forest ecosystem services and biodiversity through empirical forest simulation and multi-objective optimization methods. We show that key European timber-producing countries - Finland, Sweden, Germany (Bavaria) - cannot fulfil the increased harvest demands linked to the ambitious 1.5°C target. Potentials for harvest increase only exists in the studied region Norway. However, focusing on EU climate targets conflicts with several national policies and causes adverse effects on multiple ecosystem services and biodiversity. We argue that the role of forests and their timber resources in achieving climate targets and societal decarbonization should not be overstated. Our study provides insight for other European countries challenged by conflicting policies and supports policymakers.

Land-use policies aim at enhancing the sustainable use of natural resources. The Triad approach has been suggested to balance the social, ecological, and economic demands of forested landscapes. The core idea is to enhance multifunctionality at the landscape level by allocating landscape zones with specific management priorities, i.e., production (intensive management), multiple use (extensive management), and conservation (forest reserves). We tested the efficiency of the Triad approach and identified the respective proportion of above-mentioned zones needed to enhance multifunctionality in Finnish forest landscapes. Through a simulation and optimization framework, we explored a range of scenarios of the three zones and evaluated how changing their relative proportion (each ranging from 0 to 100%) impacted landscape multifunctionality, measured by various biodiversity and ecosystem service indicators. The results show that maximizing multifunctionality required around 20% forest area managed intensively, 50% extensively, and 30% allocated to forest reserves. In our case studies, such landscape zoning represented a good compromise between the studied multifunctionality components and maintained 61% of the maximum achievable net present value (i.e., total timber economic value). Allocating specific proportion of the landscape to a management zone had distinctive effects on the optimized economic or multifunctionality values. Net present value was only moderately impacted by shifting from intensive to extensive management, while multifunctionality benefited from less intensive and more diverse management regimes. This is the first study to apply Triad in a European boreal forest landscape, highlighting the usefulness of this approach. Our results show the potential of the Triad approach in promoting forest multifunctionality, as well as a strong trade-off between net present value and multifunctionality. We conclude that simply applying the Triad approach does not implicitly contribute to an overall increase in forest multifunctionality, as careful forest management planning still requires clear landscape objectives.

Eine nachhaltige Waldbewirtschaftung ist für die Bereitstellung von Waldleistungen von zentraler Bedeutung. Für die Forstbetriebe ist dies jedoch eine komplexe Planungsaufgabe, da eine Vielzahl an Waldleistungen und die Biodiversität berücksichtigt werden müssen. Zudem stellt der wachsende Einfluss des Klimawandels eine besondere Herausforderung dar. Im Projekt SessFor wurde der Prototyp eines Entscheidungs-Unterstützungssystems (Decision Support System, DSS) für die strategische und langfristige Planung von Forstbetrieben entwickelt. Das DSS simuliert die Waldentwicklung unter verschiedenen Bewirtschaftungs- und Klimaszenarien und bewertet die Bereitstellung von Waldleistungen mittels einer multikriteriellen Entscheidungsanalyse. Das DSS wurde in drei Fallstudien im Mittelland und den Voralpen über einen Zeitraum von 50 Jahren angewandt. Dabei wurden die Auswirkungen von unterschiedlichen Bewirtschaftungsstrategien auf die Waldleistungen Holzproduktion, Erholung (visuelle Attraktivität), Schutzfunktion und Kohlenstoffspeicherung sowie auf die Biodiversität (v.a. Strukturvielfalt und Baumartendiversität) bewertet. Der höchste Gesamtnutzen für die betrachteten Waldleistungen unter gegenwärtigem und zukünftigem Klima ergab sich in fast allen Fällen unter der aktuellen Bewirtschaftungspraxis. Eine Ausnahme bildete eine Fallstudie im Mittelland, bei der der höchste Gesamtnutzen unter einer reduzierten Holznutzung resultierte. Die untersuchten Klimaszenarien hatten eine relativ geringe Auswirkung auf den Gesamtnutzen. Einzelne Waldleistungsindikatoren zeigten jedoch negative Auswirkungen des Klimawandels für die Betriebe im Mittelland und positive Auswirkungen für den höher gelegenen Forstbetrieb in den Voralpen. Insgesamt zeigte die Studie auf, wie mithilfe des DSS die langfristige Entwicklung von Waldleistungen und Biodiversitätsindikatoren unter verschiedenen Bewirtschaftungsstrategien und Klimabedingungen untersucht werden kann. Die Stärken des DSS liegen insbesondere in der grossen Anzahl berücksichtigter Waldleistungen und in der breiten empirischen Datengrundlage. Die multikriterielle Entscheidungsanalyse unterstützt zudem eine wissenschaftlich fundierte und transparente Entscheidungsfindung für die langfristige Planung.

European countries have national sectoral polices to regulate and promote the provision of a wide range of forest ecosystems services (FES). However, potential incoherencies among these policies can negatively affect the efficient provision of FES. In this work, we evaluated the coherence among three national policies from Germany and their ability to effectively provide FES in the future: the Forest Strategy 2020 (FS), the National Strategy on Biological Diversity (BDS), and the German National Policy Strategy on Bioeconomy (BES). Using forest inventory data from the Federal State of Bavaria, we simulated a range of forest management options under three climate trajectories for 100 years into the future (2012-2112). Then, with multi-objective optimization, we translated each policy into a specific scenario and identified the best combination of management regimes that maximizes the targets defined in each policy scenario. The three policies were vague in the definition of FES. The FS was the most comprehensive policy aiming for a higher degree of multifunctionality, whereas the BES and BDS focused on less FES. The FS and the BDS showed the highest coherence, while the BES showed a stronger focus on timber production. As a result, the optimal management programs of FS and BDS showed high integration, with a dominance of Continuous Cover Forestry (CCF), and certain shares of set asides. Climate change led to an increase of set aside areas due to increased productivity. In the BES, the share of land among management regimes was strongly segregated between CCF and rotation forestry. Our policy coherence analysis showed that achieving a multifunctional provision of FES requires policy coherence, fostering a diverse management of the landscape that mainly takes advantage of integrative management, like CCF, but also segregates important parts of the landscape for intensive use and set asides. Nevertheless, the current high standing volumes in Bavaria will pose an additional risk to implement such management.

Forests provide a range of vital services to society and are critical habitats for biodiversity, holding inherent multifunctionality. While traditionally viewed as a byproduct of production-focused forestry, today's forest ecosystem services and biodiversity (FESB) play an essential role in several sectoral policies’ needs. Achieving policy objectives requires careful management considering the interplay of services, influenced by regional aspects and climate. Here, we examined the multifunctionality gap caused by these factors through simulation of forest management and multi-objective optimization methods across different regions - Finland, Norway, Sweden and Germany (Bavaria). To accomplish this, we tested diverse management regimes (productivity-oriented silviculture, several continuous cover forestry regimes and set asides), two climate scenarios (current and RCP 4.5) and three policy strategies (National Forest, Biodiversity and Bioeconomy Strategies). For each combination we calculated a multifunctionality metric at the landscape scale based on 5 FESB classes (biodiversity conservation, bioenergy, climate regulation, wood, water and recreation). In Germany and Norway, maximum multifunctionality was achieved by increasing the proportion of set-asides and proportionally decreasing the rest of management regimes. In Finland, maximum MF would instead require that policies address greater diversity in management, while in Sweden, the pattern was slightly different but similar to Finland. Regarding the climate scenarios, we observed that only for Sweden the difference in the provision of FESB was significant. Finally, the highest overall potential multifunctionality was observed for Sweden (National Forest scenario, with a value of 0.94 for the normalized multifunctionality metric), followed by Germany (National Forest scenario, 0.83), Finland (Bioeconomy scenario, 0.81) and Norway (National Forest scenario, 0.71). The results highlight the challenges of maximizing multifunctionality and underscore the significant influence of country-specific policies and climate change on forest management. To achieve the highest multifunctionality, strategies must be tailored to specific national landscapes, acknowledging both synergistic and conflicting FESB.

Purpose of Review Boreal forests provide a wide range of ecosystem services that are important to society. The boreal biome is experiencing the highest rates of warming on the planet and increasing demand for forest products. Here, we review how changes in climate and its associated extreme events (e.g., windstorms) are putting at risk the capacity of these forests to continue providing ecosystem services. We further analyze the role of forest management to increase forest resilience to the combined effects of climate change and extreme events.
Recent Findings Enhancing forest resilience recently gained a lot of interest from theoretical perspective. Yet, it remains unclear how to translate the theoretical knowledge into practice and how to operationalize boreal forest management to maintain forest ecosystem services and functions under changing global conditions. We identify and summarize the main management approaches (natural disturbance emulation, landscape functional zoning, functional complex network, and climate-smart forestry) that can promote forest resilience.
Summary We review the concept of resilience in forest sciences, how extreme events may put boreal forests at risk, and how management can alleviate or promote such risks. We found that the combined effects of increased temperatures and extreme events are having negative impacts on forests. Then, we discuss how the main management approaches could enhance forest resilience and multifunctionality (simultaneous provision of high levels of multiple ecosystem services and species habitats). Finally, we identify the complementary strengths of individual approaches and report challenges on how to implement them in practice.

Forests provide a wide variety of ecosystem services (ES) to society. The boreal biome is experiencing the highest rates of warming on the planet and increasing demand for forest products. To foresee how to maximize the adaptation of boreal forests to future warmer conditions and growing demands of forest products, we need a better understanding of the relative importance of forest management and climate change on the supply of ecosystem services. Here, using Finland as a boreal forest case study, we assessed the potential supply of a wide range of ES (timber, bilberry, cowberry, mushrooms, carbon storage, scenic beauty, species habitat availability and deadwood) given seven management regimes and four climate change scenarios. We used the forest simulator SIMO to project forest dynamics for 100 years into the future (2016–2116) and estimate the potential supply of each service using published models. Then, we tested the relative importance of management and climate change as drivers of the future supply of these services using generalized linear mixed models. Our results show that the effects of management on the future supply of these ES were, on average, 11 times higher than the effects of climate change across all services, but greatly differed among them (from 0.53 to 24 times higher for timber and cowberry, respectively). Notably, the importance of these drivers substantially differed among biogeographical zones within the boreal biome. The effects of climate change were 1.6 times higher in northern Finland than in southern Finland, whereas the effects of management were the opposite—they were three times higher in the south compared to the north. We conclude that new guidelines for adapting forests to global change should account for regional differences and the variation in the effects of climate change and management on different forest ES.