Adam Felton

Maintaining forest connectivity is vital for supporting the movement of forest-dwelling species and for sustaining the multiple ecosystem services and benefits forests provide to humanity. Forest Area Density (FAD) is the required metric for monitoring forest connectivity under the European Union Nature Restoration Regulation (EU NRR). FAD is a scale-dependent structural index, meaning that assessments of connectivity can change depending on the spatial scale of observation, as well as the local landscape context. Promoting biodiversity conservation under the EU NRR may involve a reduction in clear-cutting (CC) and the adoption of alternative, uneven-aged management strategies. Here, we simulate clear-cutting, and three alternative management strategies (AM1-AM3) in two contrasting Swedish regions. The simulations are designed to reflect the aggregated nature of harvesting blocks in CC management, and the more dispersed nature of harvesting blocks in alternative strategies. We calculate FAD relative to baseline (ΔFAD) at 11 observation scales (10–1,000 ha) and model the effects of management strategy, observation scale, and region. We show that, at fine observation scales, dispersed harvesting strategies consistently produce more negative ΔFAD than aggregated clearcuts. This reverses at observation scales of approximately 570-620 ha, as dispersed strategies result in gradually less negative ΔFAD. This is a mathematical property of the FAD metric itself, independent of the region. Our findings reveal an important tension between FAD as a structural connectivity metric and the ecological expectations of uneven-aged forestry. Policymakers should therefore consider that the choice of scale has direct consequences for how management outcomes are assessed.

Bark beetle outbreaks are an increasingly important disturbance in boreal forests, yet empirical evidence is limited on how management systems influence stand- and tree-level susceptibility. We quantified infestation patterns of Ips typographus, Pityogenes chalcographus, and Polygraphus spp. across 29 spruce-dominated forest stands in central Sweden representing mature even-aged, uneven-aged, and unmanaged forests. Using GLMs and GLMMs, we evaluated how management type, stand structure, and tree characteristics influenced stand-level infestation intensity and tree-level infestation probability. Stand-level infestation patterns were driven primarily by structural variables rather than management type. Deadwood basal area was the strongest and most consistent predictor for all species, positively associated with infestation intensity. For P. chalcographus, negative associations with spruce density and pine basal area highlighted species-specific responses to stand composition. At the tree level, both I. typographus and P. chalcographus showed higher infestation probability in even-aged stands, independent of diameter, sun exposure, and tree condition. Ips typographus preferentially colonized larger and more sun-exposed trees, whereas P. chalcographus favoured smaller trees. Polygraphus spp. showed no detectable response to tree size or sun-exposure but favoured standing trees. Our results show that forest susceptibility to primary bark beetles is shaped more by structural attributes than by management type alone. However, even-aged management increased infestation risk at the tree-level, suggesting that management can affect tree-level susceptibility without necessarily increasing stand-level infestation. These findings highlight that susceptibility to bark beetles cannot be inferred from management system alone but depends on the specific habitat conditions present within the stands.

The forest policy landscape is dominated by contrasting ambitions and targets, with large inconsistencies between EU targets, national targets, conflicting stakeholder interests, and the implementation by landowners, who ultimately take the management decisions. To explore options for resolving these inconsistencies, we organised a workshop with stakeholders from six European countries (BG, DE, ES, PL, SE, SI). Under three different future policy scenarios, we presented strategies to spatially implement different policy targets using the concepts of land sparing, land sharing and TRIAD. During the workshop, stakeholders were asked how alternative policy scenarios could be most effectively achieved considering the different national contexts. The cross-country comparison enabled the examination of differences in national preferences, including how to distribute biodiversity protection commitments and spatially allocate additional forest reserves across different types of forest owners. Generally, stakeholders across countries considered land sharing the most effective strategy to implement both biodiversity and economic goals for forest management. Spain, Sweden and Poland preferred land sparing, particularly for implementing bioeconomy-focused goals. This trend was most pronounced in countries with remote forest areas with a low population density. The main barriers to implementation across policy objectives were insufficient funding, difficulty triggering behavioural change in private forest owners, insufficient knowledge transfer, and climate change. The European Union’s policy goals require consideration on how they may be adapted to the distinct contexts of the diverse socio-economic circumstances and forest management traditions in the member states.

Cervid (Cervidae) populations that are overabundant with respect to their food resources are expected to show declining physiological and reproductive fitness. A proactive solution to such declines is to integrate the monitoring of food resources with animal harvesting strategies, but there are few studies available to guide managers regarding which food resources to monitor and how to do so. In this study, we used a large, rare data set that included detailed absolute measures of available food quantities and browsing intensity from field inventories, to test their relationship with fitness indices of moose Alces alces in 24 management units in four regions across Norway. We found that calf body mass and calves seen per cow during the autumn hunt were strongly and positively related to the availability of tree forage, especially the species most selected for by the study moose (e.g., rowan [ Sorbus aucuparia ] and sallow [ Salix caprea ]). The strength of the correlations varied between regions, apparently being stronger where the moose were closer to being overabundant or had a legacy of past overabundance. As expected, the intensity of browsing on the three most common tree species, that is, birch ( Betula spp.), rowan, and pine ( Pinus sylvestris ), was also negatively and strongly related to the fitness. We discuss how our approach to food monitoring can facilitate a management that proactively adjusts densities of moose, and possibly other cervids, to trends in food availability and browsing intensity, thereby avoiding detrimental effects of overabundance.

Most insect pollinators are ectothermic and rely on external heat sources for temperature regulation. Forests, with their diverse canopy structures and sunlight penetration levels, create a mosaic of microclimates influencing these insects' behaviour. This study examined how macro‐ and microclimatic temperatures, precipitation, forest structure, and flower resources affect pollinator activity in the understory of two Swedish mixed forests using a combination of artificial flower stations, time‐lapse pictures, and high‐resolution climate data. Diptera was the most abundant order of flower visitors, with Muscidae, Phoridae and Syrphidae being the most recorded families. Our results show that macroclimate was the main driver of flower visitation rates, while microclimatic conditions better predicted foraging time. Based on our models, forest fly pollinators increase their flower visitation rates within a narrow temperature window. Thus, we anticipate that the effects of rising temperatures due to climate change on flower visitation rates by insects will largely depend on baseline temperature. Additionally, temperature appears more important than changes in other macroclimatic variables such as rain. Precipitation reduced pollinator visits, and pollinators increased their activity with time since the last rainfall. Forest density negatively impacted pollinator presence, with effects varying by pollinator group and species, but suggesting that increasing canopy openness could enhance pollinator habitats and support biodiversity. Higher flower species richness decreased visitation rates but extended pollinator foraging time in some cases. Conversely, abundant wildflowers increased pollinator visitation rates but reduced their overall foraging time, probably due to competition. Our study highlights the complex relationships that occur between forest structure, climate, flower resources, and pollinator activity. Understanding species‐specific responses to forest composition and understory vegetation can guide tree species selection in afforestation or reforestation projects to support diverse pollinator communities, ultimately informing effective conservation and forest management practices to maintain healthy pollinator populations and ecosystem resilience under a changing climate.

Recording flower‐associated taxa can be challenging in contexts where plant–arthropod interactions are limited, thereby constraining the assessment of their ecological responses. For example, forests typically provide fewer floral resources for pollinators than other ecosystems, such as grasslands, while understory microclimates influence the spatiotemporal dynamics of insect activity, further complicating their detection. In this study, we use environmental DNA (eDNA) to address these challenges and investigate the influence of forest microclimate, density, and tree composition on the diversity of flower‐associated arthropods in a Swedish forest. We used two flowering plant species, Fragaria vesca and Trifolium pratense , as sentinel plants, translocating them to a mixed forest across 40 plots spanning a gradient of forest density and broadleaf tree dominance. The metabarcoding of flower eDNA documented a high diversity of arthropods with very specific communities in different forest plots. This high species turnover suggests either short eDNA persistence on flowers or unmeasured ecological factors structuring these communities. We found that forest structure, particularly light availability in broadleaf‐dominated open plots, positively influenced species richness of arthropods detectable in flowers, while microclimate had a small impact. These effects varied between plant species, likely due to differences in flower visitor communities. Our study also offers significant methodological insights into using flower eDNA for detecting flower‐associated taxa. We also emphasize the need for optimized sampling and DNA extraction processes to enhance the likelihood of successful amplification. We show that the number of flowers pooled in the same DNA extraction positively influences the number of taxa detected. By improving methods in flower eDNA sampling and analysis, future studies can more accurately assess the ecological interactions and conservation needs of forest environments and other ecosystems.

Storm Gudrun represents one of the most significant meteorological events in recent Swedish history, causing widespread forest destruction in southern Sweden. Now, 20 years after the storm, it is time to reflect on its impact on the forest sciences. We highlight key research themes that emerged in response to the storm, emphasising the critical role of research and monitoring infrastructure in facilitating the generation of valuable insights. We identified 18 articles focusing on storm Gudrun within forest-related research fields, which were, in turn, cited by over 600 subsequent studies. A citing network analysis resulted in eight research clusters, including, wind dynamics, carbon dynamics due to disturbances, spruce bark beetle responses, and storm damage in Sweden and Europe. Our review of primary literature underscores their dependence on established environmental monitoring and research infrastructure to provide essential background data. Maintaining these infrastructures is central to the advancement of forest-related sciences.