Forest Ecology and Management

With climate change, the area affected by and the intensity of forest disturbances such as windthrow, insect outbreaks and fire will be increasing. Post-disturbance forest management will be varied, and it is difficult to predict how much natural succession will be allowed in comparison to reforestation. Both, disturbance and reforestation will affect forest biodiversity globally, but potential shifts in species distribution, abundance and community composition are poorly understood. We studied the response of breeding bird communities to windthrow and different reforestation strategies in one of Central Europes largest contiguous windthrow areas created by storm Kyrill in 2007. A decade after the disturbance, we compared bird species diversity, population densities and community composition on plots in replanted beech, replanted conifers and secondary succession (all salvage-logged after the storm), with undisturbed old Norway spruce Picea abies as a control, in the setting of a natural experiment. Of the stands blown down, 95% were Norway Spruce. Reforestation strategies varied, with Spruce and non-native conifers planted on twice the area that was replanted with European Beech Fagus sylvestris. Large areas were still dominated by successional tree species a decade after the storm, especially birch, mirroring recommendations of sub-national forestry agencies to include secondary succession in future forest development. Birds responded strongly to windthrow, with a pronounced community turnover. Species associated with high conifer stands reached significantly lower densities on sample plots in disturbed areas. Replanted areas were characterized by mostly ubiquitous bird species. Areas dominated by secondary succession, especially birch Betula spp., were characterized by high densities of long-distance migrants (often species of conservation concern) and shrubland species, among them several indicator species. Our results suggest that an increase of forest disturbance across Central Europe will lead to a pronounced reorganisation of biodiversity. Strategies that allow more secondary succession, and avoid replanting allochthonous tree species are likely to benefit populations of depleted bird species, even at salvage-logged and cleared disturbance sites.

Tree-related microhabitats (TreMs) are key features for forest biodi-versity, and knowing their accumulation rate is essential to design inte-grative management strategies. Many types of TreMs are associated to large old trees and show slow ontogenical processes. The rarity of such TreMs (particularly in intensively managed forests) hinder the estimation of their occurrence rate along tree growth. Here, we used a continental meta-analysis on TreMs occurrence rate along tree growth to build in-formative priors for a model of trunk-base rot-hole occurrence on oaks within the Gresigne forest, France -- a context where stand management and tree DBH were confounded. We explored whether the use of infor-mative priors could improve the identifiability, the precision of estimates and the predictive abilities of the model. Without prior information, the low variance of tree DBH within management modalities rendered the model poorly identifiable and prevented the detection of an effect of tree DBH per se across the range of explored tree DBH. By contrast, using informative priors contributed to improve the precision of estimates and lead to detecting a positive effect of tree DBH per se. Informative priors did not degrade the model fit and clearly improved predictive abilities on new stands. In particular, while the model without prior information did not predict the occurrence of trunk-base rot-holes significantly better than a purely random guess, the model with informative priors did. Ir-respective of the prior used, models suggested that the high recruitment of trunk-base rot-holes in Gresigne may be a temporary management ef-fect in stands undergoing conversion from coppice-with-standards to high forest through sprout thinning, which will lead to conservation issues for cavicolous saproxylic species when all conversions are complete. Because using informative priors was simple and beneficial in our study, it should be further explored in other local applied contexts to orientate forest man-agement.

The age-class distribution of forests is a key indicator of both carbon stock potential and biodiversity conservation, playing a vital role in sustainable forest management. In Norway, birch (Betula spp.) is the most abundant tree species, covering 42% of the forest area. Understanding the factors that shape the age structure of birch is essential for developing management practices that balance timber production, carbon sequestration, and biodiversity conservation. Using data from the Norwegian National Forest Inventory (NFI), we examined the age-class distribution of birch trees across various site conditions. Our analysis revealed that middle-aged trees (50-100 years) were prevalent in most regions, while older trees were notably scarce, particularly in highly productive areas. This pattern reflects management strategies prioritizing younger, fast-growing trees to maximize economic returns. In contrast, less productive sites, which are often managed less intensively, tend to support older trees. Additionally, younger birch trees revealed significantly greater radial growth than older generations when evaluated at the same biological age (e.g., at 10 years old), particularly under favorable site conditions. These findings underscore the combined effects of site productivity, forest management, and environmental factors on growth dynamics and age-class distribution.

Selective logging is a widely applied forest management strategy in the tropics, yet it is insufficiently documented how it affects the genetic and demographic processes of seedling recruitment in timber species in the Guiana Shield. Our study investigates how selective logging influences genetic diversity, gene dispersal, and seedling establishment in Dicorynia guianensis by comparing a logged and an unlogged forest plot in French Guiana. We genotyped 703 individuals using 66 nuclear SSR markers and applied parentage analyses to infer dispersal patterns and reproductive success. We analysed genetic diversity and spatial genetic structure across life stages, and tested whether seedling recruitment was associated with logging-related canopy openings. Genetic diversity indices were broadly similar between logged and unlogged plots, with no evidence of genetic erosion in adults or seedlings. Seedling establishment was associated with logging-induced canopy openings. Parentage analyses revealed shorter mean dispersal distances in the logged plot but substantial long-distance pollen flow, ensuring admixture and inter-plot connectivity. Reproductive success was more evenly distributed among mothers, whereas male contributions were skewed in the logged plot. Selective logging did not cause immediate genetic erosion but altered dispersal dynamics and reproductive patterns. These findings underline the resilience of D. guianensis under current management practices, while emphasizing the need for long-term monitoring of regeneration to ensure sustainable recruitment and evolutionary resilience across logging cycles.

O_LIManaging multifunctional forest landscapes requires a better understanding of how biodiversity dimensions respond to habitat structures and management regimes. While species richness is commonly used to assess conservation value, it may not capture compositional differences critical for maintaining regional biodiversity. C_LIO_LIWe examined how local species richness (alpha diversity) and community turnover (beta diversity) relates to forest structure and management in Swedish boreal forests. We surveyed lichens, bryophytes, and polypore fungi, representing three sessile taxo-ecological groups across 120 sites.. The sites were distributed between three management types: young production forests, retention patches (trees left during harvest to support mature forest species in production forests), and unmanaged set-asides. We used generalised linear models and generalised dissimilarity modelling to assess how habitat structures (deadwood and living tree metrics) and spatial distance explained patterns of richness and turnover across taxa and management types. C_LIO_LIFor all taxa, species richness increase with lying deadwood volume. Lichen species richness also increased with living tree volume, and decreased with tree density in retention patches. Lichens had higher species richness in retention patches and set-asides, whereas only set-asides had statistically higher bryophyte richness, and there were no differences for polypore richness. In contrast, beta diversity was more often associated with geographic distance, with only limited influence of deadwood volume. The relationships between lichen beta diversity and habitat structures were not consistent between retention patches and set-asides, suggesting that retention patches may have limitations in conserving mature forest species despite supporting similar lichen species richness. C_LIO_LISynthesis and applications. Our results demonstrate that alpha and beta diversity can be driven by different ecological processes and management contexts, and that while tree retention can support higher biodiversity than young production forests in some taxa, it cannot replace the value of conserving mature forests. Effective conservation therefore needs to combine habitat quality and spatial complementarity when planning conservation initiatives to maintain diversity patterns across managed landscapes. C_LI

Root rot is a major problem for forestry, leading to reduced timber quality, growth losses, and increased disturbance risks. Harvester data provides a promising source of information for improving the knowledge on the root rot distribution. Here, we used harvester data (1) to map the risk of spruce root rot in southern and central Finland, and (2) to understand the drivers of the spatial patterns in rot occurrence. First, we built a statistical model predicting the percentage of stems affected by root rot on stand-level. To train the model, we used an extensive set of harvester data, containing 10,402 clear-cut forest stands, where the presence of root rot was recorded for each cut tree using an algorithm based on bucking patterns (i.e., cutting of the stem into different log assortments) recorded by the harvester. The model consisted of two parts, a fixed component describing the effects of different drivers of root rot, and a spatial random component describing the spatial patterns not explained by the fixed part of the model. The fixed part included forest and site attributes, landscape characteristics and proxies of forest-use legacies. The model was then used to map root rot risk, by predicting the probability of root rot occurrence using spatial data sets of the variables in the fixed part of the model, and the known rot status of locations in the data set for the random part of the model. Finally, the map was tested with an independent validation data, verifying its ability to identify the high-risk areas. Proxies of forest-use legacies, tree size and site fertility were found to drive the percentage of rot-affected stems in stands. The results quantify the root rot risk in Finland in higher detail than before and demonstrate the large potential of harvester data in informing about the risk of root rot in boreal forests.

ContextMixed beech and hornbeam regenerations are quite common in the east of France but their management is based more on general principles linked to ecosystem functions or services than on silvicultural practices. This is why it is so useful to establish stand trajectories to characterizing the evolution of density during stand development, as well as individual tree mortality models to predict how each species may react, particularly in a changing environment. AimsThis study was conducted to establish size-density trajectories of mixed even-aged beech and hornbeam natural regenerations, using an already tested piecewise polynomial function, and develop an individual tree mortality model based on a logit function. Material and methodsThe study took place in a mixed beech-hornbeam naturally regenerated stand in Hesse forest (NE of France), where a square design 42*42m comprising 64 square plots of 5.25m side was inventoried each year since 2001 until 2012. Measurements included tree species and status (dead or alive), girth at breast height for all trees and total height for a sample of living trees (beech and hornbeam). The size-density trajectories of the 64 plots describing the course of the number of living trees in relation with the mean stand girth, in logarithmic scales, were modeled with a piecewise polynomial function fitted with a mixed-effects model. On the other hand, the individual tree mortality model was fitted with a logit function including several independent variables defined at tree, plot and stand levels. ResultsThe size-density trajectory of mixed beech-hornbeam naturally regenerated stands was successfully fitted using the same function as for pure stands, with a plot-level random component that appeared linearly related to site fertility, initial density of trees (N0) and relative initial proportion of beech trees. The mortality onset appeared to occur at a higher density (RDI = 0.5) in mixed beech-hornbeam naturally regenerated stands than in pure beech even-aged stands (RDI = 0.29), while the maximum density (RDI = 1) was reached at a comparable relative number of surviving trees (N/N0). An individual tree mortality model could also be fitted using a logit function. The probability of mortality of trees appeared linked to individual (social status, species), collective (relative density) and site (fertility, water stress) factors. ConclusionThe size-density trajectory model first developed for pure even-aged stands appeared well adapted to mixed beech and hornbeam natural regenerations, and the individual tree mortality model constructed at the same time for these stands revealed that water stress induced mortality was relatively comparable for beech and hornbeam. These two models give the opportunity to simulate the development of mixed beech and hornbeam regenerations with the addition of a growth model.

Increasing forest structural complexity is a key objective of future-proof forest management, with potential benefits for biodiversity. However, empirical evidence for consistent biodiversity-structure relationships across taxa is still limited. We investigated whether structurally more complex forests support greater species richness and higher multidiversity across taxonomic and functional groups in 19 mature forest plots in Flanders, Belgium. As one of the most densely populated and urbanized regions in Europe, with limited and highly fragmented forest cover, Flanders provides a particularly informative and policy-relevant context to test structure-biodiversity relationships. Its forests, often dominated by a few tree species and subject to long-term anthropogenic pressures and management, represent a realistic gradient of structural complexity. Structural complexity was quantified using a Structural Complexity Index (SCI), and biodiversity was assessed using a multidiversity index integrating scaled species richness across five taxonomic and seven arthropod functional groups. Using mixed-effects models and multivariate Bayesian analyses, we tested both direct effects of SCI on biodiversity and the covariation in species richness among groups. Contrary to expectations, SCI was not a consistent predictor of multidiversity, and most groups showed weak or inconsistent responses. These findings might suggest that structural complexity alone may be insufficient to enhance biodiversity in simplified forests. HighlightsO_LIForest structural complexity does not consistently predict biodiversity. C_LIO_LIResponses vary among taxonomic and functional groups. C_LIO_LICross-taxon congruence in diversity is limited and scale-dependent. C_LIO_LIKeywords: Forest structural complexity; Multidiversity, Species richness; Functional groups; Sustainable forest management C_LI

Tree height is a key variable for assessing forest functioning and resources (e.g volume, carbon stocks) at both tree and stand levels. However, direct field measurements are costly and time-consuming. Developing accurate and unbiased height-diameter allometries applicable over large spatial scales is therefore crucial for forest research and management. Based on the French National Forest Inventory, with 269,460 tree-height observations on 49,120 plots measured, we developed generalized, species-specific height-diameter allometries that integrate stand dendrometrical characteristics and stand structure. The models cover 41 European tree species and the four main stand structures: even-aged, uneven-aged, coppice-with-standards and coppice. To enhance local accuracy, we developed an optional recalibration method at the plot level, assessing how many additional trees should be measured and which ones to select to maximize the improvement of the model. By integrating basal area as stand density and quadratic mean diameter as an indicator of stand development stage, our models enable us to assess the influence stand dendrometrical characteristics on these allometries and evaluate how different species responded to competition. Results indicate that with increasing competition, tree height tends to be higher for a given diameter, and that stand structure significantly influences 28 out of the 41 species. Local recalibration showed that measuring just one to six trees (among the largest and thinnest diameter) per plot reduced prediction error by 10 to 70%, depending on species. This study provides a useful, robust and scalable tool for forest research and management, for the most widespread species in Europe, while offering precision for local applications.

Tree planting programs now need to consider climate change increasingly, therefore, the resistance to pests plays an essential role in enabling tree adaptation to new ranges through tree population movement. The weevil Pissodes strobi (Peck) is a major pest of spruces and substantially reduces lumber quality. We revisited a large Interior spruce provenance/progeny trial (2,964 genotypes, 42 families) of varying susceptibility, established in British Columbia. We employed multivariate mixed linear models to estimate covariances between, and genetic control of, juvenile height growth and resistance traits. We performed linear regressions and ordinal logistic regressions to test for impact of parental origin on growth and susceptibility to the pest, respectively. A significant environmental component affected the correlations between resistance and height, with outcomes dependent on families. Parents sourced from above 950 m a.s.l. elevation negatively influenced host resistance to attacks, probably due to higher P. engelmannii proportion. For the genetic contribution of parents sourced from above 1,200 m a.s.l., however, we found less attack severity, probably due to a marked mismatch in phenologies. This clearly highlights that hybrid status might be a good predictor for weevil attacks and delineates the boundaries of successful spruce population movement. Families resulting from crossing susceptible with resistant parents generally showed fast-growing trees were the least affected by weevil attacks. Such results indicate that these "hybrids" might be genetically better equipped with an optimized resource allocation between defence and growth and might provide the solution for concurrent improvement in resistance against weevil attacks, whilst maintaining tree productivity.

1) BackgroundUnderstanding how caterpillar communities vary within tree canopies is key to interpreting forest trophic dynamics and responses to environmental change, yet such variation remains poorly quantified due to the challenges of sampling in three dimensions. 2) AimsWe quantified within-canopy heterogeneity in caterpillar densities, diversity, and herbivory and explored relationships with host tree phenology and commonly used ground-based monitoring approaches. 3) MethodsUsing direct canopy access, we sampled branches from lower, middle, and upper canopy strata of 34 mature pedunculate oaks (Quercus robur) in Wytham Woods, UK, during the spring abundance peak over three consecutive years (2023-2025). We tested for vertical stratification in caterpillar community metrics, examined patterns in early instar distributions at emergence, assessed associations with host tree phenology across spatiotemporal scales, and evaluated how well ground-based methods (water and frass traps) reflect canopy communities. 4) ResultsVertical stratification was modest but varied among years: densities and species richness increased with canopy height in 2023, decreased in 2024, and were uniformly low across strata in 2025. Although within-crown budburst timing varied systematically, with upper branches bursting approximately two days earlier than lower branches, tree phenology did not explain within- or between-year variation in caterpillar communities. Frass trap data correlated moderately well with canopy caterpillar densities, whereas water traps showed weaker and less consistent relationships, reflecting behavioural and methodological biases. 5) ConclusionsCaterpillar communities showed no consistent patterns of vertical stratification across years, instead they are shaped more strongly by inter-annual and tree-level variation. Integrating targeted canopy sampling with scalable ground-based proxies could greatly improve monitoring of arboreal Lepidoptera and inform studies of trophic synchrony and wood-land resilience under environmental change.

The leaf area index (LAI) is a key characteristic of forest stand aboveground net productivity (ANP), and many methods have been developed to estimate the LAI. However, every method has flaws, e.g., methods may be destructive, require means or time and/or show intrinsic bias and estimation errors. A relationship using basal area (G) and stand age to estimate LAI was proposed by Sonohat et al. (2004). We used literature data in addition to data form measurements campaign made in the northern half of France to build a data set with large ranges of pedoclimatic conditions, stand age and measured LAI. We validated the Sonohat et al. (2004) relationship and attempted to improve or modify it using other stand/dendrometric characteristics that could be predictors of the LAI. The result is a series of three models using the G, age and/or quadratic mean diameter (Dg), and the models were able to estimate the LAI of an oak only even-aged forest stand with good confidence (root mean square error, RMSE < 0.75) While G is the main predictor here, age and Dg could be used conjointly or exclusively given the available data, with variable precision in the estimations. Although these models could not, by construction, relate to the interannual variability of the LAI, they may provide the theoretical LAI of an untouched forest (no meteorological, biotic or anthropogenic perturbation) in recent years. additionally, the use of this model may be more interesting than an LAI measurement campaign, depending on the means to be invested in such a campaign.

Logging is the main human disturbance impacting biodiversity in forest ecosystems. However, the impact of forest harvesting on biodiversity is modulated by abiotic conditions through complex relationships that remain poorly documented. Therefore, the interplay between forest management and climate change can no longer be ignored. Our aim was to study the expected long-term variations in the assemblage of bird and beetle communities following modifications in forest management under different climate change scenarios. We developed species distribution models to predict the occurrence of 87 species of birds and beetles in eastern Canadian boreal forests over the next century. We simulated three climate scenarios (baseline, RCP4.5 and RCP8.5) under which we varied the level of harvesting. We also analyzed the regional assemblage dissimilarity by decomposing it into balanced variations in species occupancy and occupancy gradient. We predict that forest harvesting will alter the diversity by increasing assemblage dissimilarity under all the studied climate scenarios, mainly due to species turnover. Species turnover intensity was greater for ground-dwelling beetles, probably because they have lower dispersal capacity than flying beetles or birds. A good dispersal capacity allows species to travel more easily between ecosystems across the landscape when they search for suitable habitats after a disturbance. Regionally, an overall increase in the probability of occupancy is projected for bird species, whereas a decrease is predicted for beetles, a variation that could reflect differences in ecological traits between taxa. Our results further predict a decrease in the number of species that increase their occupancy after harvest under the most severe climatic scenario for both taxa. We anticipate that under severe climate change, increasing forest disturbance will be detrimental to beetles associated with old forests but also with young forests after disturbances.

About half of all forests are tropical and secondary, making tropical forest regeneration integral to future forests. Tree stand biomass and taxonomic richness can recover in a few decades, but relative abundances may lag indefinitely. Since most forests are within a km of a habitat edge, edge effects likely affect community composition regeneration. However, most studies assess how degraded edges affect intact forests, leaving it unclear whether higher-quality edges could facilitate regeneration of nearby degraded forests. Notably, higher quality edges near intact forests could promote processes like dispersal and wood biomass accumulation that effectively accelerate succession, leading to better performance of shade-tolerant taxa compared to pioneer taxa in the early stages of forested plantation regeneration. This study addressed how wet tropical forested plantation regeneration was affected by distance to adjacent intact forest edge. It was hypothesized that old timber plantations facilitate regeneration by increasing available shade, favoring the presence and biomass of later-successional taxa, ultimately changing community composition overall. A wet neotropical timber plantation reforested after 20 years and adjacent to primary forest was censused for trees along a 300 m edge distance gradient, and analysis matched identified taxa to broad dispersal mode and wood density traits using relevant literature. As distance from primary forest edge increased, stem and wood density tended to increase significantly, with ~10% variation explained, while biomass and canopy light surprisingly tended to stay the same. Stand tree richness also tended to increase significantly, but diversity decreased steeply and non-linearly, explained in part by wood density, and taxonomic composition varied notably. Finally, tree taxa associated with both early and late successional stages decreased significantly, as well as genus Ficus, but biomass by dispersal mode did not tend to change. Overall this study supports that stand composition is less resilient and more subject to edge effects than biomass and richness, suggesting that global forests will likely be distinctly new assemblages in the future, with timber and biodiversity trade-offs occurring based on local and regional management activity.

O_LIThe global decline of natural forests is accompanied by a rapid expansion of commercial tree plantations, which are expected to further increase to meet growing demand for wood products. However, planted forests generally support lower biodiversity than natural forests, particularly when monospecific and intensively managed. In this context, broadleaved hedgerows have been proposed as a nature-based solution to enhance biodiversity within conifer-dominated plantation landscapes. Such features may be especially beneficial for small mammals, including rodents and shrews, which are key contributors to forest ecosystem functioning. However, their effects on small mammal communities remain largely unquantified. C_LIO_LIHere, we assessed variation in small mammal communities among habitat types within a native pine plantation-dominated landscape in southwestern France. Using a multi-year, multi-season survey, we compared species richness and abundance among plantation edges, broadleaved hedgerows embedded within plantations and natural broadleaved forests. We further tested whether environmental descriptors of hedgerow sites influenced dominant species and whether seasonal and interannual demographic dynamics modified habitat-related patterns. C_LIO_LIPine plantation edges and broadleaved hedgerows supported lower small mammal species richness than natural broadleaved forests and were dominated by two habitat generalists, Apodemus sylvaticus and Crocidura russula. This pattern was driven by the near absence of the forest specialist Clethrionomys glareolus. Hedgerows did not increase species richness relative to plantations, but provided favourable habitat for A. sylvaticus, which was scarce in pine plantation, while supporting fewer C. russula. Variation in hedgerow structure and composition further influenced A. sylvaticus abundance, while seasonal and interannual rodent population dynamics modulated habitat-related differences. C_LIO_LIOur results indicate that intensively managed pine plantations act as environmental filters, excluding forest-associated small mammals. While broadleaved hedgerows benefited one species, their capacity to restore forest-specialist communities was limited without broader landscape-scale interventions. These findings highlight both the ecological benefits and constraints of edge-based habitat interventions and provide guidance for designing and evaluating biodiversity-oriented management in plantation landscapes. C_LI

The changing forest disturbance regimes emphasize the need for improved damage risk information. Here, our aim was to (1) improve the current understanding of snow damage risks by assessing the importance of abiotic factors, particularly the modelled snow load on trees, versus forest properties in predicting the probability of snow damage, (2) produce a snow damage probability map for Finland. We also compared the results for winters with typical snow load conditions and a winter with exceptionally heavy snow loads. To do this, we used damage observations from the Finnish national forest inventory (NFI) to create a statistical snow damage occurrence model, spatial data layers from different sources to use the model to predict the damage probability for the whole country in 16 x 16 m resolution. Snow damage reports from forest owners were used for testing the final map. Our results showed that best results were obtained when both abiotic and forest variables were included in the model. However, in the case of the high snow load winter, the model with only abiotic predictors performed nearly as well as the full model and the ability of the models to identify the snow damaged stands was higher than in other years. The results showed patterns of forest adaptation to high snow loads, as spruce stands in the north were less susceptible to damage than in southern areas and long-term snow load reduced the damage probability. The model and the derived wall-to-wall map were able to discriminate damage from no-damage cases on a good level. The damage probability mapping approach identifies the drivers of snow disturbances across forest landscapes and can be used to spatially estimate the current and future disturbance risks in forests, informing practical forestry and decision-making and supporting the adaptation to the changing disturbance regimes.

The protection of infrastructure against gravitational natural hazards is one of the most important ecosystem services (ES) of mountain forests in Alpine countries. For a continuous provision of this ES, forests need to have a high protective effect, e.g., high canopy cover and/or stem numbers, while being resistant to and resilient after disturbances by being well-structured and stable, having a species composition adapted to the local site conditions and sufficient regeneration, all on a relatively small spatial scale. While "natural" forests may fulfill these prerequisites without human intervention, management history and high levels of ungulate browsing have produced unsustainable stand structures in many protection forests that need to be improved by management. The general principles of protection forest management are well established, but there are no quantitative, science-based recommendations for management regimes, i.e., specific sequences of interventions, that ensure a continuous protective quality. Our goal was to derive such recommendations for different stand types across three elevational zones, from mixed forests of the upper montane to spruce forests of the subalpine zone. We used an updated version of the model ProForM to simulate stand development under different levels of ungulate browsing, testing a large number of management regimes that vary in the spatial aggregation of tree removal, the intensity and interval of the interventions. We investigated the influence of browsing pressure and management on the protective quality using Boosted Regression Trees and Beta regression. High levels of ungulate browsing had such a strong negative effect on the protective quality that it could not be improved through forest management. This underlines the need for maintaining ungulate densities in Alpine forests at levels that allow for the successful regeneration of all key tree species. In stands that are influenced less by browsing, the protective quality can be improved through management in many cases, with specific management recommendations differing mostly depending on the initial stand conditions and, to a lesser extent, on the elevational zone. Well-structured stands provide a high protective quality without management interventions during at least a century across all elevational zones. In young and in mature stands, we generally recommend management regimes with relatively long return intervals of 30 to 40 years and low intervention intensities of 10 to 20% basal area removal.

Climate-induced fire regime shifts may reduce post-fire resilience of black spruce-dominated (BS; Picea mariana) North American boreal forests. While post-fire vulnerability of immature BS stands has been extensively studied, no study has evaluated simultaneous effects of fire severity and seasonality on the post-fire regeneration of mature (> 60-year-old) BS stands. This study aims to quantify post-fire regeneration levels of BS and co-occurring tree species to assess ecosystem recovery and possible loss of resilience due to regeneration failure. We analyzed effects of seed bank conditions, fire regime characteristics (fire severity and seasonality), and seedbed conditions on BS post-fire regeneration in mature forests in Quebec, Canada. Post-fire regeneration density was extensively surveyed across [~]50 400 km2 through a network of 536 plots that were distributed in 21 fires, which burned between 1995 and 2016. One-third of plots failed to regenerate (< 1750 conifer seedlings/ha) at levels adequate to produce closed-crown forest, whereas one-fifth experienced compositional changes, mainly towards jack pine (JP; Pinus banksiana) dominance. Pre-fire basal area of BS and living Sphagnum ground cover increased BS post-fire regeneration, whereas high-severity crown fires and spring fires reduced it. These findings suggest that mature BS-dominated forests may lose resilience in response to high-severity and spring fires. Given the projected increase in fire severity, and the extension towards an early-fire season in response to climate change, our study suggests that post-fire regeneration failure may become more frequent over the coming decades, with potential negative consequences on ecosystem services that are provided by BS-dominated boreal forests.

Managing for structural complexity to enhance forest ecosystem health and resiliency is increasingly incorporated in silvicultural treatments. High spatial variability in stands managed for structural complexity could obscure the effects of forest management on surface soils. Yet few studies have assessed how within-stand variation in forest structure and other local controls influence surface soil organic matter dynamics over time following timber harvests. We used a stratified random sampling design to capture variation in stand age, legacy structure, soil type, and topography in a second-growth, oak-hardwood forest in the northeastern U.S. We compared surface soil carbon and nitrogen content and availability in 15 harvested stands managed to promote tree regeneration (n = 144 plots) and five unharvested controls (n = 48 plots). We also examined changes over time since harvest in just the harvested stands using a 22-year chronosequence. Forest management strongly influenced surface soil carbon and nitrogen dynamics. The timber harvests had lower soil carbon and nitrogen, microbial biomass, and carbon mineralization but higher nitrogen mineralization. These differences were more pronounced in the drier, less fertile soil type than in more moist, fertile soils. Across the 22-year chronosequence, topography, soil type, and downed woody material density dictated the direction of changes in surface soil carbon and nitrogen over time. Soil carbon and nitrogen accrued over time at drier, higher elevation ([~]300 m) sites and under higher densities of fine woody material but declined at lower elevations ([~]180 m) and under lower fine woody material. Proximity to legacy trees was associated with higher soil carbon and nitrogen concentrations and availability. Our findings underscore the importance of silvicultural practices that retain structural legacies and downed woody material in shaping surface soil carbon and nitrogen dynamics over time. Our results also highlight how accounting for spatial variation in local controls on soil carbon and nitrogen, such as topography, can improve detection of changes from forest management practices that increase spatial heterogeneity within stands, such as irregular shelterwood and seed tree regeneration methods.

Afforestation and reforestation are integral components of the wider field of land management. When these initiatives integrate the diverse eco-biological, landscape, cultural, and socioeconomic characteristics of the intervention area they can achieve substantial environmental improvements also by improving ecosystem functions, commonly referred to as ecosystem services (ES). European black pines are some of most frequently used tree species for afforestation and reforestation in Mediterranean regions, thanks to their ability to grow in poor soil conditions and their resistance to environmental stressors. In this study, we adopted a validated process-based modeling approach to explore the effects of thinning intensity and frequency on the provision of some ES from European black pine stands, which have been established through afforestation and reforestation in Italy. We found a net financial gain when basal area removal reaches 25% with a 25-year thinning interval, highlighting the higher financial efficiency of more intensive interventions. Non-provisioning ES (erosion protection, carbon sequestration, and aesthetic/recreational value) tend to decrease with increased basal area removal and benefit from longer intervals between thinning. Remarkably, the economic values of aesthetic appeal and carbon sequestration far exceed those of timber production and erosion protection, regardless of thinning regime. Based on our results, we claim that strategic, long-term planning of thinning operations is essential to ensure a balanced trade-off between wood production and other ES while maintaining the cost-effectiveness of operations. Ultimately, our approach can provide guidelines for forest managers to ensure the provision of multiple ES.