Key message Climate change will induce a change in fire frequency in Mediterranean region and that could impact fire-adapted plant species. We showed that fire-related traits of some pine species are strongly related to other factors than fire but the recent fire history has nonetheless an impact on the variation of key traits for different fire adaptive strategies. Context In fire-prone Mediterranean

Key message Patterns of stem radial variations showed that Cedrus libani A. Rich. was less limited by summer drought than co-occurring Juniperus excelsa M. Bieb. Cedrus libani recovered faster from tree water deficit and showed significantly higher radial growth rates and annual stem increments than J. excelsa . However, the ability of J. excelsa to grow more hours per year may indicate a potential

Key message Unprecedented forest declines and diebacks are expected worldwide in response to global change. Insects can trigger or contribute to these disturbances, which can in turn have either beneficial or detrimental retroactive cascading effects on insect communities. However, we are still unsure of the effects that pests will have on these disturbances in the future, and new biodiversity and

• Key message Strong density differences were observed between stem wood at 1.30 m and other tree components (stem wood, stem bark, knots, branch stumps and branches). The difference, up to 40% depending on the component, should be taken into account when estimating the biomass available for industrial uses, mainly fuelwood and wood for chemistry. • Context Basic density is a major variable in the

This correction stands to correct the listed errors in the original article:

Key message This literature review identified the main factors for the success of different silvicultural approaches to regenerate sessile oak naturally and unveiled at the same time important knowledge gaps. Most previous studies were only short-term and restricted to a few factors and single locations. Hence, the findings of these studies are of limited explanatory power and do not allow to develop

Key message Dormancy in Arecaceae diaspores is due to underdeveloped embryos, therefore, morphological dormancy or morphophysiological dormancy. Consequently, claims such as external seed structures inhibit germination, embryos are fully developed at maturity, and underdeveloped embryo is not a form of dormancy are rejected, because embryo size of the diaspore at the time of dispersal was not taken

Key message Late-season extreme climatic events induced variations in wood density and extended growth for more than a month in 2016 in Juniperus przewalskii Kom. growing on the Northeastern Tibetan Plateau, suggesting extraordinary growth resilience of the species in response to short extreme events over the cold and arid region. Context Monitoring xylem formation (xylogenesis) during extreme meteorological

Key message French forests exhibit the fastest relative changes across Europe. Growing stock increases faster than area, and is greatest in low-stocked private broadleaved forests. Past areal increases and current GS levels show positive effects on GS expansion, with GS increases hence expected to persist. Context Strong increases in growing stocks (GS) of European forests for decades remain poorly

Key message The precise demarcation and cross-dating of tree rings in Aspidosperma tomentosum Mart., a valuable timber species in the tropical dry forests of South America, were used to develop the first well-replicated chronology covering the period 1843–2015. A. tomentosum Mart. tree growth is strongly regulated by soil water availability prior to and during the current growing season. In the context

Key message The potential of airborne laser scanning (ALS) and multispectral remote sensing data to aid in generating improved wind damage risk maps over large forested areas is demonstrated. This article outlines a framework to generate such maps, primarily utilizing the horizontal structural information contained in the ALS data. Validation was done over an area in Eastern Finland that had experienced

Key message To be useful for silvicultural and forest management practices, the models of Site Index (SI) should be based on accessible predictor variables. In this study, we used spatially explicit data obtained from digital elevation models and climate data to develop SI prediction models with high local precision. Context Predicting tree growth and yield is a key component to sustainable forest

Key message In recent decades, there has been a decline in growth in a rear-edge broadleaf forest of Fagus sylvatica , Quercus petraea , and Q uercus pyrenaica . Although temperatures have been rising due to climate change, the observed decline in growth was mainly attributed to increased density and competition between trees since the cessation of traditional uses such as logging in the 1960s. Context

Key message Different tree species have dissimilar capacities to sequester soil organic carbon (SOC). Deciduous broadleaved trees show the most stable increase in SOC stock after afforestation than other tree species, while sempervirent conifer trees show the lowest rate of SOC stock change. Sempervirent broadleaved trees show the greatest increase in SOC stock 20 years after afforestation. Context

Key message Discovery of the first case of allotriploid juniper in a wild population in the French Alps where the parental species occurs in sympatry. Context Interspecific hybridization and polyploidy are important evolutionary phenomena in vascular plants. Natural hybridization between species living in sympatry can sometimes occur. Less frequent are successful hybridizations between species having

Key message On the selected sites in the investigated Oriental beech ( Fagus orientalis L.) dominated forests in Iran with an extensive individual tree selection system, tree microhabitats (MH) are more influenced by tree level factors such as tree species and DBH than by plot level factors such as plot basal area or size and species diversity. Context Despite the ecological importance of tree microhabitats

Key messageTree structure equations derived from pipe model theory (PMT) are well-suited to estimate biomass allocation in Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies [L.] Karst.). However, age dependence of parameters should be accounted for when applying the equations. ContextPipe model theory-based (PMT-based) structure equations have been incorporated in many process-based

Key message The important anatomical changes in tension wood, e.g., the high fiber ratio and rich mesopores, did not significantly increase the air and nitrogen flow; thus the gas permeability in the longitudinal direction of poplar ( Populus deltoides CL.’55/65′) tension wood is actually affected by the cell tissue macroporous porosity. ContextGas permeability is one of the most important physical

Key message This synthesis of the literature on incorporation of genetic gain into growth and yield models reveals a fundamental challenge associated with the rapid progress in genetics and breeding and limited empirical data on improved stands. Model improvements depend on a better understanding of both the biological basis for gain and of interactions between genetic and non-genetic factors on gain

• Key message This special issue gathers articles arising from the ERA-NET BiodivERsA3 research project “Unraveling the Potential of Spontaneous Forest Establishment for Improving Ecosystem Functions and Services in Dynamic Landscapes (SPONFOREST)”. Using a broad spectrum of research approaches, they provide detailed insights into how new forest stands establish and which consequences the establishment

Key message Radial growth in a group of Pinus radiata D. Don. trees varies in magnitude around the circumference and follows synchronous but arrhythmic dynamics. ContextEccentric and irregular girth growth is typically associated to specific growth responses, but it is generally assumed to be small or absent during normal development. The dynamics by which excess growth is formed are unclear. AimsThe

Key message Decline can affect the structure, resources, and microclimates of the forest canopy, and potentially have cascading effects on canopy-dwelling species. Our survey shows that an oak decline can promote saproxylic beetles, especially xylophagous ones, and generalist phyllophagous weevils. However, it negatively affects specialist leaf-eating species and has no effect on seed-eating weevils

Key message We examined the accuracy of the stand attribute data based on airborne laser scanning (ALS) provided by the Finnish Forest Centre. The precision of forest inventory data was compared for the first time with operative logging data measured by the harvester. ContextAirborne laser scanning (ALS) is increasingly used together with models to predict the stand attributes of boreal forests. The

Key messageStructural and ultrastructural traits of leaf xylem vary among European beech ( Fagus sylvatica L.) provenances in relation to climate. High tracheary element lumen area was observed in central Europe and decreased towards the range margins, while tracheary element density displayed opposite trend. Leaf anatomy and xylem cell-wall deformation were associated with climate continentality at

Key messageAnalyses of dendrochronological data from 15 recently established tablished stands of pedunculate oak (Quercus robur L.) revealed that functions describing potential tree growth in the absence of neighbours varied more between stands than functions describing competitive effects of conspecific neighbours. This suggests that competition functions can more easily be transferred among stands

Key message Faced with wicked problems such as climate change, managers of complex forest social-ecological systems require more than experimental sciences alone. Yet, mitigation and adaptation studies underuse social sciences in forest research, as shown here with the French case study. Therefore, we stress the value of social sciences for forest researchers, and extend this reflection to research

Key message NAC transcription factors may play important roles in the biological processes in Persian walnut. A total of 102 JrNAC s were identified in Persian walnut. The conserved domains, transcriptome profile, expression analysis, and interaction network suggest that JrNAC1-4 plays potential roles in Persian walnut flowering development. Context NACs are plant-specific transcription factors that

Key message In older, unlogged rainforest of Hainan Island, China, leaves of saplings were larger, and fine root systems of saplings were thicker with fewer root tips than in historically logged areas. These results were consistent among 15 Angiosperm lineages, even though families differed widely in their leaf and root traits. ContextHow plant organ morphologies vary with environment is key for inferring

Key messageFew studies have linked the origin of dispersed tree seeds with their post-dispersal fate. We show that habitat-dependent mortality in a pedunculate oak ( Quercus robur L.) seedling cohort reshapes the effective fecundity of individual mother trees but has little effect on the cohort’s genetic diversity. ContextInitial tree recruitment plays a key role in forest regeneration, yet little

Key message Centenary forest statistics informing major attributes of French forests were digitized, checked for consistency, and used to infer forest dynamics. Comparison to forest inventory data highlights increases in forest area and tree diversity, and substantial maturation of forests. Dataset access at https://doi.org/10.5281/zenodo.3739458 ContextThe history of European forest dynamic remains

Key message National Forest Inventories (NFIs) hold promise for monitoring and valuing of non-productive forest functions, including social and recreational services. European countries use a range of methods to collect social and recreational information within their NFI methodologies. Data collected frequently included general and recreation-specific infrastructure, but innovative approaches are

Key message A moderate genetic diversity, the absence of a significant genetic differentiation between wild and cultivated stands and a highly admixed genetic structure of sweet chestnut with two main clusters were observed in France using two different data sets with 10 and 18 microsatellites. ContextRenewed interest in European chestnut in France is focused on finding locally adapted populations

Key messageThis study presents an easy-to-apply variable probability sample design that is an efficient and cost-effective method to correct for local bias in regional LiDAR-assisted forest inventory estimates. This design is especially useful for small woodlot owners. ContextLight detection and ranging (LiDAR)-derived forest inventory estimates are generally unbiased at landscape levels but may be

Key messageThe wood of Pinus nigra populations planted in Portugal, comparatively to Pinus pinaster , has higher total extractive content, lower Klason lignin and H/G ratio, and similar mechanical properties, presenting advantages for industrial purposes. ContextP. nigra was used in the reforestation of mountainous areas in Portugal, but its wood chemical and mechanical properties were never studied

Key messageAn increase in the stiffness of lumber with a decrease in initial tree spacing was confirmed for Pinus patula Schiede ex Schltdl. & Cham. The underlying properties of microfibril angle, wood density and knot frequency explained 71% of the variation in lumber stiffness. Tree spacing also influenced wood properties independent of radial growth rate. ContextRapid growth rates and reduced harvesting

Key message This study showed that regeneration success (presence of oaks ≥ 150 cm in total height) in artificial canopy openings of a mature mixed sessile oak stand was mainly driven by initial oak seedling density. ContextSmall-scale harvesting methods as practiced in close-to-nature forestry may disadvantage the regeneration of more light-demanding tree species including sessile oak (Quercus petraea

Key messageThe change in forest productivity was simulated in six stands in Wallonia (Belgium) following different climate scenarios using a process-based and spatially explicit tree growth model. Simulations revealed a strong and positive impact of the CO 2 fertilization while the negative effect of the transpiration deficit was compensated by longer vegetation periods. The site modulated significantly

Key message Fertilization is a feasible management technique for Pinus pinea L. cropping, with increased cone production up to 9 years after the application and superior trunk diameter growth every year. Fertilization effects on cone size-weight indicate the value of re-fertilizing. ContextStone pine (Pinus pinea) is a species of economic interest for its highly in demand pine nuts. Despite the high

Key message Considering anisotropy in image reconstruction algorithm for ultrasound computed tomography of trees resulted in a more accurate detection of defects compared to common approaches used. ContextUltrasound computed tomography is a suitable tool for nondestructive evaluation of standing trees. Until now, to simplify the image reconstruction process, the transverse cross-section of trees has

Key message In our study of colonisation of abandoned farmland by Juniperus thurifera L., environmental and geographic distances were stronger drivers of functional differentiation among trees than genetic distance and tree intrinsic features. However, these effects varied both along the colonisation gradient and across predictors’ values, highlighting the complexity of the conditions under which functional

Key message The use of reduced planting spacings is an important strategy to increase the carbon storage in the above-belowground biomass and should be recommended for future exploitation of forest energy plantations when the purpose intended is the production of biomass for energy. ContextRecent concerns about global warming have resulted in more concerted studies on quantifying carbon storage in

Key message Radial variation of wood properties affects product recovery from veneer logs. In Eucalyptus nitens , the radial variation in wood density, microfibril angle and modulus of elasticity was described using non-linear models. The timing of radial change was trait-dependent, and the age at which thresholds for structural products were reached differed between sites. ContextEucalyptus nitens

Key message Pinus nigra J.F. Arnold has an ecological and economic interest in Europe, but many of the planted populations have an unknown origin and infraspecific taxonomy. Six Portuguese P. nigra populations characterised with microsatellites revealed high intra-population diversity structured into two clusters with low differentiation that might suggest two provenances or infraspecific taxa. Despite

Key message Mechanical properties of small-diameter round timber from hardwood thinnings of common alder ( Alnus glutinosa (L.) Gaertn.), European ash ( Fraxinus excelsior L.), European birch ( Betula pendula Roth. and Betula pubescens Ehrh.), and sycamore ( Acer pseudoplatanus L.) can be evaluated by non-destructive testing on either standing trees or green logs without wood density determination

Key messageSpecies interactions implicate a complex balance of facilitation and competition, which may shift during community development, thus structuring the subalpine ecotone of Mediterranean mountain ranges through time and space. This study highlights that encroachment of grasslands and simultaneous downward/upward movement of forest tree species involve species interferences and environmental

Key message During the first summer, wood biochar amendments increased soil temperature, pH, and soil CO 2 effluxes in a xeric boreal Scots pine forest. The increase of soil CO 2 efflux could be largely explained by increases in by soil temperature. Higher biochar application rates (1.0 vs 0.5 kg m −2 ) led to higher soil CO 2 efflux while the pyrolysis temperature of biochar (500 or 650 °C) had no

Key message Acacia longifolia and Acacia mearnsii exhibit different reproductive behavior (viability, germination, and dormancy) in relation to fire and seed maturation. The potential of invasion of A. longifolia is stronger than that of A. mearnsii . A. longifolia germinates abundantly between fires and after fires, while A. mearnsii only germinates after fire and needs higher thermal thresholds to

Key message Malus sylvestris (L.) Mill., Pyrus communis (L.), Sorbus aucuparia (L.), Prunus avium (L.), Prunus padus (L.), and Cornus sanguinea (L.) are related, co-occurring species producing orthodox seeds. However, we observed differences in their response to storage conditions, such as storage at different seed moisture contents (5%, 8%, and 11%) and/or temperatures (− 3 °C, − 18 °C, and − 196

Key message The 19-year monitoring study revealed continuously positive and dynamic responses of tree growth to logging residue loadings. However, the lack of changes in soil nutrients suggested that increased growth might result from enhanced nutrient cycling with no net accumulation in the soil. ContextUnderstanding how logging residue loadings affect soil nutrients and forest growth is critical

Key message We propose a methodology to develop a preliminary version of a growth model when tree-level growth data are unavailable. This modelling approach predicts individual tree growth using only one-time observations from temporary plots. A virtual dataset was generated by linking the whole stand and diameter distribution models. The individual tree model was parameterized using Bayesian calibration

Key message Nitrogen addition during 4 years to the canopy of Castanopsis chinensis (Sprengel) Hance promoted xylem formation, mainly by increasing radial growth during the early growth season. ContextIncreased atmospheric nitrogen (N) deposition caused by intensive anthropogenic activities resulted in inconsistent effects on the xylem formation of trees, in N-limited boreal and temperate forests.

Key message Intra-annual wood density fluctuations are valuable indicators of the role of the local climate and provenance origins on tree growth. These intra-ring wood features were the most informative about local adaptation and phenotypic plasticity of Pinus halepensis Mill. in a provenance trial. This highlights the importance of taking provenance into account when selecting forest reproductive

Key message The ongoing global warming tends to reduce Larix decidua radial growth and ring wood density at the bottom of an elevational gradient in the French Alps, while it has a less marked effect at the top. ContextThe ongoing climate warming affects most tree species across their biogeographic distribution range. The bottom and the top of an elevational gradient are appropriate environments to

Key message Defoliation modality significantly affected leaf traits and carbon allocation especially in the early recovery period of two Leguminosae woody species . Robinia pseudoacacia L. recovered more quickly following defoliation than Amorpha fruticosa L. ContextDefoliation resulting from anthropogenic disturbance, insects, and grazing animals affects plant growth and vegetation dynamics. Robinia

Key message Decreasing stand density increases resistance, resilience, and recovery of Quercus petraea trees to severe drought (2003), particularly on dry sites, and the effect was independent of tree social status. ContextControlling competition is an advocated strategy to modulate the response of trees to predicted changes in climate. AimsWe investigated the effects of stand density (low, medium

Key message Chestnut timber is a resource that has so far been underestimated. The production of laminated chestnut beams represents important progress; it is necessary to check its market performances and the opportunities offered from non-market characteristics. To ensure competitiveness margins in the future, dedicated chestnut timber policy is required. ContextEuropean Union policies for sustainable

Key message During the past decades, a multitude of oak stands have spontaneously established across the pine-dominated landscapes of the French Landes de Gascogne. Yet their future performance under modern climate change is unknown. We show that coppiced, dominant trees are most prepared to cope with drought episodes, displaying higher basal area increment and lower sensitivity to extreme events.

Key message In this exploratory study, we show how combining the strength of tree diversity experiment with the long-term perspective offered by forest gap models allows testing the mixture yielding behavior across a full rotation period. Our results on a SW France example illustrate how mixing maritime pine with birch may produce an overyielding (i.e., a positive net biodiversity effect). ContextUnderstanding

Key message The adoption of new silvicultural methods and approaches requires an understanding of the differences between those and “old” or “conventional” approaches, along with extensive training to break previous knowledge bias. Context Forestry is in transition towards ecosystem-based management, and new silvicultural approaches are appearing worldwide. However, the adoption of an alternative silvicultural

Key messageUsing the three characteristic points of a forest stand, dg (mean quadratic diameter), dmin(diameter of the smallest tree) anddmax (diameter of the largest tree), appears informative enough to determine the parameters of the whole diameter distribution and, hence, the standing volume, with an accuracy of 2–3%. This is related principally with a particular feature of the Weibull distribution