Key message Whole-tree harvesting makes forests more profitable than conventional harvest as long as the impact on tree growth remains under 2.3% for even-aged oak ( Quercus petraea (Matt.) Liebl.) and 3.4% for sweet chestnut ( Castanea sativa Mill.) coppice with oak standards. Coppice-with-standards may have potential to be more profitable than even-aged oak in case of 50% rise in fuelwood prices

Key message A new process-based model, SurEau , is described. It predicts the risk of xylem hydraulic failure under drought. Context The increase in drought intensity due to climate change will accentuate the risk of tree mortality. But very few process-based models are currently able to predict this mortality risk. Aims We describe the operating principle of a new mechanistic model SurEau that computes

Key message We found high accuracy classification (Fmeasure = 95%, on cross-validation) of Araucaria angustifolia (Bertol.) Kuntze, an endangered native species, and Hovenia dulcis Thunb. an aggressive, invasive alien species in WorldView-2 multispectral images. In applying machine learning algorithms, the spectral attributes mainly related to the near-infrared band were the most important for the

Key message Cork porosity, due to lenticular channels, varied along the stem of Quercus suber L. Lenticular channels’ area, rather than their number, decreased upwards along the stem. Area decrease was observed regardless of tree size and of its intrinsic porosity. Context The cork of Quercus suber L. is radially crossed by lenticular channels, defining cork’s natural porosity. It has been suggested

Key message Melolontha hippocastani is a major pest in European mixed and broadleaf forests. Investigating its oviposition behavior, we observed that a dense shrub layer reduces the density of egg clusters and eggs in the soil. Conversely, canopy openness and a large proportion of oak appear as favoring conditions. Context Melolontha hippocastani is a major pest in European mixed and broadleaf forests

Abstract Key message We assessed forest users’ willingness to pay (WTP) for regulating and cultural forest services based on their socio-economic status (rich vs. poor), proximity to forests (nearby vs. distant), and forest management modalities (community forestry vs. collaborative forest management). As expected, a huge variation was found in WTP among these sub-groups. The wealthier households (HH)

Key message We assessed the narrow-sense heredity and genetic gains of multiple traits obtained using the indirect selection method for progeny of Cryptomeria japonica D. Don by artificial crossing. Using stress wave velocity and Pilodyn penetration depth as indicative parameters, wood properties could be improved in future generations of C. japonica plus trees and forest breeding programs will become

Key message Large-scale forest resource maps based on national forest inventory (NFI) data and airborne laser scanning may facilitate synergies between NFIs and forest management inventories (FMIs). A comparison of models used in such a NFI-based map and a FMI indicate that NFI-based maps can directly be used in FMIs to estimate timber volume of mature spruce forests. Context Traditionally, FMIs and

Key message Potentially nodulating Leguminosae species had high density and biomass in young stands of forests in Northeast Brazil, except in a dry forest on a low-fertility soil. Context Leguminosae species, especially potentially nodulating ones, appear to be important components of tropical secondary forests, although information is still scarce concerning their contributions to richness and biomass

Key message The history of the relationship between plant growth and water consumption is retraced by following the progression of scientific thought through the centuries: from a purely philosophical question, to conceptual and methodological developments, towards a research interest in plant functioning and the interaction with the environment. Context The relationship between plant growth and water

• Key message Natural disturbances and management are key drivers for forest carbon balance. We modelled the impact of Vaia storm on forest sink at national scale in Italy. We demonstrate that after Vaia, carbon fluxes among pools and through harvested wood products from salvage logging limit the carbon losses. Our findings can improve the effectiveness of mitigation actions under disturbance scenarios

Key message The size of the structural components of the root–pit–mound complex was crucial for high moss species richness. Root plates, pits, and mounds were similar in terms of moss species composition, which was mostly determined by forest type. Context Uprooted trees may be colonized by different terricolous mosses including common species and specialists. Aims The main aim of the present study

Key message We present a structured and curated database covering 21 years of LFMC measurements in the Catalan region, along with an associated R package to manage updates and facilitate quality processing and visualisation. The data set provides valuable information to study plant responses to drought and improve fire danger prediction. Dataset access is at https://doi.org/10.5281/zenodo.4675335,

Key message This genomic dataset provides highly variable SNP markers from georeferenced natural Quercus petraea (Matt.) Liebl. populations collected in Bulgaria, Hungary, Romania, Serbia, Bosnia and Herzegovina, Kosovo* and Albania. These SNP loci can be used to assess genetic diversity, differentiation, and population structure, and can also be used to detect signatures of selection and local adaptation

• Key message Due to social and environmental changes over the last decade, managers use multi-attribute decision-making techniques and geographic information systems to support participatory planning. Several studies have indicated that the combined use improves forest planning by applying a set of key criteria to simultaneously evaluate various ecosystem services. • Context Forest landscapes are

Key message Late-embryogenesis-abundant proteins (LEA) typically accumulate to high levels during seed dehydration and have an important role in the plant response to abiotic stresses. Transgenic hybrid poplars of 9-year-old TaLEA lines showed adaptation to drought and saline–alkali conditions. The exogenous gene was expressed normally, and the T-DNA insertion sites were identified on different chromosomes

• Key message The increase in climate variability is likely to generate an increased occurrence of both frost-induced and drought-induced damages on perennial plants. We examined how these stress factors can potentially interact and would subsequently affect the vulnerability to each other. Furthermore, we discussed how this vulnerability could be modulated by shifts in the annual phenological cycle

Key message We compared (lognormal) universal kriging with the area-based approach for estimation of forest inventory variables using LiDAR data as auxiliary information and showed that universal kriging could be an accurate alternative when there is spatial autocorrelation. Context Forest inventories supported by geospatial technologies are essential to achieve a spatially informed assessment of forest

Key message During the non-growing season, environmental factors changed after fire, leading to significantly increased non-growing season soil heterotrophic respiration (Rh) and potentially decreasing the amount of net C stored in cold temperate forest ecosystems of China. Context Intensifying forest fire regimes are likely to influence future C budgets of forest ecosystems. However, the mechanism

• Key message Hybrids had overall intermediate cold and heat tolerances compared to their progenitors, Juglans cinerea and Juglans ailantifolia . Differences in hybrids were small compared to J. cinerea though, indicating that when considering extreme temperature tolerances, hybrids might be usesd in some restoration circumstances. However, hybrids might exceed their cold tolerance in especially cold

Context Black poplar (Populus nigra L.) is a keystone species of European riparian ecosystems that has been negatively impacted by riverside urbanization for centuries. Consequently, it has become an endangered tree species in many European countries. The establishment of a suitable rescue plan of the remaining black poplar forest stands requires a preliminary knowledge about the distribution of genetic

• Key message In this study, genetic variation in polycyclic growth was investigated in a young Pinus brutia Ten. study in Turkey. The number of flushes was partially under additive genetic control and was moderately correlated with the tree height at age 4. • Context Pinus brutia is the most economically important tree species in Turkey. Previous limited studies suggested that its cyclic shoot elongation

Key message Local climate exerted a stronger effect on leaf litter decomposition of deciduous Quercus acutissima Carruth. and evergreen Quercus glauca Thunb. than initial leaf litter quality: the decomposition was much faster for leaves of the two species in warm-temperate forest than in the cool-temperate one. Context Litter decomposition mainly depends on initial litter quality (e.g., physical features

• Key message We designed a novel method allowing to automatically detect and measure defects on the surface of trunks including branches, branch scars, and epicormics from terrestrial LiDAR data by using only high-density 3D information. We could automatically detect and measure the defects with a diameter as small as 0.5 cm on either oak (Quercus petraea (Matt.) Liebl.) or beech (Fagus sylvatica

Key message Simulated spruce budworm (SBW; Choristoneura fumiferana (Clem.)) defoliation generally becomes ubiquitous in 3 years after its initiation in agreement with historical observations despite varying environmental and stand conditions over large ranges. Current-year defoliation has almost no correlation with defoliation more than 1 year ago at the same location, which may be related to the

• Key message Distinct chemical fingerprints of the wood of Afzelia pachyloba and A. bipindensis demonstrated an effective method for identifying these two commercially important species. Direct analysis in real-time (DART) time-of-flight mass spectrometry (TOFMS) allowed high-throughput examination of chemotypes with vast potential in taxonomic, ecological, and forensic research of wood. • Context

• Key message Modern forest managers operate in a world characterised by increasing variability in multiple factors impacting forest productivity, survival and product quality. Being able to predict, as accurately as possible, how forests will develop in the future is perhaps of more importance than ever before. At an international IUFRO conference held in Stellenbosch, South Africa, in September 2018

• Key message Nitrogen (N) addition (10 and 15 g N m −2 year −1 as dissolved \({\mathbf{N}\mathbf{H}}_{4}{\mathbf{N}\mathbf{O}}_{3}\) ) significantly increased the CO 2 efflux from the forest soil and the fine root biomass in a maple (Acer velutinum Bioss.) plantation. Following a seasonal pattern, soil CO 2 efflux showed an exponential relationship with the fine root biomass and soil temperature.

• Key message This document provides valuable environmental information about a triplets’ essay of Scots pine and Maritime pine in Spain. The dataset characterizes the soil profile (physicochemical parameters of organic and mineral horizons), climate, physiography, understory and overstory. Dataset access is at https://doi.org/10.5281/zenodo.4384530 and associated metadata is available at https://metadata-afs

•Key message We developed a dataset of the potential distribution of seven ecologically and economically important tree species of Europe in terms of their climatic suitability with an ensemble approach while accounting for uncertainty due to model algorithms. The dataset was documented following the ODMAP protocol to ensure reproducibility. Our maps are input data in a decision support tool “SusSelect”

• Key message Understanding the adaptive mechanisms of forest species is vital to ensure their survival in a climate change scenario. This study aimed at uncovering the relationship between genetic variability and environmental variables in natural Castanea sativa populations, unveiling how different climate scenarios drove local adaption processes using a landscape genomics approach. Our findings

• Key message Visual perception of the appearances of different wood surfaces is greatly influenced by their features, such as color, grain, and gloss. Among these features, human visual perception of wood grain type occurs through a later and higher-ordered cognitive process than the perception of color or gloss. Dark wood was subjectively preferred to light- or medium-colored wood, and both matte

• Key message The specific dynamic elastic modulus, acoustic radiation, logarithmic decrement, sound transmission parameter, and acoustic conversion efficiency of spruce wood (Picea jezoensis var. microsperma (Lindl.) W.C.Cheng & L.K.Fu) were improved by extraction treatment with deionized water, dichloromethane, benzyl alcohol, and ethanol. A larger improvement was achieved after extraction with benzoyl

• Key message Parametric indirect models derived from stem analysis of dominant trees were more robust than rule-based machine learning techniques for predicting Site Index of Scots pine stands as a function of climate. • Context The uncertainties derived from climate change make it necessary to develop new methods for representing the relationships between site conditions and forest growth. • Aims

• Key message Pronounced additive genetic variation and high narrow-sense heritability for lesion length caused by Neonectria neomacrospora were found in a Nordmann fir progeny test. Significant inbreeding depression was detected in traits important for Christmas tree production. Recurrent selection for multiple traits would be successful for Christmas tree quality traits. • Context The fungal pathogen

• Key message The browsing level of oak (Quercus petraea and Quercus robur) and fir (Abies alba) provided only a rough estimate of the expected regeneration success. Thus, it cannot be recommended as a standard measurement to predict forest development, unless the number of saplings and the height of those saplings are considered. • Context Browsing by large herbivores may affect regeneration success

• Key message Canopy closure and stand age significantly affected the litter decomposition. Therefore, stand-specific decomposition constants (k) should be calculated in forest carbon models for more accurate carbon budget estimation. Furthermore, to reduce the carbon release from decomposing litter, regeneration cutting should be carried out at later ages, and heavy thinning should not be implemented

• Key message Invasive tree species alter taxonomic diversity and functioning of forest shrub layers: Prunus serotina increases shrub layer biomass two to three times but decreases its biodiversity, Robinia pseudoacacia slightly increases shrub layer biomass and has no effect on its biodiversity, while Quercus rubra both biomass and biodiversity of the shrub layer. • Context Although the impact of

• Key message Errors in forest stand attributes can lead to sub-optimal management prescriptions concerning the set management objectives. When the objective is net present value, errors in mean diameter result in greater losses than similar errors in basal area, and underestimation greater losses than overestimation. • Context Errors in forest inventory data can cause inoptimality losses in the objectives

The original article was published with an erroneous affiliation details for co-author, David J. Lee. The correct affiliation for the author is Forest Industries Research Centre, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, QLD, 4558, Australia. The original article has been corrected

• Key message Sampling needs differ by forest type for timber inventory and structural complexity metrics. We demonstrate in a typical mixed Eastern Hardwoods forest that optimal sampling of timber inventory metrics and spatially explicit structure indices may be achieved in one large plot plus a cruise for large diameter trees, but accurately capturing inventory metrics may not be possible with sparse

• Key message Wavy grain, a rare figure type of wood, leads to highly priced timber in Acer pseudoplatanus L. The influence of this trait on growth performance and its causes are not known. Analyzed wavy and straight grain sycamore maple progenies show comparable growth performance in a field trial. Stability of wavy grain after vegetative propagation is confirmed and genetic inheritance indicated

• Key message Ash dieback decreases individual reproductive success of ash trees leaving healthy ash overrepresented as seed and pollen parents for next-generation seedlings. Substantial gene flow over hundreds of meters combined with superior fertility of healthy trees creates optimism for the species’ future in European forests. • Context Hymenoscyphus fraxineus is causing high mortality in European

• Key message Total fidelity value index can be used for the assignment of new relevés to existing vegetation units and it can be used to refine classifications derived from unsupervised clustering. • Context Diagnostic species is an important concept in vegetation classification. Apart from its usefulness to characterize species niche preferences, the diagnostic species concept is used in vegetation

• Key message We successfully transformed Pinus sylvestris yield tables into diameter distribution models. The best results were obtained with the parameter recovery method based on both mean and quadratic mean diameter, which explained 70% of the variability of frequencies by diameter classes and provided better results in the analysis of errors. On the other hand, the method based on stand density

• Key message Litter trap is considered the most effective method to quantify seed production, but it is expensive and time-consuming. Counting fallen seeds using a quadrat placed on the ground yields comparable estimates to the litter traps. Ground quadrat  estimates derived from either visual counting in the field or image counting from quadrat photographs are  comparable, with the latter being also

• Key message Mechanisms controlling germination of > 2600 Arecaceae species adapted to the tropical forests are not clearly understood. This contribution underpins the notion that the coexistence of dormancy and desiccation sensitivity in some Arecaceae species could significantly affect the germination ecology. Although the evolutionary and ecological significance behind this occurrence is unknown

• Key message A recent paper by Ceccherini et al.( 2020a ) reported an abrupt increase of 30% in the French harvested forest area in 2016–2018 compared to 2004–2015. A re-analysis of their data rather led us to conclude that, when accounting for the singular effect of storm Klaus, the rate of change in harvested area depended on the change year used to separate the two periods to compare. Moreover

• Key message A novel non-destructive method has been developed to predict modulus of elasticity (MOE) of logs using measurements taken from cores extracted from discs. The trees were felled and cut into logs to allow validation of our method; however, similar results would be obtained if the cores were extracted from standing trees. The method shows that a single core from breast height is sufficient

• Key message A multi-criteria analysis can be an interesting tool to assess the effects of silvicultural treatments on ecosystem services supply. In the degraded forests, thinning has a positive effect on the provision of ecosystem services such as timber and bioenergy production, climate change mitigation, and recreational attractiveness. • Context The Millennium Ecosystem Assessment highlights the

• Key message Decomposition of forest herb species litter was not always completed in less than a year and was not always faster than decomposition of tree leaf litter in an oak-hornbeam forest in Western Poland. Litter decomposition of herbaceous plants is connected with their life strategy and functional traits of their leaves. • Context Forest understories are frequently ignored in ecological research

• Key message An ensemble modelling approach was performed to predict the distributions of seven sympatric sclerophyllous oak species in the Hengduan Mountains of Southwest China. Spatial eigenvector filters revealed missing factors in addition to commonly used environmental variables, thus effectively improved predictive accuracy for the montane oak species. This study identified a richness center

Abstract Key message We modeled 10-year net stand volume growth with four machine learning (ML) methods, i.e., artificial neural networks (ANN), support vector machines (SVM), random forests (RF), and nearest neighbor analysis (NN), and with linear regression analysis. Incorporating interactions of multiple variables, the ML methods ANN and SVM predicted nonlinear system behavior and unraveled complex

Key message A piecewise polynomial function already used to represent the size-density trajectories of pure even-aged stands of beech, oak, and Douglas-fir proved its ability to represent the size-density trajectories of a new species, ash. The widespread ash dieback caused departures from the expected size-density trajectories. These abnormalities can be used to detect an extra level of mortality

Key message A novel multi-environment competition individual-tree mixed model resulted in better fit, and greater individual narrow- and broad-sense heritabilities than the model without competition, notably for traits showing competition. In multi-environment tests, the proposed model would allow tree breeders to select genotypes with the best performance in both additive direct and competition breeding

• Key message Non-selective thinning of a hybrid aspen coppice stands via corridor or cross-corridor cutting impacts residual trees differently depending on their competitive status. Suppressed residual trees’ metabolic profile indicates increased stress level, especially after cross-corridor thinning. • Context Early thinning with regular corridor harvests is proposed for the management of post-harvest

The original article was published with a small but significant mistake.

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

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. In fire-prone Mediterranean areas, climate change

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 benefit in