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Black locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introduced to Europe probably in 1601 and currently extends over 2.3 × 106 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide after Eucalyptus spp. This wide-spreading planting is because black locust is an important multipurpose species, producing wood, fodder, and a source of honey as well as bio-oil and biomass. It is also important for carbon sequestration, soil stabilization and re-vegetation of landfills, mining areas and wastelands, in biotherapy and landscaping. In Europe, black locust is drought tolerant so grows in areas with annual precipitation as low as 500–550 mm. It tolerates dry, nutrient poor soils but grows best on deep, nutrient-rich, well-drained soils. It is a fast-growing tree and the height, diameter and volume growth peak before the age of 20. It mostly regenerates vegetatively by root suckers under a simple coppice system, which is considered the most cost-effective management system. It also regenerates, but less frequently, by stool sprouts. Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots, and cleaning-respacing to remove low-quality stems, reduce the number of shoots per stool, and adjust spacing between root suckers. In addition, early, moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees. The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes.

In forestry, harvest models have become popular for forecasting thinning under business-as-usual scenarios. There are two binary processes involved in thinning operations: (i) whether a plot is to be thinned and (ii) whether a particular tree within that plot is to be harvested. These processes can be modeled using logistic regressions. The data used to fit such models come from forest inventories, where the observations are not usually independent. Random effects can be used to deal with these correlations. However, fitting the plot-level and tree-level models independently hinders the estimation of the covariance between the random effects of both models. The objective of this paper was to develop a statistical method for the simultaneous prediction of harvest probabilities at the plot and tree levels in a single mixed-effects model. We developed a maximum likelihood estimator based on the joint distribution of the probability that a given plot is thinned and the probability that a given tree within that plot is harvested. The estimator was derived from a zero-altered binomial form, but it assumed distinct harvest probabilities for each single tree. The estimator was tested in the case study of mixed stands of oak (Quercus spp.) and beech (Fagus sylvatica L.) in Northern France.

International audience; In a recent communication, Cruz et al. (2017) called attention to several recurring statements (mantras) in the wildland fire literature regarding empirical and physical fire behaviour models. Motivated by concern that these mantras have not been fully vetted and are repeated blindly, Cruz et al. (2017) sought to verify five mantras they identify. This is a worthy goal and here we seek to extend the discussion and provide clarification to several confusing aspects of the Cruz et al. (2017) communication. In particular, their treatment of what they call physical models is inconsistent, neglects to reference current research activity focussed on combined experimentation and model development, and misses an opportunity to discuss the potential use of physical models to fire behaviour outside the scope of empirical approaches.

Recent studies projecting future climate change impacts on forests mainly consider either the effects of climate change on productivity or on disturbances. However, productivity and disturbances are intrinsically linked because 1) disturbances directly affect forest productivity (e.g. via a reduction in leaf area, growing stock or resource-use efficiency), and 2) disturbance susceptibility is often coupled to a certain development phase of the forest with productivity determining the time a forest is in this specific phase of susceptibility. The objective of this paper is to provide an overview of forest productivity changes in different forest regions in Europe under climate change, and partition these changes into effects induced by climate change alone and by climate change and disturbances. We present projections of climate change impacts on forest productivity from state-of-the-art forest models that dynamically simulate forest productivity and the effects of the main European disturbance agents (fire, storm, insects), driven by the same climate scenario in seven forest case studies along a large climatic gradient throughout Europe. Our study shows that, in most cases, including disturbances in the simulations exaggerate ongoing productivity declines or cancel out productivity gains in response to climate change. In fewer cases, disturbances also increase productivity or buffer climate-change induced productivity losses, e.g. because low severity fires can alleviate resource competition and increase fertilization. Even though our results cannot simply be extrapolated to other types of forests and disturbances, we argue that it is necessary to interpret climate change-induced productivity and disturbance changes jointly to capture the full range of climate change impacts on forests and to plan adaptation measures., published version, peerReviewed

Survival analysis methods make better use of temporal information, accommodate multiple levels of explanatory variables, and are meant to deal with interval-censored data. In a context of harvest modeling, this approach could improve some known limitations. In this study, we used data from a network of permanent plots in the province of Quebec, Canada, as a real-world case study. We tested the potential of survival analysis to predict plot-level harvest probabilities from plot- and regional-level variables. The approach also included random effects to account for spatial correlations.The results showed the potential of survival analysis to provide annual predictions of harvest occurrence. Both regional and time-varying variables, as well as spatial patterns, had important effects on the probability of a plot to be harvested. Respectively, reductions in the annual allowable cut volumes led to a decrease in the harvest probabilities. Greater harvest probabilities were associated with the broadleaved dynamics class and higher values of basal area. In contrast, they were decreased by stem density and slope classes.The spatial random effect resulted in an improvement of the model fit. Our plot- level model improved some limitations reported in previous studies by taking the effect of a time-varying regional variable into account.; Les méthodes d’analyse de survie utilisent mieux l’information temporelle, tiennent compte de multiples niveaux de variables explicatives et sont destinées à traiter des données censurées par intervalle.Dans un contexte de modélisation de la récolte, cette approche pourrait améliorer certaines limites connues. Dans cette étude, nous avons utilisé des données d’un réseau de placettes permanentes de la province de Québec, au Canada, pour servir d’étude de cas concret. Nous avons testé le potentiel de l’analyse de survie pour prédire les probabilités de récolte à l’échelle de la placette, à partir de variables associées à la placette et à la région. L’approche comprenait également des effets aléatoires pour tenir compte des corrélations spatiales.Les résultats ont montré le potentiel de l’analyse de survie pour fournir des prédictions annuelles de l’occurrence de la récolte. Les variables régionales et les variables qui évoluent en fonction du temps, ainsi que la configuration spatiale, avaient des effets importants sur la probabilité qu’une placette soit récoltée. Les réductions de la possibilité annuelle de coupe entraînaient une diminution des probabilités de récolte. Des probabilités de récolte plus grandes étaient associées à la classe de dynamique forestière feuillue et à des valeurs plus élevées de la surface terrière. Inversement, elles étaient diminuées par la densité des tiges et les classes de pente.L’effet aléatoire spatial a entraîné une amélioration de l’ajustement du modèle. Notre modèle à l’échelle de la placette a amélioré certaines limites signalées dans les études précédentes en prenant en compte l’effet d’une variable régionale qui évolue dans le temps.

Wind damage to commercial plantations and natural forests is a serious concern for forest owners and managers all over the world, with notable losses having been reported in the last few decades in Europe, the Americas, and Oceania. Wind-risk models such as ForestGALES allow for a good understanding of the dynamics involved in wind damage, and for calculations of risk to be made, therefore providing vital information on the best practices to minimise such risk. In this paper we parameterise ForestGALES for Eucalyptus globulus (Labill.), arguably one the most widespread and commercially important species for pulp and biomass production, with tree-pulling data obtained in Asturias, Spain. Despite the scarce data on tree and stand characteristics available for wind damaged stands of Eucalyptus spp., we provide an evaluation of our model's performance under different stocking densities by comparing our simulations with real wind damage data acquired from the literature. We show that ForestGALES is able to accurately model the critical wind speeds responsible for Eucalypts stand damage, hence extending the model's applicability to this important commercial genus. In line with good modelling practice, we present the results of a sensitivity analysis of the model, performed with a Global variance-based method. Our sensitivity analysis confirmed the main role of Dbh, stocking density, and tree height in driving the model outputs, and highlighted the importance of accurately knowing the size of any upwind gaps adjacent to a stand to reduce uncertainty in model predictions.

International audience; In order to determine the mechanical resistance of several forest tree species to rockfall, an inventory of the type of damage sustained in an active rockfall corridor was carried out in the French Alps. The diameter, spatial position and type of damage incurred were measured in 423 trees. Only 5% of trees had sustained damage above a height of 1.3 m and in damaged trees, 66% of broken or uprooted trees were conifers. Larger trees were more likely to be wounded or dead than smaller trees, although the size of the wounds was relatively smaller in larger trees. The species with the least proportion of damage through stem breakage, uprooting or wounding was European beech (Fagus sylvatica L.). Winching tests were carried out on two conifer species, Norway spruce (Picea abies L.) and Silver .r (Abies alba Mill.), as well as European beech, in order to verify the hypothesis that beech was highly resistant to rockfall and that conifers were more susceptible to uprooting or stem breakage. Nineteen trees were winched downhill and the force necessary to cause failure was measured. The energy (Efail) required to break or uproot a tree was then calculated. Most .r trees failed in the stem and spruce usually failed through uprooting. Beech was either uprooted or broke in the stem and was twice as resistant to failure as .r, and three times more resistant than spruce. Efail was strongly related to stem diameter in European beech only, and was signi.cantly higher in this species compared to Norway spruce. Results suggest that beech would be a better species to plant with regards to protection against rockfall. Nevertheless, all types of di.erent abiotic stresses on any particular alpine site should be considered by the forest manager, as planting only broadleaf species may compromise the protecting capacity of the forest e.g. in the case of snow avalanches. In order to determine the mechanical resistance of several forest tree species to rockfall, an inventory of the type of damage sustained in an active rockfall corridor was carried out in the French Alps. The diameter, spatial position and type of damage incurred were measured in 423 trees. Only 5% of trees had sustained damage above a height of 1.3 m and in damaged trees, 66% of broken or uprooted trees were conifers. Larger trees were more likely to be wounded or dead than smaller trees, although the size of the wounds was relatively smaller in larger trees. The species with the least proportion of damage through stem breakage, uprooting or wounding was European beech (Fagus sylvatica L.). Winching tests were carried out on two conifer species, Norway spruce (Picea abies L.) and Silver .r (Abies alba Mill.), as well as European beech, in order to verify the hypothesis that beech was highly resistant to rockfall and that conifers were more susceptible to uprooting or stem breakage. Nineteen trees were winched downhill and the force necessary to cause failure was measured. The energy (Efail) required to break or uproot a tree was then calculated. Most .r trees failed in the stem and spruce usually failed through uprooting. Beech was either uprooted or broke in the stem and was twice as resistant to failure as .r, and three times more resistant than spruce. Efail was strongly related to stem diameter in European beech only, and was signi.cantly higher in this species compared to Norway spruce. Results suggest that beech would be a better species to plant with regards to protection against rockfall. Nevertheless, all types of di.erent abiotic stresses on any particular alpine site should be considered by the forest manager, as planting only broadleaf species may compromise the protecting capacity of the forest e.g. in the case of snow avalanches.

International audience; & Context A strategy widely proposed for increasing the resil-ience of forests against the impacts of projected climate change is to increase the number of species planted to spread and reduce the risks from a range of biotic and abiotic hazards. & Aims We tested this strategy in two case study areas in planted conifer forests in New Zealand and Scotland. & Methods The performance of the major tree species and an alternative was compared: radiata pine and Eucalyptus fastigata in New Zealand and Sitka spruce and Scots pine in Scotland. The process-based model 3-PG2S was used to simulate the effects of projected climate change at the end of this century, with and without CO 2 fertilisation, upon pro-ductivity and financial returns. The effects of an abiotic hazard and two biotic hazards were considered. & Results Under the current climate, the major species outperform alternatives in nearly all circumstances. However, with climate change, their relative performance alters. In New Zealand, planting of E. fastigata becomes more attractive particularly when various hazards and elevated CO 2 concen-trations are considered. In Scotland, Scots pine becomes more attractive than Sitka spruce at lower interest rates. & Conclusions The major plantation species in both coun-tries are well suited to the current climate, but deployment of alternative species and/or breeds can help to adapt these planted forests to the impacts of climate change.

International audience; Gene flow is a key factor in the evolution of species, influencing effective population size, hybridisation and local adaptation. We analysed local gene flow in eight stands of white oak (mostly Quercus petraea and Q. robur, but also Q. pubescens and Q. faginea) distributed across Europe. Adult trees within a given area in each stand were exhaustively sampled (range [239, 754], mean 423), mapped, and acorns were collected ([17,147], 51) from several mother trees ([3], [47], 23). Seedlings ([65,387], 178) were harvested and geo-referenced in six of the eight stands. Genetic information was obtained from screening distinct molecular markers spread across the genome, genotyping each tree, acorn or seedling. All samples were thus genotyped at 5–8 nuclear microsatellite loci. Fathers/parents were assigned to acorns and seedlings using likelihood methods. Mating success of male and female parents, pollen and seed dispersal curves, and also hybridisation rates were estimated in each stand and compared on a continental scale. On average, the percentage of the wind-borne pollen from outside the stand was 60%, with large variation among stands (21–88%). Mean seed immigration into the stand was 40%, a high value for oaks that are generally considered to have limited seed dispersal. However, this estimate varied greatly among stands (20–66%). Gene flow was mostly intraspecific, with large variation, as some trees and stands showed particularly high rates of hybridisation. Our results show that mating success was unevenly distributed among trees. The high levels of gene flow suggest that geographically remote oak stands are unlikely to be genetically isolated, questioning the static definition of gene reserves and seed stands.

International audience; Adaptation of forest management practices in the context of rapid climatic and socioeconomic changes is a global concern. Stakeholders in the forest-based sector as well as policy makers need improved methods and tools to assess potential impacts of changes in management on sustainability indicators. In this special feature, we introduce a methodological framework for classification of forest management approaches in European forestry and explore how changes in forest management might affect the delivery of various ecosystem goods and services and appropriate sustainability indicators over time and space from local to continental scales. The complementary papers in this special feature explore different aspects of sustainability and risks in representative European forest systems as affected by forest management. We show how a common framework plus supporting growth models and indicators can be used to examine the effects of management on ecosystem services and so provide a first step toward the development of a more integrated approach for strategic forest planning and sustainable use of forest ecosystems.

International audience; Due to climate change, forests are likely to face new hazards, which may require adaptation of our existing silvicultural practices. However, it is difficult to imagine a forest management approach that can simultaneously minimize all risks of damage. Multicriteria decision analysis (MCDA) has been developed to help decision makers choose between actions that require reaching a compromise among criteria of different weights. We adapted this method and produced a multicriteria risk analysis (MCRA) to compare the risk of damage associated with various forest management systems with a range of management intensity. The objective was to evaluate the effect of four forest management alternatives (FMAs) (i.e., close to nature, extensive management with combined objectives, intensive even-aged plantations, and short-rotation forestry for biomass production) on biotic and abiotic risks of damage in eight regional case studies combining three forest biomes (Boreal, Continental, Atlantic) and five tree species ( Eucalyptus globulus, Pinus pinaster, Pinus sylvestris, Picea sitchensis, and Picea abies) relevant to wood production in Europe. Specific forest susceptibility to a series of abiotic (wind, fire, and snow) and biotic (insect pests, pathogenic fungi, and mammal herbivores) hazards were defined by expert panels and subsequently weighted by corresponding likelihood. The PROMETHEE ranking method was applied to rank the FMAs from the most to the least at risk. Overall, risk was lower in short-rotation forests designed to produce wood biomass, because of the reduced stand susceptibility to the most damaging hazards. At the opposite end of the management intensity gradient, close-to-nature systems also had low overall risk, due to lower stand value exposed to damage. Intensive even-aged forestry appeared to be subject to the greatest risk, irrespective of tree species and bioclimatic zone. These results seem to be robust as no significant differences in relative ranking of the four FMAs were detected between the combinations of forest biomes and tree species.

International audience; Until recently Phytophthora lateralis was known only as the cause of dieback and mortality of Chamaecyparis lawsoniana in its native range in the Pacific Northwest (PNW). Since the 1990s however disease outbreaks have occurred increasingly on ornamental C. lawsoniana in Europe; and in 2007 the pathogen was discovered in soil around old growth Chamaecyparis obtusa in Taiwan, where it may be endemic. When the phenotypes of over 150 isolates of P. lateralis from Taiwan, across the PNW (British Columbia to California) and from France, the Netherlands and the UK were compared three growth rate groups were resolved: one slow growing from Taiwan, one fast growing from the PNW and Europe, and one of intermediate growth from a small area of the UK. Within these growth groups distinct subtypes were identified based on colony patterns and spore metrics and further discriminated in a multivariate analysis. The assumption that the three main growth groups represented phylogenetic units was tested by comparative sequencing of two mitochondrial and three nuclear genes. This assumption was confirmed. In addition two phenotype clusters within the Taiwan growth group were also shown to be phylogenetically distinct. These four phenotypically and genotypically unique populations are informally designated as the PNW lineage, the UK lineage, the Taiwan J lineage, and the Taiwan K lineage. Their characteristics and distribution are described and their evolution, taxonomic, and plant health significance is discussed.