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Knowledge acquisition on the response of tree species to drought in the Mediterranean hotspot is an important step to guide adaptation strategies to climate change impacts, e.g., assisted migration.We assessed the resilience components - i.e., resistance, recovery, and resilience - to droughtin 2003 in five provenances of maritime pine planted in four common gardens in Sardinia, and analysed the possible influence of climate variables on these indices. The provenances showed differences in growth rate but not in the components of resilience. Among the provenances, Corsicawas the most productive, while Tuscany was the least. One of the two provenances from Sardinia (Limbara) showed good performance in terms of tree growth in the comparatively drier site. The resilience components were influenced by prevailing environmental conditions at the common gardensites. In the relatively drier sites, trees showed the lowest resistance but the highest recovery values. However, two sites - which had the lowest stand density - showed the opposite trend during the drought year, probably due to moderate thinning. Predictive models showed different probability inthe response of resilience components to climate variables. Resistance and resilience had a similar pattern, both being positively related to temperature, while recovery showed an opposite trend. The models’ results indicate a noticeable adaptation of maritime pine to the drought conditions of Sardinia, though the age factor should be considered as well. Despite only minor differences among provenances being found, environmental conditions and management practices at the common gardens were important in determining tree growth patterns. This study suggests that the provenance of Corsica may provide appropriate material for forest plantations in Mediterranean conditions with mitigation purposes.

Process-based models and empirical modelling techniques are frequently used to (i) explore the sensitivity of tree growth to environmental variables, and (ii) predict the future growth of trees and forest stands under climate change scenarios. However, modelling approaches substantially influence predictions of the sensitivity of trees to environmental factors. Here, we used tree-ring width (TRW) data from 1630 beech trees from a network of 70 plots established across European mountains to build empirical predictive growth models using various modelling approaches. In addition, we used 3-PG and Biome-BGCMuSo process-based models to compare growth predictions with derived empirical models. Results revealed similar prediction errors (RMSE) across models ranging between 3.71 and 7.54 cm2 of basal area increment (BAI). The models explained most of the variability in BAI ranging from 54 % to 87 %. Selected explanatory variables (despite being statistically highly significant) and the pattern of the growth sensitivity differed between models substantially. We identified only five factors with the same effect and the same sensitivity pattern in all empirical models: tree DBH, competition index, elevation, Gini index of DBH, and soil silt content. However, the sensitivity to most of the climate variables was low and inconsistent among the empirical models. Both empirical and process based models suggest that beech in European mountains will, on average, likely experience better growth conditions under both 4.5 and 8.5 RCP scenarios. The process-based models indicated that beech may grow better across European mountains by 1.05 to 1.4 times in warmer conditions. The empirical models identified several drivers of tree growth that are not included in the current process-based models (e.g., different nutrients) but may have a substantial effect on final results, particularly if they are limiting factors. Hence, future development of process-based models may build upon our findings to increase their ability to correctly capture ecosystem dynamics.

Accurate measurement of forest growing stock is a prerequisite for implementing climate-smart forestry strategies. This study deals with the use of airborne laser scanning data to assess carbon stock at the tree level. It aims to demonstrate that the combined use of two unsupervised techniques will improve the accuracy of estimation supporting sustainable forest management. Based on the heterogeneity of tree height and point cloud density, we classified 31 forest stands into four complexity categories. The point cloud of each stand was further divided into three horizontal layers, improving the accuracy of tree detection at tree level for which we calculated volume and carbon stock. The average accuracy of tree detection was 0.48. The accuracy was higher for forest stands with lower tree density and higher frequency of large trees, as well as a dense point cloud (0.65). The prediction of carbon stock was higher with a bias ranging from –0.3% to 1.5% and a root mean square error ranging from 0.14% to 1.48%.

Leaf shape in European beech provenances varies geographically, with narrower and longer lamina observed in southern provenances, indicating a direct selection favoring leaf shape that likely safeguards trees performances under less favorable growing conditions. Spatial and environmental patterns of European beech (Fagus sylvatica L.) leaf size and shape variations were studied using landmark-based geometric morphometrics. The study involved eight provenances originating from three biogeographic regions (i.e., Alpine, Continental, and Pannonian), spanning across six European countries (Bosnia and Herzegovina, Croatia, Germany, Hungary, Romania and Serbia). All specimens were cultivated in a common garden experiment. The symmetric component of leaf shape variation was analyzed by Procrustes ANOVA and multi‐variate analyses [principal component analysis and canonical variate analysis (CVA)], whereas MANOVA was used to examine asymmetry. Partial least square (PLS) analysis was used to assess the covariation between leaf shape and size, and geographical position and environmental variables at the sites of provenance origin, respectively. A highly observed phenotypic variation for the shape and size of leaf both within and among provenances, indicates a strong local adaptation of provenances within the species natural range. CVA revealed the existence of two clusters of provenances based on the leaf shape, i.e., the first group included provenances originating from Balkan Peninsula and Central Europe, while the second group consisted of two Romanian provenances and the northernmost provenance from Germany. Likewise, PLS evidenced that leaf shape was spatially structured along latitudinal (− 0.64) and longitudinal (0.60) gradients, with southern provenances having longer and narrower (ovate) lamina compared to the northern ones. In contrast, no correlation was found between centroid size and spatial and environmental variables. Results suggest the presence of direct selection favoring a leaf shape that likely safeguards trees from heat and water loses under less favorable growing conditions.

Forest composed of Picea abies L., Abies alba Mill. and Fagus sylvatica L. cover a large area in the European mountain regions and have a high ecological and socio-economic importance as they supply many ecosystems services. Because of climate change, these forests are exposed to warming, and this effect increases with elevation, which may impact their delivery of goods and services. Previous studies did not find significant changes in the overall productivity of these species over the last 30 years, but they observed changes in species competitiveness at the species and tree levels. In this study, we aimed to link previous results on tree, species and stand level growth in spruce-fir-beech mixed mountain forests by analysing species size distribution dynamics under different climate conditions and their effect on stand growth. We developed a matrix model based on data from 76 long-term experimental plots distributed throughout Europe. We used the change in stand basal area to explore whether temperature modifies species size dominances and proportions, whether the temperature effects on changes in species basal area depend on species size dominance, and whether the effect of species size dominance on changes in the stand basal area varies with temperature. Our results showed that annual mean temperature is an important climatic driver of species dynamics in spruce-fir-beech mixed mountain forests, such that stand basal area growth was favored by higher temperatures, particularly due to positive responses of silver fir which were greater than negative effects of temperature on European beech. The high temperatures also favored the size-dominance of silver fir, while European beech tended to have smaller diameters, independent of the temperature. We also found that the identity of the size-dominant species also influenced changes in stand basal area, with the highest or the lowest changes when Norway spruce and European beech were the size-dominant species, respectively. Silver fir was less influenced by the identity of the size-dominant species than by temperature. Therefore, although mixed mountain forests of spruce-fir-beech were found to be resilient systems in terms of stand productivity, we conclude that increasing temperatures may modify species dynamics and consequently silvicultural interventions will be needed to control species proportions and dominances.

Despite growing interest in predicting plant phenological shifts, advanced spring phenology by global climate change remains debated. Evidence documenting either small or large advancement of spring phenology to rising temperature over the spatio-temporal scales implies a potential existence of a thermal threshold in the responses of forests to global warming. We collected a unique data set of xylem cell-wall-thickening onset dates in 20 coniferous species covering a broad mean annual temperature (MAT) gradient (−3.05 to 22.9°C) across the Northern Hemisphere (latitudes 23°–66° N). Along the MAT gradient, we identified a threshold temperature (using segmented regression) of 4.9 ± 1.1°C, above which the response of xylem phenology to rising temperatures significantly decline. This threshold separates the Northern Hemisphere conifers into cold and warm thermal niches, with MAT and spring forcing being the primary drivers for the onset dates (estimated by linear and Bayesian mixed-effect models), respectively. The identified thermal threshold should be integrated into the Earth-System-Models for a better understanding of spring phenology in response to global warming and an improved prediction of global climate-carbon feedbacks.

Climate change is increasingly favouring the occurrence of extreme weather events, affecting species distribution and tree growth. It has been proposed that mixed forests are more resistant to drought spells and heat waves than corresponding monocultures. We sampled tree cores in nine plots along a latitudinal gradient of the Italian Peninsula (Trentino, Molise and Calabria). The objective of the study was to identify radial growth responses in mixed-species and pure plots of European beech and silver fir to climate dynamics and extreme events. Pointer years, as well as correlation and response functions, were used to analyse the climate–growth relationships in mixed-species and pure plots. Climate–growth relationships showed differences between mixed-species and pure plots only at the regional level. In particular, Trentino differed from Molise and Calabria, when considering maximum temperatures. In Trentino, winter (for silver fir) and summer (for both species) temperatures had a less negative impact on the radial growth of trees, in comparison with Molise and Calabria. Nevertheless, correlations between the radial growth and drought indices, and the principal component analysis, showed that plots were relatively unresponsive to summer drought. These results can be important for the implementation of operational techniques that increase the adaptation of silver fir and European beech to climate change, as well as for assisted migration.

The main objectives of this research were to (i) investigate the concentration; (ii) characterize the distribution; (iii) determine the sources apportionment; (iv) estimate environmental and health risks of heavy metals in soil from mountain beech forest. A total of 76 soil samples from 20 pure beech forest stands from Bosnia and Her- zegovina (BA), Bulgaria (BG), Check Republic (CZ), Germany (DE), Italy (IT), Poland (PL), Romania (RO), Serbia (RS), Slovakia (SK), Slovenia (SL), and Spain (ES) were collected. The content of major elements was measured by X-ray fluorescence spectroscopy (XRF). The content of heavy metals was measured by inductively coupled plasma–optical emission spectrometry (ICP/OES). Heavy metals had a specific concentration range, which fol- lowed in soil samples from depth 0–40 cm the common order (low to high): Hg < Cd < As < Co < Pb < Ni < Cu < Cr < Zn, and from depth 40–80 cm: Hg < Cd < As < Pb < Co < Ni < Cu < Cr < Zn. The grouping of the examined parameters according to rock types, soil types, and localities indicated the separation of carbonate rocks from other substrates, luvisol, and rendzina from other soil types, and samples from BA, SL, and IT from other localities. According to sources apportionment As, Pb and Zn are of anthropogenic origin, Cd, Co, Cr, and Ni are of geogenic origin, while the middle position of Cu and Hg indicates a combined contribution of both sources. Elements Cd and Hg indicated severe to extremely severe enrichment with a mean value of 24.3 and 70.6, respectively. Based on the determined values Ni, Cr, As and Cd do not pose a health risk.

Climate-Smart Forestry (CSF) is a developing concept to help policymakers and practitioners develop focused forestry governance and management to adapt to and mitigate climate change. Within the EU COST Action CA15226, CLIMO (Climate-Smart Forestry in Mountain Regions), a CSF definition was developed considering three main pillars: (1) adaptation to climate change, (2) mitigation of climate change, and (3) the social dimension. Climate mitigation occurs through carbon (C) sequestration by trees, C storage in vegetation and soils, and C substitution by wood. However, present and future climate mitigation depends on the adaptation of trees, woods, and forests to adapt to climate change, which is also driven by societal change.Criteria and Indicators (C & I) can be used to assess the climate smartness of forestry in different conditions, and over time. A suite of C & I that quantify the climate smartness of forestry practices has been developed by experts as guidelines for CSF. This chapter charts the development of this definition, presents initial feedback from forest managers across Europe, and discusses other gaps and uncertainties, as well as potential future perspectives for the further evolution of this concept.

Introduction Silver fir (Abies alba Mill.) is one of the most valuable conifer wood species in Europe. Among the main opportunistic pathogens that cause root and butt rot on silver fir are Armillaria ostoyae and Heterobasidion abietinum. Due to the different enzymatic pools of these wood-decay fungi, different strategies in metabolizing the phenols were available. Objective This work explores the changes in phenolic compounds during silver fir wood degradation. Methodology Phenols were analyzed before and after fungus inoculation in silver fir macerated wood after 2, 4 and 6 months. All samples were analyzed using high-performance liquid chromatography coupled to a hybrid quadrupole-orbitrap mass spectrometer. Results Thirteen compounds, including simple phenols, alkylphenyl alcohols, hydroxybenzoketones, hydroxycinnamaldehydes, hydroxybenzaldehydes, hydroxyphenylacetic acids, hydroxycinnamic acids, hydroxybenzoic acids and hydroxycoumarins, were detected. Pyrocatechol, coniferyl alcohol, acetovanillone, vanillin, benzoic acid, 4-hydroxybenzoic acid and vanillic acid contents decreased during the degradation process. Methyl vanillate, ferulic acid and p-coumaric were initially produced and then degraded. Scopoletin was accumulated. Pyrocatechol, acetovanillone and methyl vanillate were found for the first time in both degrading and non-degrading wood of silver fir. Conclusions Despite differences in the enzymatic pool, both fungi caused a significant decrease in the amounts of phenolic compounds with the accumulation of the only scopoletin. Principal component analysis revealed an initial differentiation between the degradation activity of the two fungal species during degradation, but similar phenolic contents at the end of wood degradation.

Models to predict the effects of different silvicultural treatments on future forest development are the best available tools to demonstrate and test possible climate-smart pathways of mountain forestry. This chapter reviews the state of the art in modelling approaches to predict the future growth of European mountain forests under changing environmental and management conditions. Growth models, both mechanistic and empirical, which are currently available to predict forest growth are reviewed. The chapter also discusses the potential of integrating the effects of genetic origin, species mixture and new silvicultural prescriptions on biomass production into the growth models. The potential of growth simulations to quantify indicators of climate-smart forestry (CSF) is evaluated as well. We conclude that available forest growth models largely differ from each other in many ways, and so they provide a large range of future growth estimates. However, the fast development of computing capacity allows and will allow a wide range of growth simulations and multi-model averaging to produce robust estimates. Still, great attention is required to evaluate the performance of the models. Remote sensing measurements will allow the use of growth models across ecological gradients.

Trees are long-lived organisms that contribute to forest development over centuries and beyond. However, trees are vulnerable to increasing natural and anthropic disturbances. Spatially distributed, continuous data are required to predict mortality risk and impact on the fate of forest ecosystems. In order to enable monitoring over sensitive and often remote forest areas that cannot be patrolled regularly, early warning tools/platforms of mortality risk need to be established across regions. Although remote sensing tools are good at detecting change once it has occurred, early warning tools require ecophysiological information that is more easily collected from single trees on the ground.Here, we discuss the requirements for developing and implementing such a tree-based platform to collect and transmit ecophysiological forest observations and environmental measurements from representative forest sites, where the goals are to identify and to monitor ecological tipping points for rapid forest decline. Long-term monitoring of forest research plots will contribute to better understanding of disturbance and the conditions that precede it. International networks of these sites will provide a regional view of susceptibility and impacts and would play an important role in ground-truthing remotely sensed data.

In this chapter, we review the current long-term growth trends and short-term growth reaction to single or repeated stress events on tree and stand level in Europe. Based on growth trend analyses, the chapter reveals the strong human footprint on forest ecosystems.First, we use long-term experiments and increment cores to show change in growth trends within the last centuries. Growth reactions are caused by deposition and climate change rather than by silvicultural measures. Second, we look closer on regional-specific deviations from the general trend. Climate change, drought events, acid rain and O3 are causing regional-specific growth reaction patterns. Third, we assess stress events and the resilience and resistance of monospecific and mixed stands against biotic and abiotic stress in view of the ongoing growth trends.The revealed tree and stand growth behaviours are highly relevant, as any changes of forest growth and structure have strong impacts on the provision of goods and ecosystem services. The results underline the importance of biomonitoring and suggest counteracting measures by forest planning, adaptation of silvicultural guidelines for existing forest and innovative design of future forests stands.

Climate-smart forestry can be regarded as the evolution of traditional silviculture. As such, it must rely on smart harvesting equipment and techniques for a reliable and effective application. The introduction of sensors and digital information technologies in forest inventories, operation planning, and work execution enables the achievement of the desired results and provides a range of additional opportunities and data. The latter may help to better understand the results of management options on forest health, timber quality, and many other applications. The introduction of intelligent forest machines may multiply the beneficial effect of digital data gathered for forest monitoring and management, resulting in forest harvesting operations being more sustainable in terms of costs and environment. The interaction can be pushed even further by including the timber processing industry, which assesses physical and chemical characteristics of wood with sensors to optimize the transformation process. With the support of an item-level traceability system, the same data could provide a formidable contribution to CSF. The “memory” of wood could support scientists to understand the response of trees to climate-induced stresses and to design accordingly an adaptive silviculture, contributing to forest resilience in the face of future changes due to human-induced climate alteration.

National Forest Inventory (NFI) data are the main source of information on forest resources at country and subcountry levels. This chapter explores the strengths and limitations of NFI-derived indicators to assess forest development with respect to adaptation to and mitigation of climate change, that is, the criteria of Climate-Smart Forestry (CSF). We reflect on harmonizing NFI-based indicators across Europe, use literature to scrutinize available indicators to evaluate CSF, and apply them in 1) Switzerland, where CSF is evaluated for NFI records and simulation model projections with four management scenarios; 2) 43 selected European countries, for which the indicators for Sustainable Forest Management (SFM) are used. The indicators were aggregated to composite indices for adaptation and mitigation and to an overall CSF rating. The Swiss NFI records showed increased CSF ratings in mountainous regions, where growing stocks increased. Simulations under business-as-usual management led to a positive CSF rating, whereas scenarios of increased harvesting decreased either only adaptation or both mitigation and adaptation. European-level results showed increases in CSF ratings for most countries. Negative adaptation ratings were mostly due to forest damages. We discuss the limitations of the indicator approach, consider the broader context of international greenhouse gas reporting, and conclude with policy recommendations.

The goal to limit the increase in global temperature below 2 °C requires reaching a balance between anthropogenic emissions and reductions (sinks) in the second half of this century. As carbon sinks, forests can potentially play an important role in carbon capture. The Paris Agreement (2015) requires signatory countries to reduce deforestation, while conserving and enhancing carbon sinks. Innovative approaches may help foresters take up climate-smart management methods and identify measures for scaling purposes. The EU’s funding instrument COST has supported the Action CLIMO (Climate-Smart Forestry in Mountain Regions – CA15226), with the aim of reorienting forestry in mountain areas to challenge the adverse impacts of climate change.Funded by the EU’s Horizon 2020, CLIMO has brought together scientists and experts in continental and regional focus assessments through a cross-sectoral approach, facilitating the implementation of climate objectives. CLIMO has provided scientific analysis on issues including criteria and indicators, growth dynamics, management prescriptions, long-term perspectives, monitoring technologies, economic impacts, and governance tools. This book addresses different combinations of CLIMO’s driving/primary objectives and discusses smarter ways to develop forestry and monitor forests under current environmental changes, affecting forest ecosystems.

Understanding tree and stand growth dynamics in the frame of climate change calls for large-scale analyses. For analysing growth patterns in mountain forests across Europe, the CLIMO consortium compiled a network of observational plots across European mountain regions. Here, we describe the design and efficacy of this network of plots in monospecific European beech and mixed-species stands of Norway spruce, European beech, and silver fir.First, we sketch the state of the art of existing monitoring and observational approaches for assessing the growth of mountain forests. Second, we introduce the design, measurement protocols, as well as site and stand characteristics, and we stress the innovation of the newly compiled network. Third, we give an overview of the growth and yield data at stand and tree level, sketch the growth characteristics along elevation gradients, and introduce the methods of statistical evaluation. Fourth, we report additional measurements of soil, genetic resources, and climate smartness indicators and criteria, which were available for statistical evaluation and testing hypotheses. Fifth, we present the ESFONET (European Smart Forest Network) approach of data and knowledge dissemination. The discussion is focussed on the novelty and relevance of the database, its potential for monitoring, understanding and management of mountain forests toward climate smartness, and the requirements for future assessments and inventories.In this chapter, we describe the design and efficacy of this network of plots in monospecific European beech and mixed-species stands of Norway spruce, European beech, and silver fir. We present how to acquire and evaluate data from individual trees and the whole stand to quantify and understand the growth of mountain forests in Europe under climate change. It will provide concepts, models, and practical hints for analogous trans-geographic projects that may be based on the existing and newly recorded data on forests.

Fagus sylvatica L. is widely distributed across Europe thanks to its high adaptability in a wide variety of soils and climate. Microbial communities are essential for maintaining forest soil quality and are responsible for forest ecosystem functioning; the ability of soil microorganisms to respond to abiotic stressors (e.g., organic carbon losses, water scarcity, temperature changes) is crucial under ongoing environmental changes and also supports tree health. In this study, soil samples were collected from pure beech plots as part of the COST Action project CLIMO to find differences in microbial community characteristics and evaluate the effects of soil properties on microbial communities across gradients of elevation, latitude, and longitude. Positive relationships were found between organic carbon content and both microbial abundance and dehydrogenase activity. Dehydrogenase and catalase activities were elevation-correlated and microbial activities were longitude-correlated. In the most southern beech plot, the microbial community was abundant and displayed high activities. This shows that microbial communities could help tree populations to better adapt to predicted changes in environmental conditions in the future. We suggest that research into forest health and beech performance should also test soil microbial enzymatic activity, particularly under changing climate conditions, to assist in identifying adaptation strategies.

Centro de Investigación Forestal (CIFOR), Spruce-fir-beech mixed forests cover a large area in European mountain regions, with high ecological and socio-economic importance. As elevation-zone systems they are highly affected by climate change, which is modifying species growth patterns and productivity shifts among species. The extent to which associated tree species can access resources and grow asynchronously may affect their resistance and persistence under climate change. Intra-specific synchrony in annual tree growth is a good indicator of species specific dependence on environmental conditions variability. However, little attention has been paid to explore the role of the inter-specific growth asynchrony in the adaptation of mixed forests to climate change. Here we used a database of 1790 tree-ring series collected from 28 experimental plots in spruce-fir-beech mixed forests across Europe to explore how spatio-temporal patterns of the intra- and inter-specific growth synchrony relate to climate variation during the past century. We further examined whether synchrony in growth response to inter-annual environmental fluctuations depended on site conditions. We found that the inter-specific growth synchrony was always lower than the intra-specific synchrony, for both high (inter-annual fluctuations) and low frequency (mid- to long-term) growth variation, suggesting between species niche complementarity at both temporal levels. Intra- and inter-specific synchronies in inter-annual growth fluctuations significantly changed along elevation, being greater at higher elevations. Moreover, the climate warming likely induced temporal changes in synchrony, but the effect varied along the elevation gradient. The synchrony strongly intensified at lower elevations likely due to climate warming and drying conditions. Our results suggest that intra- and inter-specific growth synchrony can be used as an indicator of temporal niche complementarity among species. We conclude that spruce-fir-beech mixtures should be preferred against mono-specific forests to buffer climate change impacts in mountain regions., This study was supported by the COST Action CLIMO (Climate-Smart Forestry in Mountain Regions – CA15226) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. This publication is also part of a project that has received funding from the European Union’s HORIZON 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778322 (CARE4C)., 10 Pág.

There is concern in the scientific community and among forest managers about potential reductions in the provisioning of forest ecosystem services due to the loss of tree species diversity. Many studies have shown how species diversity influences forest functioning, especially productivity, but the influence of structural diversity, such as tree size heterogeneity, has received much less attention. This study focused on understanding the relationship between stand productivity and several structural characteristics of spruce-fir-beech mountain forest stands in Europe. We used a dataset of 89 long-term plots in spruce-fir-beech forests distributed along the European mountains where the three species, Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.), represent at least 75% of the basal area. Site-dependent conditions were accounted for in a linear mixed-effect basic model, which related the stand productivity with the morphological, climatic and pedological characteristics. The influence of tree species diversity, tree size heterogeneity, species size dominance, and species overlapping in the size distribution on stand productivity was analysed by adding variables to the basic model one by one and evaluating the change in the Akaike's Information Criterion (AIC). The variables that resulted in significant reductions in the AIC, and that were not correlated with each other, were used to build a model to estimate stand productivity. The model showed that in spruce-fir-beech mixed mountain forests (i) when Norway spruce, silver fir and European beech are evenly present within the size distribution (high evenness) the productivity decreases, (ii) the stand productivity increases when the diameter distribution is skewed to the right (higher numbers of smaller individuals), (iii) the stand productivity increases as the proportion of basal area that is spruce increases, and (iv) stand productivity increases with the variability in diameter. We discuss the implications of our results for the management of spruce-fir-beech mountain forest in Europe and for preserving and increasing the stand productivity of these mixed forests.

In Europe, mixed mountain forests, primarily comprised of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.), cover about 10 × 106 ha at elevations between ∼600 and 1600 m a.s.l. These forests provide invaluable ecosystem services. However, the growth of these forests and the competition among their main species are expected to be strongly affected by climate warming. In this study, we analyzed the growth development of spruce, fir, and beech in moist mixed mountain forests in Europe over the last 300 years. Based on tree-ring analyses on long-term observational plots, we found for all three species (i) a nondecelerating, linear diameter growth trend spanning more than 300 years; (ii) increased growth levels and trends, the latter being particularly pronounced for fir and beech; and (iii) an elevation-dependent change of fir and beech growth. Whereas in the past, the growth was highest at lower elevations, today’s growth is superior at higher elevations. This spatiotemporal pattern indicates significant changes in the growth and interspecific competition at the expense of spruce in mixed mountain forests. We discuss possible causes, consequences, and silvicultural implications of these distinct growth changes in mixed mountain forests.

The relationships between structural complexity, deadwood abundance, microhabitat type and species-diversity indicators are excellent tools to monitor biodiversity in forest ecosystems. In spite of their importance, correlations between structural traits and Coleoptera communities in Mediterranean mountain forests have only rarely been investigated. Consequently, the magnitude and direction of the relationships between forest traits and biodiversity indicators remain poorly understood. In this study, we analyzed whether biodiversity indices of saproxylic and non-saproxylic beetle communities could be influenced by stand structure, microhabitat type, and deadwood abundance in two protected beech forests located in the central and southern Apennines (namely Gran Sasso e Monti della Laga National Park, GSML, and Cilento, Vallo di Diano e Alburni National Park, CVDA). Standard measurements of forest structural traits and quantitative assessment of tree microhabitats and deadwood were carried out. Adult beetles were collected using window flight traps and emergence traps on decaying deadwood. The two beech forests were different in terms of both beetle communities and structural traits. A two-block partial least squares analysis 2B-PLS highlighted differences in biodiversity indices and structural traits between the two forest ecosystems. In GSML, we observed that biodiversity indices were positively correlated with the volume of coarse woody debris and the presence fungal infections, clefts into the sapwood, and woodpecker cavities, while more dominant beetle communities were found under denser canopy cover. In CVDA, Coleoptera abundance was positively correlated with the basal area and crown broken microhabitats. Our results point toward the relevance of ecological attributes in tracking changes in beetle biodiversity in specific forest contexts. In these protected Mediterranean mountain beech stands, in which the main forest management strategies have the primary objective of biodiversity conservation, we suggest to progressively increase the structural diversity and canopy dynamics, as well as the volume of coarse woody debris.

Although greenspaces in built-up areas (GSB) heavily contribute to human health and wellbeing in anthropized environments, large-scale data and information on GSB are still lacking. This study aims to estimate abundance, coverage and average size of GSB in Italy through the integration of inventory and cartographic data, even considering GSB patches smaller than 0.5 ha. GSB were classified according to their type (forested and non-forested), canopy cover and location with respect to population density (from thinly to densely populated areas). We refer to built-up areas instead urban, thus including, for example, road infrastructures, buildings and sparse settlements in rural areas, otherwise neglected. Results show that 43.5% of built-up areas in Italy is unsealed, of which more than 18% is covered by GSB, mainly dominated by forested ones. Results also reveal that the number of forested GSB, their coverage and average patch size decrease with the increase of the population density, while their canopy cover follows the opposite trend. Main findings demonstrate that the proposed approach provides reliable GSB estimates to better understand interactions between humans and nature along an urban-rural gradient, thus representing a valuable support towards the implementation of Nature-Based Solutions in urban planning.

Deadwood and microhabitats play a fundamental role in many forest ecosystem processes. Deadwood provides the substrate for a multitude of wood-dependent organisms, as well as a variety of microhabitats. Deadwood is a key factor in maintaining the ecosystem functionality and increasing the overall forest biodiversity. In Mediterranean forests, the relationship between stand-structure attributes and species-diversity indicators is still poorly investigated. In this study, we hypothesized that the abundance of saproxylic species was influenced by (i) the composition and amount of deadwood, and (ii) the heterogeneity in types and density of microhabitats. The investigation was carried out in a broadleaved mixed forest located in Central Apennine (Italy), in which silvicultural interventions were interrupted for several decades. The experimental area extends on approximately 240 ha; structural traits, deadwood and microhabitats were sampled on 50 plots of 530 m2. Saproxylic beetles were collected using window flight traps and emergence traps on decaying deadwood. We applied joint species distribution models (JSDM) to quantify the relationship between forest attributes and the abundance of saproxylic species, explicitly including their functional traits (e.g., trophic level). Results demonstrated that microhabitats, living biomass, basal area and coarse woody debris had a significant effect of saproxylic beetles belonging to different trophic categories. Considering the conservation status, only the stand basal area significantly affected the abundance of Near Threatened (NT) saproxylic beetles. This study highlighted the importance of integrating multiple biodiversity indicators to find sustainable solutions for conservation purposes, unlike many studies on conservation-oriented management strategies, more frequently focused on independent forest biodiversity indicators.

Maritime pine (Pinus pinaster) stands in Italy have recently been invaded by maritime pine bast scale (Matsucoccus feytaudi), resulting in widespread tree mortality. Clearcutting has been applied to progressively remove infected maritime pine, concurrent with planting of holm oak (Quercus ilex) seedlings. Establishment of holm oak regeneration has, however, been severely constrained by fallow deer (Dama dama) browsing pressure. We hypothesized that the ability of planted holm oak to grow above the browse line was closely correlated with protective cover provided by natural regeneration. This study was carried out in a coastal protected area in central Italy, where overall performance of planted holm oak was assessed under browsing pressure in relation to the relative distance of seedlings to surrounding vegetation. To interpret the results, four categories of holm oak were identified: (i) dead plants, (ii) sprouts from stump, (iii) repeatedly browsed plants without growth, and (iv) plants that were able to develop at least one tall shoot safe from browsing. The occurrence of the latter was positively related to increasing canopy cover and plant height of surrounding vegetation, especially maritime pine. Density, height, canopy cover, and crown radius of maritime pine, as well as its relative distance from holm oak all promoted the survival and growth of target plants. Complete protection around holm oak was not required for facilitation, but the presence of crown and branches occupying the space above the target plants was crucial. Maritime pine saplings primarily served as a mechanical barrier to browsing and thereby favored the development of holm oak shoots. Site-specific, long-term monitoring studies on competition from and facilitation by surrounding vegetation are required, before implementing under-planting strategies.

European beech (Fagus sylvatica) is a widespread and economically important temperate tree species in Europe. Expected future warmer temperatures and severe drought events, especially in Mediterranean areas, could affect vitality and productivity of beech stands that historically were under intensive management in those areas. In this study, we aim to address the lack of knowledge on intra-annual wood anatomical responses of beech to environmental variability and silvicultural practices by investigating three beech stands along an elevational gradient (1200 to 1950 m a.s.l.) in the Apennines (Italy). Several wood cell anatomical features were quantified on increment cores collected from five trees per stand. Results showed that high-elevation trees are hydraulically limited, and mid-elevation trees meet their hydraulic requirements with a different anatomical setup/configuration compared to low and high sites. Maximum xylem vessel size and theoretical hydraulic conductivity were associated with the temperatures of previous summer, previous winter and current summer as well as precipitation at the onset of radial growth and at time of maximum growth rates. Cessation of coppicing did not trigger main intra-annual differences in wood anatomical traits. Similarly, years with extreme climate (e.g. mean temperature and/or precipitation values above or below one standard deviation) did not have strong effects on intra-annual wood anatomical traits, maybe due to buffering through the several active sapwood rings present in beech. In conclusion, elevation had a higher impact on intra-annual wood anatomical traits in the studied trees than either cessation of silvicultural practices or years with extreme climate.

Interactions between tree species determine the dynamics of forest communities. Spatial and temporal changes in resource availability, variation in species composition and spatial distribution of trees may alter competitive interactions between species and, therefore, affect tree growth and forest productivity. In this study, we analyzed the intra and inter-specific interactions between European beech (Fagus sylvatica L.) and silver fir (Abies alba Mill.) in southern Italy (Molise and Calabria regions), and how these interactions affect basal area increments in mixed-species and pure stands. Results showed that intra-specific interactions have a negative effect on the basal area increment, both in pure and mixed-species stands of Molise and Calabria. Basal area increment was higher influenced by intra-specific interactions in pure stands than in mixed-species stands. Silver fir in Molise showed higher basal area increment in mixed-species stand, probably in relation with stand structure and space occupation that resulted in less competition between individual trees. European beech showed high values of intra-specific interactions in pure stands, likely related to the low self-tolerance of this species and to the spatial arrangement of trees, due to canopy closure. The absence of inter-specific interactions in mixed-species stands could be explained by the sub-dominant position of European beech, which may have limited the benefit derived from niche separation and complementarity for silver fir.

Centro de Investigación Forestal (CIFOR), The increasing demand for innovative forest management strategies to adapt to and mitigate climate change and benefit forest production, the so-called Climate-Smart Forestry, calls for a tool to monitor and evaluate their implementation and their effects on forest development over time. The pan-European set of criteria and indicators for sustainable forest management is considered one of the most important tools for assessing many aspects of forest management and sustainability. This study offers an analytical approach to selecting a subset of indicators to support the implementation of Climate-Smart Forestry. Based on a literature review and the analytical hierarchical approach, 10 indicators were selected to assess, in particular, mitigation and adaptation. These indicators were used to assess the state of the Climate-Smart Forestry trend in Europe from 1990 to 2015 using data from the reports on the State of Europe’s Forests. Forest damage, tree species composition, and carbon stock were the most important indicators. Though the trend was overall positive with regard to adaptation and mitigation, its evaluation was partly hindered by the lack of data. We advocate for increased efforts to harmonize international reporting and for further integrating the goals of Climate-Smart Forestry into national-and European-level forest policy making., This study generated from the COST (European Cooperation in Science and Technology) Action CLIMO (Climate-Smart Forestry in Mountain Regions — CA15226) was financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. Most of the work was carried out during the Short Term Scientific Mission that Giovanni Santopuoli undertook at the WSL in Birmensdorf (Switzerland) hosted by Christian Temperli, Alessandra Bottero, Paolo Cherubini, and Marco Ferretti., 10 Pág.

Although aspects of forest ecophysiology and forest environments have received considerable attention from research scientists in the last three decades, assessment of implications for meeting the climate targets and international agreements is still a matter of debate [...]

International audience; Climate-smart forestry (CSF) is an emerging branch of sustainable adaptive forest management aimed at enhancing the potential of forests to adapt to and mitigate climate change. It relies on much higher data requirements than traditional forestry. These data requirements can be met by new devices that support continuous, in situ monitoring of forest conditions in real time. We propose a comprehensive network of sensors, i.e., a wireless sensor network (WSN), that can be part of a worldwide network of interconnected uniquely addressable objects, an Internet of Things (IoT), which can make data available in near real time to multiple stakeholders, including scientists, foresters, and forest managers, and may partially motivate citizens to participate in big data collection. The use of in situ sources of monitoring data as ground-truthed training data for remotely sensed data can boost forest monitoring by increasing the spatial and temporal scales of the monitoring, leading to a better understanding of forest processes and potential threats. Here, some of the key developments and applications of these sensors are outlined, together with guidelines for data management. Examples are given of their deployment to detect early warning signals (EWS) of ecosystem regime shifts in terms of forest productivity, health, and biodiversity. Analysis of the strategic use of these tools highlights the opportunities for engaging citizens and forest managers in this new generation of forest monitoring.