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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.

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.

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.

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.

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.

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.

Tree-related microhabitats (hereafter TreMs) are structures occurring on trees, such as rot holes, cavities, large nests, mould, fruiting bodies and mycelia of decomposer fungi. TreMs have been widely recognized as important substrates and structures useful for biodiversity conservation in forest ecosystems, and they can be used as indicators for describing and monitoring forest naturalness. However, most studies on the occurrence of TreMs have been mainly done in forest ecosystems of Central Europe, while less research has been conducted in Mediterranean mountain forests. In this study, we investigated the diversity and abundance of 23 types of TreMs on living trees and on deadwood in seven Mediterranean mountains unmanaged forests located in the Apennines (Italy). The abundance of TreMs was evaluated by counting the number of TreMs per tree, while the diversity of TreMs was evaluated by means of the Shannon-Wiener index. We focused on the relationships between diversity and abundance of TreMs, and tree size (e.g., diameter, height, volume), and the time since the last harvest. Among the investigated stands, 2612 living trees, 457 standing dead trees and snags, and 1247 lying deadwood pieces were analysed. For living trees, a generalized linear mixed model was applied to test the effect of several variables on the abundance of TreMs per tree. Diameter at breast height (DBH) of tree stems influenced the abundance and diversity of TreMs. The time since the last harvest also significantly affected the probability that TreMs could be formed in a long-term perspective. The interaction of the predictors “DBH2” and “Years since the last harvest” generated a better model than the one in which the two variables were kept separate. Indeed, these two factors together would better represent the transition of a previously managed forest to a more natural state over time. This study might provide useful information to land managers committed to forestry practices towards sustainable management and biodiversity conservation, especially referring to survey and inventory of forests of high nature value.

Key message: In Abies alba Mill. (silver fir), the frequency of intra-annual density fluctuations (IADFs) increases along the latitudinal transect, from North to South, is higher in pure than in mixed stands, and their formation is linked to spring and/or summer drought conditions. Abstract: Trees respond to climate, recording information in tree rings and their anatomical features, such as IADFs. The IADFs are regions within the tree ring where density changes in response to tree physiological processes and environmental conditions. The objective of this study was to assess the effect of different forest-stand structures and of climate on IADF formation and frequency in populations of silver fir along a latitudinal gradient in Italy (Trentino, Molise and Calabria regions). In doing so, we aimed to compare the frequency of IADFs in pure or mixed stands and to understand the ability of silver fir to cope with environmental fluctuations. Results showed higher frequency of IADFs in pure than mixed stands (in Trentino and Calabria) and in younger trees (namely in the pure stand in Calabria), because of the higher sensitivity to environmental variability. The formation of IADFs in silver fir emerged as a response to cope with drought. Summer precipitation (both pure and mixed stands in Trentino) and early spring/summer (both pure and mixed stands in Calabria) played a key role in the formation of IADF-type E+. The formation of IADF-type L+, on the other hand, was related to temperature/precipitation in late summer and early autumn (both pure and mixed stands in Molise) and to precipitation in summer (pure stand in Calabria). Our findings support the theory that IADFs are an important structural/functional mechanism for responding to climate fluctuations.

Mixed mountain forests of European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) Karst), and silver fir (Abies alba Mill.) cover a total area of more than 10 million hectares in Europe. Due to altitudinal zoning, these forests are particularly vulnerable to climate change. However, as little is known about the long-term development of the productivity and the adaptation and mitigation potential of these forest systems in Europe, reliable information on productivity is required for sustainable forest management. Using generalized additive mixed models this study investigated 60 long-term experimental plots and provides information about the productivity of mixed mountain forests across a variety of European mountain areas in a standardized way for the first time. The average periodic annual volume increment (PAI) of these forests amounts to 9.3 m3ha−1y−1. Despite a significant increase in annual mean temperature the PAI has not changed significantly over the last 30 years. However, at the species level, we found significant changes in the growth dynamics. While beech had a PAI of 8.2 m3ha−1y−1 over the entire period (1980–2010), the PAI of spruce dropped significantly from 14.2 to 10.8 m3ha−1y−1, and the PAI of fir rose significantly from 7.2 to 11.3 m3ha−1y−1. Consequently, we observed stable stand volume increments in relation to climate change.

International audience; AbstractKey messageSpecies interactions implicate a complex balance of facilitation and competition, which may shift during community development, thus structuring the subalpine ecotone of Mediterranean mountain ranges through time and space. This study highlights that encroachment of grasslands and simultaneous downward/upward movement of forest tree species involve species interferences and environmental feedbacks, with differential effects on mountain pine and European beech, and the grassland communities of the Majella Massif.ContextThe transitional ecotone from the European beech closed forest to the mountain pine krummholz vegetation in the Majella Massif (Apennines, Italy) is a sensitive area to climate and land-use changes. Vegetation shifts in these ecotonal zones may cause a negative impact on the spatial distribution and survival of rare or endemic herbaceous species, thus influencing the appearance, structure, and productivity of the subalpine ecotone of the Majella National Park.AimsWe focused on determining the structures and dynamics of this Mediterranean tree line, and the climate–growth relationships of European beech and mountain pine. We investigated the upward and downward movement of pine into areas potentially suitable for beech expansion, and the concurrent beech encroachment upward.MethodsGrowth dynamics and canopy cover of European beech closed forest and mountain pine krummholz vegetation were analyzed in relation to disturbances at four different sites.ResultsSpring and summer temperatures and summer precipitation affected stem radial growth of both species. In details, spring and summer temperatures negatively affected tree ring width (TRW) of European beech, except for the highest site, whereas spring temperatures affected positively and summer temperatures negatively TRW of mountain pine. Mountain pine expanded upward, encroaching formerly grazed pastures and harvested areas, especially where the soil is shallow and rocky; downward expansion is also occurring, following progressive abandonment of forest management practices. At the same time, European beech recruitment is moving upward, interspersed within mountain pine krummholz, taking advantage from canopy shelter and higher temperature.ConclusionClimate and land-cover simultaneous changes induce species interactions and a complex balance of facilitation and competition, which may shift during community development and structure the subalpine European beech-mountain pine ecotone of the Majella Massif through time and space.

Climate-Smart Forestry (CSF) is an emerging branch of sustainable forest management that aims to manage forests in response to climate change. Specific CSF strategies are viewed as a way forward for developing suitable management responses and enhancing the provision of ecosystem services. However, there is currently a lack of comprehensive and cohesive assessment to implement CSF. This paper describes the step-by-step process that developed a comprehensive and shared definition of CSF, and the process for selecting indicators that assess the “climate-smartness” of forest management. Adaptation, mitigation and social dimensions are the core focus of the CSF definition, which recognises the need to integrate and avoid development of these aspects in isolation. An iterative participatory process was used with a range of experts in forest-related fields from the CLIMO project, this was subsequently supported by a network analysis to identify sustainable forest management indicators important to CSF. The definition developed here, is an important first step in to promote CSF that will aid practice in the forestry sector. It can be used as a template across Europe, tailored to local contexts. Further work communicating CSF to practitioners and policy-makers will create a CSF practice and culture that will help to safeguard future forest economies and communities.

The area of the Mediterranean basin is expected to be threatened by more severe and prolonged droughts and heat waves. Therefore, a more exhaustive knowledge about growth-climate responses in forest trees is necessary in order to adopt mitigation and adaptation strategies in forest management and planning. Climate change will cause shifts of the climate envelope for tree species, potentially leading to migration of species distribution. Under these circumstances, investigations on growth-climate relationships in trees of different provenances of the same species are important for the success of climate-smart forestry. Provenance trials are useful for understanding the response of this species to drought stress. We studied growth-climate relationships in 40-year-old trees of maritime pine (Pinus pinaster Ait.) from five provenances (Corsica, Portugal, Tuscany, and two native ones: Telti and Limbara) grown on four different sites in Sardinia island (Montes, Montarbu, Uatzo and Usinavà), Italy. In details, for all trees in each site, measurements of stem diameter at breast height (DBH) and plant height (H) were collected. For each site-provenance combination, two incremental cores were collected for each tree; successively, samples were cross-dated and standardized. Weather data (temperature and precipitation) were collected from CRU data online (http://www.cru.uea.ac.uk/). Differences in DBH and H were found among sites. In particular, the highest values for DBH and H were found in Montes and Uatzo, respectively. Instead, Montarbu showed the lowest mean values for both parameters. Differences among provenances were also observed. Specifically, in Montarbu, the greatest H were found for Tuscany and the lowest for Corsica (p0.5). In Uatzo, Corsica showed the highest mean values for both H and DBH, while the lowest DBH was observed for Tuscany (p=0.0008), and the lowest H was found for Limbara (p

Chestnut (Castanea sativa Mill.) has been exploited over the centuries for different uses. Nowadays, chestnut is mostly managed as coppice or orchard, creating a matrix of different forest structures. In particular, saproxylic species may provide information to correlate forest naturalness with stand structure. In this study, we evaluated how different management methods might influence the diversity of beetles hosted in chestnut agroforestry systems. Three management options were considered: young and mature coppice stands, and the traditional fruit orchard. Microhabitats occurring on veteran trees were also surveyed to investigate their effect on saproxylic communities, in the fruit orchard. The study area is located in Southern Italy, Aspromonte National Park, where Coleoptera were collected using window flight traps and the stand structural traits were also quantified. In the fruit orchard, a census of the occurring microhabitats was also realized. We used the following diversity indeces (α-diversity) to assess the state of conservation of the analysed forests: (i) Shannon Index; (ii) Margalef’s Richness index; (iii) Equitability index; (iv) Dominance index. Results revealed that forest management have a fundamental role in influencing the diversity of Coleoptera communities and saproxylic beetles. A lower species richness was observed in the mature coppice in comparison with the young coppice and fruit orchard. Nevertheless, these agroforestry systems, reflecting differentiated structural traits, allowed the development of highly specialized and threatened species (34.3% included in IUCN risk categories), with important contribution to conservation of biodiversity in the rural landscape. Finally, the abundance and diversity of microhabitats in the traditional fruit orchard had positive effects on many saproxylic beetle families. These beetle communities, particularly saproxylic species, can be used as excellent bioindicators in actively managed agroforestry systems, suggesting sustainable forest management options for chestnut, while the conservation of veteran trees rich in microhabitats can be considered fundamental for preserving many endangered insects.

Forested patches play an important ecological role in urbanized landscapes. Nevertheless, in particular conditions, trees can paradoxically worsen air quality through the emission of Biogenic Volatile Organic Compounds (BVOCs) (i.e., isoprenoids), which participate to the reactions forming O 3 together with anthropogenic VOCs and nitrogen oxides (NO X ). Given the continuous increase in urban population, there is the necessity of providing urban managers with sustainability indices in urban areas related to these subtle pollutants. Our study aims to give an overview of reference cities or typology of urban areas suitable for expanding the research on future BVOC-O 3 dynamics. Such “reference” cities represent a sort of study target in order to better model and forecast the future behaviours of BVOC emissions and O 3 pollution. Contexts have been selected on both a regional and global scale in both warmer and colder environments, considering future climate scenarios and gradients from more natural conditions. Urban Heat Island and Urban Cold Island effects were also discussed as representative models for anticipating the impact of climatic change on urban trees. Finally, other factors, such as UV rays, Secondary Organic Aerosols wind transportation and the surrounding biome were considered as interactive drivers of the change.

There is a growing need for understanding the timing of wood formation in relation to the dynamics of bud phenology at wide geographical scale. This study analysed the relationships between long-term chronologies of xylem growth and the timing of plant phenology detected by Normalized Difference Vegetation Index (NDVI) in five permanent stands across the latitudinal distribution of black spruce [ Picea mariana (Mill.) BPS] in the boreal forest of Quebec, Canada. Xylogenesis was studied weekly from April to October for thirteen years (2002–2014) on anatomical sections derived by wood microcores. The timing of the growing season detected by remote sensing was extracted from MODerate resolution Imaging Spectroradiometer (MODIS) 250 m 16-days NDVI data. The NDVI time-series were fitted using a double-logistic curve. Phenological chronologies from remote sensing and xylem phenology showed a latitudinal trend. The models correlating the data inferred from satellite sensors and the spring observations of xylem phenology were significant ( p

The dynamics of Pinus mugo krummholz during concomitant change in pastoral land use and climate in central Italy since the mid-20th century was investigated. Krummholz dynamics were detected using sequential aerial photography and fitted to a logistic regression model with elevation, grazing, proximity to beech forest, and proximity to krummholz as explanatory variables. Dendrochronological series were correlated with temperature and precipitation and fitted to a linear model. During this period krummholz doubled in extent and migrated 35–65 m upslope. Expansion was positively associated with krummholz proximity, residual pastoral grazing, and proximity to beech forest beyond 10 m and negatively associated with elevation and beech forest closer than 10 m. The logistic regression model forecasts krummholz migration by an additional 30 m upslope by 2060. During the 20th century, winter and spring minimum temperatures increased but did not result in increased radial stem growth of P. mugo. The combined evidence suggests that krummholz dynamics can be explained by the legacy of summer pastoralism and the dispersal limitations of P. mugo, rather than by climate change.

The relevance of the environmental pollution by heavy metals warrants the necessity to develop and assess more efficient plant-based technologies. This study was conducted to evaluate a quick screening approach in order to investigate the cadmium (Cd) and copper (Cu) phytoextraction potential of Quercus pubescens in a micro-propagation system. Increasing concentrations of Cd (0, 5, 50, and 250 µM) and Cu (0, 5, 50, 250 and 500 µM) were separately applied to evaluate the effect of metals on their absorption and accumulation in downy oak plants. At high concentrations, Cd and Cu significantly reduced the dry biomass of shoots and roots and the plant tolerance index. Cd was toxic at increasing concentrations, inducing higher reduction of shoot dry mass than roots, whereas Cu increased dry mass at 5 µM. This study represents the first attempt to assess Cd and Cu uptake in Q. pubescens under in vitro conditions. The in vitro screening potential is meanly related to the following purposes: (i) proper selection of plant materials resilient to excess metals in the growth substrate; (ii) efficient removal of metals by the selected tree species; (iii) minor interference with the growth of plants accumulating metals in their tissues; (iv) rapid provision of plant materials for tree breeding programs.

International audience; AbstractKey messageConventional methods for estimating the current annual increment of stand volume are based on the uncertain assumption that height increment decreases with tree age. Conversely, size, rather than age, should be accounted for the observed senescence-related declines in relative growth rate and, consequently, implemented in silvicultural manuals. Results stem from a study onAbies albaMill. at its southern limit of distribution.ContextMany factors limit height increment when age and size increase in large-statured tree species. Height–diameter allometric relationships are commonly used measures of tree growth.AimsIn this study, we tested if tree age was the main factor affecting the reduction in height increment of silver fir trees (Abies alba Mill.), verifying also whether tree size had a significant role in ecophysiological-biomechanical limitations to tree growth.MethodsThe study was carried out in a silver fir forest located in Southern Italy, at the southernmost distribution limit for this species. Through a stratified random sampling, 100 trees were selected. All the selected trees were then felled and the total tree height, height increments (internode distances), diameter at breast height, and diameter increments (ring widths) were measured.ResultsThe analyses of allometric models and scaling coefficients showed that the correlation between tree age and height increment was not always significant.ConclusionWe may conclude that tree age did not statistically explain the decrease in height increment in older trees. Instead, the increase in tree size and related physiological processes (expressed as product between diameter at breast height and tree height) explained the reduction in height increment in older trees and was the main factor limiting height growth trends in marginal population of silver fir.

Due to the recent spread of forest die-off worldwide, concerns arise about the relative influence of specific climate parameters on tree growth decline in semi-arid environments, such as the Mediterranean mountain forests. As temperatures increase, drought may reduce tree productivity and survival across these forest ecosystems. Drought-induced tree growth decline can be interpreted as an early-warning signal of forest vulnerability. Here, we modeled the relationship between tree-ring width index (RWI) of beech populations in mountain forests of south-central Italy and the standardized precipitation evapotranspiration index (SPEI) derived from local weather stations. The aim of the research was to propose a procedure to determine the tipping point of drought severity triggering tree decline in beech forests. We focused on the cumulative water balance over the previous 1 month, which was particularly appropriate in relationship with the soil water conditions of these Mediterranean mountains. Under drier conditions, the correlation between RWI and SPEI was stronger, soil water supply (early fall of current year) and atmospheric evaporative demand (late spring of current year) being the dominant factors limiting tree growth of southern beech populations.

The conservation of biological diversity is one of the main goals for managing forests in an ecologically sustainable way. Presence and abundance of microhabitats, such as tree cavities or bark pockets, can be conveniently used as indicators to evaluate the effectiveness of sustainable forest management measures. In Mediterranean forest ecosystems, the relationships between stand-structure attributes and species-diversity indicators are still poorly studied. We described the structural attributes, deadwood characteristics and microhabitat occurrence in a silver fir forest of Central Apennines (Italy), which has not been submitted to silvicultural interventions for several decades. We assessed linkages between these characteristics and the abundance, distribution and diversity of saproxylic beetle fauna. A systematic aligned sampling method was conduced on 240 ha, examining 50 plots of 530 m 2 each. Saproxylic beetles were sampled using window flight traps and emergence traps in relation to abundance and species richness at the plot level, but also on decaying deadwood. The heterogeneity in types and frequencies of microhabitats, and the link between structural attributes associated with stand complexity and saproxylic species, were also analysed. With the aim of describing the complex saproxylic ecological network, beetle species were classified according to the type of interactions with wood and other insects fauna, but also in relation to the trophic guilds. Linear regressions were conducted for highlighting metric variability and relationships between parameters, while geostatistical analyses were used to describe the spatial variability of structural features and the spatial pattern of beetle distributions. Results of linear regression and geostatistical analysis showed how the saproxylic beetle community is influenced by the amount, type and stage of decay of deadwood, but also by the forest structural complexity and the occurrence of microhabitats. Gap dynamics and natural disturbances had effects on deadwood amounts and microhabitat abundance, which was significantly higher than in managed and structurally simplified forest stands. Most of the entomological variables (namely, Families, Species, Total individuals, Saproxylic individuals, Staphylinidae, Elateridae, Nothodes parvulus, Curculionidae, Ernoporus fagi, Phyllobius emery ) were clumped, highlighting the existence of aggregation areas in the sampled forest. In several cases the insect distribution was linked to the spatial pattern of forest attributes, particularly deadwood components.

International audience; AbstractKey messageComparisons between compression and opposite wood formation in prostratingPinus mugoindicate that the secondary meristem can produce more tracheids with thicker walls by also increasing the number of contemporaneously differentiating cells, rather than only increasing the duration or the rate of cell formation.ContextAlthough cambium tissues within a stem experience the same climatic conditions, the resulting wood structure and properties can strongly differ. Assessing how meristem differently regulates wood formation to achieve different anatomical properties can help understanding the mechanisms of response and their plasticity.AimsWe monitored the formation of compression (CW) and opposite (OW) wood within the same stems to understand whether achieved differences in wood structure are caused by modifications in the process of cell formation.MethodsWe collected weekly microcores of compression and opposite wood from the curved stem of ten treeline prostrating mountain pines (Pinus mugo Turra ssp. mugo) at the Majella massif in Central Italy.ResultsResults indicate that cambium formed approximately 1.5 times more cells in CW than OW, despite that CW cell differentiation only extended 2 weeks longer and the residence time of CW cells in the wall-thickening phase was only 20% longer. Differences in their formation were thus mainly related to both the rates and the width of the enlarging and wall-thickening zones (i.e., the number of cells simultaneously under differentiation) and less to duration of cell formation.ConclusionWe conclude that to achieve such a different wood structures, the efficiency of the secondary meristem, in addition of altered rate of cell division and differentiation, can also modify the width of the developing zones. Thus, deciphering what rules this width is important to link environmental conditions with productivity.

Understanding to what extent species mixtures modify the growth of trees and their responses to climate, in comparison with pure stands, is important to support forest adaptation and mitigation strategies. In this sense, information stored in tree rings can be useful to evaluate whether the positive relationship between species diversity and tree productivity holds true under disturbance (e.g., drought). This paper aimed at assessing (i) how radial growth of trees responded to local variation in climate patterns (Standardised Precipitation-Evapotranspiration Index; SPEI), and (ii) whether there was a relationship with intrinsic water use efficiency (WUEi) and tree-ring δ18O in two important tree species, occurring in pure and mixed forest stands. Three sites with similar topographic and pedo-climatic conditions were identified in a single location in the Italian Alps. The first two are characterized by pure stands, respectively dominated by European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.). The third site refers to a mixed stand of both previous species. In particular, in order to assess the annual changes in WUEi, we analysed δ13C in tree rings. The influence of the stomatal conductance was also investigated through δ18O. Our results indicated that: (i) Basal Area Increments (BAI) consistently increased in all stands except for the pure Scots pine stand, in the 1994–2003 period; (ii) SPEI highlighted a drought period between 1991 and 2007 (62.2% of the average precipitation); and (iii) the WUEi values were generally higher in pure than in mixed stands, especially for European beech. The divergence between BAI and SPEI values in the 1990s and early 2000s could be a consequence of moderate thinning. We conclude that past forest management (namely thinning) can be more influential on tree growth than current climatic oscillations.

The sediments dredged from a waterway and decontaminated through a phytoremediation process have been used as substrates alternatively to the traditional forest nursery substrate for pot productions of holm oak (Quercus ilex L) planting stocks. The substrates, made by mixing decontaminated sediments to agricultural soil at different degrees, were tested in order to evaluate their suitability as growth substrates. The experiment was carried out at the nursery of the Department of Agricultural, Food and Forestry Systems of the University of Florence (Italy). The experimental design consisted of four randomized blocks with six pots as replicates for each of the following treatments: 100% sediments, 66% sediments, 33% sediments, 100% agronomic soil and 100% traditional peat based substrate. In each pot, one holm oak acorn was seeded. Germination and both physiological and morphological traits of the seedlings were analysed during and at the end of the first growing season. Holm oak grown in phytoremediated sediments at higher concentrations showed germination levels comparable to those in the traditional substrate, and survival capacity (especially in 66% sediments) slightly higher than in 100% soil. Physiological performance of seedlings resembled that on the traditional substrate which required the addition of fertilizer, at least for the first growing season. Seedlings grown in mixed substrates with higher sediment concentrations occasionally showed better photosynthetic capacity with improved connectivity between the units of the photosystem II. At the end of the first growing season, height as well as the number of growth flushes of the seedlings grown in sole sediment or soil-sediment substrates were similar to what generally is observed for forest nursery stock of Quercus spp.. Regarding the root system articulation and growth in depth, results in the mixed substrates were comparable to those for seedlings grown in the traditional forest nursery media, and higher than seedlings grown in 100% agronomic soil. According to our results, the reclamation of dredged sediments can provide appropriate nursery substrate for germination beds for forestry species. (C) 2018 Elsevier Ltd. All rights reserved.

Remobilization is an important mechanism of resource conservation in plants. However, our understanding of whether the responses of resource remobilization to global warming differ between deciduous and evergreen trees remains unclear. We assessed resource remobilization from leaves to 1-year-old shoots in a deciduous (Betula ermanii) and an evergreen (Quercus aquifolioides) species along elevational gradients (i.e., temperature gradient) at the end of growing season. We aimed to test the hypotheses that the reallocation rate increased with increasing elevation and that more resources were reallocated from leaves to storage tissues in deciduous species than in evergreen species. We analyzed the concentrations of non-structural carbohydrates (NSC), nitrogen (N) and phosphorus (P), and compared the differences in remobilization efficiency of NSC, N, and P between leaves and shoots within each species and between the two species along the elevational gradients. Due to the different strategies of evergreen and deciduous species in nutrients use, the deciduous species had higher N and P remobilization rate, but lower remobilization rate of sugars, starch, and NSC than the evergreen species at the end of growing season. The remobilization rate of NSC, N, and P was significantly higher in trees at their upper limits compared to lower elevations. Our results suggest that trees reallocate resources from leaves to storage tissues before leaf senescence or at the end of growing season, to increase the resource use efficiency and to adapt to the harsh alpine environments. These results contribute to better understanding of the alpine treeline phenomenon in a changing world.

Deadwood is a substantial component of forests playing a central role in many ecosystem processes. It provides habitats for a multitude of wood-dependent organisms, maintaining the ecosystem health and reducing the effect of natural disturbances. Deadwood is recognized as an indicator of local species diversity and contributes to the global carbon pools and nutrient cycles. Despite its importance, how saproxylic communities respond to deadwood dynamics across multiple spatial and temporal scales is still not clear. With the present review, we aim to summarize the effects of deadwood characteristics on the diversity and composition of saproxylic insects and fungi, with focus on European forests. We also discuss the influence of other biotic and abiotic components that indirectly affect these communities by altering wood continuity and variety. Niche differentiation is the main ecological driver of saproxylic organisms, as the presence of multiple microhabitats supports differently specialized taxa. The assemblage and richness of these saproxylic communities within forest ecosystems can be considered as indicators of climate-smart forestry trajectories. This aspect deserves to be regarded as a major target in sustainable forest management plans, especially in mountain areas, where the conservation of threatened species and the promotion of biodiverse forests are considered a priority.

Wood-inhabiting fungi are major decomposers of organic matter in forest systems, playing a crucial role for the maintenance of critical ecosystem processes. Despite their importance, very few studies have investigated wood-inhabiting fungi with biomolecular techniques, especially in Southern Europe. We studied deadwood quality along with stand structural attributes and local ecological parameters to disentangle the relationships between forest habitat characteristics and fungal community structure. Wood samples were collected from 72 lying dead logs in four forest reserves located along a latitudinal transect on the Italian Peninsula. The sites differed in tree species composition, management history and successional stage. The fungal community was investigated through fingerprinting analysis while physical properties of deadwood logs and structural attributes of the stands were assessed in the field. In addition, lignin, carbon and nitrogen content were analyzed for each sampled log. Our results indicate that the combination of structural and morphological aspects of the study areas played a great role in differentiating the fungal communities across these unmanaged forests. Among the wood chemical characteristics, only lignin content significantly affected the overall community structure, suggesting a role of decay stage and tree species in selecting specific fungal taxa. Climatic factors were found to be important only for fungal species diversity and was positively influenced by mean annual precipitation and negatively related to temperature annual range. Nevertheless, a mixed effect model showed a greater impact of living tree species richness in predicting fungal diversity within logs. Our findings suggest that decomposer communities respond to environmental changes at different spatial scales and that the structural and ecological heterogeneity of forest systems subjected to natural dynamics for a longer period support a more diverse fungal community.

Forests contribute to the sequestration of organic carbon (C). A key role in forest C cycling is played by deadwood. While a broad range of literature on deadwood decay (above-ground) exists, the mechanisms occurring in the transition zone from deadwood to the humus are poorly understood. In particular, scarce information is available on the temporal patterns of wood compounds (such as lignin and cellulose) during decay processes. Our objective was to provide a deeper understanding on deadwood decay in a Mediterranean montane environment by focussing on semi-natural forests of Fagus sylvatica L. (beech). The decay process was studied in a field experiment (in the Majella mountains, Apennine Mountains, Italy) among an altitudinal transect at different climatic conditions. Beech wood blocks (mass, cellulose, lignin) having all an equal in size (5 cm × 5 cm × 2 cm) were placed in soil mesocosms to investigate over one year changes in the overall mass, cellulose and lignin content. The sites were along an altitudinal gradient, reflecting different climatic conditions. The effect of exposure (north- vs. south-facing slopes) was also considered. Deadwood, cellulose and lignin dynamics were related to soil parameters (pH, grain size, moisture, temperature) and climate data. Deadwood decayed very fast and followed an exponential trend. The decay rate constants of the deadwood mass significantly (positively) correlated with air temperature and soil moisture: the lower the temperature, the lower the evapotranspiration, the higher the moisture availability, and the higher the decay rates. Lignin decayed more slowly than cellulose, resulting in average decay rate constants (k) between 0.368 and 0.382 y−1. Soil properties and topographic traits (slope and exposure) strongly influenced the decay processes. At south-facing sites (having an altitude

In recent decades, the conservation of biodiversity has become one of the main areas under consideration in managing forests in an ecologically sustainable way. Forest management practices are primary drivers of diversity and may enhance or decrease forest biodiversity, according to the measures applied (thinning options). We have focused on three beech (Fagus sylvatica L.) forests across a latitudinal gradient in Italy, characterised by different structures resulting from dissimilar management. We tested the short-term effects of differently-based silvicultural intervention vs. stands where no silvicultural practices were applied on biodiversity indicators and related proxies: deadwood amounts, microhabitat density, floristic richness and life form abundance. In each study area, the occurrence of the above indicators and proxies was evaluated before and after the implementation of crop tree thinning (CTT) and thinning from below (LT) methods, comparing them with control areas where no interventions were performed. After two years, the management options resulted in different responses of the investigated parameters. The CTT increased deadwood amounts in comparison with the LT ones, while stumps increased significantly after the LT thinning. Microhabitats increased significantly where intervention was not undertaken. On the contrary, they remained unaltered after the LT treatments. CTT thinning created favourable conditions for the development of microhabitats and their proliferation in the long term. Two years after the application of the CTT thinning treatment, all forest stands demonstrated a significant increase in their floristic richness and herb layer cover. Significant differences were also found in both the frequency and cover of life forms in relation to silvicultural treatment. These findings provide a better understanding of short-term effects of silvicultural treatment useful for maintaining biodiversity in mountain beech forests.

Changes in tree growth and insect distribution are projected due to climate warming. The expected effects of climate change on forest disturbance (e.g., insect outbreak) regime call for a better insight into the growth responses of trees to varying environmental conditions over geographical regions in eastern North America. In this study, the effects of a latitudinal thermal gradient and spruce budworm (SBW) outbreaks on the tree growth of black spruce (Picea mariana Mill.) were investigated along a 400 km transect from 48 degrees N to 51 degrees N across the continuous boreal forest in Quebec, Canada. Time series data were analyzed to synchronize climatic factors (temperature and precipitation trends), insect dynamics (SBW population frequency) and tree growth (ring-width chronology). Radial growth resulted as being synchronized with climate patterns, highlighting a positive effect of maximum temperatures on tree growth, especially in the northernmost site. Increasing temperatures and precipitation had a more positive effect on tree growth during epidemic periods, whereas the detrimental effects of SBW outbreaks on tree growth were observed with climate patterns characterized by lowered temperature. The lag between time series, synchrony and/or frequency of synchrony between tree growth and SBW outbreak were considered in order to link the growth of host trees and the dynamics of insect populations. The proposed analytical approach defined damage severity on tree growth in relation to population dynamics and climate fluctuations at the northern distribution limit of the insect. Overall, a decline in tree growth was observed in these boreal forests, due to SBW outbreaks acting in combination with other stress factors.

Over the last 30 years in Italy, a high percentage of tree plantations have failed to achieve the objective of enhancing the quality of forest products, and also restoring/rehabilitating abandoned or degraded agricultural lands. In this study, we evaluated the effects of nursery cultivation in large, novel containers and duration of cultivation on early field establishment of 2-year-old seedlings of Quercus robur L. and Juglans regia L. Two sizes (9800 and 15,500 cm3) of a new container (Superoots Air-pot®) and one size (4900 cm3) of a traditional container (Plastecnic®) were tested and seedlings were sampled for shoot and root growth and biomass allocation. Prolonging the cultivation period to 2 years had a positive effect on both species, with a marked increase in above- and below-ground biomass, maintaining a desirable balance between shoot and root systems. Both sizes of Air-pots for Q. robur and the bigger Air-pot for J. regia produced seedlings that were taller than 1.5 m, with a low branch component combined with a high frequency of apical dominance. The quantity and size of first order lateral roots varied between years within containers, and increased in deeper substrate layers during the second year. Early field results did not show marked signs of transplanting stress, but with low height growth in all treatments. Seedlings grown in both Air-pots exhibited well-developed and well-structured root and shoot systems, thus showing promise in the establishment of high quality timber plantations of fine hardwoods; such attributes can be beneficial wherever proper seedling shoot and/or root sizes confer an advantage in reforestation and restoration scenarios.

Although forest ecosystems are fundamental sources of services and global biodiversity, their capacity to maintain these benefits in the future is potentially threatened by anthropogenic impacts such as climate change, land use, and unsustainable management practices. Thus far, studies focusing on forests and their services have gained less attention compared with studies on other biomes. Additionally, management practices may potentially undermine the capacity of forests to sustain biodiversity conservation and services in the future, especially outside protected areas. This study linked the concepts of biodiversity and forest ecosystem services at the national level in Italy. Through a downscaled review, we first analyzed management issues, challenges, and needs within the context of forest ecosystem services. We then carried out a survey on protected areas. The results show that forest biodiversity supports the provision of other services and, hence, needs to be preserved and supported by adaptive management practices. Current research on forest ecosystem services must extend policy trajectories to protected areas (i.e., National Parks) as centers of biodiversity and models of the sustainable use of resources.