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The objective of this study was to investigate the role of the oomycete Phytophthora× cambivora in the decline affecting European beech (Fagus sylvatica) in the Nebrodi Regional Park (Sicily, southern Italy). In a survey of a beech forest stand in the heart of the park, Phytophthora× cambivora was the sole Phytophthora species recovered from the rhizosphere soil and fine roots of trees. Both A1 and A2 mating type isolates were found. Direct isolation from the stem bark of trees showing severe decline symptoms and bleeding stem cankers yielded exclusively P. gonapodyides, usually considered as an opportunistic pathogen. The mean inoculum density of P.× cambivora in the rhizosphere soil, as determined using the soil dilution plating method and expressed in terms of colony forming units (cfus) per gm of soil, the isolation frequency using leaf baiting, and the percentage of infected fibrous roots from 20 randomly selected beech trees with severe decline symptoms (50 to 100 foliage transparency classes) were 31.7 cfus, 80%, and 48.6%, respectively. These were significantly higher than the corresponding mean values of 20 asymptomatic or slightly declining trees, suggesting P.× cambivora is a major factor responsible for the decline in the surveyed stand. [ABSTRACT FROM AUTHOR]

Background and aims - The research aim was to investigate the relation between large-scale geographic factors and the functional structure of the herbaceous layer of calcareous beech forests in the Apennines, managed as high forest. Material and methods - We selected 163 plots (20 × 20 m), ranging from Central to South Italy, using a random stratified sampling design. We correlated the effect sizes of traits' community-weighted means, functional richness, evenness, divergence, dispersion, and Rao's quadratic entropy, with the main axes of variation in species composition. Key results - The geographical range played a weak role in shaping the species composition of the herbaceous layer. However, we found evidence of functional convergence towards the northern sectors of the study area, where traits linked to resource retention strategies and vegetative spread are filtered. We did not find any evidence of convergence northwards for leaf phenology and pollination types. Conclusion - The increase of the intensity in the environmental stress was associated with a decrease of diversity for traits related to resource conservation strategies and vegetative propagation. On the contrary, the lower cold stress intensity southwards fostered a better niche partitioning, ensuring the coexistence of species with different modalities of resource acquisition and conservation. [ABSTRACT FROM AUTHOR]

Fagus sylvatica (beech) dominates the montane forests of the Apennines and builds old-growth high-conservation value stands. However, recent severe drought-induced diebacks raise concern on the future persistence of these forests and of Southern European mesophilous woodlands overall, growing at their dry edge. To explore the history of Apennine beech-dominated forests, we draw on the multiproxy paleoecological record from Lago Verdarolo, which includes a robust vegetation-independent temperature reconstruction. Numerical techniques are used to investigate the drivers of long-term Mediterranean mountain forest dynamics. Specifically, we focus on disentangling the ecological factors that caused the shift from high-diversity mixed forests to beech-dominated stands and on assessing the occurrence of legacy effects on present-day forests. Abrupt climate change largely drove vegetation dynamics during the Late Glacial and Early Holocene. Species-rich mixed Abies alba (silver fir) forests dominated about 10,500—5500 years ago, under rather dry and warmer-than-today conditions (+ 1—2 °C) and limited fire occurrence. Cooler and moister summers and increasing fire activity caused declines in several fire-sensitive temperate deciduous trees (for example, Ulmus, Tilia, Fraxinus) and favored the establishment of fir-beech forests around 5500 years ago. Further enhancement of fire activity and farming around 2000 years ago led to local Abies alba extinction and forest impoverishment. We conclude that the currently widespread monospecific Apennine beech forests are the result of multi-millennial land-use intensification superimposed on Late Holocene cooling and moistening. Given their higher drought-tolerance compared to beech stands, reviving ancient species-rich mixed fir forests represents a feasible and 'tested' possibility to adapt forests to climate change. [ABSTRACT FROM AUTHOR]

• Forest diversity is hypothesized to enhance vitality of trees. • Defoliation is currently assessed in European forests as proxy of tree vitality. • Relationships between tree diversity and defoliation vary per site and per species. • In Italy, there is a general trend of more defoliation in high diversity stands. • Tree diversity is more beneficial in stressful conditions and after stress events. Tree diversity is found to enhance ecosystem functions in forests and increase the resistance and resilience of trees subjected to environmental stress, including climate change. This effect, however, can be different depending on tree species assemblages and ecological contexts. The pan-European programme for monitoring forest health (ICP Forests) considers crown defoliation as an indicator of tree vitality. Only a few studies have analysed the role of tree diversity in crown defoliation, with contrasting results. This paper analyses the relationships between defoliation and forest diversity in a country (Italy) characterised by heterogeneous bioclimatic and edaphic characteristics (from Mediterranean to Alpine) and with a wide range of forest tree species and functional groups. National-scale results show that defoliation increased in more diverse forest stands. This result can be explained by the fact that the tree mixtures reflect varying ecological conditions in heterogeneous environments. The most relevant factors that explain tree defoliation at the national level, investigated through random forest analysis, were the geographic position, tree species identity and forest stand age and structure. Cluster analysis was applied to identify homogeneous groups of plots based on their ecological and vegetation features. Four clusters were selected. Within each homogeneous cluster, the crown defoliation of the tree species showed different and contrasting patterns, changing their relationships with diversity over time. A beneficial role of diversity on defoliation (i.e. decrease of defoliation) has been observed in Quercus ilex , growing in Mediterranean conditions, and Picea abies in Alpine areas after dry periods. In the latter species, drought led to a greater increase in defoliation in monospecific than in mixed stands, suggesting the stabilising role of tree diversity. [ABSTRACT FROM AUTHOR]

Quantitative descriptions of natural disturbance regimes are lacking for temperate forest regions in Europe, primarily because a long history of intensive land-use has been the overriding driver of forest structure and composition across the region. The following contribution is the first attempt to comprehensively describe the natural disturbance regime of the dominant forest communities in the Dinaric Mountain range, with an emphasis on the range of natural variability of regime components for the main disturbance agents. Compared to other forest regions in Europe, the mountain range has a history of less intensive forest exploitation and provides a suitable record of natural disturbance processes. Our synthesis is based on multiple types of evidence, including meteorological information, historical documentation, evidence from old-growth remnants, and salvage logging data from National forest inventories. Taken together, the results show that no single disturbance agent dominates the regime in the dominant forest types (i.e. beech and mixed beech-fir forests), and any given agent exhibits remarkable variation in terms of severity and spatial extent both within and among individual disturbance events. Thunderstorm winds cause the most severe damage (i.e. near stand replacement), but blowdown patches are typically limited to stand-scales (e.g. 10s of ha). Ice storms and heavy snow typically cause intermediate severity damage and affect much larger areas (e.g. 100s of km 2 ). A notable exception was the 2014 ice storm, which was nearly an order of magnitude larger and more severe than any other event recorded in the synthesis. Severe and prolonged periods of drought have occurred several times over the past century, and along with secondary insect damage (e.g. bark beetles), have caused episodes of forest decline. Overall, our synthesis indicates that on top of the background of relatively continuous gap dynamics, stand-scale intermediate severity events are an important part of the regime; these events likely have rotation periods that are less than the lifespan of a tree cohort (e.g. several centuries) and create canopy openings large enough to alter successional trajectories. [ABSTRACT FROM AUTHOR]

Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests ( Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species ( Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso-mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees ( Fagus sylvatica, Ilex aquifolium) dominated in the natural or quasi-natural forests of the oro-mediterranean belt. Forests were repeatedly opened for agricultural purposes. Fire activity was closely associated with farming, providing evidence that burning was a primary land use tool since Neolithic times. Land use and fire activity intensified during the Early Neolithic at 5000 bc, at the onset of the Bronze Age at 2500 bc and at the onset of the Iron Age at 800 bc. Our data and previous studies suggest that the large majority of open land communities in Sicily, from the coastal lowlands to the mountain areas below the thorny-cushion Astragalus belt (ca. 1,800 m a.s.l.), would rapidly develop into forests if land use ceased. Mesophilous Fagus- Ilex forests developed under warm mid Holocene conditions and were resilient to the combined impacts of humans and climate. The past ecology suggests a resilience of these summer-drought adapted communities to climate warming of about 2 °C. Hence, they may be particularly suited to provide heat and drought-adapted Fagus sylvatica ecotypes for maintaining drought-sensitive Central European beech forests under global warming conditions. [ABSTRACT FROM AUTHOR]

• Roe deer browsing impact was investigated in temperate hardwood coppice forests. • Browsing effects were monitored for 11 years in an exclusion experiment. • High browsing impact in the early years after coppicing on more palatable species. • Coppice forests showed significant post-browsing recovery in the medium term. • Long-term monitoring is key to assess browsing impact and management implications. In southern European temperate forests, coppicing is a traditional form of forest management that shaped the present cultural landscape, providing multiple ecosystem services. Roe deer densities have been growing notably during the last decades mainly due to the abandonment of rural areas, changes in human land use and restocking. The impact of roe deer on coppice forests can affect the resprouting and, in turn, compromise the products and ecosystem services provided by these forests. During coppicing, stems are cut down close to the ground, where the growing shoots are exposed to deer browsing, especially during the early years following cutting. In this study, using a browsing exclusion experiment, we investigated the impact of browsing on temperate mountain hardwood coppice forests in the western Italian Alps over a period of eleven years following coppicing. We found that the impact of browsing was highest in the first two years following coppicing, with Quercus pubescens and Castanea sativa being the most affected tree species. The height of shoots was the variable that showed the biggest difference between fenced and unfenced areas. A significant negative effect of browsing on shoot height was found at the beginning of the experiment, with shoots growing in unfenced area showing the lowest height increments. After the third year, when the browsing intensity diminished, we observed the opposite trend, with shoots growing in unfenced areas showing higher height increments compared with fenced areas. A similar trend was observed also for the diameter of shoots over the course of the experiment. Eleven years after coppicing, however, the structural characteristics of the natural regeneration converged at all sites and in both fenced and unfenced areas. This study shows that coppice forests are resilient to browsing and are capable to recover growth loss within a few years after browsing has naturally diminished and stopped. The research conducted also points out the importance of medium- to long-term monitoring to assess post-disturbance dynamics and evaluate implications for management. [ABSTRACT FROM AUTHOR]

Dinoderus (Dinoderastes) japonicus, a species native of the Eastern Palaearctic, is reported for the first time from Italy on the basis of a female specimen collected in a beech forest (Veneto Region, Treviso Province, Foresta del Cansiglio). The possible establishment of this alien species in Italy is briefly discussed. [ABSTRACT FROM AUTHOR]

In the framework of sustainable forest management, deadwood plays an essential role within forest ecosystems. In recent years it has properly become a fundamental indicator of sustainability in the management of forest resources. In fact, deadwood plays many ecological and functional roles, for instance it provides a habitat for many living organisms (contributing to the conservation of biodiversity), acts as a long-term carbon stock, increases and maintains the overall productivity of the forest, contributes to the development of soil and nutrients cycles. The pan-European criteria recognize the value of forest deadwood as an indicator of sustainable management and the standards for forest management certification give to the evaluation of deadwood a primary role in the assessment process. Although the importance of deadwood to assess the sustainability of forest management, the information on this fundamental parameter of forest ecosystems is widely documented mainly for primary forests, while for managed forests it is much scarcer. Taking into account these considerations, this work aims to quantify and qualify the woody deadwood present within the managed beech forests of the Abruzzo, Lazio and Molise National Park. These beech forests have an important socio-economic function for local populations: they are actively managed, and residents are allowed to collect deadwood according to specific rules established by the Park Authority. Forest parcels of the local forest management plan were taken into consideration, within which sample areas were created to collect data concerning quantity and type of deadwood present in the stand. Samples were also collected to qualify the deadwood present according to widely recognized scientific protocols. It has been observed that silvicultural management and good accessibility to the forest affect the volume and type of deadwood present. Therefore, it has been emphasized that even within a protected area there are zones in which the removal of the on-ground timber affects the volume of the deadwood due to the civic use rights to collect downed logs or branches as domestic fuel by local populations. The results obtained made it possible to compare the volumes and types of deadwood, both laying and standing, present in these managed beech forests, with the data collected from other studies concerning managed and primary forests. [ABSTRACT FROM AUTHOR]

Forest understory may be strongly affected by silvicultural practices such as thinning, which simultaneously modulates the overstory canopy cover and influences the availability of light. However, the understory layer is rarely considered in management decisions, partly because methods to estimate understory leaf area index are poorly developed. In this study we used two different restricted view angle photographic methods to estimate overstory plant area index LO (zenith cover photography), understory leaf area index LU (nadir cover photography) and their related canopy attributes (foliage clumping, foliage cover, crown cover, crown porosity). These measurements were performed in beech stands under different management regime. Results from photography indicated that not only overstory but also understory canopy attributes were significantly influenced by forest management. In addition, a significant negative correlation was found between LO and LU. We conclude that the photographic methods are effective for monitoring (overstory and understory) canopy status in managed stands, on account of their rapid and not destructive procedures, which allows large scale implementation of the methods. [ABSTRACT FROM AUTHOR]

Abstract: Among all silver fir forest types in Slovenia, most changes in forest composition are evident in Dinaric silver fir and beech forests, in which ageing and reduction of silver fir populations compared to European beech is evident. The situation has worsened due to a high browsing rate and environmental changes, causing a decline in abundance and a shift in silver fir′s spatio-temporal distribution. The photosynthesis response to different light and CO2 (max. photosynthetic rate –A max, compensation points –I c, quantum yield –Φ), the morphological response in young beech and fir to shade, and the growth response of adult trees were compared on sites with a single selection method, group selection method and old growth, during three consecutive vegetation periods (2009, 2010 and 2011). Three plots were established on each site, each with comparable light conditions according to the indirect site factor – ISF (%) under mature shelter, forest edge and open light conditions. In the old growth forest, beech and fir were more shade-tolerant and had a greater reaction to different light levels or elevated CO2 concentrations, compared to managed forest sites. Fir and beech express more physiological and morphological shade-tolerant characteristics on sites with single selection treatment, and differences are also evident in the growth responses of the two species. To establish conditions under which fir would be able to compete with beech, longer regeneration periods should be applied, with a gradual opening of the mature canopy, similar to conditions in old growth. In our study, group selection treatment proved more effective under the present environmental conditions. [Copyright &y& Elsevier]

Abstract: Converting coppices into high forests with continuous cover has often been established during the last decades as a management goal in hilly and mountainous Mediterranean areas to attenuate the negative effects that frequent clearcutting may have on soil, landscape and biodiversity conservation. The silvicultural tool usually adopted for this purpose is the gradual thinning of sprouts during the long span of time required to complete the conversion, that also allows the owner to keep harvesting some wood. This research compared the effects of various thinning intensities (three treatments plus control) on the stand growth and structure of a beech coppice with standards. The optimal density after thinning was assessed by expressing mean tree spacing as a function of main stand attributes like stand height and stand dbh. This system was preferred to the empirical evaluation of the percentage of basal area to be removed in order to give forest managers general reference guidelines to adapt to the varying environments of the Mediterranean mountains. Results confirmed that the positive effects of thinning on mean stem volume is due more to the higher diameter increment than to different height growth. The acceleration of crown growth in the thinned plots allowed canopy closure to be achieved 13 years after thinning. This reduced the negative effects of the opening of the stand overlayer and the elimination of most suppressed trees on soil protection. Under the conditions examined, the best thinning intensity proved to be a stand density 20% lower than normal prescribed by the yield tables elaborated for beech high forests in Central and Southern Italy. [Copyright &y& Elsevier]

Several beech woods in the Province of Savona (Liguria, Italy) were mycocoenologically investigated over a period of 5 years, during which time 392 macrofungal species were observed. The collected data was subjected to statistical analysis from several points of view. Fungal biodiversity was estimated by using two different formulas (proposed by Shannon and Brillouin). Results yielded fairly similar results, and highlighted significant levels of biodiversity in all the areas investigated. The relevant mycodiversity was also compared with that of other European beech woods based on maximum potential biodiversity (MPB), and revealed that the biodiversity of the investigated zones is fairly similar to that of the richest (i.e., with the greatest variety of species) areas considered by other mycologists. [ABSTRACT FROM AUTHOR]

We tested the "home-field advantage" hypothesis, i.e., that leaves decay faster under the parent tree species in European beech, Douglas fir, and Turkey oak stands in a mountain forest in Italy. The fate of leaves in buried litterbags was monitored for one year to document their carbon (C) and nitrogen (N) dynamics, chemical structure, and associated microbial community. The three litter types lost C continuously at a similar rate, regardless of the species they were buried under. On the other hand, the N losses varied among litter types, and beech even gained a small but significant amount of N in the first 3–6 months. Differences between the litters were evident in the alkyl region of the nuclear magnetic resonance spectra and smaller in the aromatic and aryl acids regions. By the end of the experiment, all litters had lost substantial quantities of carbohydrates, lignin, proteins, and lipids, particularly oak litter. The richness and diversity of bacterial and fungal communities increased with time. Litter type had the greatest impact on microbial community composition in the first months of decomposition; afterwards, the stand type had a greater influence on the assemblage of decomposer microorganisms. Overall, this study provides little evidence in support of the home-field advantage hypothesis, which could be valid only for oak. Instead, our findings indicate that the chemical composition of litter is the main factor affecting the early stages of litter decomposition. Tree species and soil properties within the stand play an important role in the advanced stages of decomposition since these factors control the assemblage and functions of the soil microbial community. • In a mountain forest in Italy, we found little evidence that leaves decay faster under their parent trees. • In early stages, the nature of the litter prevailed over the type of tree cover as driving factor of litter decay. • Three types of litter investigated showed different decay pathways, as highlighted by NMR. • Type of tree cover impact on microbial communities became increasingly evident as decay progressed. [ABSTRACT FROM AUTHOR]

• Small-diameter beech deadwood hosts at least 132 species of Coleoptera in Italy. • Number of species in deadwood is low in even-aged stands. • Distance between forests is negatively correlated to assemblage similarity. Beetles (Coleoptera) are the most diverse and species-rich insect order in saproxylic communities, and play a key role in forest dynamics. To prioritize conservation measures, a clear understanding is needed of what habitat features are the most important for beetles that depend on deadwood. Here, we investigate (i) how the assemblages of saproxylic beetles emerging from small-diameter beech deadwood (Fagus sylvatica L.) are influenced by several environmental factors and type of forest management, and (ii) if geographical distance of the investigated sites influences the similarity of these saproxylic beetle assemblages. We visited 10 high beech forest stands along a latitudinal gradient from northern to southern Italy, and collected 200 logs of 50 cm length, 12 ± 2 cm diameter, and Hunter's decay class 2, from deadwood lying on the forest floor. Logs were stored in ex-situ emergence traps, in common garden conditions, from April to September, and individuals emerging from the deadwood were collected weekly. A total of 2571 beetles were collected, including several species which were either threatened, firstly recorded or endemic. We found that, compared to even-aged stands, forests managed to increase structural heterogeneity (uneven-aged high forests, and former coppice stands converted to high forest), with closed canopy, were colonized by the richest and most abundant saproxylic beetle assemblages. Additionally, we observed distance decay of similarity between sites, indicating geographical structure in community composition. Our findings have important implications for biodiversity conservation in beech forests: (1) small-diameter deadwood hosts a rich biodiversity of Coleoptera and should therefore be left on the ground; (2) forest management practices should aim at preserving or restoring structural heterogeneity and closed canopies; (3) these conservation measures should be carried out along the entire area of occurrence of beech forests, due to turnover in species composition with geographical distance. [ABSTRACT FROM AUTHOR]

Climate change is increasing the frequency of extreme climate events, causing profound impacts on forest function and composition. Late frost defoliation (LFD) events, the loss of photosynthetic tissues due to low temperatures at the start of the growing season, might become more recurrent under future climate scenarios. Therefore, the detection of changes in late-frost risk in response to global change emerges as a high-priority research topic. Here, we used a tree-ring network from southern European beech (Fagus sylvatica L.) forests comprising Spain, Italy and the Austrian Alps, to assess the incidence of LFD events in the last seven decades. We fitted linear-mixed models of basal area increment using different LFD indicators considering warm spring temperatures and late-spring frosts as fixed factors. We reconstructed major LFD events since 1950, matching extreme values of LFD climatic indicators with sharp tree-ring growth reductions. The last LFD events were validated using remote sensing. Lastly, reconstructed LFD events were climatically and spatially characterized. Warm temperatures before the late-spring frost, defined by high values of growing-degree days, influenced beech growth negatively, particularly in the southernmost populations. The number of LFD events increased towards beech southern distribution edge. Spanish and the southernmost Italian beech forests experienced higher frequency of LFD events since the 1990s. Until then, LFD events were circumscribed to local scales, but since that decade, LFD events became widespread, largely affecting the whole beech southwestern distribution area. Our study, based on in-situ evidence, sheds light on the climatic factors driving LFD occurrence and illustrates how increased occurrence and spatial extension of late-spring frosts might constrain future southern European beech forests' growth and functionality. Observed alterations in the climate-phenology interactions in response to climate change represent a potential threat for temperate deciduous forests persistence in their drier/southern distribution edge., Competing Interests: Declaration of competing interest The authors declare no conflict of interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)