Quercus Petraea Research Articles

Impact of Site Conditions on Quercus robur and Quercus petraea Growth and Distribution Under Global Climate Change

Climate change has significant natural and economic implications, but its extent is particularly challenging to assess in forest management, a field which combines both of the previous aspects and requires the evaluation of the impact of climate change on tree species over a 100-year timeframe. Oaks are among the tree species of significant natural and economic value in Europe. Therefore, the aim of this study was to analyze all oak stands in Poland and verify the hypothesis regarding differences between Quercus robur and Quercus petraea stands in terms of soil type, annual total precipitation, average annual air temperature, and the length of the growing season. Additionally, this study aimed to analyze the impact of these differences on the growth rates of both oak species and test whether climate change may affect oak stands. A database containing 195,241 tree stands, including different oak species with varying shares in the stand (from 10% to 100%), was analyzed. A particular emphasis was placed on Q. robur and Q. petraea. The results show that, although both oak species have a wide common range of occurrence, there are clear differences in their habitat preferences. Based on the ordinal regression analysis of selected oak stands, it was concluded that an increase in air temperature of 1 °C could impair the growth of Q. robur and slightly improve the growth of Q. petraea. This may indicate the possibility of expanding the geographic range of sessile oaks towards the east and northeast under warming climatic conditions, provided that appropriate moisture conditions are maintained.

Long-Term Effects of Thinning in Sub-Mountainous Thermophilic Sessile Oak (Quercus petraea Mill.) and European Beech (Fagus sylvatica L.) Coppices in the Croatian Dinarides

Coppicing has been neglected in recent decades, leaving gaps in knowledge on silvicultural interventions, especially the long-term effects on coppices of Southeast Europe. The recent economic crisis, the sudden increase in energy prices, and the increased demand for assorted wood products have initiated higher interest in coppices in Croatia. Thus, our work aims to define the long-term effects of thinning in sessile oak (Quercus petraea (Matt.) Liebl.) and European beech (Fagus sylvatica L.) sub-mountainous thermophilic low coppices in the Croatian Dinarides. The experiment includes two localities with thinning and control plots. Thinning was performed in 2002, with 17.71% of wood volume removed in the European beech coppice and 26.09% in the sessile oak coppice. In 2020, 1276 trees were marked, measured (DBH, tree height, number of stems per stump), and assessed for vitality, origin, and six silvicultural features revealing tree quality. In 2022, trees were again measured (DBH, tree height) to gain data on tree growth. Conventional data analysis methods were used. The results show a statistically significant positive long-term effect of thinning on tree growth, stem, and crown features and support findings that thinning, by increasing growth and quality, is a necessary intervention in European beech and sessile oak low coppices. Thinning promoted the healthiest and best quality trees/stems, resulting in a more valuable range of wood products and the potential for higher income. It had a positive impact on tree growth regardless of the tree’s origin (seed or stump) and improved the growth and quality of trees among the supporting tree species. Short-term effects of thinning in trial plots suggested that thinning supported tree species diversity, but this effect diminished over time, showing no positive effect after twenty years. The study points to the need for more frequent thinning in coppices to support tree species diversity (i.e., to allow growth to less competitive tree species) but underlines the need for further research.

Assessing the ecological complexity and uncertainty of predicting forest ecosystem services under climate change

Climate change affects Central European forest ecosystems in different ways and, consequently, these changes result in different feedbacks on the provision of forest ecosystem services. Regarding the complexity and the variability in climate-forest interactions outcome, forest decision makers necessitate reliable information about changes in the forest ecosystem services for planning and adaptation purposes. However, forest productivity predictions incorporate multiple levels of uncertainty that have to be regarded to ensure building realistic expectations in forest decision-making. Besides the chosen forest simulation model, uncertainties come from the climate change data represented by a set of representative concentration pathways (RCP), within the underlying ensemble of global circulation and regional climate models (GCM-RCM), and further in the treatment of the CO2-fertilization effect. We considered the mentioned uncertainties in a framework on simulating forest growth and water services for two forest sites, a Sessile oak and a Scots pine stand in Rhineland-Palatine, Germany. The framework revealed a high variability in future forest ecosystem services. Particularly, the variability among the selected GCM-RCM models within the same Representative Concentration Pathway (RCP) was higher than the variability among different RCPs (RCP2.6 and RCP8.5 representing the low and high CO2-emission scenarios, respectively). Sessile oak productivity increased under all scenarios, whereas Scots pine growth declined in the lower end of the RCP8.5 scenario. Water services remained mostly stable at both sites. Moreover, we applied a panel data model to estimate what climate indices caused changes in the forest ecosystem services. We found that Scots pine is more sensitive to a multitude of climate indices, such as temperature changes and Sessile oak showed strong response to the CO2-fertilization. We propose applying this framework to evaluate forest management options under climate change.

Artificial tree microhabitats: Wound depth and position affect saproxylic beetles attracted to freshly veteranised trees

Abstract Veteran and ancient trees are key structures sustaining biodiversity in wooded landscapes. Their value depends on tree‐related microhabitats (TreMs) such as hollows, cracks and other structures related to wounds and wood decay. Decline and loss of veteran trees results in the loss of TreMs thus threatening the biodiversity associated with them. Veteranisation, that is, interventions aimed at creating or accelerating formation of rare TreMs in live trees, are thus increasingly applied to bridge gaps in habitat continuity and sustain the biodiversity associated with veteran trees. Several studies investigated the use of artificially created TreMs by various organisms. No study has, however, investigated saproxylic beetles attracted to freshly veteranised trees, and how different veteranisation techniques affect attractivity of veteranised trees to saproxylic beetles. We veteranised 48 sessile oaks using two types of deep and two types of shallow cuts and trapped saproxylic beetles on the veteranised and control trees in the first season after the intervention. The sampling yielded 280 species (6171 individuals) of saproxylic beetles, including 64 that are threatened. Veteranised trees attracted more abundant and diverse communities than control trees. Community composition differed between shallow and deep cuts and between the two types of deep cuts. Freshly veteranised trees thus attract diverse and abundant communities of saproxylic beetles consisting mainly of species potentially exploiting the wounds. The high proportion of threatened species, often associated with old oaks, suggests that veteranised trees benefit even some threatened saproxylic biodiversity already during the first year after the veteranisation.

The aroma of toasted oak wood (<i>Quercus petraea</i>): from sensory analysis to molecular characterisation

The chemical complexity of the aroma compounds developed by oak wood during the toasting process is known to contribute to the quality of wines and spirits after barrel ageing. Molecular characterisation of toasted oak wood has increased steadily in recent years, using the traditional olfactory-guided approach by gas chromatography coupled with olfactometry and mass spectrometry (GC-O-MS); however, few studies have focused on its sensory characterisation. In this study, a sensory characterisation of oak wood (Quercus petraea) was first carried out during toasting in order to identify any descriptors that had not yet been characterised from a molecular point of view. Thus, in the second part of this work, we were able to identify volatile compounds associated with the aroma of toasted oak wood.Based on previous work in oenology, the sensory characterisation of oak wood was carried out in three stages: identification, structuring and description of a sensory space. Data processing of the 215 descriptors generated by the panel of experts revealed six descriptors specific to the aroma of oak wood throughout its toasting (i.e., fresh wood, fresh green, sweet, roasted, spicy and smoky). The results were represented graphically in the form of an aroma wheel, which was used to highlight the descriptors that had not yet been characterised from a molecular point of view. Thus, two volatile compounds were identified: thymoquinone (pencil and cedar odour) and verbenone (fresh, menthol and tealeaf odour). Their evolution in oak wood during toasting and their distribution in different wood species used in oenology (sessile oak, pedunculate oak, American oak, Caucasian oak, acacia and chestnut) were studied. Their sensory impact was studied by assessing their olfactory detection threshold in a model wine solution. The thresholds were evaluated at 49 ng/L for thymoquinone and 193 µg/L for verbenone.

Offspring may succeed well next to their relatives, but it needs particular traits.

There is ongoing debate about whether offspring perform best next to phylogenetically distantly related adult neighbours (due to the scarcity of enemies and competitors) or next to closely related adults (due to the abundance of mutualists). Here we hypothesise that relatedness of adult neighbours affects which traits confer performance rather than performance itself. We studied seed removal, seed germination and sapling growth in Sessile Oaks (Quercus petraea and hybrids), and how they depend on size, shape and other traits, under both closely and distantly related canopies, manipulating offspring-density, presence of insects, and fungi, and spatial proximity to oaks. We found that phylogenetic distance of adult neighbours affects only little performance of offspring but strongly which traits confer performance to offspring, in particular the size and shape of seeds and saplings. Differences in trait-performance relationships mostly disappear once insects or conspecific competitors are excluded (albeit exclusion of fungi reinforced these differences). Effects of phylogenetic distance of neighbours were not replaceable by the percentage of the gymnosperms among neighbours, nor the environmental conditions considered. We suggest that by responding to a biotic micro-mosaic of selection pressures, Sessile Oak flexibly succeeds in diverse neighbourhoods. Sessile Oak might maintain the potential for both, convergence with and divergence from phylogenetically distantly related species, thereby reinforcing or eroding phylogenetic signal of niches.

Root anatomical adaptations of contrasting ectomycorrhizal exploration types in Pinus sylvestris and Quercus petraea across soil horizons

Abstract Aims The anatomical characteristics of ectomycorrhizal exploration types in response to soil variability remain insufficiently understood. We examined the root anatomy of contact and long-distance exploration types in Pinus sylvestris and Quercus petraea, species with distinct ecological needs, across different soil horizons. Methods The diameter of ectomycorrhizal roots, the root absorptive traits i.e. proportion of cortex and mantle area, the percentage stele in the diameter, and the weighted average diameter of vessels (Ra) in the ectomycorrhizas were measured within ectomycorrhizas collected from organic and mineral soils across the soil profile. Results The absorptive traits varied along soil horizons, in which water and nutrient availability changed inversely. The proportion of cortex was associated with exploration type, but was not specific to tree species. However, the ectomycorrhizal diameter and the percentage of mantle within the root forming contact exploration type of P. sylvestris showed no variation among soil horizons. In contrast, the soil horizon significantly influenced all root anatomical traits in the contact exploration type of Q. petraea by enhancing the contribution of the absorption area of the root area, mainly in the illuvial horizon, but reaching the smallest value in the organic horizon. The Ra and the cell wall thickness of the vessels were strongly dependent on tree species. With increasing soil depth, Ra in Q. petraea increased, and stele proportion in root diameter decreased. Conclusion The results suggest that water acquisition traits differ among tree species, but traits associated with nutrient absorption (proportion of cortex and mantle area) within specific soil horizons are closely related to the ectomycorrhizal exploration type.

The effects of thermal aging on color and glossiness in UV cured coatings applied to sessile oak

The effects of thermal aging on color and glossiness in UV cured coatings applied to sessile oak

Green synthesis of platinum nanoparticles using aqueous bark extract of Quercus sp. for potential antioxidant and antimicrobial applications

Oak bark, which is commonly used in the wood industry, has by-products often repurposed as fuel. Its extracts are rich in compounds with anticancer, antibacterial, antifungal, and anti-inflammatory properties. This study synthesized platinum nanoparticles (PtNPs) using aqueous extracts from Quercus dalechampii (QD), Q. frainetto (QF), and Q. petraea (QP). Key factors during nanoparticle formation included reaction time, metal ion concentration, pH, extract-to-metal ion ratio, and temperature. The PtNPs were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy. The average diameters were 58.5 ± 7.6 nm for QD-PtNPs, 41.6 ± 5.4 nm for QF-PtNPs, and 41 ± 5.3 nm for QP-PtNPs. Antioxidant and antimicrobial activities were also analyzed. The QP-PtNPs had the highest DPPH (2,2-Diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power), and CUPRAC (Cupric Reducing Antioxidant Capacity) free radical scavenging activities, while QD-PtNPs excelled in ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) scavenging. All PtNPs showed strong antimicrobial properties, particularly against Enterococcus faecalis, Escherichia coli, Candida krusei, and Candida auris. These findings suggest that Quercus-mediated PtNPs have significant potential for developing treatments against bacterial and fungal infections, with promising applications in medicine.

Allometry and biomass dynamics in temperate mixed and monospecific stands: Contrasting response of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.)

Mixed forests generally outperform monospecific forests in terms of productivity, stability, and resilience and are becoming increasingly important for sustainable forest management. However, accurate estimates of tree biomass allocation, as well as aboveground and component biomass in mixed forests, remain scarce. Our study addressed three different objectives to identify differences in biomass between mixed and monocultures and develop biomass models: (1) identification of biomass growth patterns in mixed and monoculture stands using analysis of covariance (ANCOVA), (2) investigation of the best fitting approach to modeling aboveground biomass using logarithmic regression and nonlinear mixed-effects models, and (3) fitting compartment biomass proportion models by Dirichlet regression, considering the additivity property. We analyzed 52 harvested trees from six plots within an experimental triplet in northern Spain, consisting of mixed and single-species stands of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.). Moreover, diameter at breast height and tree height were used as covariate variables to determine the most accurate and unbiased models. The research findings showed that (i) allometric patterns of individual-tree biomass in mixed stands significantly differed from those in monospecific stands for sessile oak, while those in Scots pine did not change; (ii) nonlinear mixed-effect models demonstrated a better fit – indicated by lower Furnival index values – than logarithmic regression models in predicting aboveground biomass; and (iii) the fitted biomass equations provided good performance and accurate estimates of biomass component proportions compared to those of existing models. Consequently, our results offer a better understanding of biomass and carbon storage within mixed and monoculture forests in the context of climate change.

Application of the solitary red mason bee, Osmia rufa L. (syn. O. bicornis), in forest monocultures in Poland

Seed orchards are utilised in forestry to avoid monoculture cultivation in forest areas and also constitute a gene bank for various tree species. In order to meet seed needs, preserve species diversity and genetic resources of forest management of the country, several hundred seed orchards served the purposes in Poland today. The paper presents an innovative solution to increase tree yield by introducing nests of solitary bees Osmia rufa L. (syn. O. bicornis) into monocultures. These insects are a natural solution that allows increasing the yield of selected tree and shrub species, especially fruit trees and shrubs and selected forest species. In order to determine the suitability of Osmia rufa L. to support the seed production process, a several-year research project was pursued consisting in assessing the quality of seeds, bee reproduction and identifying natural populations of insects in forest areas that were already present there before the introduction of bees. The research clearly shows that red mason bee, Osmia rufa L., can be employed with great success in forest areas to increase the productivity of selected forest tree species. Additionally, the work presents the results of study of red mason bee reproduction, showing that these bees in forest areas can also develop properly. Keywords: seed orchards; Tilia cordata; Quercus petraea; Prunus avium; insects; rearing of bees

Photosynthetic Response to Phosphorus Fertilization in Drought-Stressed Common Beech and Sessile Oak from Different Provenances.

Increasingly frequent and severe droughts pose significant threats to forest ecosystems, particularly affecting photosynthesis, a crucial physiological process for plant growth and biomass production. This study investigates the impact of phosphorus fertilization on the photosynthesis of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl.). In a common garden experiment, saplings originating from two provenances (wetter KA and drier SB provenances) were exposed to regular watering and drought in interaction with moderate and high phosphorus concentrations in the growing substrate. Results indicated that drought significantly reduced pre-dawn leaf water potential (ΨPD), net photosynthesis (Anet), stomatal conductance (gs) and photosynthetic performance index (PIabs) in both species. Phosphorus fertilization had a negative impact on Anet and PIabs, thus exacerbating the negative impact of drought on photosynthetic efficiency, potentially due to excessive phosphorus absorption by saplings. Provenance differences were notable, with the KA provenance showing better drought resilience. This research highlights the complexity of nutrient-drought interactions and underscores the need for cautious application of fertilization strategies in reforestation efforts under changing climatic conditions.

Correction: Canopy nitrogen application effects on Quercus petraea L. and Fagus sylvatica L. ring width and wood density

Correction: Canopy nitrogen application effects on Quercus petraea L. and Fagus sylvatica L. ring width and wood density

High heat tolerance, evaporative cooling, and stomatal decoupling regulate canopy temperature and their safety margins in three European oak species.

Heatwaves and soil droughts are increasing in frequency and intensity, leading many tree species to exceed their thermal thresholds, and driving wide-scale forest mortality. Therefore, investigating heat tolerance and canopy temperature regulation mechanisms is essential to understanding and predicting tree vulnerability to hot droughts. We measured the diurnal and seasonal variation in leaf water potential (Ψ), gas exchange (photosynthesis Anet and stomatal conductance gs), canopy temperature (Tcan), and heat tolerance (leaf critical temperature Tcrit and thermal safety margins TSM, i.e., the difference between maximum Tcan and Tcrit) in three oak species in forests along a latitudinal gradient (Quercus petraea in Switzerland, Quercus ilex in France, and Quercus coccifera in Spain) throughout the growing season. Gas exchange and Ψ of all species were strongly reduced by increased air temperature (Tair) and soil drying, resulting in stomatal closure and inhibition of photosynthesis in Q. ilex and Q. coccifera when Tair surpassed 30°C and soil moisture dropped below 14%. Across all seasons, Tcan was mainly above Tair but increased strongly (up to 10°C > Tair) when Anet was null or negative. Although trees endured extreme Tair (up to 42°C), positive TSM were maintained during the growing season due to high Tcrit in all species (average Tcrit of 54.7°C) and possibly stomatal decoupling (i.e., Anet ≤0 while gs >0). Indeed, Q. ilex and Q. coccifera trees maintained low but positive gs (despite null Anet), decreasing Ψ passed embolism thresholds. This may have prevented Tcan from rising above Tcrit during extreme heat. Overall, our work highlighted that the mechanisms behind heat tolerance and leaf temperature regulation in oak trees include a combination of high evaporative cooling, large heat tolerance limits, and stomatal decoupling. These processes must be considered to accurately predict plant damages, survival, and mortality during extreme heatwaves.

Biomass Carbon and Nitrogen Content of Hardwoods in Novi Pazar (Serbia)

To investigate and compare hardwood species based on their carbon (C) and nitrogen (N) storage capacity, a study of the C and N content of the bark and wood of nine common hardwood broadleaves in Novi Pazar, southwestern Serbia, was conducted. Compared with sycamore maple, Norway maple, common ash, common hornbeam, black locust, European beech, Turkey oak, and sessile oak, field maple has the highest C/N ratio in wood (37.05 ± 3.23), representing the best hardwood species for biomass production.

The ongoing range expansion of the invasive oak lace bug across Europe: current occurrence and potential distribution under climate change

In recent years, the oak lace bug, Corythucha arcuata, has emerged as a significant threat to European oak forests. This species, native to North America, has in the last two decades rapidly extended its range in Europe, raising concerns about its potential impact on the continent's invaluable oak populations. To address this growing concern, we conducted an extensive study to assess the distribution, colonization patterns, and potential ecological niche of the oak lace bug in Europe.We gathered 1792 unique presence coordinates from 21 Eurasian countries, utilizing diverse sources such as research observations, citizen science initiatives, GBIF database, and social media reports. To delineate the realized niche and future distribution, we employed an ensemble species distribution modelling (SDM) framework. Two future greenhouse gas scenarios (RCP 4.5 and RCP 8.5) were considered across three-time intervals (2021–2040, 2061–2080, and 2081–2100) to project and evaluate the species' potential distribution in the future.Our analysis revealed that significant hotspots rich in host species occurrence for this invasive insect remain uninvaded so far, even within its suitable habitat. Furthermore, the native ranges of Turkey oak (Quercus cerris L.) and Hungarian oak (Quercus frainetto L.) species offer entirely suitable environments for the oak lace bug. In contrast, the pedunculate oak and sessile oak distribution ranges currently show only 40 % and 50 % suitability for colonization, respectively. However, our predictive models indicate a significant transformation in the habitat suitability of the oak lace bug, with suitability for these two oak species increasing by up to 90 %. This shift underlines an evolving landscape where the oak lace bug may exploit more of its available habitats than initially expected. It emphasises the pressing need for proactive measures to manage and stop its expanding presence, which may lead to a harmful impact on the oak population across the European landscape.

Distribution, Ecology, Chorology and Phytocenology of Sweet Chestnut (Castanea sativa) in the Oltenia Region, Romania

This article provides useful information on the distribution of sweet chestnut (Castanea sativa) and presents additional data on the ecology, chorology and phytocenology of the species in the Oltenia region, Romania, based on literary sources, herbaria and field observations. By providing accurate and detailed data, this study contributes significantly to the existing knowledge, as well as mapping efforts of the species at the European level. In the subspontaneous flora of the Oltenia region, the C. sativa species is found in sheltered resorts in the counties of Gorj (Glogova, Valea Perilor, Tismana, Pocruia, Polovragi, etc.) and Mehedinți (Comăneşti, Baia de Aramă, etc.), on mesobasic soils, balanced from a hydraulic point of view. The phytocenoses where this species grows are rich in southern elements (e.g., Cornus mas L., Cerasus avium (L.) Moench, Quercus dalechampii Ten., Tilia tomentosa Moench). They are included in the Castaneo-Quercetum Horvat 1938 association. In Romania, habitats that include areas occupied by sweet chestnut are classified within habitat R4141—Daco-Balkan forests of oak (Quercus petraea) and chestnut (C. sativa) with Genista tinctoria. This habitat has a very high biodiversity conservation value and ecological importance. According to the Natura 2000 directive, sweet chestnut forests are included in the habitat category 9260, which underlines the importance at the European level for biodiversity conservation.

The Effect of Climate on Strongly Disturbed Vegetation of Bait Sites in a Central European Lower Montane Zone, Hungary

Human landscape-transforming activities contribute to the global change in vegetation in different forms. Hunting is one of the most ancient human landscape-shaping activities. Feeders for hunting are particularly disruptive to vegetation. In the present study, we conducted a vegetation survey in these highly disturbed places. We investigated the vegetation dynamics over several years in the turkey oak–sessile oak zone, in two areas with different moisture and shade conditions (forest and clearing). Important background factors are the changes in precipitation and temperature. Our results confirm that weed infestation is detectable at bait sites over a long period. The seasonal changes in field weed vegetation, as well as the increase in the number and coverage of weed species at the end of summer, resulting from lifestyle characteristics, were generally detectable in all years and locations, especially in the case of open and more strongly degraded clearings. Meteorological factors played a role in the degree of weed infestation in each year. Degradation was more significant in drought years, while regeneration was also observed in wetter periods. At baits located in the clearing, we showed a positive correlation between the amount of summer precipitation and the total coverage of weed species, as well as between the average spring temperature and the coverage of certain weed species. With the drying of the climate, the disturbed areas are constantly losing their natural value, but wetter weather is not an automatic solution either. Considering that there are approx. 30,000 bait sites in the country, and they are used regularly and very intensively, they can serve as major infection hotspots for alien species in a network.

From single trees to country-wide maps: Modeling mortality rates in Germany based on the Crown Condition Survey

Most years in the period from 2018 to 2022 have been exceptionally dry in Central Europe. In Germany’s forests, this long-lasting drought has caused unprecedented tree mortality. Systematic ground-based surveys, such as the annual Crown Condition Survey, provide information on the vitality status of the different tree species and their mortality rates. However, models are needed to be able to map the spatial patterns of mortality for each tree species based on cause-effect relationships derived from field observations. In this study, logistic regression models were used to identify the most important drivers of mortality for the most important tree species in Germany. For this purpose, the dead and surviving trees from the Crown Condition Survey were combined with a large set of potential predictor variables from the domains of climate, topography, soil, land cover and deposition. After feature selection, the models were evaluated using the area under the curve (AUC) statistic. Norway spruce (Picea abies; AUC = 0.9) showed by far the greatest increase in mortality, with the country-wide average observed and predicted rates approaching almost 10% per year from 2020 to 2022, and much higher predicted rates at the regional level. Much of the spruce mortality was explained by the climatic water balance of the driest summer in previous years. The other main tree species also showed clear mortality responses to the drought conditions. However, in the case of European beech (Fagus sylvatica; AUC = 0.94) and Pedunculate and Sessile oak (Quercus robur and petraea; AUC = 0.88), the peaks in the time series of the country-wide mortality rates stayed below 1%. For these broadleaved species, mortality was more dependent on a range of site conditions, i.e., soil and topography. For Scots pine (Pinus sylvestris; AUC = 0.76), for which the observed mortality rate peaked at 1.2% in 2020, the given drivers could explain mortality only to a lesser degree than for the other species. The regression models were used for spatial prediction to produce country-wide maps of species-specific mortality rates at annual temporal and 100-m spatial resolution, covering all years from 1998 to 2022. The maps visualize the spatial patterns of mortality over time. The regions in western and central Germany, which were most seriously affected by spruce dieback can clearly be identified. The models and maps presented can be used for risk assessment, forest planning, and tree species selection, providing decision support for forest practitioners.

Pest categorisation of Coniella castaneicola.

The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Coniella castaneicola (Ellis & Everh) Sutton, following commodity risk assessments of Acer campestre, A. palmatum, A. platanoides, A. pseudoplatanus, Quercus petraea and Q. robur plants from the UK, in which C. castaneicola was identified as a pest of possible concern to the EU. When first described, Coniella castaneicola was a clearly defined fungus of the family Schizoparmaceae, but due to lack of a curated type-derived DNA sequence, current identification based only on DNA sequence is uncertain and taxa previously reported to be this fungus based on molecular identification must be confirmed. The uncertainty on the reported identification of this species translates into uncertainty on all the sections of this categorisation. The fungus has been reported on several plant species associated with leaf spots, leaf blights and fruit rots, and as an endophyte in asymptomatic plants. The species is reported from North and South America, Africa, Asia, non-EU Europe and Oceania. Coniella castaneicola is not known to occur in the EU. However, there is a key uncertainty on its presence and geographical distribution worldwide and in the EU due to its endophytic nature, the lack of systematic surveys and possible misidentifications. Coniella castaneicola is not included in Commission Implementing Regulation (EU) 2019/2072 and there are no interceptions in the EU. Plants for planting, fresh fruits and soil and other growing media associated with infected plant debris are the main pathways for its entry into the EU. Host availability and climate suitability in parts of the EU are favourable for the establishment and spread of the fungus. Based on the scarce information available, the introduction and spread of C. castaneicola in the EU is not expected to cause substantial impacts, with a key uncertainty. Phytosanitary measures are available to prevent its introduction and spread in the EU. Because of lack of documented impacts, Coniella castaneicola does not satisfy all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.