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Fungi can be used as bioindicators to assess the biodiversity and conservation status of different habitats because of their high adaptability and sensitivity to changes in water, air, and soil quality. In this study, records of macrofungi and lichenised fungi were extracted from GBIF, surveyed using GIS software, and used to compare the fungal diversity of the Pyrenean oak and chestnut groves of Castilla y León, analysing the possible implications of their presence for the conservation of these forest habitats. In Quercus pyrenaica forests, a greater number of lichen and macrofungi species and records were recorded than in Castanea sativa forests, although the greater area occupied by the former could have influenced this diversity. The higher presence of ectomycorrhizal macrofungal species in chestnut groves, as well as the higher sensitivity to pollution of lichens in Pyrenean oak-dominated environments, showed the relevance of the analysis of these data for a better understanding of the conservation status of forest habitats. However, in order to obtain more accurate results, it would be necessary to carry out specific studies on a smaller scale. [ABSTRACT FROM AUTHOR]

Quercus pyrenaica Willd thrives in the intermediate zone between the Mediterranean sclerophyllous and the temperate deciduous forest. In December 2022, the presence of the bacteria Xylella fastidiosa (Xf) was confirmed in samples collected from a Quercus pyrenaica located in Sabrosa, Vila Real, Portugal. Following Xf infection, the transport of water and nutrients is hindered due to the occlusion of xylem vessels. This loss of hydraulic conductivity may lead to vessel blockage and subsequent embolism formation. The objective of this study was to investigate the interaction between Xf and Quercus pyrenaica tissues, as well as the mechanism by which the bacteria can spread through the plant's xylem vessels, ultimately resulting in the formation of vascular plugs. At the time of the sample collection (10 months post-detection), symptoms of Bacterial Leaf Scorch (BLS) began to appear. Examination of xylem vessels using both light and scanning electron microscopy (SEM) revealed the presence of various types of occlusions, predominantly tyloses. Additionally, fibrillar networks, gums, starch grains, and crystals were observed. The stem vessels exhibited significantly more occlusions compared to the leaves. Furthermore, individual bacterial cells were observed to be attached to the vessel wall. This implies that occlusions were primarily induced by tyloses and gums as a defensive response to the invasion of vascular pathogens, in addition to the pathogen itself. This study highlights the presence of starch grains in stems, which may function as a refilling mechanism, thereby preventing the loss of hydraulic conductivity in plants and potentially acting as a means to entrap the bacteria. These mechanisms exemplify the constitutive defense systems of the plant against Xf. Understanding the interaction between Xylella fastidiosa and Quercus pyrenaica is crucial, given that the latter species occupies nearly 95% of the natural distribution area of Portugal. [ABSTRACT FROM AUTHOR]

Background: The Iberian Peninsula comprises one of the largest boundaries between Mediterranean and Eurosiberian vegetation, known as sub-Mediterranean zone. This ecotone hosts many unique plant species and communities and constitutes the low-latitude (warm) margin of numerous central European species which co-occur with Mediterranean vegetation. Two of the main species found in this region are the Eurosiberian European beech (Fagus sylvatica L.) and the Mediterranean Pyrenean oak (Quercus pyrenaica Willd.). It remains unclear how the different physiological and adaptive strategies of these two species reflect their niche partitioning within a sub-Mediterranean community and to what extent phenotypic variation (intraspecific variability) is driving niche partitioning across Eurosiberian and Mediterranean species. Methods: We quantified functional niche partitioning, based on the n-dimensional hypervolume to nine traits related to resource acquisition strategies (leaf, stem and root) plus relative growth rate as an additional wholeplant trait, and the environmental niche similarity between Pyrenean oak and European beech. Further, we analyzed the degree of phenotypic variation of both target species and its relationship with relative growth rates (RGR) and environmental conditions. Plant recruitment was measured for both target species as a proxy for the average fitness. Results: Species' functional space was highly segregated (13.09% overlap), mainly due to differences in niche breadth (59.7%) rather than niche replacement (25.6%), and beech showed higher trait variability, i.e., had larger functional space. However, both species shared the environmental space, i.e., environmental niches were overlapped. Most plant traits were not related to abiotic variables or RGR, neither did RGR to plant traits. Conclusions: Both target species share similar environmental space, however, show notably different functional resource-use strategies, promoting a high complementarity that contributes to maintaining a high functionality in sub-Mediterranean ecosystems. Therefore, we propose that conservation efforts be oriented to preserve both species in these habitats to maximize ecosystem functionality and resilience. [ABSTRACT FROM AUTHOR]

Background: The Iberian Peninsula comprises one of the largest boundaries between Mediterranean and Eurosiberian vegetation, known as sub-Mediterranean zone. This ecotone hosts many unique plant species and communities and constitutes the low-latitude (warm) margin of numerous central European species which co-occur with Mediterranean vegetation. Two of the main species found in this region are the Eurosiberian European beech (Fagus sylvatica L.) and the Mediterranean Pyrenean oak (Quercus pyrenaica Willd.). It remains unclear how the different physiological and adaptive strategies of these two species reflect their niche partitioning within a sub-Mediterranean community and to what extent phenotypic variation (intraspecific variability) is driving niche partitioning across Eurosiberian and Mediterranean species. Methods: We quantified functional niche partitioning, based on the n-dimensional hypervolume to nine traits related to resource acquisition strategies (leaf, stem and root) plus relative growth rate as an additional whole-plant trait, and the environmental niche similarity between Pyrenean oak and European beech. Further, we analyzed the degree of phenotypic variation of both target species and its relationship with relative growth rates (RGR) and environmental conditions. Plant recruitment was measured for both target species as a proxy for the average fitness. Results: Species’ functional space was highly segregated (13.09% overlap), mainly due to differences in niche breadth (59.7%) rather than niche replacement (25.6%), and beech showed higher trait variability, i.e., had larger functional space. However, both species shared the environmental space, i.e., environmental niches were overlapped. Most plant traits were not related to abiotic variables or RGR, neither did RGR to plant traits. Conclusions: Both target species share similar environmental space, however, show notably different functional resource-use strategies, promoting a high complementarity that contributes to maintaining a high functionality in sub-Mediterranean ecosystems. Therefore, we propose that conservation efforts be oriented to preserve both species in these habitats to maximize ecosystem functionality and resilience.

Treelines are sensitive to environmental changes, but few studies provide a mechanistic approach to understand treeline dynamics based on field experiments. The aim of this study was to determine how changes in the abiotic and/or biotic conditions associated with global change affect the performance of tree seedlings (later saplings) at the treeline in a 10-year experiment. A fully factorial experiment in the Central Pyrenees was initiated in autumn 2006; 192 Pinus uncinata seedlings were transplanted into microplots with contrasting environmental conditions of (1) increased vs. ambient temperature, (2) increased nutrient availability vs. no increase, and (3) presence vs. absence of the dominant shrub Rhododendron ferrugineum. We assessed the performance of young pines on several occasions over 10 years. The pines were removed at the end of the experiment in autumn 2016 to characterize their morphology and to conduct chemical and isotopic analyses on their needles. Both the warming and the fertilization treatments increased seedling growth soon after the start of the experiment. R. ferrugineum facilitated the survival and development of pine seedlings during the early years and affected the chemical composition of the needles. Toward the end of the experiment, the transplanted P. uncinata individuals, by then saplings, competed with R. ferrugineum for light and nutrients; the presence of the shrub probably altered the strategy of P. uncinata for acquiring nutrients and buffered the effects of warming and fertilization. The pines were highly sensitive to all factors and their interactions throughout the entire experimental period. These findings indicated that the interactive effects of several key abiotic and biotic drivers associated with global change should be investigated simultaneously for understanding the contribution of young trees to treeline dynamics. [ABSTRACT FROM AUTHOR]

Examples of tool-use behaviors by birds outside foraging contexts are scarce and limited to a handful of species. We report a field experiment aimed to test whether an observed suite of odd behaviors by European Honey-buzzards (Pernis apivorus) represents use of green twigs cut from trees and woody shrubs as a tool to attract ants for anting. Specifically, we tested whether buzzards are selective in their choice of twigs, under the assumption that birds would prefer easy-to-collect twigs from plants that effectively attract ants. Experimental results lend support to our hypothesis that European Honey-buzzards cut green twigs of Montpellier maple trees (Acer monspessulanum) and, to a lesser extent, of Pyrenean oaks (Quercus pyrenaica) for their immediate use as ant attractors. Fresh twigs of both tree species attracted large numbers of ants, suggesting that their preferential use in the reported behavior of Honey-buzzards is not a random selection of the available plant material. Maple twigs, however, were the easiest to break and oak twigs the hardest compared to other plants in the community. This suggests that the relative ease of cracking of maple twigs may account for the preference Honey-buzzards have for this plant species as compared with Pyrenean oak, whose twigs demand considerable more effort from the birds to break. Our results lend support to the inclusion of the reported behavioral sequence by this raptor species as a potential example of tool use in birds outside the usual foraging context. [ABSTRACT FROM AUTHOR]

This study presents a reanalysis of ozone (O 3 ) exposure experiments performed on deciduous broadleaf oak species in the Mediterranean region and a proposal of critical levels to improve the O 3 risk assessment in this area for these widely distributed forest species. Two experiments performed in Spain and Italy were considered, and the following 3 oak species were studied: Quercus pyrenaica , Q. faginea and Q. robur . All the experiments were performed with irrigated potted seedlings growing in Open-Top Chambers exposed to different O 3 levels (with charcoal-filtered air as the control treatment) for two consecutive growing seasons. The Phytotoxic Ozone Dose above an instantaneous threshold of 1 nmol O 3 m −2 s −1 (POD 1 ) was calculated by applying a Jarvis type model for the estimation of the stomatal conductance ( g s ), and by adopting a big-leaf resistive scheme to account for the O 3 deposition on the vegetation. Two parameterisations were used for the g s multiplicative model: one species-specific based on the “local” g s measurements performed during each experiment, and the other “generic” based on the “Deciduous Mediterranean broadleaf” parameterisation described in the Manual on Methodologies and Criteria for Mapping Critical Loads and Levels and Air Pollution Effects, Risks and Trends of the UN/ECE (CLRTAP, 2015). The two different parameterisations were used to derive dose-response functions and ozone critical levels for the biomass loss of the deciduous oak species. The dose-response functions for roots and total biomass were statistically significant, with both the parameterisations tested ( p  < 0.05). The O 3 critical levels obtained indicate that deciduous broadleaf oaks in Mediterranean environment could be more tolerant to O 3 than other European broadleaf species and that O 3 is more harmful to the below-ground biomass of the plants rather than the above-ground biomass. [ABSTRACT FROM AUTHOR]

Quercus pyrenaica is one of the most widespread species in pure or mixed stands across the Iberian Peninsula. It mostly occurs in mountain areas within the Mediterranean region, but also dominates forests along the boundary to the Atlantic northern Iberia. Given this role as a transitional species, the understanding of its behavior is of great relevance in a context of climate change. We analyzed five Q. pyrenaica stands in northwestern Iberia, located along a transect of increasing elevation in the Atlantic/Mediterranean biogeographical boundary. Tree-ring chronologies were obtained by measuring the earlywood vessel size, and the radial increment on a representative number of trees. Three variables were used, namely (i) the hydraulically-weighted diameter for the earlywood vessels in the first row ( D H -r1), (ii) for vessels outside this row ( D H -nr1), and (iii) the latewood width (LW). Variable chronologies were compared to monthly meteorological records, and to the North Atlantic Oscillation index (NAO). LW variation was controlled by water availability during late spring-early summer all throughout the study area, but differences among sites were mostly driven by the presence of abrupt growth changes linked to forest disturbance regime. In contrast, earlywood responses were modulated by the topographic position. The three low-elevation sites, located at windward of a central mountain range, were related to environmental conditions during quiescence, whereas the two others responded at the moment of wood formation; D H -r1 was more controlled by climate than D H -nr1. The close association between NAO and vessel size was in accordance with the elevation gradient. Our results showed relevant signals related to micro-, meso-, and macroclimatic conditions, and pointed out to the existence of cause-effect relationships. Therefore, the combined time-series analysis of earlywood vessels and latewood increment is a powerful tool to understand the ecological behavior of marcescent oaks in marginal populations, which often dominate transitional areas. [ABSTRACT FROM AUTHOR]

The use of alternative oak products (AOP) for wine aging is a common practice in which micro-oxygenation (MOX) is a key factor to obtain a final wine that is more stable over time and with similar characteristics as barrel-aged wines. Therefore, the oxygen dosage added must be that which the wine is able to consume to develop correctly. Oxygen consumption by red wine determines its properties, so it is essential that micro-oxygenation be managed properly. This paper shows the results from the study of the influence on red wine of two different MOX strategies: floating oxygen dosage (with dissolved oxygen setpoint of 50 μg/L) and fixed oxygen dosage (3 mL/Lmonth). The results indicated that the wines consumed all the oxygen provided: those from fixed MOX received between 3 and 3.5 times more oxygen than the floating MOX strategy, the oxygen contribution from the air entrapped in the wood being more significant in the latter. Wines aged with wood and MOX showed the same color and phenolic evolution as those aged in barrels, demonstrating the importance of MOX management. Despite the differences in the oxygen consumed, it was not possible to differentiate wines from the different MOX strategies at the end of the aging period in contact with wood. [ABSTRACT FROM AUTHOR]

Long-term coppicing leads to the development of massive root systems. A disproportionate carbon investment in root maintenance has been pointed as a cause of the widespread decline of abandoned coppices. We aimed at assessing how coppicing has influenced root and shoot development and related carbon loss ascribed to maintenance of woody tissues in Quercus pyrenaica. For this goal, results from published studies on root dynamics, woody biomass and respired CO2 fluxes in an abandoned Q. pyrenaica coppice were integrated and extended to quantify overall respiratory expenditures of above- and below- ground woody organs. Internal and external CO2 fluxes together with soil CO2 efflux were monitored in eight stems from one clone across a growing season. Stems and roots were later harvested to quantify the functional biomass and scale up root and stem respiration (RR and RS, respectively) to the clone and stand levels. Below- and above-ground biomass was roughly equal. However, the root-to-shoot ratio of respiration (RR/RS) was generally below one. Relatively higher RS suggests enhanced metabolic activity aboveground during the growing season, and highlights an unexpected but substantial contribution of RS to respiratory carbon losses. Moreover, soil and stem CO2 efflux to the atmosphere in Q. pyrenaica fell in the upper range of reported rates for various forest stands distributed worldwide. We conclude that both RS and RR represent an important carbon sink in this Q. pyrenaica abandoned coppice. Comparatively high energetic costs in maintaining multiple stems per tree and centennial root systems might constrain aboveground performance and contribute to coppice stagnation. [ABSTRACT FROM AUTHOR]

A quantitative method was tested to describe crown phenophases in relation to water content and to secondary growth in ring-porous species, based on the hypothesis that new shoots require hydrated tissues to maintain the necessary turgor for extension, leading to a reduction in dry matter content (DMC). We collected a three-year-old branch from 11 Quercus pyrenaica Willd. trees at 10-day intervals to estimate DMC of newly developing buds, leaves, and twigs, and processed two opposite stem microcores for xylogenesis. Branch phenophases and shoot length were recorded in the field. The DMC of all organs decreased during crown development, with a minimum in early June, followed by a gradual increase up to initial values in late September. The shoot extension period concurred with the lowest DMC, but also with the beginning of earlywood maturation in the main stem, suggesting a high tissue hydration only when earlywood vessels become functional to fulfill enough water requirements for shoot and leaf extension. These results confirm the usefulness of DMC to accurately quantify the phenology of primary growth from bud swelling up to full leaf extension, as a complement to qualitative methods. This variation in DMC appears to be linked to secondary growth as a result of earlywood vessel development. [ABSTRACT FROM AUTHOR]

Sustainable production of wood is one of the main services provided by forest systems. Site productivity in the case of forests is often evaluated through the site quality. However, most of the works addressing the site quality have been done at local or regional scale. In this work, we aim to develop site quality models for five dominant species in Spanish forests ( Fagus sylvatica , Pinus pinaster atlantica , Quercus pyrenaica , Pinus nigra , Pinus sylvestris ) and create site quality maps at a national-scale from these models. First, we develop site quality models using site form (height-diameter relationship) as the reference index and the Spanish National Forest Inventory as dataset. Then, we fit spatial additive models entering physiographic and climatic variables in order to predict the site quality over the whole country. Additionally, we plot site form maps for the five species in order to describe spatial pattern in site quality at a national scale. Altitude and aspect appeared to be fundamental variables in the assessment of site quality. The accuracy of the spatial additive models ranged from 38.2% to 47.9%. The correspondence between the predicted and observed maps of site qualities is clear. Our results provide a tool which could be used by forest managers in land use planning as well as in forest policy decision-making at a national scale. We suggest that this method could be used in other countries and that the maps could be expanded to the European scale to assessing the way in which site quality varies across Europe always considering that the relationships between forest productivity and environmental variables could vary among biogeoclimatic zones. [ABSTRACT FROM AUTHOR]

The ability of trees to cope with climate change is a pivotal feature of forest ecosystems, especially for rear-edge populations facing warm and dry conditions. To evaluate current and future forests threats, a multi-proxy focus on the growth, anatomical and physiological responses to climate change is needed. We examined the long-term xylem adjustments to climate variability of the temperate Quercus robur L. at its rear edge and the sub-Mediterranean Quercus pyrenaica Willd. Both species coexist at a mesic (ME, humid and warmer) and a xeric (XE, dry and cooler) site in northern Spain, the latter experiencing increasing temperatures in recent decades. We compared xylem traits at each site and assessed their trends, relationships and responses to climate (1960-2008). Traits included basal area increment, earlywood vessel hydraulic diameter, density and theoretical-specific hydraulic conductivity together with latewood oxygen (δ18O) stable isotopes and δ13C-derived water-use efficiency (iWUE). Quercus robur showed the highest growth at ME, likely through enhanced cambial activity. Quercus pyrenaica had higher iWUE at XE compared with ME, but limited plasticity of anatomical xylem traits was found for the two oak species. Similar physiological performance was found for both species. The iWUE augmented in recent years especially at XE, likely explained by stomatal closure given the increasing δ18O signal in response to drier and sunnier growing seasons. Overall, traits were more correlated at XE than at ME. The iWUE improvements were linked to higher growth up to a threshold (~85 μmol mol-1) after which reduced growth was found at XE. Our results are consistent with Q. pyrenaica and Q. robur coexisting at the central and dry edge of the climatic species distribution, respectively, showing similar responses to buffer warmer conditions. In fact, the observed adjustments found for Q. robur point towards growth stability of similar rear-edge oak populations under warmer climate conditions. [ABSTRACT FROM AUTHOR]

A new species of Didymium from Spain. Bol. Soc. Micol. Madrid 41: 17–22. A new folicolous species, Didymium radiaticolumellum is described from Spain. The new species has been collected on leaves of Quercus pyrenaica. Macro and microphotographs of fruiting bodies and morphological features as observed under magnifying glass and light microscope (LM) are provided, along with micrographs of spore ornamentation as observed by scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Questions Can shrubs ( Cytisus multiflorus) and large herbivore exclusion (fence) facilitate seedling survival and growth of marcescent and sclerophyllous oaks ( Quercus pyrenaica vs Q. ilex subsp. ballota) under a bioclimatic limit in Mediterranean grazed areas? Location Open oak woodlands, central-western Spain. Methods A 2-yr field experiment was conducted by planting 200 seedlings of each Quercus species under four different treatments combining the influence of nurse shrubs and fencing on Quercus seedling survival and growth. Results Cytisus multiflorus enhanced poor Quercus seedling survival found in the study area, at least during the first 2 yr after planting and particularly during the first dry season. The improvement in soil organic matter under the shrub canopy may have contributed to this positive effect, which was more pronounced on Q. pyrenaica seedlings. Seedling herbivory did not seem to be a limitation to survival. Increased seedling growth in both species was also very low, and no growth was recorded 2 yr after planting without shrubs. The positive shrub effect on seedling growth, especially marked in fenced areas, was more important in Q. pyrenaica in the first growing period and in Q. ilex in the second; 2 yr after planting no difference in shrub effect on growth was found in either Quercus species. Seedling herbivory was a limitation to seedling growth in areas without shrubs, mainly in the case of Q. pyrenaica. Conclusions In Mediterranean grazed areas with important summer drought and very sandy soil, shrubby C. multiflorus plants have a clear facilitative effect on seedlings of ecologically contrasted Quercus species. The facilitative effect was found in both marcescent and sclerophyllous oak seedlings, but to a different degree depending on the species considered and the variable measured (survival or growth). In terms of survival, the marcescent species was more favoured by shrub cover than the sclerophyllous one, and this effect was accentuated through time. However, in terms of growth, although Q. pyrenaica was initially more favoured by shrubs, differences between the two species were attenuated after 2 yr. Therefore, C. multiflorus can have a key role in restoration of these oak degraded environments. [ABSTRACT FROM AUTHOR]

The temporal factor has been widely neglected in studies related to species distribution. However, knowing the species phenology throughout the year could be a key element in ecological studies, more so considering the current climate change framework. The intra-annual temporal patterns of the saproxylic beetle assemblage inhabiting the oak forests in the western Iberian Peninsula were evaluated in terms of species richness and composition. Moreover, we analysed the temporal patterns of species richness and body size, with respect to the abiotic factors of temperature and relative humidity. The marked seasonality of the Mediterranean weather governed, to a great extent, the temporal patterns of the assemblage, as both species richness and body size showed a positive correlation with temperature and a negative correlation with relative humidity. The high temperatures reached in August limited the activity of certain species, causing a marked decrease in species richness. The results revealed that species body size decreased in the colder months of the year and vice versa, which could fit with the inverse of Bergmann's rule; nevertheless, studies are needed to address the contribution of species physiology and autoecology to the observed temporal patterns. Regarding species composition, the partition of beta diversity in its two components showed a constant process of species turnover throughout the year. We conclude that, due to global warming, the study of temporal patterns of assemblages is becoming all the more important, since it could significantly affect the spatio-temporal distribution of species and the interactions between them. [ABSTRACT FROM AUTHOR]

Climatic scenarios for the Mediterranean region forecast increasing frequency and intensity of drought events. Consequently, a reduction in Pinus sylvestris L. distribution range is projected within the region, with this species being outcompeted at lower elevations by more drought-tolerant taxa such as Quercus pyrenaica Willd. The functional response of these species to the projected shifts in water availability will partially determine their performance and, thus, their competitive success under these changing climatic conditions. We studied how the cambial and leaf phenology and xylem anatomy of these two species responded to a 3-year rainfall exclusion experiment set at their elevational boundary in Central Spain. Additionally, P. sylvestris leaf gas exchange, water potential and carbon isotope content response to the treatment were measured. Likewise, we assessed inter-annual variability in the studied functional traits under control and rainfall exclusion conditions. Prolonged exposure to drier conditions did not affect the onset of xylogenesis in either of the studied species, whereas xylem formation ceased 1–3 weeks earlier in P. sylvestris. The rainfall exclusion had, however, no effect on leaf phenology on either species, which suggests that cambial phenology is more sensitive to drought than leaf phenology. P. sylvestris formed fewer, but larger tracheids under dry conditions and reduced the proportion of latewood in the tree ring. On the other hand, Q. pyrenaica did not suffer earlywood hydraulic diameter changes under rainfall exclusion, but experienced a cumulative reduction in latewood width, which could ultimately challenge its hydraulic performance. The phenological and anatomical response of the studied species to drought is consistent with a shift in resource allocation under drought stress from xylem to other sinks. Additionally, the tighter stomatal control and higher intrinsic water use efficiency observed in drought-stressed P. sylvestris may eventually limit carbon uptake in this species. Our results suggest that both species are potentially vulnerable to the forecasted increase in drought stress, although P. sylvestris might experience a higher risk of drought-induced decline at its low elevational limit. [ABSTRACT FROM AUTHOR]

The Middle Spotted Woodpecker ( Leiopicus medius) is a strict forest bird whose habitat preferences during the breeding season are well known. However, a lack of information about its habitat selection during the non-breeding season may hamper recommendations for the management and conservation of the species. Here we study habitat selection of this woodpecker at its southwestern boundary range (Izki Natural Park, northern Spain) during the non-breeding season (October-December) by means of a use-availability approach. We also examined seasonal differences in habitat use between the breeding season (April-May) and the non-breeding season. Results of ANOVA and backward-stepwise logistic regression revealed a clear selection of high forest cover, large Pyrenean oaks ( Quercus pyrenaica), and presence of dead trees during the non-breeding season. Despite very similar habitat use in both seasons, minor but interesting differences between seasons were observed, with a potential expansion during the non-breeding season into less mature forests (lower forest cover and fewer large trees) with a greater abundance of dead trees. These differences may reflect seasonal changes in the spatial requirements of the species and a decrease in food abundance during autumn-winter. On the basis of these findings, we propose management measures to improve the conservation status of the species in the Iberian Peninsula. [ABSTRACT FROM AUTHOR]

We selected two sites dominated by the sub-Mediterranean oak Quercus pyrenaica Willd. close to its distribution boundary in northwestern Iberia, within a mountain region with a high winter precipitation. The sites differed in their soil water regime, corresponding to the edge of a peat bog, and to a moderate slope. We obtained tree-ring chronologies of total ring width (RW), and mean earlywood vessel area (MVA); their responses to climatic factors were compared for the period 1945-2002. RW presented a higher chronology quality than MVA, but was rather independent of climate, probably because of the presence of recurrent growth reductions. In contrast, MVA was closely related to precipitation during April and May, whereby a high water availability was coupled to smaller vessels. We found remarkable differences between the climatic signal of both stands, as trees growing on the peat soil responded later and with considerably lower intensity. We hypothesize that spring waterlogging causes that the response at the wettest site occurs only when soil desiccation begins, which results in a delayed climatic signal, and also lower intra- and inter-annual variation due to more homogeneous conditions. Climate-growth relationships at the driest site were mainly associated with the first row, whereas it is vessels expanding later in the season that show this relation for the moist site. Our results confirm that MVA chronologies are reliable proxies of both regional and local climatic conditions, but only a careful optimization by selecting vessel subsets does provide a complete view of their potential. [ABSTRACT FROM AUTHOR]

Genetic, dendrochronological and physiological studies are reviewed to investigate causes of tree stagnation of abandoned Quercus pyrenaica coppices. Tree decline - displayed by slow stem growth, branch dieback and scarce acorn production - has led to advice on the conversion of abandoned oak coppices into high forests by thinning. However, this practice has often failed. The shortage of genetic diversity and disequilibrium between above- and below-ground organs in large, over-aged stools (clones) are adduced consequences of centenary coppicing driving stand stagnation in Q. pyrenaica. Our results evidence that historical coppicing has not enhanced genetic diversity losses; on the contrary, it has allowed for the recruitment of new genotypes and the existence of uneven-aged stands of heterogenic clonal structure. Tree excavations have revealed widely spread root systems. High carbon expenditures in root respiration in large and centennial clones may constrain their aboveground development, and thinning practices aiming at converting Q. pyrenaica coppices into high forests might not succeed or even enhance a physiological root-to-shoot imbalance. [ABSTRACT FROM AUTHOR]

Stand Density Management Diagrams are useful tools for designing and evaluating alternative density management regimes without the need of implementing any silvicultural action, and allowing the future stand conditions to be predicted prior to implementing management schedules. In this study, stand density management diagrams were developed for Pyrenean oak (Quercus pyrenaica Willd.) stands in north-west Spain by including data on stand volume, stand aboveground biomass, stand stem biomass and carbon pools. Data were obtained from Third National Forest Inventory plots (n=1860). The large geographical area analyzed in this study was classified by provenance regions, which were compared in terms of biomass production in order to define areas with similar characteristics for use as management units. The comparisons identified 6 independent groups. Different stand-level models and the associated diagrams for the aforementioned stand variables were therefore developed for each group.

Deciduous oak coppices ( Quercus pyrenaica Willd.) of the ' Sierra de Gata' mountains (central western Spain) are located on acid rocks and subjected to annual rainfall higher than 700 mm year. Accordingly, the soils are acidic (soil pH is often below 5.0) and feature the presence of Mn and Al in the exchangeable complex. The aim of the present study was to assess the response of these soils to the addition of a lime residue from a sugar beet mill to reach pH values close to 7.0 and 6.0 with in situ and in vitro experiments, respectively. Initially, the quality of the lime by-product was evaluated, which showed content close to 75 % CaCO. Based on that analysis, calculations were accomplished to determine the dose of lime by-product necessary for achieving the targeted soil pH. We first performed an in vitro liming experiment, incubating 0.50 kg soil (0-20 cm layer) with 23.92 g CaCO kg soil (20 °C and soil moisture equivalent to that of field capacity). Subsequently, another experiment was done adding an equivalent quantity of sub-product in lieu of the pure CaCO; the factors monitored were: soil pH, exchange acidity, CEC, and exchangeable bases, every 24 h. The in situ experiment was performed in a forest plot located in Western Spain (Navasfrías), liming with 16.0 Mg DM by-product ha (September 1999). Soil samples (two depths: 0-10 and 10-20 cm) were taken from both the control and the experimental forest plots for monitoring the liming effect. Sampling dates were September and December 1999; June 2000, January, June and September 2001; October 2002 and 2003, and March 2005). The dissolution of the lime by-product at the laboratory was almost immediate, but the effects in the field occurred approximately 2 years after initial liming, since lime dissolution depends on both the amount and distribution of rainfall and, also, on the application procedure. [ABSTRACT FROM AUTHOR]

Prediction of future forest carbon (C) stocks as influenced by forest management and climate is a crucial issue in the search for strategies to mitigate and adapt to global change. It is hard to quantify the long-term effect of specific forest practices on C stocks due to the high number of processes affected by forest management. This work aims to quantify how forest management impacts C stocks in Mediterranean mountain forests based on 25 combinations of site index, tree species composition and thinning intensity in three different climate scenarios using the CO2Fix v.3.2 model Masera et al. (Ecol Modell 164:177-199, 2003). The study area is an ecotonal zone located in Central Spain, and the tree species are Scots pine ( Pinus sylvestris L.) and Pyrenean oak ( Quercus pyrenaica Willd.). Our results show a strong effect of tree species composition and a negligible effect of thinning intensity. Mixed stands have the highest total stand C stocks: 100 % and 15 % more than pure oak and pine stands respectively, and are here suggested as a feasible and effective mitigation option. Climate change induced a net C loss compared to control scenarios, when reduction in tree growth is taken into account. Mixed stands showed the lowest reduction in forest C stocks due to climate change, indicating that mixed stands are also a valid adaptation strategy. Thus converting from pure to mixed forests would enhance C sequestration under both current and future climate conditions. [ABSTRACT FROM AUTHOR]

Land use change and global warming are important drivers in the distribution of tree species. The Mediterranean mountain forest ecosystems can be severely affected by climate change since an increment in temperature has been observed. The main aim of this work was to analyze shifts in the distribution and changes in the abundance of Pyrenean oak ( Quercus pyrenaica Willd.) and Scots pine ( Pinus sylvestris L.) in Mediterranean mountains over a period of 47 years (1965–2012) by using data from the National Forest Inventories, extending the Universal Kriging/Cokriging models to the space–time case for long-term forest inventory data analysis including climatic variables. Our results indicated that both the distribution and the abundance of Scots pine remained quite constant during the study period. Pyrenean oak increased its presence by 42% whereas its abundance doubled between 1965 and 2012. This movement took place towards both higher and lower altitudes. With regard to climatic factors, the kriging models showed a negative association between the presence of Scots pine and the temperature. However, we found a quadratic relationship between the Pyrenean oak and temperature, pointing to the occurrence of at intermediate altitudes. Additionally, we found significant relationships between the rainfall and the abundance of both species. Rainfall was positively related to the abundance of Scots pine and negatively to that of Pyrenean oak. Our results indicate that there has been a threefold increase in the area covered by mixed stands. However, successive land use changes as well as forest policies related to conservation have played an important role in the distribution of both species and therefore are taken into account in the discussion of these results. [ABSTRACT FROM AUTHOR]

Slow growth, branch dieback and scarce acorn yield are visible symptoms of decay in abandoned Quercus pyrenaica coppices. A hypothetical root-to-shoot (R:S) imbalance provoked by historical coppicing is investigated as the underlying driver of stand degradation. After stem genotyping, 12 stems belonging to two clones covering 81 and 16 m 2 were harvested and excavated to measure above- and below-ground biomass and nonstructural carbohydrate (NSC) pools. To study root system functionality, root connections and root longevity were assessed by radiocarbon analysis. Seasonality of NSC was monitored on five additional clones. NSC pools, R:S biomass ratio and fine roots-to-foliage ratio were higher in the large clone, whose centennial root system, estimated to be 550 years old, maintained large amounts of sapwood (51.8%) for NSC storage. 248 root connections were observed within the large clone, whereas the small clone showed comparatively simpler root structure (26 connections). NSC concentrations were higher in spring (before bud burst) and autumn (before leaf fall), and lower in summer (after complete leaf expansion); they were always higher in roots than in stems or twigs. The persistence of massive and highly inter-connected root systems after coppicing may lead to increasing R:S biomass ratios and root NSC pools over time. We highlight the need of surveying belowground organs to understand aboveground dynamics of Q. pyrenaica , and suggest that enhanced belowground NSC storage and consumption reflect a trade-off between clonal vegetative resilience and aboveground performance. [ABSTRACT FROM AUTHOR]

• Key message: Xylem and soil CO fluxes in coppiced oak forests increase with clonal size, suggesting larger expenditures of energy for root respiration. An imbalance between root demand and shoot production of carbohydrates may contribute to the degradation of abandoned coppices. • Context: Our understanding of root respiration is limited, particularly in root-resprouting species with many stems and a large system of interconnected roots resulting from long-term coppicing. • Aims: We tested the hypothesis that clone size influences the internal flux of CO dissolved in xylem sap ( F) from roots into the stem and soil CO efflux ( F) as indicators of root respiration. We predicted that large clones would exhibit higher F per stem and F than small clones due to larger root system per stem in large clones. • Methods: Genetic analyses were performed to elucidate clonal grouping. F was measured continuously for 100 days in 16 similar-sized stems of Quercus pyrenaica belonging to two large and two small clones. F was measured in 20 clones of varying size. • Results: F per stem and F were higher in large clones. F was 2 % of the root-respired CO that diffused through soil to the atmosphere. • Conclusions: Relative to other studies, the contribution of F to root respiration was very low, pointing to large differences depending on species or site. Higher stem F and F in large clones compared with small clones suggest greater carbon consumption by roots in large clones, pointing to a root/shoot biomass and physiological imbalance resulting from long-term coppicing that would partially explain the degradation of currently abandoned stands of Q. pyrenaica. [ABSTRACT FROM AUTHOR]

Reforestation is common to restore degraded ecosystems, but tree-species choice often neglects ongoing environmental changes. We evaluated the performance of planted seedlings of two oak species at two sites in a Mediterranean mountain (Sierra Nevada, SE Spain): one located within the current altitudinal forest range (1,600-1,760 m), and one above the upper forest limit (1,970-2,120 m). The forest service planted 1,350 seedlings of the deciduous Pyrenean oak and the evergreen Holm oak in a postfire successional shrubland. After 2 years, seedlings were monitored for survival, and a subset of 110 Pyrenean oaks and 185 Holm oaks were harvested for analyses of biomass and foliar nutrient status, δ13C, and δ18O. Both species showed the highest survival and leaf N status above the upper forest limit, and survival increased with altitude within each plot. The deciduous oak benefited most from planting at higher altitude, and it also had greater biomass at the higher site. Correlations between foliar N, δ18O, and δ13C across elevations indicate tighter stomatal control of water loss and greater water-use efficiency with increasing plant N status at higher altitude, which may represent a so-far overlooked positive feedback mechanism that could foster uphill range shifts in water-limited mountain regions. Given ongoing trends and future projections of increasing temperature and aridity throughout the Mediterranean region, tree-species selection for forest restoration should target forecasted climatic conditions rather than those prevailing in the past. This study highlights that ecosystem restoration provides an opportunity to assist species range shifts under rapidly changing climate. [ABSTRACT FROM AUTHOR]

Logs of three common Southern and mid-European woods ( Quercus pyrenaica , Populus nigra and Fagus sylvatica ) were burned in two different combustion appliances, a fireplace and a stove. The flue gas composition was monitored continuously in the exhaust ducts of both burning appliances for total hydrocarbons (THC) and carbon oxides (CO 2 and CO). Particulate matter with aerodynamic diameter below 2.5 μm (PM 2.5 ) was sampled in a dilution tunnel under isokinetic conditions and chemically characterised for water soluble-inorganic ions, organic and elemental carbon and levoglucosan, mannosan, and galactosan. The evolution of the emission factors of these components throughout the combustion cycle was studied. The fireplace was the combustion appliance with the highest CO, CO 2 , THC and PM 2.5 emission factors. The carbonaceous matter represented 72–84% of the particulate mass emitted, regardless of species burned and combustion devices. OC/EC ratios were higher for the fireplace than for the stove, and showed a significant potential relation with K + /levoglucosan. The dominant water soluble inorganic ions in smoke particles were K + , PO 4 3 − , SO 4 2 − , and Na + . Anhydrosugar emissions were strongly enhanced in the start-up phase, when lower temperatures are registered, and decreased progressively until the glowing combustion phase. However, K + emission seems to be higher in flaming-dominated combustion at higher temperature. Statistical analyses, including the Kruskal–Wallis test, principal component analysis and Pearson correlation between emission factors, were carried out. A significant correlation between NH 4 + and levoglucosan was found for both appliances. [ABSTRACT FROM AUTHOR]

The implementation of the Natura 2000 network requires methods to assess the conservation status of habitats. This paper shows a methodological approach that combines the use of (satellite) Earth observation with ontologies to monitor Natura 2000 habitats and assess their functioning. We have created an ontological system called Savia that can describe both the ecosystem functioning and the behaviour of abiotic factors in a Natura 2000 habitat. This system is able to automatically download images from MODIS products, create indicators and compute temporal trends for them. We have developed an ontology that takes into account the different concepts and relations about indicators and temporal trends, and the spatio-temporal components of the datasets. All the information generated from datasets and MODIS images, is stored into a knowledge base according to the ontology. Users can formulate complex questions using a SPARQL end-point. This system has been tested and validated in a case study that uses Quercus pyrenaica Willd. forests as a target habitat in Sierra Nevada (Spain), a Natura 2000 site. We assess ecosystem functioning using NDVI. The selected abiotic factor is snow cover. Savia provides useful data regarding these two variables and reflects relationships between them. [ABSTRACT FROM AUTHOR]

In the Mediterranean region, over the past few centuries human activity has modeled the landscape, leading to forest degradation. However, as in many parts of the European continent since the second half of the twentieth century, the Iberian Peninsula has been subject to a substantial degree of land abandonment that has led to the expansion of important secondary forests. One of the dominant tree species in the transitional forests of mountain areas between the Mediterranean and Euro-Siberian regions of the Iberian Peninsula is the deciduous oak, Quercus pyrenaica Willd. The main objectives of the present work were to study the mode of regeneration and forest dynamics of Q. pyrenaica in several types of stands: young forests, mature and previously perturbed forests, and abandoned Pinus reforestations. With this in mind we established eight plots in the mountain range of the Sierra de Francia–Quilamas, in the west subdivision of the Spanish Central System. We analyzed the age and dbh distributions, regeneration density, and the spatial structure of trees and saplings. Young Q. pyrenaica stands were seen to show episodic recruitment after land abandonment consistent with a ‘catastrophic’ mode of regeneration. These stands were characterized by unimodal age-cohorts, with tree recruitment dropping drastically as the canopy developed and closed in, except at some study sites where the more shade-tolerant Castanea sativa was found. Older and previously disturbed Q. pyrenaica stands showed bimodal age cohorts, the young ones exhibiting a clumped pattern associated with canopy gaps and/or a lower tree density of the older cohort. In abandoned Pinus reforestations, the recruitment of Q. pyrenaica was also associated with canopy openings. These findings show that Q. pyrenica also undergoes a gap-phase mode of regeneration. An abundant regeneration of Q. pyrenaica could be found at all the stands, guaranteeing the persistence of seedling banks (but a scarcity or lack of saplings) under closed forests, until canopy gaps may allow some Q. pyrenaica individuals to grow and reach the main canopy. [ABSTRACT FROM AUTHOR]

Consumers are exhibiting increasing interest in honeydew honey, principally due to its functional properties. Some plants can be sources of honeydew honey, but in north-western Spain, this honey type only comes from Quercus pyrenaica. In the present study, the melissopalynological and physicochemical characteristics and the antioxidant properties of 32 honeydew honey samples are described. Q. pyrenaica honeydew honey was defined by its colour, high pH, phenols and flavonoids. Multivariate statistical techniques were used to analyse the influence of the production year on the honey's physicochemical parameters and polyphenol content. Differences among the honey samples were found, showing that weather affected the physicochemical composition of the honey samples. Optimal conditions for oak growth favoured the production of honeydew honey. [ABSTRACT FROM AUTHOR]

Background and Aims: Tree species composition shifts can alter soil CO and NO effluxes. We quantified the soil CO and NO efflux rates and temperature sensitivity from Pyrenean oak, Scots pine and mixed stands in Central Spain to assess the effects of a potential expansion of oak forests. Methods: Soil CO and NO effluxes were measured from topsoil samples by lab incubation from 5 to 25 °C. Soil microbial biomass and community composition were assessed. Results: Pine stands showed highest soil CO efflux, followed by mixed and oak forests (up to 277, 245 and 145 mg CO-C m h, respectively). Despite contrasting soil microbial community composition (more fungi and less actinomycetes in pine plots), carbon decomposability and temperature sensitivity of the soil CO efflux remain constant among tree species. Soil NO efflux rates and its temperature sensitivity was markedly higher in oak stands than in pine stands (70 vs. 27 μg NO-N m h, Q, 4.5 vs. 2.5). Conclusions: Conversion of pine to oak forests in the region will likely decrease soil CO effluxes due to decreasing SOC contents on the long run and will likely enhance soil NO effluxes. Our results present only a seasonal snapshot and need to be confirmed in the field. [ABSTRACT FROM AUTHOR]

Purpose: The study aimed to use the Soil and Water Assessment Tool (SWAT) model to simulate erosion processes in an alpine-prealpine catchment in order to provide data and information that may be relevant for managers so as to minimize reservoir siltation and water quality degradation. The main objective was to assess sediment production across the catchment and sediment supply to the main reservoir. Materials and methods: The Barasona reservoir catchment (1,509 km) is located in the Central Spanish Pyrenees, in the Ebro Basin. This catchment was selected for the case study given the regional significance of the Barasona reservoir and its siltation problems. The catchment has a mountain climate, with strong altitudinal and north-south gradients. The catchment is characterized by heterogeneous topography and lithology, resulting in a varied mosaic of slopes, soil types, and land covers. The Jueu karst system and two small headwater reservoirs were parameterized and calibrated in the model. The SWAT model sediment calibration for the catchment was based on a prior monthly hydrologic calibration, and the model validation was based on the sediment depositional history of the Barasona reservoir. Results and discussion: The simulation period (2003-2006) and the validation period (1993-2002) produced average sediment yields to the reservoir of 643,000 and 575,000 t year, respectively. Large variations in sediment production were found between the subcatchments in the Barasona catchment due to differences in rock outcrops, land cover, and slope gradient. Sediment loss in the Jueu karst system was 15,500 t and the two small headwater reservoirs retained 31,200 and 50,300 t. Sediment production in relation to precipitation showed high temporal variability, with specific sediment yields to the Barasona reservoir ranging from 2.74 to 8.25 t ha year. Strong lithological control was observed for sediment production in the subcatchments. The main sediment sources were located in the badlands developed on marls in the middle part of the catchment (internal depressions). Conclusions: The proposed model has proved useful for identifying areas where significant erosion processes take place in large alpine-prealpine catchments at a regional level and also for assessing discharge losses by the karst system and the sedimentary role of the small reservoirs. The information obtained through this research will be of interest in assessing the spatial distribution of sediment sources and areas of high sediment yield, which will be useful to establish criteria for remediation strategies. [ABSTRACT FROM AUTHOR]

The 'dehesa' is a traditional Iberian agrosilvopastoral ecosystem characterized by the presence of old scattered trees that are considered as 'keystone-structures', which favor the presence of a wide range of biodiversity. We show the high diversity of saproxylic beetles and syrphids (Diptera) in this ecosystem, including red-listed species. We analyzed whether saproxylic species distribution in the 'dehesa' was affected by tree density per hectare, dominant tree species or vegetation coverage. Species diversity did not correlate with tree density; however, it was affected by tree species and shrub coverage but in a different way for each taxon. The highest beetle diversity was linked to Quercus pyrenaica, the most managed tree species, with eight indicator species. In contrast, Q. rotundifolia hosted more species of saproxylic syrphids. Regarding vegetation coverage, shrub coverage was the only variable that affected insect richness, again in a different way for both taxa. In contrast, beetle species composition was only affected by dominant tree species whereas syrphid species composition was not affected by tree species or shrub coverage. We concluded that the high diversity of saproxylic insects in the 'dehesa' is related to its long history of agrosilvopastoral management, which has generated landscape heterogeneity and preserved old mature trees. However, the richness and composition of different taxa of insects respond in different ways to tree species and vegetation coverage. Consequently, conservation strategies should try to maintain traditional management, and different saproxylic taxa should be used to monitor the effect of management on saproxylic diversity. [ABSTRACT FROM AUTHOR]

We evaluate for the first time the effect of Wolbachia infection, involving two different supergroups, on the structure and dynamics of the hybrid zone between two subspecies of Chorthippus parallelus (Orthoptera) in the Pyrenees. Wolbachia infection showed no effects on female fecundity or a slight increment in females infected by F supergroup, although in the last case it has to be well established. Cytoplasmic incompatibility ( CI) is confirmed in crosses carried out in the field between individuals from a natural hybrid population. This CI, registered as the relative reduction in embryo production ( sh), was of sh = 0.355 and sh = 0.286 in unidirectional crosses involving B and F supergroups, respectively. CI also occurred in bidirectional crosses ( sh = 0.147) but with a weaker intensity. The transmission rates of the two Wolbachia strains (B and F) were estimated by the optimization of a theoretical model to reach the infection frequencies observed in certain population. To fit this scenario, both supergroups should present transmission rates close to 1. Further, we have simulated the infection dynamics, and hence, the capacity of Wolbachia to structure the population of the host insects and to affect to reproduction and genetic introgression in the hybrid zone. This represents a first example of the influence of Wolbachia in an insect natural hybrid zone. [ABSTRACT FROM AUTHOR]

Shrubs are important microsites that facilitate seedling performance in abiotically stressed environments. However, shrub facilitation might work differently in ecosystems with high biotic stress (e.g., ungulate-dominated environments). We wonder whether ungulates through their preferences for different shrubs affect the facilitation process of seedlings, and whether this process remains consistent across different levels of abiotic stress. We study seedling performance (survival and growth) of a Mediterranean oak ( Quercus pyrenaica) in three microsites (open, preferred and non-preferred shrubs by ungulates) for two contrasting climatic environments and throughout a complete growing season (increasing abiotic stress). Overall, there was a positive effect of shrubs in seedling survival. We found a microsite effect on seedling growth but this effect differed depending on the abiotic environment, with seedlings growing better in open microsites in the less stressful site. The larger abiotic context (climate) played an important role in determining which microsite is the most favorable for seedling growth but not necessarily for the eventual survival of seedlings. Wild ungulates started to damage seedlings early in the growing season, whereas abiotic stress (desiccation) affected mostly those plants that were not previously attacked by animals, showing the hierarchical effect (earlier and longer effect) of the biotic over the abiotic mortality agents. Non-preferred shrubs worked better as nurse shrubs only under high ungulate pressure. From the abiotic perspective, preferred and non-preferred shrubs did not apparently differ in the facilitation effect. Importantly, we found a greater facilitative effect of shrubs on the survival than on the growth of seedlings. [ABSTRACT FROM AUTHOR]

Forests modify their productivity, composition, and distribution in response to global change. We studied the radial growth trends of the Western Mediterranean oak Quercus pyrenaica over the last two centuries to analyze whether trees exhibited instability in productivity in response to climatic changes. Trees were sampled to build annual growth chronologies following climatic gradients of increasing moisture availability and decreasing temperature with altitude and latitude. The species' response to climate showed high variability linked to local climatic conditions. The strength in the positive response of trees to moisture availability was inversely related to precipitation (that is, enhanced by higher water stress) whereas high temperature in the growing season was positive for tree-growth only at cold sites. The oldest ages of trees expanded back to the late 1500 s. These old-growth trees were located at the coldest sites and exhibited a long-term increase in productivity starting 150 years ago which could express a dominant positive effect of warming temperatures since the mid 1800 s at cold-humid sites. Conversely, trees at dry sites exhibited negative growth trends. Particularly low elevation stands located at latitudes below 40° displayed enhanced growth constraints with the increase in water stress around 1970, which suggests vulnerability of Quercus pyrenaica at the sampled altitudinal dry edge. The response of trees to future changes in climate should be monitored, particularly in threatened transitional zones. [ABSTRACT FROM AUTHOR]

Emissions of trace gases (carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbons (THC)), and volatile organic compounds (VOCs) from combustion of European beech, Pyrenean oak and black poplar in a domestic woodstove and fireplace were studied. These woods are widely used as biofuel in residential combustion in Southern and mid-European countries. VOCs in the flue gases were collected in Tedlar bags, concentrated in sorbent tubes and analysed by thermal desorption-gas chromatography–flame ionisation detection (GC–FID). CO2 emissions ranged from 1415 ± 136 to 1879 ± 29 g kg−1 (dry basis). The highest emission factors for CO and THC, 115.8 ± 11.7 and 95.6 24.7 ± 6.3 g kg−1 (dry basis), respectively, were obtained during the combustion of black poplar in the fireplace. European beech presented the lowest CO and THC emission factors for both burning appliances. Significant differences in emissions of VOCs were observed among wood species burnt and combustion devices. In general the highest emission factors were obtained from the combustion of Pyrenean oak in the woodstove. Among the VOCs identified, benzene and related compounds were always the most abundant group, followed by oxygenated compounds and aliphatic hydrocarbons. The amount and the composition of emitted VOCs were strongly affected by the wood composition, the type of burning device and operating conditions. Emission data obtained in this work are useful for modelling the impact of residential wood combustion on air quality and tropospheric ozone formation. [ABSTRACT FROM AUTHOR]

Recent land use changes entailed the abandonment of traditional forest practices, which genetic and ecological sustainability should be evaluated in the frame of current socioeconomic and ecological changes. The present study aimed to assess the conservation value of Quercus pyrenaica Willd. in stands subjected to two traditional rural practices, one specific (coppicing) and the other generic (maintenance of open parklands), and their effects on genetic diversity and clonal structure in this singular root sprouting oak at the southern limit of its distribution. Genetic diversity measures of seven nuclear simple sequence repeat markers were compared, and Hardy-Weinberg disequilibria were tested to be originated from recent population demography. Results showed that, regardless of forest structure, the degree of clonality was very similar (∼60 %), being allele and lineage density proportional to stem density. Nevertheless, evenness of clonal distribution was higher in coppice, suggesting more homogeneous management than in open woodland. Contrary to previous beliefs, coppice stands do not involve genetic diversity losses; rather, the process of forest conversion into open woodland leads to the removal of numerous genetic lineages and low frequency alleles. The ancient presence of Q. pyrenaica in the region, which constituted quaternary glacial refuge, may contribute to its high genetic diversity. Historical vicissitudes in this anthropogenic deforested territory remark its resilient character; based on a specific fire pre-adaptive trait, continued coppicing fostered the preservation of its natural genetic diversity. This study evidences the importance of the integration of molecular and historical approximations to assess the genetic and conservation status of a secularly profited woody species. [ABSTRACT FROM AUTHOR]

A study on the phenolic composition of Portuguese and Spanish Castanea sativa and Quercus pyrenaica woods used in cooperage has been carried out with the aim of looking for an extra value for the wood residues generated in cooperage industries. Results showed that both species are an important source of valuable phenolic compounds, although differences in the phenolic content were found. Chestnut samples showed the highest concentration of total phenolic compounds, being especially rich in vescalagin, gallic acid, vanillic aldehyde and syringaldehyde. The geographical origin was another parameter to take into account. Portuguese chestnut samples showed higher amounts of phenolic compounds than the Spanish samples, with vescalagin, gallic acid, vanillic acid and syringaldehyde being the most important features. As a consequence, the residues generated in the cooperage industry from chestnut and Q. pyrenaica heartwood seem to be an important source of valuable phenolic compounds, particularly those from Portuguese chestnuts. [ABSTRACT FROM AUTHOR]

The identification and quantification of the relative importance of reproductive isolating barriers is of fundamental importance to understand species maintenance in the face of interspecific gene flow between hybridising species. Yet, such assessments require extensive experimental fertilisations that are particularly difficult when dealing with more than two hybridising and long-generation-time species such as oaks. Here, we quantify the relative contribution of four postmating reproductive isolating barriers consisting of two prezygotic barriers (gametic incompatibility, conspecific pollen precedence) and two postzygotic barriers (germination rate, early survival) from extensively controlled pollinations between four oak species ( Quercus robur, Quercus petraea, Quercus pubescens and Quercus pyrenaica) that have been shown to frequently hybridise in natural populations. We found high variation in the strength of total reproductive isolation between species, ranging from total reproductive isolation to advantage toward hybrid formation. As previously found, Q. robur pollen was unable to fertilise Q. petraea due to a strong reproductive isolating mechanism. On the contrary, Q. pubescens pollen was more efficient at fertilising Q. petraea than conspecific pollen. Overall, prezygotic barriers contribute far more than postzygotic barriers to isolate species reproductively, suggesting a role for reinforcement in the development of prezygotic barriers. Conspecific pollen precedence reduced hybrid formation when pollen competition was allowed; however, presence of conspecific pollen did not totally prevent hybridization. Our results suggest that pollen competition depends on multiple ecological and environmental parameters, including species local abundance, and that it may be of uppermost importance to understand interspecific gene flow among natural multispecies populations. [ABSTRACT FROM AUTHOR]

Abstract: Quercus pyrenaica Willd. had been historically subjected to intense coppice management in order to supply firewood, charcoal and cattle forage. Due to the emergence of new energy sources and rural exodus, more than 1,200,000 hectares of coppice stands in Spain have been abandoned since 1970. Stand degradation, stem top drying, low production, scarce acorn yield and absence of sexual regeneration are major problems of these coppices. The need to establish new uses by conversion to high forest has been widely recognized and several attempts by thinning have been tested. We suggest that through a shift in the scale of species knowledge, from stand to clonal individual level, we can achieve a better understanding of Q. pyrenaica dynamics for the purpose of applying more effective silvicultural methods. Our objective in this study was to evaluate the effect of individual stool (clonal clump) characteristics influencing stem growth. We performed genetic analyses to assess clonal membership in a one-hectare plot, and 145 stems belonging to 15 different stools were sampled to model individual stem section growth, considering both stem and clonal stool variables. Principal component and cluster analyses were performed to analyze variability among stools. Results revealed that initial stem diameter explained most of the variability in stem growth (). However, the inclusion of clonal stool variables and clonal membership as a qualitative variable improved every modeling performance criterion, reducing mean square error 11% and 25%, respectively. Stems belonging to large biomass stools (determined by large spatial extent, high number of stems within stool, and a high value of a stump root biomass indicator) had lower growth potential than those belonging to small biomass stools. Based on these results, we suggest that root aging (enlarged root biomass) leads to a root/shoot imbalance increase, which consumes, through root respiration, a great proportion of the resources supplied by photosynthesis, thus limiting stem growth. This work attempts to highlight the importance of multidisciplinary perspectives to successfully face management challenges in these forests. [Copyright &y& Elsevier]

Abstract: The degraded state, scattered distribution and substrate type of Quercus pyrenaica forests in eastern Spain make them a subject of particular interest, as well as a priority for conservation efforts. An extension of Dufrêne and Legendre''s indicator value (IndVal) analysis was applied to one hundred relevés. This extension of the IndVal method allowed us, by considering the preference of species for combinations of relevé groups, to obtain those species that represent local, but also regional, characteristics (as a new practical use). Our objective was to identify the species that best indicate the main ecological features of these broad-leaved oak forests. The usefulness of our analysis was evidenced at two levels: local indicator species, showing the characteristic species of individual sites and including the presence of endemics in the area; and indicator species of combinations of two or more sites, reflecting the affinities or relationships between these scattered forests. Most singular forests showed a higher number of local indicator species. The indicator species of each site combination represent the main ecological traits shared by these groups – such as proximity to the coast, land uses or postglacial migration pathways – thereby defining their relationships. Indicator value analysis with site group combinations (Multipatt function) proved to be a useful tool for the identification of different species that could serve both to determine the local forest conservation status and aid in its preservation, as well as contributing to an understanding of the life history of larger territories. [Copyright &y& Elsevier]

Abstract: Biomass as an energy source has a lot of advantages over fossil residues, but it presents an important drawback: in local environments, such as homes, people are exposed to some harmful gases evolved during the biomass degradation process. Thus, many efforts have been made in order to dismiss these pollutants, being the blending with less pollutant biomass materials (that is, dilution), the optimization of the energy obtaining process and the use of catalysts and adsorbents the most popular ways to achieve this goal. The aim of this research was to assess the effectiveness of dilution over grape pomace, a quite abundant residue in Extremadura (Spain), blending it with Pyrenean oak. During the combustion of these blends, some parameters were measured by a coupled TG-MS technique, which allowed us to obtain much information about kinetics and evolved gases emissions. It is shown how the dilution effect affects both the amount of evolved gases (reducing them) and the combustion mechanism. [Copyright &y& Elsevier]

Abstract: As a result of agroindustrial activities in southwestern Europe, a great amount of residues are generated; among them, olive pomace stands out as one of the most abundant. One interesting alternative to increase its potential as biofuel can be its densification. However, in order to achieve high quality pellets, it is necessary to blend this material with other feedstocks. In this work, the properties of blends of pelletized residues from olive pomace and pyrenean oak were analyzed with a view to find the best option. In order to compare the characteristics of the obtained pellets, such as moisture content, mechanical durability, ash content and calorific value, these parameters were determined according to the Technical Specifications for Solid Biofuels CEN/TS. Moreover, the pellets produced were subjected to a combustion test in a pellet stove to analyze the emissions associated to each sample. The results show that not all residues pelletize satisfactorily, which is due to the different conditions of the precursors. Adding pyrenean oak residues to the olive pomace samples guarantees a more effective compression of the pellet, improving its manipulation and transport, without significantly modifying its thermal properties. Concerning the pellet combustion, emissions are slightly worse with olive pomace pellet, concluding that it is not recommendable to use blends with more than 50% of this product. [Copyright &y& Elsevier]

Context: Information about variations in basic density (BD) and carbon content (%C) along tree stems is key to assessing forest carbon sinks. Aims: The aim of the study was to determine any differences in %C and BD between different woody tissues (bark, sapwood and heartwood) in two widespread European oak species ( Quercus pyrenaica and Quercus petraea). Methods: Twenty trees were felled in northern Spain, and 317 discs cut from the trees were dried and analysed to determine %C and BD. Results: There were significant differences in %C between bark, heartwood and sapwood, and between species. There were also significant differences in BD between the tissues (heartwood > sapwood > bark), and the BD was higher in Q. petraea than in Q. pyrenaica. Both %C and BD varied along the stem. Conclusion: More accurate estimates of carbon contents were obtained by using specific values for different heights and anatomical parts, than by using single values. [ABSTRACT FROM AUTHOR]