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Good knowledge of the factors that influence cork quality and the health of forests is essential when making decisions regarding the management of productive cork oak forests. The quality of cork planks depends on: plank thickness, plank porosity and the presence of anomalies. So far, no studies have evaluated cork quality based on cork anomalies, partly due to the difficulty of obtaining adequate data. In 1985, it was developed the first Cork Quality Field Assessment Plan (CQFAP) to provide information about the quality of harvested cork by collecting data of very high quality. This work analyzes the anomalies present in 2049 cork sampling units collected from ten stands under the CQFAP for the period 1986–2012 in three consecutive cork stripping cycles. Data on diseases, pests and stripping damages are also analyzed in the 654 trees where cork sampling units were collected in the third stripping cycle. Additionally, mean monthly temperature and precipitation values for the 35 years covering the three stripping periods were calculated. A progressive deterioration of cork quality was observed in the sampled cork oak stands. It was found a positive relationship between cork thickness and temperature indicating that the cork growing period could be extended when temperatures are moderate. Sampled cork oaks were more affected by Cerambycidae attacks and Coraebus undatus indicating their prevalent nature. The presence of Coraebus undatus were higher in stands with good health status. The studied diseases were Biscogniauxia mediterranea, Phytophthora sp. and fungi of the family Botryosphaeriaceae, finding a not previously reported correlation between the presence of Crematogaster scutellaris and the three studied diseases. Stripping damages increase with smaller cork thickness but climate is not a decisive factor for a proper stripping. Although having room for improvement, the CQFAP is proving to be an effective tool for assessing the quality of cork, the health status

Cork value is determined mainly by its thickness at the moment of debarking but is also affected by the presence of any discontinuities related to porosity characteristics and/or the presence of anomalies in the cork plank. Cork quality is closely related to the final price of the raw material, so inventories conducted prior to the cork debarking are aimed at identifying the characteristics of the cork and therefore its potential price. Besides information from these cork inventories, forest managers also need a reliable prediction of the final cork thickness to help them determine the most profitable moment to harvest. In this work, a three-level nonlinear mixed effects cork growth model was developed for Spanish cork oak forests using 1027 cork samples taken in nine regions of provenance into which Spain is divided for identification of forest reproductive material. The fitting step revealed that the region and the stand level explained much less variability than the tree level in the three-level mixed-effects models. Therefore, subject–specific predictions were obtained with the joint use of region-, stand-and tree-level random effects. The subject–specific predictions were compared with three alternative prediction options when no additional measurements are available. The precision of predictions with calibrated mixed-effects model using region-, stand-, and tree-level random effects was 0.1 mm when taking one additional measurement at any time during the rotation period. The developed model is more precise and has a wider range of application than the previous model, being suitable for predicting accumulated cork thickness in more than 90% of the cork oak distribution area in Spain. However, it should only be applied to make predictions within a given cork rotation period and not to simulate cork growth over potential successive cork rotations. In the future, it would be necessary to develop an annual cork growth model which includes site, stand and tree varia

The aim of this study was to develop applications of near infrared spectroscopy (NIRS) to detect certain anomalies in cork used in the manufacture of stoppers for wine bottling. 326 spectra of cork planks were used in a qualitative analysis to evaluate the feasibility of NIRS to discriminate between pure cork, yellow stain and lignified cork. Classification and validation errors varied between 0 % and 11.4 %. In addition, 360 spectra of cork granulate were used in a quantitative analysis to determine the percentage of yellow stain and corkback. A root mean standard error of cross validation (RMSECV) of 1.50 % was obtained for yellow stain percentage (R² = 99.62 %). For corkback percentage RMSECV was 2.96 % (R2 = 98.53 %). These results show that NIRS technology has potential, alongside traditional methods, to determine the quality of cork used to manufacture stoppers.

The proportion of planted forests in the Mediterranean Basin is one of the largest in the world. These plantations are dominated by pine species and present a series of characteristics such as low elevation, high competition or small tree size that make them more vulnerable to droughts. However, quantitative assessments of their post-drought growth resilience in accordance with species, site factors and tree characteristics are lacking. In this study we sampled 164 trees at four forest sites located in the drought-prone Sierra Nevada, southeastern Spain. We compared growth responsiveness to drought in rear-edge planted vs. relic natural Scots pine (Pinus sylvestris) and coexisting Pyrenean oak (Quercus pyrenaica) stands. Our objective was to characterize and compare the different growth responses to drought between species and sites and the effect of the main physiographic factors (altitude, aspect, and slope) on these responses since the influence of these factors on post-drought resistance and resilience has received little attention to date. Our results reveal that the planted pine sites with the lowest mean growth rates displayed greater resistance during drought, and that higher altitude was associated with improved resistance and/or resilience for all species and sites. Natural pine and Pyrenean oak stands were better adapted to the dry climatic conditions of the Mediterranean region where the study was undertaken, displaying greater resistance and/or resilience and lower influence of drought on growth in comparison to stands of planted pines. These results suggest that promoting the conservation of high-elevation pine plantations and enhancing the regeneration of natural pine and oak may improve the resistance and resilience of these drought-prone forest ecosystems.

The role of climatic extremes on forest dynamics is still not fully understood. This is the case for droughts in temperate forests where growth of tree species is more driven by tree-to-tree competition than by climate. In this study we examine whether droughts shape growth trends and forest dynamics in a temperate forest of beech, oak and birch located in the “Picos de Europa” National Park in northern Spain. We used a dendroecological approach to quantify climate-growth associations and to evaluate growth resilience after droughts. We detected growth releases and quantified the increase in the number of trees established following each drought. Beech was the dominant tree species. Tree growth was only weakly related to climate variables in the three species studied. Oak was more resistant to drought than the other two species in terms of growth, with beech displaying higher vulnerability to drought. A significant association is displayed by all three species among droughts, growth releases and tree establishment pulses. After 1923 and following the dry 1940s, beech presented a peak of growth releases, whereas growth releases in oak and birch were concentrated in the 1960s and 1990s, respectively. Drought-induced growth releases probably reflect gap formation, these gaps being filled by recruitment of the three species.

Over recent decades, forest management in Europe has increasingly moved towards the emulation of natural dynamics. Natural dynamics in beech-oak forests leads to the formation of monospecific beech stands, the oak usually being excluded or restricted to sites with poor growing conditions. However, beech is more vulnerable than oak to drought and high temperatures. In this study, we examine whether climate change could attenuate the dominance of beech and improve the competitive capacity of oak in an old-growth temperate forest located in the “Picos de Europa” National Park, northern Spain. We used a dendroecological approach to reconstruct the competitive capacity of beech and oak and developed a projection for the 21st century based on forecasted climate conditions under three different emission scenarios. Beech is the dominant tree species in the studied forest, where the disturbance regime has favored the replacement of oak by beech. In general oaks are older than beeches and most of the small trees are beeches. Our results show that this substitution process may weaken due to the vulnerability of beech to warmer and drier conditions. Climate change will benefit oak growth over beech over the course of the 21st century, as was observed in the late 20th century. However, the natural gap dynamic benefits beech due to its greater shade-tolerance. Therefore, if the resilience of the ecosystem is to be increased, management strategies favoring oak regeneration are necessary given the better adaptation of oak to climate change.

The data in this paper are related to the research article entitled “Assessing the percentage of cork that a stopper should have from a mechanical perspective” (González and Terrazas, 2018). This data article contains data on the mechanical properties of different types of wine stoppers: 18 types of micro-agglomerated stoppers, three types of natural stoppers, and one type of co-extruded synthetic closure. Mechanical properties were evaluated with different analysis: Compression test for the maximum radial compression force, the young’s moduli and the diameter recovery, relaxation test for the relaxation force and the extraction test for the displacement force.

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.

The ability of trees to grow and survive during periods of water scarcity is determined by the water use strategy of each individual. In this study we evaluated how water use strategies can influence the establishment phase of three coexisting species in forests where harvesting intensity and silvicultural interventions have been reduced over recent decades. We conducted a greenhouse experiment between February and July, applying two watering regimes (moist and dry) to current year seedlings in 1.5 m high pots to avoid root growth constraint. At the same time, the physiological performance of seedlings of the same species was monitored under natural conditions in the field over a period of decreasing soil moisture. Our results indicated that resprouter species allocated more than 40% of total biomass to roots whereas the non-resprouter P. pinea allocated only 26%. The plasticity index for the root traits was highest in Q. ilex, in which the highest stomatal conductance was measured in early summer. The slowest growth and lowest root plasticity, root hydraulic conductance and leaf water potential were measured in J. oxycedrus. The three species exhibited a positive carbon balance under low water availability. Coexisting species displayed a continuum in the water use strategies adopted. P. pinea would be the least competitive species under the forecasted increasing drought conditions in contrast to J. oxycedrus, which presents traits more suited to coping with droughts. © 2016 Elsevier B.V.

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. © 2016.

The sustainable production of lignocellulosic biomass in Short Rotation Coppice (SRC) in the context of bioeconomic development in Europe demands an ever greater understanding of the plant material. Different species and, in some cases, different genotypes (Populus deltoides 'Baldo', Populus x canadensis 'Orion', 'Oudenberg', 'Ballottino' and 'I-214'; Robinia pseudoacacia 'Nyirsegi', Salix matsudana x Salix spp. 'Levante' and Platanus x hispanica 'Girona') were tested at four contrasting Mediterranean locations to determine the biomass yield after three years. Besides production, genotypic stability is a key factor in furthering our understanding of the plant material, with important implications for the management of plantations as well as for breeding. To study this factor, several stability models were compared (additive mixed model, Shukla's stability variance model, Finlay-Wilkinson and Eberhart-Russell models) and differences in the response capacity of the material were evaluated in the different environments. This evaluation of genotypic stability, based on the measurement of variances, was complemented by an analysis of the mean genotypic value and the variability in genotype productivity. Intrinsic water use efficiency was also evaluated as it is an important trait of plant material destined for use in Mediterranean conditions. S. matsudana x Salix spp. 'Levante' exhibited the highest production and showed an intermediate reactivity (stability) as well as high intrinsic water use efficiency under the conditions in which it was tested. P. x canadensis 'Orion' also displayed a good overall performance and was highly sensitive to improving environmental conditions. Conversely, R. pseudoacacia and P. x hispanica presented yields well below the average as well as low responsiveness to improved environmental conditions. Our findings will contribute to a better understanding of plant material, enabling improved recommendations for plantations the Mediterranean ar

Forests play an important role in the mitigation of global warming, acting as carbon sinks. However, the effects of forest management on the carbon pools over the rotation period in Mediterranean areas are scarcely understood. The objective of this work is to assess the way in which two alternative management systems; one more intensive and the other more moderate (with less severe harvesting and more spread over time) affect the carbon stocks in the living tree biomass, coarse woody debris, forest floor and mineral soil in Mediterranean forests. For this purpose, two chronosequences were established covering the whole rotation period in two Pinus sylvestris L. forests. We conducted four forest inventories over a period of 15years, measuring the diameter and the height of all the trees higher than 1.3m in order to calculate the carbon stored in the living parts of the tree. Soil pits were excavated and we collected soil samples to estimate the soil organic carbon. We found that the temporal trends for living tree biomass were similar in both forests. However, the total living tree carbon stored at the end of the rotation period was greater in the forest with the longer rotation period and lighter thinning regime (345.5Mgha-1 of carbon) than in the intensively-managed forest (223.8Mgha-1 of carbon). On average, more carbon was found to be stored in the forest floor under the more intensive management system, whereas more carbon was present in the first 20cm of mineral soil under the moderate management system. Moreover, in each forest, the carbon stocks of the forest floor and in the uppermost cm of the soil remained constant over the rotation period. Therefore, management systems with longer rotation periods and moderate harvesting intensities are recommended to increase carbon fixation in Mediterranean forests. © 2015 Elsevier B.V.

A diameter increment model for cork oak was developed based on measurements taken twice at 72 permanent plots in cork oak forest in southern Spain. Empirical and semi-empirical models were compared. In the empirical model diameter increment was expressed as a function of tree and stand characteristics such as diameter, density and site index. In the semi-empirical model, the diameter increment was expressed as a function of the potential diameter growth multiplied by a modifier, applying a correction factor to the potential growth to take into account the variability associated with different climatic conditions in the years when the plots were measured. The first step was to select the best model for each one of these methods, considering both statistical properties and predictive ability. The two chosen models were then compared through the characterisation of the model error. Both models behaved similarly explained about the same amount of variation in diameter increment and provided realistic diameter increment predictions. © 2006 Elsevier B.V. All rights reserved.