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Climate change represents an important challenge for forest management and the silviculture of stands and it is known that climate change will have complex effects on cork oak forest ecosystems. North Africa and the Mediterranean basin are especially vulnerable to climate change. Under the effect of climate change, cork oak will disappear from a large area in the future, and the rest will migrate to higher altitudes and latitudes. This study aimed to evaluate the effect of climate change on the spatial distribution of Quercus suber L. and cork production in the Mediterranean area, and the risk of its exclusion by the Aleppo pine (Pinus halepensis Mill.) expansion. The literature review showed that up to 40% of current environmentally suitable areas for cork oak may be lost by 2070, mainly in northern Africa and the southern Iberian Peninsula. Temperature directly influences atmospheric evaporative demand and should affect cork productivity. Precipitation is the main factor that positively influences cork growth and several authors have confirmed the negative effect of drought on this growth. Currently, cork oak habitats are colonized in several places mainly by the Aleppo pine. Under climate change, Aleppo pine is projected to occupy higher altitude sites and several authors have predicted that current and future global warming will have a positive influence on Aleppo pine growth in wet sites. In the future and under climate change, there is a strong possibility that the Aleppo pine will colonize cork oak habitat. Finally, we proposed management practices to protect cork oak against climate change and Aleppo pine expansion.

In temperate forests, the roots of various tree species are colonized by ectomycorrhizal fungi, which have a key role in the nitrogen nutrition of their hosts. However, not much is known about the molecular mechanisms related to nitrogen metabolism in ectomycorrhizal plants. This study aimed to evaluate the nitrogen metabolic response of oak plants when inoculated with the ectomycorrhizal fungus Pisolithus tinctorius. The expression of candidate genes encoding proteins involved in nitrogen uptake and assimilation was investigated in ectomycorrhizal roots. We found that three oak ammonium transporters were over-expressed in root tissues after inoculation, while the expression of amino acid transporters was not modified, suggesting that inorganic nitrogen is the main form of nitrogen transferred by the symbiotic fungus into the roots of the host plant. Analysis by heterologous complementation of a yeast mutant defective in ammonium uptake and GFP subcellular protein localization clearly confirmed that two of these genes encode functional ammonium transporters. Structural similarities between the proteins encoded by these ectomycorrhizal upregulated ammonium transporters, and a well-characterized ammonium transporter from E. coli, suggest a similar transport mechanism, involving deprotonation of NH4+, followed by diffusion of uncharged NH3 into the cytosol. This view is supported by the lack of induction of NH4+ detoxifying mechanisms, such as the GS/GOGAT pathway, in the oak mycorrhizal roots.

Cork Oak Woodlands on the Edge is an important book for anyone interested in the future of cork oak woodlands, or in the management of cultural landscapes and their associated land-use systems. In a changing world full of risks and surprises, it represents an excellent example of a multidisciplinary and holistic approach to studying, managing, and restoring an ecosystem, and will serve as a guide for other studies of this kind.

This comprehensive book describes cork as a natural product, as an industrial raw-materials, and as a wine bottle closure. From its formation in the outer bark of the cork oak tree to the properties that are of relevance to its use, cork is presented and explained including its physical and mechanical properties.The industrial processing of cork from post-harvest procedures to the production of cork agglomerates and composites is described.Intended as a reference book, this is the ideal compilation of scientific knowledge on state-of-the-art cork production and use Key Features:*Presents comprehensive coverage from cork formation to post-harvest procedures*Explains the physical properties, mechanical properties and quality of cork*Addresses topics of interest for those in food science, agriculture and forestry

Although forest areas have been growing in Europe, some forest types have been declining regionally. Since the 1980 s, there have been reports of defoliation and mortality in evergreen oak woodlands of the Iberian Peninsula. However, long-term and large-scale trends of Iberian oak decline are still poorly understood. We quantified trends in canopy cover for cork oak (Quercus suber) and holm oak (Q. rotundifolia) woodlands in mainland Portugal for a 50 year period (1965 to 2015). We considered loss of canopy cover a proxy of forest degradation and asked how it changed over time, in association with human activity and climate. Between 1965 and 2015, both cork oak and holm oak canopy cover showed declining trends (57.9% and 71.1% of sampling points, respectively). Canopy cover dynamics, however, differed across time. Between 1965 and 1990, canopy cover gains (over 35% of sampling points) prevailed over losses (under 20%), with larger differences for cork oak than holm oak. Between 1990 and 2015, canopy cover losses (over 70% of sampling points) were much higher than gains (under 9%). Oak canopy cover decrease was associated with flatter areas (usually having more intensive land use) for both oak species, higher cattle numbers (holm oak only) and higher mean temperature (cork oak only). Contrastingly, loss of holm oak canopy cover seems to have occurred in less hot and dry regions that enable more intensive land uses. Active restoration is urgently needed to reverse the current decline in canopy cover in Mediterranean evergreen oak woodlands.

This paper investigates the reliability of free and open-source algorithms used in the geographical object-based image classification (GEOBIA) of very high resolution (VHR) imagery surveyed by unmanned aerial vehicles (UAVs). UAV surveys were carried out in a cork oak woodland located in central Portugal at two different periods of the year (spring and summer). Segmentation and classification algorithms were implemented in the Orfeo ToolBox (OTB) configured in the QGIS environment for the GEOBIA process. Image segmentation was carried out using the Large-Scale Mean-Shift (LSMS) algorithm, while classification was performed by the means of two supervised classifiers, random forest (RF) and support vector machines (SVM), both of which are based on a machine learning approach. The original, informative content of the surveyed imagery, consisting of three radiometric bands (red, green, and NIR), was combined to obtain the normalized difference vegetation index (NDVI) and the digital surface model (DSM). The adopted methodology resulted in a classification with higher accuracy that is suitable for a structurally complex Mediterranean forest ecosystem such as cork oak woodlands, which are characterized by the presence of shrubs and herbs in the understory as well as tree shadows. To improve segmentation, which significantly affects the subsequent classification phase, several tests were performed using different values of the range radius and minimum region size parameters. Moreover, the consistent selection of training polygons proved to be critical to improving the results of both the RF and SVM classifiers. For both spring and summer imagery, the validation of the obtained results shows a very high accuracy level for both the SVM and RF classifiers, with kappa coefficient values ranging from 0.928 to 0.973 for RF and from 0.847 to 0.935 for SVM. Furthermore, the land cover class with the highest accuracy for both classifiers and for both flights was cork oak, which occupies the largest part of the study area. This study shows the reliability of fixed-wing UAV imagery for forest monitoring. The study also evidences the importance of planning UAV flights at solar noon to significantly reduce the shadows of trees in the obtained imagery, which is critical for classifying open forest ecosystems such as cork oak woodlands.

• Interaction effects of different stressors, such as extreme drought and plant invasion, can have detrimental effects on ecosystem functioning and recovery after drought. With ongoing climate change and increasing plant invasion, there is an urgent need to predict the short- and long-term interaction impacts of these stressors on ecosystems. • We established a combined precipitation exclusion and shrub invasion (Cistus ladanifer) experiment in a Mediterranean cork oak (Quercus suber) ecosystem with four treatments: (1) Q. suber control; (2) Q. suber with rain exclusion; (3) Q. suber invaded by shrubs; and (4) Q. suber with rain exclusion and shrub invasion. As key parameter, we continuously measured ecosystem water fluxes. • In an average precipitation year, the interaction effects of both stressors were neutral. However, the combination of imposed drought and shrub invasion led to amplifying interaction effects during an extreme drought by strongly reducing tree transpiration. Contrarily, the imposed drought reduced the competitiveness of the shrubs in the following recovery period, which buffered the negative effects of shrub invasion on Q. suber. • Our results demonstrate the highly dynamic and nonlinear effects of interacting stressors on ecosystems and urges for further investigations on biotic interactions in a context of climate change pressures.

Background Soil microbiomes are important to maintain soil processes in forests and confer protection to plants against abiotic and biotic stresses. These microbiomes can be affected by environmental changes. In this work, soil microbial communities from different cork oak Portuguese forests under different edaphoclimatic conditions were described by using a metabarcoding strategy targeting ITS2 and 16S barcodes. Results A total of 11,974 fungal and 12,010 bacterial amplicon sequence variants (ASVs) were obtained, revealing rich and diverse microbial communities associated with different cork oak forests. Bioclimate was described as the major factor influencing variability in these communities (or bioclimates/cork oak forest for fungal community), followed by boron and granulometry. Also, pH explained variation of fungal communities, while C:N ratio contributed to bacterial variation. Fungal and bacterial biomarker genera for specific bioclimates were described. Their co-occurrence network revealed the existence of a complex and delicate balance among microbial communities. Conclusions The findings revealed that bacterial communities are more likely to be affected by different edaphoclimatic conditions than fungal communities, also predicting a higher impact of climate change on bacterial communities. The integration of cork oak fungal and bacterial microbiota under different bioclimates could be further explored to provide information about useful interactions for increasing cork oak forest sustainability in a world subject to climate changes.

Cork oak woodlands are socio-ecosystems recognized as biodiversity hotspots, a fundamental economic source for companies and local communities as well as an identitarian landscape for residents and visitors. Cork oak woodlands, however, are facing tree mortality and lack of regeneration. Considering the oak decline scenario, we present Iberian cork oak montado/dehesa as a socio-ecosystem facing climate change, management transformations, local knowledge crisis and social uncertainty. We review montados/dehesas research through time and by different scholar perspectives. We defend that from an interdisciplinary and transdisciplinary perspective, including the experience and evidence observed in terrain, debate should be stimulated, and novel conceptual approaches may contribute to finding solutions. We argue that the confluence of ecology, genetics, anthropology and local knowledge can be explored to unveil the complexities and the challenges of these socio-ecosystems and contribute to prevent and mitigate threats to it. We propose a methodological approach built together with scientists, managers and workers, that can explore oak translocations, socio-ecological interactions models, knowledge transfer and other ways to overcome Iberian cork oak woodlands socio-environmental crisis.

Cork rings have been extensively used in dendroecological studies of the Mediterranean evergreen cork oak (Quercus suber L.). Through measurements of cork-ring width only, strong relationships have been found between cork-ring widths and climate parameters. To our knowledge, cork-ring density, which is an important cork quality attribute, has never been used in any dendroecological study to explore physiological responses of the cork oak to climate change. In this study, we measured cork-ring width and density over 50 years (1962–2013), corresponding to five consecutive cork harvests, and analyzed their inter-annual fluctuations in eight trees from two different sites, a wetter peneplain area (Benavente) and a drier mountainous area (Grândola). Our results revealed a statistically significant correlation between cork-ring width and density (p < 0.05) at both sites; however, it was negative (r =− 0.261) and relatively weaker at Benavente, and positive at Grândola (r = 0.410). Moreover, a direct relationship between cork density and spring–summer temperature was found only at Grândola. Here, cork growth sensitivity to inter-annual variability of precipitation and temperature in summer-autumn of the current growth year (p < 0.01) was the highest and, respectively, positive and negative. We conclude that in drier Mediterranean environments, summer drought stress might negatively affect both cork growth and density, by changing tree physiological processes involved in cork formation, resulting in narrower and denser cork rings. Considering scenarios of future climate change effects in Southern Europe, in particular the longer drought periods and rising temperatures, it seems that both cork yield and cork density will be affected, with implications on cork quality.